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The lithium‐ion batteries (LIBs) with high nickel cathode have high specific energy, but as the nickel content in the cathode active material increases, batteries are suffering from temperature limitations, unstable performance, and transition metal dissolution during long cycling. In this work, a functional electrolyte with P‐phenyl diisothiocyanate (PDITC) additive is developed to stabilize the performance of LiNi0.8Co0.1Mn0.1O2 (NCM811)/graphite LIBs over a wide temperature range. Compared to the batteries without the additive, the capacity retention of the batteries with PDITC‐containing electrolyte increases from 23 % to 74 % after 1400 cycles at 25 °C, and from 15 % to 85 % after 300 cycles at 45 °C. After being stored at 60 °C, the capacity retention rate and capacity recovery rate of the battery are also improved. In addition, the PDITC‐containing battery has a higher discharge capacity at −20 °C, and the capacity retention rate increases from 79 % to 90 % after 500 cycles at 0 °C. Both theoretical calculations and spectroscopic results demonstrate that PDITC is involved in constructing a dense interphase, inhibiting the decomposition of the electrolyte and reducing the interfacial impedance. The application of PDITC provides a new strategy to improve the wide‐temperature performance of the NCM811/graphite LIBs. [ABSTRACT FROM AUTHOR]

Black phosphorus–carbon (BP–C) composite is a potential high‐energy anode material for lithium‐ion batteries (LIBs); however, the local stress concentration that occurs during lithiation/delithiation cycling leads to poor cycling performance. Herein, an electrochemically inactive TiP nanocrystal is used to reconstruct the BP–C composite via ball milling to form a BP–TiP–C multiphase structure with excellent lithium storage performance. The TiP intermediate optimizes the TiP–BP interface and relieves the local stress of the BP–TiP–C composite, thereby enhancing the electron transfer, structural stability, and utilization of the active material. This BP–TiP–C composite exhibits a high coulombic efficiency of 99.85%, an enhanced cyclic stability of 557.6 mAh g−1 after 1000 cycles with a 72.5% capacity retention at 2.0 A g−1, and an excellent rate performance of 548.2 mAh g−1 at 10.0 A g−1. Thus, this study not only provides a high‐energy BP–TiP–C material, but also offers new ideas for material synthesis to advance the research on BP‐based LIBs. [ABSTRACT FROM AUTHOR]

Based on a strategy of stabilizing the LiMn2O4 (LMO) cathode interface, the high‐temperature cycling and storage performance of 18 650‐type LMO/graphite lithium‐ion batteries (LIBs) is effectively improved. The LMO cathode is prepared using lithium carboxymethyl cellulose (CMCLi)–polyacrylic acid/acrylate copolymer composite binder and nanoscale CaCO3 functional component (marked as binder C). Compared with the traditional oily binder, the dissolution of Mn2+ from LMO cathode into the electrolyte can effectively decrease, and the structure stability of LMO cathode can increase. The batteries exhibit retention capacity of 80.3% at 1 C after 600 cycles at room temperature and 76.7% at 1 C after 200 cycles at temperature of 45 °C. The high‐temperature storage performance is also improved and there are 81.1% and 73.5% residual capacities when the fully charged batteries are stored in 60 °C for 14 and 28 days. The enhanced performance is mainly attributed to the interfacial stability of LMO cathode due to the bonding ability of composite binders and the elimination of HF by CaCO3. These results reveal the application prospect of as‐developed aqueous binders and provide a way to improve the performance of LMO‐based LIBs through stable interface strategy. [ABSTRACT FROM AUTHOR]

Iron oxides are considered as potential anode materials for lithium‐ion batteries thanks to their high theoretical capacity, rich resources, and environmental friendliness. However, the rapid capacity decay and sluggish kinetics greatly limit their practical application. Herein, a simple surface fluorination strategy is developed to greatly improve the electrochemical properties of Fe3O4. The fluorinated layer can act as a protective film to stabilize the electrode/electrolyte interface, enhance the wettability of the electrode to shorten the Li+ diffusion pathway, and provide more active centers to facilitate charge storage. Consequently, the fabricated fluorinated Fe3O4 electrode demonstrates high specific capacity (1379 mAh g−1 at 0.5 A g−1 after 300 cycles) and impressive high‐rate performance (876, 802, and 456 mAh g−1 at 5, 10, and 20 A g−1, respectively, after 1000 cycles), which outperforms most of the Fe3O4‐based electrodes recorded so far. This material design strategy may open up a new way for the development of high‐performance anode materials for energy storage based on earth‐rich materials, and advance the understanding of the core role of electrode surfaces/interfaces in battery systems. [ABSTRACT FROM AUTHOR]

To overcome the shortcomings in the thermal stability and electrolyte wettability when a commercial polyethylene (PE) separator is used alone, a PE/glass fiber (GF)−Mg(OH)2/PE composite (PGMP) separator is developed, and the electrochemical and safety performance of lithium‐ion batteries is effectively enhanced. The PGMP separator is prepared by soaking a mixed dispersion solution of polyacrylate and Mg(OH)2 into the GF fabric substrate and subsequently bonding the PE microporous film on both substrate sides. Compared with the PE separator, PGMP separator exhibits enhanced mechanical strength (≥250 MPa), ionic conductivity, and electrolyte wettability. Furthermore, there is almost no shrinkage when this PGMP is annealed at 350 °C for 30 min. The nail penetration, impact, overcharge, and adiabatic rate calorimeter tests of LiNi0.5Co0.2Mn0.3O2/graphite pouch cell with a nominal capacity of 2500 mAh show that the PGMP separator effectively improves the safety performance. The thermal runaway temperature of the pouch cells is increased from about 120 to 146 °C, and the electrolyte wettability ability of the PGMP separator gives the cell a capacity retention of 85% after 500 cycles at 1.0 C. Combined with the advantages, it is indicated that this PGMP separator has great potential in commercial applications. [ABSTRACT FROM AUTHOR]

Water‐soluble polyacrylate copolymers are developed as green functional binders of graphite anode to improve the performance of lithium‐ion batteries (LIBs). Using five basic binders, it is demonstrated that the graphite plate with the alkanol acrylate crosslinker (type U20)‐acrylic acid/acrylate copolymer (type LA138) composite binder (marked as Binder B) exhibits larger adhesive force, higher compaction density, and better electrolyte adsorption capacity compared to other plates with aqueous binders. In particular, the electrochemical performance of the batteries with Binder B is enhanced both at room temperature and low temperature, and retention capacity of 82.8 % at 1 C and 25 °C after 930 cycles and 91.3 % at 0.5 C and 0 °C are obtained. In addition, the batteries with Binder B also exhibit enhanced safety and heat stability. The enhanced performance is attributed to the good chemical stability of polyacrylate copolymers and unique film‐forming properties. These results indicate that the graphite anode with aqueous Binder B has promising prospects for practical application, and it also provides a reference for solving the poor low‐temperature performance of graphite anodes. [ABSTRACT FROM AUTHOR]

The behaviors and mechanism for the different performance degradation trends of 18650 cylindrical lithium‐ion batteries (LIBs) with LiNi0.33Co0.33Mn0.33O2 cathodes under long‐term storage at a high temperature (HT) of 80 °C are investigated to gain insight on the safe use of LIBs. It is indicated that the direct current resistance (DCR) increases sharply within 240 h and then slows down gradually, whereas the open‐circuit voltage (OCV) and the recoverable capacity (RC) fading are relatively stable in the initial 240 h, but then speeds up from 240 h to 720 h. With the aid of analyses of the anode, cathode, and separator materials in batteries stored at 80 °C for 0 h, 240 h, 480 h, and 720 h, the mechanism of the performance degradation of batteries is elucidated. It is pointed out that the DCR rise is mainly caused by the anode materials peeling off from the copper foil, as is the subsequent interface resistance increase. The RC fading is attributed to the partial break of the cathode structure, owing to the dissolution of transition metal ions (Ni2+, Co3+, and Mn4+), and the dissolution becomes more severe as the time extends. In addition, the separator suffers a combination of stretching (machine direction), squeezing (anode side), oxidation (cathode side), and destruction, resulting in internal short circuit and sharp OCV drop, as well as the other potential safety risks of LIBs. These results are valuable to establish an accelerated testing method to evaluate batteries in a short time range to advance the safe use of LIBs under high‐temperature storage. [ABSTRACT FROM AUTHOR]

A positive‐temperature‐coefficient graphite anode as a thermal runaway firewall of LiCoO2/graphite lithium‐ion batteries (LIBs) is prepared by introducing thermally sensitive polymer microspheres (TSPMs) into the anode to improve battery safety under abusive conditions. The TSPMs are composed of an acrylonitrile and acrylate copolymer shell and a cyclopentane hydrocarbon core. Due to the thermally sensitive properties of TSPMs, the graphite anode swells under abusive conditions, and the electric connection of active materials and current collector can be cut off. Thus, the resistance of LIBs is increased to solve the thermal runaway and safety problems before the temperature of LIBs approaches explosion limit. The TSPMs with a size distribution of 4–20 μm and an initial foaming temperature of 95–110 °C exhibit excellent stability and foaming properties. Compared with the batteries without TSPMs, under abusive conditions including overcharge at 1 C/10 V, thermal shock from 20 to 130 °C, and external short circuit with a resistance of ≈80 mΩ, the batteries with TSPMs effectively mitigate thermal runaway. In addition, TSPMs do not show obvious influences on the conventional performances of LIBs, indicating that adding TSPMs into graphite anodes is a promising method to improve the safety of LIBs under abusive conditions. [ABSTRACT FROM AUTHOR]

Abstract: Charge‐discharge reaction mechanisms of sodium‐ion batteries under various condition are studied by using a three‐electrode setup of a pouch‐type sodium‐ion battery. The sodium‐ion battery is constructed by using cost‐effective ternary layered Na0.76Ni0.3Fe0.4Mn0.3O2 and commercial hard carbon as the cathode and anode materials, respectively, and 1.0 M NaPF6 in mixed carbonate solvent as the electrolyte. The electrochemical impedance spectroscopy (EIS) results and transmission electron microscopy (TEM) images show that an apparent solid‐electrolyte interphase (SEI) film is formed on anode material surface during the formation (pre‐charging) process, and the potentials for the SEI film formation of the solvents (ethylene carbonate and ethylene carbonate) and the additive (fluorinated ethylene carbonate) in the electrolyte are 2.04 and 2.79 V, respectively. The X‐ray diffraction (XRD) results demonstrate that, during charge, the crystal structure of cathode material changes significantly with the deintercalation of Na+. When the battery is charged to 5.0 V, the diffraction peak corresponding to the (002) plane disappears, as Na+ is further deintercalated, and the structure changes from the hexagonal phase to the monoclinic phase, causing the rapid degradation of the cycle performance. When the battery is overdischarged to 0 V, the EIS results and TEM images show that the SEI film is destroyed completely, and the cycle life performance is significantly deteriorated. [ABSTRACT FROM AUTHOR]

In this paper, the LiNi0.5Mn1.5O4 cathode materials of lithium-ion batteries are synthesized by a co-precipitation spray-drying and calcining process. The use of a spray-drying process to form particles, followed by a calcination treatment at the optimized temperature of 750 °C to produce spherical LiNi0.5Mn1.5O4 particles with a cubic crystal structure, a specific surface area of 60.1 m2 g−1, a tap density of 1.15 g mL−1, and a specific capacity of 132.9 mAh g−1 at 0.1 C. The carbon nanofragment (CNF) additives, introduced into the spheres during the co-precipitation spray-drying period, greatly enhance the rate performance and cycling stability of LiNi0.5Mn1.5O4. The sample with 1.0 wt.% CNF calcined at 750 °C exhibits a maximum capacity of 131.7 mAh g−1 at 0.5 C and a capacity retention of 98.9% after 100 cycles. In addition, compared to the LiNi0.5Mn1.5O4 material without CNF, the LiNi0.5Mn1.5O4 with CNF demonstrates a high-rate capacity retention that increases from 69.1% to 95.2% after 100 cycles at 10 C, indicating an excellent rate capability. The usage of CNF and the synthetic method provide a promising choice for the synthesis of a stabilized LiNi0.5Mn1.5O4 cathode material.Micro/nanostructured LiNi0.5Mn0.5O4 cathode materials with enhanced electrochemical performances for high voltage lithium-ion batteries are synthesized by a co-precipitation spray-drying and calcining routine and using carbon nanofragments (CNFs) as additive. [ABSTRACT FROM AUTHOR]

Organic electrode materials bring about new possibilities for the next generation green and sustainable lithium/sodium ion batteries (LIBs/SIBs) owing to their low cost, environmental benignity, renewability, flexibility, redox stability and structural diversity. However, electroactive organic compounds face many challenges in practical applications for LIBs/SIBs, such as high solubility in organic electrolytes, poor electronic conductivity, and low discharge potential as postive materials. Quinone organic materials are the most promising candidates as electrodes in LIBs/SIBs because of their high theoretical capacity, good reaction reversibility and high resource availability. While quinone electrode materials (QEMs) have so far received less attention in comparison with other organic electrode materials in secondary batteries. In this paper, an overview of the recent developments in the field of QEMs for LIBs/SIBs is provided, emphasizing on the modifications of the quinone compounds in solubility, electronic conductivity, and discharge plateaus. Finally, multifaceted modification approaches are analyzed, which can stimulate the practical applications of QEMs for LIBs/SIBs. [ABSTRACT FROM AUTHOR]

Zero-dimensional fluorescent carbon dots (CDs) that are used as a cell-imaging reagent are prepared by using a simple and effective route employing lithium-intercalated graphite from lithium-ion batteries as a carbon source. Under ultrasonic exfoliation, the interlayer space increases, while the layer distortion and remaining lithium of the lithium-intercalated graphite are utilized to disrupt the graphitic structure and produce the CD suspension. Subsequently, after concentration and purification, the obtained colloidal CD suspension has a fluorescent yield of up to 1.2% and is therefore comparable to the CDs prepared in previous reports. These CD products are water-soluble, nanosized (approximately 3.5 nm), and biocompatible and can easily enter into HeLa cells to act as a cell-imaging reagent without any further functionalization. In addition, these CDs do not impose toxicity against HeLa cells and have high photostability with low photobleaching and demonstrate potential applications for bio-labeling as well as solution state optoelectronics. [ABSTRACT FROM AUTHOR]

Abstract: A novel process for the recovery of metal values from a mixture of spent lithium-ion batteries (LIBs) and nickel-metal hydride (NiMH) batteries is presented. The iron shells of spent batteries were firstly dismantled using a specially designed dismantling machine. Then after the separation of aluminum substrate and electrolyte and the subsequent heating treatment, iron shells and metal-mesh substrate in the dismantled substances were effectively separated with a sieve. The powder residues including LiCoO2, copper oxides, metal nickel and hydrogen storage alloy and their oxides were dissolved using 3 mol L−1 H2SO4 +3 wt.% H2O2 at 70 °C, S/L=1:15 for 5 h. Finally, rare earths (RE) were precipitated as sodium RE double sulfate, copper was extracted as CuSO4 with 10 wt.% Acorga M5640 at pH=1.5–1.7, cobalt and nickel were extracted as their sulfates with 1 M Cyanex272 at pH=5.1–5.3 and 6.3–6.5, respectively. The experimental results showed that the recovery exceeded 94% for all metal values. [Copyright &y& Elsevier]

Three‐dimensional (3D) SiOx‐based membrane anodes with stabilized electrochemical performances for lithium‐ion batteries are fabricated ingeniously using high‐capacity SiOx active material. The flexible self‐supporting substances of poly(vinylidene fluoride) and carbon nanotubes are chosen as the supporting substances, which not only provide the 3D framework for the flexible self‐supporting membrane but also act as a protective layer with enhanced conductive pathway. In particular, this unique 3D structure can prevent the SiOx surface from contacting the electrolyte directly and can buffer the volumetric expansion of SiOx particles. This optimized membrane anode exhibits a high reversible specific capacity of 1436 mAh g−1 and a capacity retention rate of 88% after 100 cycles. In addition, it also demonstrates an outstanding rate performance, a specific capacity of 1245 mAh  g−1 is obtained at 1200 mA g−1, which is about 91% at 100 mA g−1. The stabilized performances of the as‐prepared membrane anodes indicate their promising prospects in the practical applications, and the fabricating method also provides a reference for the preparation of other flexible self‐supporting membrane electrodes. Poly(vinylidene fluoride) (PVDF) and carbon nanotubes (CNTs) provide a framework for the membrane, in which SiOx is stably embedded to prevent corrosion from direct contact with the electrolyte. Due to the excellent structural characteristics, 3D SiOx‐based membrane anodes with stable electrochemical performances are obtained. The preparation method of such a flexible self‐supporting film provides a reference for other flexible materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • A synergistic strategy of metal doping and in-situ carbon coating is developed to synthesize Cu-FeP@C anode. • The dispersed ultrasmall FeP is encapsulated in a 3D carbon framework and uniformly doped with Cu. • Excellent rate capability, high reversible capacity and notable long-term cycle performance is presented. • EIS, GITT and capacitive distribution calculations verified the fast ion/electron transfer kinetics. • DFT calculations are performed to understand the effect of Cu doping on electronic mobility and conductivity. FeP has emerged as an appealing anode material for lithium-ion batteries (LIBs) thanks to its high theoretical capacity, safe voltage platform and rich resources. Nevertheless, sluggish charge transfer kinetics, inevitable volume expansion and easy agglomeration of active materials limit its practical applications. Here, novel Cu-doped FeP@C was synthesized by a synergistic strategy of metal doping and in situ carbon encapsulation. The optimized Cu-doped FeP@C anode demonstrates a highly reversible specific capacity (920 mAh g−1 at 0.05 A g−1), superb rate performance (345 mAh g−1 at 5 A g−1) and long-term cycle stability (340 mAh g−1 at 2 A g−1 after 600 cycles). The electrochemical mechanism was investigated by cyclic voltammetry, kinetic analysis and DFT calculations. The results reveal that carbon frameworks can improve the conductivity and slow down the volume expansion, with highly dispersed FeP facilitating Li-ion migration during the charge and discharge processes. Additionally, Cu doping leads to rearrangement of the charge density and an additional lattice distortion in FeP, which boosts the electron mobility and enriches the surface-active sites, promoting electrochemical reaction and charge storage. This study presents a feasible and effective design for developing transition metal phosphate (TMP) anodes for high-performance LIBs. [ABSTRACT FROM AUTHOR]

Lithium-ion batteries (LIBs) with LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) cathodes have a high energy density, but their long-cycle performance, especially at high temperature, should still be improved due to the instability of the NCM811 cathode-electrolyte interphase. In this work, 2, 2, 2-Trifluoroethyl p -Toluenesulfonate (TPTS) is introduced as a functional film-forming electrolyte additive design to improve the long-term stability of graphite/NCM811 batteries. The preferential redox reactions of TPTS molecules play a pivotal role in fostering the creation of a sulfur-riched interphase, characterized by low impedance. This interphase works to fortify the interfacial structure, effectively inhibiting the dissolution of transition metal ions. Therefore, in comparison to the graphite/NCM811 pouch batteries lacking additive, TPTS enhance the long-cycle capacity retention from 47 % to 80 % after 450 cycles at 45 °C. What's more, TPTS suppresses outgassing and demonstrates enhanced capacity maintenance for the battery even after storage at 60 °C. This work not only demonstrates the stabilizing impacts of TPTS on the electrode-electrolyte interphase and its enhancement of cycling performance at elevated temperatures but also introduces a novel approach for the practical utilization of functional electrolytes matching high-nickel LIBs. 2, 2, 2-trifluoroethyl p -toluenesulfonate (TPTS) is developed as a bifunctional film-forming electrolyte additive to enhance the long-cycle stability of graphite/NCM811 pouch batteries at elevated temperature. The dense interphase constructed by TPTS inhibits the dissolution of TMs and maintains the integrity of electrode materials. This work provides an effective electrolyte design strategy for the application of high nickel lithium-ion batteries. [Display omitted] • TPTS constructs low-impedance interphase with sulfur-containing components. • TPTS improve the high temperature stability of graphite/NCM811 pouch battery. • TPTS-derived interphase maintains structure integrity. • Working mechanism of TPTS is elucidated. [ABSTRACT FROM AUTHOR]

A functional electrolyte containing conventional carbonate esters solvents, LiPF 6 salt, and novel 2-fluorobenzenesulfonyl fluoride (2FF) additive is developed to stabilize the LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) cathode interface and enhance the performance of NCM811/graphite lithium-ion batteries (LIBs). It is indicated that due to the unique C-F and sulfonyl fluoride groups of 2FF, the NCM811/Li half batteries containing 2% 2FF electrolyte show the highest cycling performance, a coulombic efficiency of 98.4% and a capacity retention of 89.4% are obtained after 100 cycles at 0.5C. And compared to the pouch NCM811/graphite full batteries with blank electrolyte, the long cycle performance of the batteries with 2% 2FF is also increased after 500 cycles at 45 °C, the discharge capacity retention rate retains at 80.04% and the coulombic efficiency closes to 100%. The spectroscopic characterization and theoretical calculation demonstrate that the electrolyte with 2FF additive preferentially react and generate uniform CEI film. These results show that this 2FF-containing electrolyte can stabilize NCM811 cathode interface, revealing a promising prospect of the commercial application of high-nickel LIBs. • Developed a 2-fluorobenzenesulfonyl fluoride (2FF)-containing multi-functional electrolyte. • The formation of electrode/electrolyte interfacial films is regulated by using 2FF. • The performance of the batteries at high temperature is enhanced with 2FF additive. • SEI layer formed by 2FF reduces intergranular cracking of NCM cathodes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Design of an N-SXP water-based binder based on the double helix structure of XG. • N-SXP forms biopolymer networks in SiO x to effectively buffer volume expansion. • N-SXP has excellent electrochemical performance under different conditions. • N-SXP action mechanism is illustrated by simulation and spectral analysis. Although SiO x can exhibit a higher specific energy than graphite material in lithium-ion batteries (LIBs), its mass commercial application still suffers from the performance degradation of SiO x anode caused by volume expansion. In this work, based on a biomimetic strategy and the unique double helix structure of xanthan gum (XG), sodium alginate (SA), XG and polyacrylic acid (PAA) are used to design and prepare a new water-based binder (N-SXP) to form a biomorphic polymer binder network in the SiO x anodes and effectively improve the cycling performance. It is indicated that the hydrogen and chemical bonding forces of N-SXP binder can form a solid multiple chain structure, and in particular, the supramolecular ion–dipole effect of each side chain is similar to that of a millipede's leg and can firmly adsorb the SiO x surface, and together with large hydroxyl groups form bonds between N-SXP and SiO x. After 600 cycles at 0.5C, the reversible capacity is 1105 mAh/g. Even after 300 cycles at 1C and 2C, a stable performance can still be obtained. In addition, 250 cycles at 40 °C 0.5C still provide 1101 mAh g-1 de-lithium specific capacity. The full battery capacity remains stable after 150 cycles at 200 mA g−1, and a rate capacity of 115 mAh g-1can be kept at 3C. The quantitative calculations by molecular simulations yield the role of N-SXP in forming the hydrogen bonds on SiO x surfaces, and combining with the spectroscopic characterization results further elucidate the functional mechanism of N-SXP binder in the SiO x anode. This biomimetic binder network pathway derived from N-SXP not only enhances the performance of SiO x anode but also provides an idea for the development of new bonding candidates of silicon-based materials. [ABSTRACT FROM AUTHOR]

A sulfur-containing compound S-phenyl Benzenethiosulfonate (SPBS) is developed as an electrolyte additive to improve the electrochemical performance of LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811)/graphite lithium-ion batteries (LIBs) in a wide temperature range. Compared with the batteries without SPBS, the capacity retention of the batteries containing SPBS increases from 58.15% to 91.48% after 1100 cycles at 25 °C and from 70.09% to 80.68% after 550 cycles at 45 °C. And after stored at 60 °C for 7 days, 14 days, and 28 days, the capacity retention rate and capacity recovery rate of the batteries containing SPBS are obviously improved. In addition, it is also shown that SPBS can inhibit the internal polarization and capacity attenuation of the batteries during low-temperature cycling, the capacity retention of the batteries containing SPBS increases from 46.3% to 81.9% after 100 cycles at −10 °C. The experimental and theoretical results demonstrate that SPBS facilitates the construction of high-quality electrode-electrolyte interfaces, reduces the electrolyte decomposition and inhibits the impedance increase. The excellent temperature performance of NCM811/graphite LIBs means the promising application prospect of SPBS-containing electrolyte. • A S-phenyl Benzenethiosulfonate (SPBS)-containing multi-functional electrolyte is developed. • The formation of electrode/electrolyte interfacial films is regulated by using SPBS. • The temperature performance of the NCM811/graphite batteries with SPBS additive is enhanced. • The film-forming mechanism of SPBS-containing electrolyte is elucidated. [ABSTRACT FROM AUTHOR]

A 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI–BF 4) ionic liquid is introduced into an electrolyte as a functional additive to enhance the low-temperature performance of LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM523)/graphite batteries. Linear sweep voltammetry (LSV), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) tests show that EMI–BF 4 can be oxidized in advance and produce low impedance solid-electrolyte interphase (SEI) films on the electrode surfaces. Compared with the batteries without the EMI–BF 4 additive, the capacity retention of the NCM523/graphite batteries with 1% EMI–BF 4 additive is enhanced from 82.3% to 93.8% after 150 cycles at a low temperature of −10 °C. In addition, at −30 °C, the discharge capacity of the batteries with 1% EMI–BF 4 additive is nearly doubled. And at the room temperature of 25 °C and after 400 cycles, the capacity retention also increases from 80.3% to 85.9%, and the coulomb efficiency remains at approximately 100%. These results demonstrate that EMI–BF 4 used as a functional electrolyte additive has promising prospects for application to improve the low-temperature performance of NCM523-based lithium-ion batteries. Image 1069882 • 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI-BF 4) is evaluated as a low temperature electrolyte additive. • EMI-BF 4 can form interfacial films on both electrode surfaces of NCM523/graphite batteries. • The interfacial films formed on both electrodes improve their cycle stability. • The capacity retention rate of the batteries with EMI-BF4 is increased under low temperature. [ABSTRACT FROM AUTHOR]

Abstract A poly(vinylidene fluoride)/ethyl cellulose and amino-functionalized nano-SiO 2 (PVDF-EC-(A-SiO 2)) composite coated on polyethylene (PE) is developed as the functional separator of 5 V high-voltage lithium ion batteries with enhanced performance. Compared with the PE separator, the composite membrane has a uniform interconnected structure, an increased melting temperature from 138 °C (PE) to 140.8 °C, a decreased contact angle from 49.5° to 23.2°, and higher ionic conductivity from 0.34 mS cm−1 to 0.79 mS cm−1. In particular, the electrochemical window is raised to 5.3 V (vs. Li/Li+). LiNi 0.5 Mn 1.5 O 4 /Li batteries with this separator display a high discharge capacity of 131.6 mAh g−1 and a superior cycling stability with a capacity retention of 95.7% after 200 cycles at 0.5 C. Those results demonstrate that the PVDF-EC-(A-SiO 2)/PE composite separator exhibits a good-performance in cycling stability and thermal stability, implying promising potential application in high-voltage lithium ion batteries. Graphical abstract Image 1 Highlights • A new composite coated layer was prepared by PVDF-EC and A-SiO 2. • The uniform interconnected structure was formed by the good dispersion layer. • This structure could offer favorable channels for Li+ to improve conductivity. • The composite separator enhanced the mechanical and thermal stability remarkably. [ABSTRACT FROM AUTHOR]

The overcharge safety and behaviors of lithium-ion batteries (LIBs) with LiCoO 2 cathode are investigated under a successive constant current (CC) and constant voltage (CV) charge mode. It is indicated that in the case of smaller charge currents, a higher probability for the LIBs passing the overcharging test can be obtained. The batteries can safely pass CC overcharge test at 0.25C to 10 V, and then about 80% batteries can also pass CV overcharge test. Whereas, with increasing the CC currents to 0.33C, 0.5C, and 1C, about 50%, 30%, and 10% batteries can directly pass the overcharge test at the CC step, and then about 20%, 10%, and 0% batteries approach 10 V and subsequent pass CV overcharge test, respectively. Besides the charge current, it is also demonstrated that whether the LiCoO 2 /graphite batteries are likely to achieve energy balance and pass the overcharge test basically depends on the formation of the internal short-circuit pathways derived from the cobalt and lithium deposition in the separator during the overcharge process. The cobalt deposition will be more uniform when the battery core has shape stability of assembly-structure, which can be used as an effective measure to raise LIBs through the overcharge test. In addition, relative more uniform cobalt dendrites can also be formed if a double layer separator is adopted, which reduces the local short-circuit risk caused by the melting or shrinkage of the separator and correspondingly improves the ratio of LIBs passing through the overcharge test. These risk reduction measures can be used in the battery manufacture to improve the overcharge safety of LIBs. [ABSTRACT FROM AUTHOR]

Today, with the massive application of lithium ion batteries (LIBs) in the portable devices and electric vehicles, to supply the active materials with high-performances and then to recycle their wastes are two core issues for the development of LIBs. In this paper, the spent graphite (SG) in LIBs is used as raw materials to fabricate two comparative high-capacity graphite anode materials. Based on a microsurgery-like physical reconstruction, the reconstructed graphite (RG) with a sp 2 +sp 3 carbon surface is prepared through a microwave exfoliation and subsequent spray drying process. In contrast, the neural-network-like amorphous sp 2 +sp 3 carbon-coated graphite (AC@G) is synthesized using a self-reconfigurable chemical reaction strategy. Compared with SG and commercial graphite (CG), both RG and AC@G have enhanced specific capacities, from 311.2 mAh g −1 and 360.7 mAh g −1 to 409.7 mAh g −1 and 420.0 mAh g −1 , at 0.1C after 100 cycles. In addition, they exhibit comparable cycling stability, rate capability, and voltage plateau with CG. Because the synthesis of RG and AC@G represents two typical physical and chemical methods for the recycling of SG, these results on the sp 2 +sp 3 carbon layer coating bulk graphite also reveal an approach for the preparation of high-performance graphite anode materials derived from SG. [ABSTRACT FROM AUTHOR]

As lithium-ion batteries (LIBs) find application in new fields, the specific capacity of single LIBs must be enhanced, and the backward-cell problem in battery modules must be solved. Here, Mn 3 O 4 and carbon nanofragment (Mn 3 O 4 /CNF) composites are synthesized and shown to have higher capacities than commercial graphite (theoretical capacity of approximately 372 mAh·g −1 ) and hierarchical voltage plateaus. Nanosized Mn 3 O 4 particles are introduced into the CNFs to simultaneously increase the specific capacity and prevent the corresponding LIB modules from over-discharging. The Mn 2+ -modified CNFs are spray-dried and calcined to form Mn 3 O 4 /CNF composites with 1.62%, 3.21%, and 6.74% Mn, which exhibit enhanced reversible specific capacities of 486.1, 609.3, and 539.0 mAh·g −1 , respectively, at 0.1C after 100 cycles. Furthermore, the additional voltage plateau at 1.2 V due to Mn 3 O 4 can help prevent the corresponding LIB modules from over-discharging and metallic lithium deposition on the anode. [ABSTRACT FROM AUTHOR]

The effect of diphenyl disulfide (DPDS) as a bifunctional additive on the performance of Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 /graphite batteries cycled at elevated temperature was evaluated. The batteries with 1.0 wt.% DPDS exhibited a capacity retention of 68.4% after 100 cycles under 55 °C, which was higher than that without DPDS (44.4%). In addition, the self-discharge of the Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 /graphite battery was also suppressed in a storage test at 85 °C for 8 h by adding 1.0 wt.% DPDS in the electrolyte. Linear sweep voltammetry and cyclic voltammetry combined with density functional theory calculations indicated that DPDS was oxidized and reduced prior to the solvent to participate in the formation of solid electrolyte interface (SEI) films on the cathode and anode simultaneously. The alternating current impedance and X-ray diffraction suggest that the SEI films derived from DPDS are helpful for enhancing the interface performance of the electrodes and protecting the Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 and graphite structures from deterioration during high-temperature cycling, which is responsible for the improvement in the performance of the Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 /graphite batteries at elevated temperature. [ABSTRACT FROM AUTHOR]

[Display omitted] • MnO@3D N-PCF composite was developed by a two-step rapid freeze-drying-calcination strategy. • The MnO@3D N-PCF anode exhibits exceptional high-rate performance and long-term stability. • The N doping contributes to additional active sites for Li-ion storage and improves conductivity. • The 3D open structure provides space to buffer volume changes and fast ions diffusion channels. Although transition metal oxides have the advantages of large theoretical capacity, low cost and eco-friendliness, their application as anodes for lithium-ion batteries (LIBs) is still limited due to their undesirable electrical conductivity and large volume expansion. Herein, a novel two-step rapid freeze-drying-calcination strategy was applied to prepare highly dispersed nano-MnO-anchored three-dimensional nitrogen-doped porous carbon framework composites (MnO@3D N-PCF). Compared with MnO and undoped MnO@3D PCF, the MnO@3D N-PCF anode exhibits superb cycle stability, remarkable specific capacity and impressive high-rate performance (1037.0 mAh g−1 over 100 cycles at 0.1 A g−1 and 760.9 mAh g−1 over 500 cycles at 5 A g−1), mainly due to its well-designed 3D nanoarchitecture. It is found that 3D nitrogen-doped carbon networks can act as stable conductive bridges to facilitate electron transport and sufficient diffusion channels for Li ions. The MnO nanoparticles obtained by rapid lyophilization and calcination technology are highly dispersed in the porous 3D carbon skeleton, which can buffer volume expansion and preserve the stability of the electrode. It is expected that this simple and green synthesis strategy will open the door for the development of transition metal oxide/carbon three-dimensional nanocomposites with high stability and excellent electrochemical properties. [ABSTRACT FROM AUTHOR]

A composite separator is prepared to improve the safety of lithium ion batteries (LIBs) based on a gravure coating aqueous slurry and post-hot-pressing method. An environmentally friendly aqueous slurry with an Al 2 O 3 ceramic holder and polyvinylidene difluoride-hexafluoropropylene (PVdF-HFP ) and carboxymethyl cellulose (CMC) dual-binders is coated on a polyolefin (PE) substrate to form a prototype Al-PHC/PE separator. Then, after assembling the separator in the batteries and hot-pressing at 70 °C and 0.8 MPa for 3 h, the granular PVdF-HFP is transformed into a colloidal structure containing an electrolyte, which can binds the Al 2 O 3 nanoparticles together and increases the battery hardness. Compared with a PE separator (9 μm), the Al-PHC/PE-2 separator (12 μm, with a Al 2 O 3 /PVdF-HFP weight ratio of 7/3) displays a comparative ionic conductivity of 9.3 × 10 −4 S cm −2 and exhibits no obvious thermal deformation at 110 °C for 60 min. All of the batteries assembled with Al-PHC/PE-2 separators passed nail penetration and impact tests. In addition, the capacity retention increases from 83.4% to 87.6% when the battery is assembled with Al-PHC/PE-2 instead of a PE separator and charge-discharged at 0.7C/1.0C for 350 cycles. The enhanced safety and cycle performance indicate the promising prospect of Al-PHC/PE separators in LIBs. [ABSTRACT FROM AUTHOR]

Based on the concepts of self-assembly and re-construction, flower-like porous carbon nanosheet powders (CNPs), which exhibit almost double theoretical capacity of prototype graphite powders, are prepared by spray drying a suspension of graphite oxide and cetyltrimethylammonium bromide (CTAB) and subsequent thermally-reducing treatment. The functional groups, edges, and defective sites of nanoscale graphite oxide intermediate and their interaction with CTAB additive are utilized to construct the CNP micro-/nanostructure with abundant wrinkles. This unique micro-/nanostructure not only facilitates coating CNPs on the anode substrate of lithium-ion batteries (LIBs) but also improves their electrochemical performances. Specifically, these CNPs display an initial specific capacity of approximately 807 mAh g −1 and a stable capacity of approximately 650 mAh g −1 after the 6 th cycle at a charge-discharge current of 100 mA g −1 . And a capacity of approximately 600 mAh g −1 is still kept after 100 cycles, showing the as-prepared CNPs have promising application in the LIBs. In addition, based on the insertion/extraction ‘path-memory effect’, a storage mechanism of lithium ions is proposed to explain the importance of wrinkles in the CNPs to the capacity and cycling stability. [ABSTRACT FROM AUTHOR]

To increase the lifespan, energy density, and temperature performance of LiCoO 2 /artificial graphite lithium-ion batteries (LCO/AG LIBs) to meet the requirements of 5G devices, three nitrile ether molecules are developed as bifunctional electrolyte additives to match 4.5 V LCO/AG LIBs. The commonalities and differences of these three nitrile ether molecules as additives are revealed. The batteries with nitrile ether additives can be cycled more than 1000 cycles at 4.5 V, 25 °C, and 1C, while the capacity retention of battery without additives after 200 cycles is close to 0%. At 45 °C, additive with four C N bonds can also lead to stable cycling over 600 cycles, whereas the batteries without additives fail after 100 cycles. It is demonstrated that nitrile ether additives participate in the repair and stabilization of interface films, which decreases the electrolyte decomposition. And the greater the number of C N bonds contained in the molecules, the stronger ability inhibits Co3+ dissolution from LCO, which is the main reason for the difference in the properties of the nitrile ether molecule. These results not only reveal the promising prospects of nitrile ether additives in practical applications but also provide a strategy to develop functional electrolytes for high voltage LCO/AG LIBs. [Display omitted] • Nitrile ether additives are used in 4.5V LiCoO 2 /graphite batteries. • Nitrile ether additives can build a self-healing interface film. • Nitrile ether additives can improve the high temperature performance of batteries. • The number of C N bonds is the key to improving batteries performance. [ABSTRACT FROM AUTHOR]

Based on the re-construction idea of carbon nanomaterials, novel folding re-constructed carbon nanosheets (re-CNSs) with unique microstructure and higher lithium-ion storage capacity than prototype graphite powders are prepared. The nanoscale carbon-fragment suspension is firstly prepared through a successive chemical oxidation of graphite and ultrasonic crushing operation, and the re-CNS powders are then obtained by spray drying the suspension and a subsequent high-temperature reducing process. The as-prepared re-CNSs exhibit a folding appearance with a width of several micrometers, with a maximum initial specific capacity of 903 mAh g −1 for the re-CNSs sample thermally reduced at 500 °C (re-CNSs500). After 100 cycles, the reversible capacity is maintained at about 400 mAh g −1 for the re-CNSs500. The abundant carboxylic and hydroxide groups, edges, and defective sites of individual graphite oxide fragments facilitate the dislocation formation in the re-CNSs. In addition, a dislocation mechanism is thus used to describe the enhanced lithium-ion storage. [ABSTRACT FROM AUTHOR]

Abstract: In order to overcome the capacity fading of LiCoO2/graphite Lithium-ion batteries (LIBs) cycled in the voltage range of 3.0–4.5 V (vs. Li/Li+), methylene methanedisulfonate (MMDS) is newly evaluated as an electrolyte additive. The linear sweep voltammetry (LSV) and cyclic voltammetry (CV) indicate that MMDS has a lower oxidation potential in the mixed solvents of ethylene carbonate (EC) and ethyl methyl carbonate (EMC), and participates in the formation process of the cathode electrolyte interface (CEI) film. With the addition of 0.5 wt.% MMDS into the electrolyte, the capacity retention of the LiCoO2/graphite cells cycled in 3.0–4.5 V is significantly increased from 32.0% to 69.6% after 150 cycles, and the rate capacity is also improved compared with the cells without MMDS additive in the electrolyte, showing the promising prospect in the electrolyte. In addition, the results of electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) demonstrate that the enhanced electrochemical performances of the cells can be ascribed to the modification of components of cathodes surface layer in the presence of MMDS, which resulting the suppression of the electrolyte oxidized decomposition and the improvement of CEI conductivity. [Copyright &y& Elsevier]

The thermal stability and electrolyte wettability of commercial polyolefin separators cannot support the safety and electrochemical performance of lithium-ion batteries (LIBs) under some limiting conditions. In this work, polyacrylate is dispersed into glass fibers by immersion, and then, a glass fiber/polyacrylate (GFP) separator is obtained after the rolling and drying process. Compared with the polyolefin (PE) separator, the GFP separator shows enhanced thermal stability, electrolyte wettability, ionic conductivity, and liquid absorption ability. There is almost no shrinkage of the GFP when it is annealed at 350 °C for 30 min. According to nail penetration, overcharge, and adiabatic rate calorimeter measurements using LiNi 0.5 Co 0.2 Mn 0.3 O 2 /graphite pouch cells with a nominal limited capacity of 2000 mAh, the GFP separator can effectively inhibit exothermic reactions in the batteries when the internal temperature is out of control. In addition, the adhesive property of polyacrylate can also strengthen the cell structure and inhibit expansion and deformation during cycling. The cells with the GFP separator also show enhanced capacity retention of 91% after 600 cycles at 1C. Thus, combined with its advantages in terms of price, preparation, electrochemical performance, and safety, the GFP separator exhibits promising prospects in the application of commercial LIBs. [Display omitted] • A glass fiber-polyacrylate (GFP) material is prepared and used as the separator. • The GFP separator can inhibit exothermic reactions. • The safety of the pouch cells with GFP separator can be effectively improved. • The pouch cells with GFP separator exhibit enhanced cycling performances. [ABSTRACT FROM AUTHOR]

Higher charging cutoff voltages of LiCoO 2 /graphite pouch-cells with high energy density can meet the advanced requirement of new generation lithium-ion batteries. However, the poor cycling performance derives from severe the electrolyte's decomposition on interface of the cathode/electrolyte at high charging cutoff voltage limits its wider commercial application. To resolve these detrimental effects of battery at high operating voltage, a novel bifunctional electrolyte additive (PTSI) is added into electrolyte for the LiCoO 2 /graphite pouch-cells. Upon operating at higher charging cut-off voltage (4.4 V) after 200 cycles, the LiCoO 2 /graphite pouch-cells with 1.0 wt.% PTSI in the electrolyte reveals preferable cycle performance over those in baseline electrolyte. The capacity retention of the pouch-cells with 1.0 wt. % PTSI in the electrolyte is 95.33% after 200 cycles, which is only 61.74% for those in baseline electrolyte. The results of electrochemical and spectroscopic techniques indicate that PTSI decomposes before the electrolyte solvents are consumed, and then took part in the interface layer formation on the interfaces of the electrodes, improving the cells performance. This work develops the novel bifunctional electrolyte additive that meets the requirement of a LiCoO 2 -based pouch-cells at high voltage. Image 1 • PTSI is first proposed as the novel bifunctional electrolyte for the cells. • The cells with PTSI exhibit improved performances operating at high voltage. • PTSI is involved in the interface layer formation on both electrodes. • PTSI-derived interfacial layers mitigate the electrolyte decomposition. [ABSTRACT FROM AUTHOR]

Lithium-ion batteries (LIBs) with high-nickel ternary material cathode can provide a high specific capacity but are more sensitive to the H 2 O/HF contents and functional additives in the electrolyte. In this work, 1,4-phenylene diisocyanate (PPDI) is developed as an H 2 O/HF scavenger and film-forming electrolyte additive to enhance the performances of pouch LiNi 0 · 6 Co 0 · 2 Mn 0 · 2 O 2 (NCM622)/graphite batteries. Compared with batteries containing the blank electrolyte, the electrochemical performances of batteries with the PPDI-containing electrolyte can be significantly improved. Thereinto, after 600 cycles at room temperature (25 °C) and 300 cycles at high temperature (45 °C), the capacity retentions for the batteries with the PPDI-containing electrolyte are 84.9% and 81.3% at 1C, while the rates for the batteries with the blank electrolyte are only 29.3% and 14.4%, respectively. With the aid of theory calculations and spectroscopic characterization, the reasons behind the performance enhancement are elucidated, and the reaction mechanism of PPDI and H 2 O/HF is proposed. It is demonstrated that PPDI can scavenge H 2 O/HF in the electrolyte and form stable and highly conductive films on two electrodes to stabilize NCM622 and improve battery performances. Besides the functionalized electrolyte, this work can also inspire new ideas to develop functionalized electrolytes for high-performance NCM622-based LIBs. Image 1 • Phenylene diisocyanate (PPDI)-containing multi-functional electrolyte is developed. • PPDI can facilitate scavenge H 2 O/HF, form conductive films, and stabilize NCM622. • The NCM622/graphite batteries with PPDI additive exhibit enhanced performances. • The mechanisms for the H 2 O/HF scavenging and interface formation are elucidated. [ABSTRACT FROM AUTHOR]

13• Single-crystal LiNi 0.83 Co 0.10 Mn 0.07 O 2 (SC-NCM) cathode materials are prepared. 13• SC-NCM shows more superior cycle performances at high voltages. 13• Single-crystal structure prevents from inter-granular cracks during cycling. 13• Single-crystal structure decreases (003) d -spacing variation at high voltages. 13• Thermal stability is improved by depressing side reactions and internal short dots. The needs for lightweight portable electronic devices and long-duration electric vehicles impel the development of high-energy lithium-ion batteries (LIBs). As a promising cathode material, the high nickel content (x) and cutoff voltage facilitate to increase energy density of LiNi x Co y Mn z O 2 (x+y+z =1) whereas they impair cycling and thermal stability. Herein, we first synthesize crack-free single crystal LiNi 0.83 Co 0.10 Mn 0.07 O 2 (SC-NCM) materials, which possess superior cycling and thermal stability at high voltages by decreasing the inter-granular fracture induced by anisotropic volume changes to retain the interior particle morphology integrity during long charge–discharge processes. Specifically, SC-NCM in full cells between 3.00 V and 4.35 V delivers reversible capacity of 167.0 mAh g−1 and capacity retention of 84.8% after 400 cycles at 0.5 C/25 °C, which are far larger than 107.7 mAh g−1 and 54.1% of conventional polycrystalline LiNi 0.83 Co 0.10 Mn 0.07 O 2 (PC-NCM). The enhanced high-voltage cyclability of SC-NCM is attributed to lower transition metal dissolution, higher anti-crack performances, better phase transition reversibility and smaller volume change, revealed by in-situ X-ray diffraction and differential capacity curves between 3.0 and 4.9 V. The SC-NCM has better floating charge durability than PC-NCM at high temperature by depressing side reactions between cathode and electrolyte, and formation of nickel dendrite-induced internal short dots. Image, graphical abstract [ABSTRACT FROM AUTHOR]

The optimization of electrode-electrolyte interfacial properties plays a key role in the stable operation of high-energy density lithium-ion batteries (LIBs) over a wide temperature range. In this work, a functional electrolyte using dihydro-1,3,2-dioxathiolo [1,3,2]dioxathiole-2,2,5,5-tetraoxide (D-DTD) molecules as an overall-functional additive is designed and used to enhance the comprehensive performance of LiNi 0.5 Co 0.2 Mn 0.3 O 2 /graphite batteries under extreme conditions, namely, a high 4.4 V working potential and a wide temperature range of −30 °C–60 °C. The batteries with D-DTD exhibit stable coulombic efficiency, enhanced cycling stability, and superior rate performance. Specifically, the batteries with D-DTD retain 89.1% of their original reversible capacities after 150 cycles at room temperature, while only 55.4% and 84.0% capacity retentions are obtained from the batteries without additive and with 1,3,2-dioxathiolane-2,2-dioxide (DTD), respectively. Interestingly, the addition of D-DTD to the baseline electrolyte promotes higher cycling retentions of 77.2% (45 °C) and 92.5% (−10 °C) after 100 cycles in comparison to 14.7% and 82.1% with DTD-added electrolyte, respectively. It is demonstrated that D-DTD can participate in the construction of interfacial films on both cathode and anode, which contributes to stabilizing the electrode-electrolyte interfaces and reducing parasitic interfacial reactions of LIBs. Image 1 • Sulfur-containing D-DTD is studied as an overall-functional electrolyte additive. • The batteries with D-DTD show enhanced performance over a wide temperature range. • D-DTD additives show better performance than well-known DTD additives. • The D-DTD-derived interfacial films exhibit high stability and low impedance. • The unique functions of the D-DTD additives in the electrolyte are proposed. [ABSTRACT FROM AUTHOR]

The design and synthesis of high-performance anode materials using environmentally friendly routes are demanded to meet the high-energy and high-power density requirements of next-generation lithium-ion batteries (LIBs). Herein, a facile and green gallic acid-assisted in situ synthetic strategy is demonstrated to fabricate novel Fe 2.8 Sn 0.2 O 4 @C composites as the anode materials of high-performance LIBs. The Fe 2.8 Sn 0.2 O 4 @C composites reveal a sphere-like morphology (2–3 μm in diameter), which is composed of highly dispersed nano iron-tin oxide particles (~25 nm) embedded in an interconnected carbon skeleton. This unique structure and composition allow Fe 2.8 Sn 0.2 O 4 @C to inhibit electrolyte adverse reactions, improve electron conductivity, and buffer mechanical stress for the entire electrode, resulting in its outstanding electrochemical performances. A high specific capacity of 2047 mA h g−1 at 0.2 A g−1 after 250 cycles, long cycling stability of 1061 mAh g−1 at 1 A g−1 after 1000 cycle, and rate capability of 572 mAh g−1 at 10 A g−1 are obtained. It is also indicated that the lithium storage in the Fe 2.8 Sn 0.2 O 4 @C anode involves both diffusion and surface capacitance mechanisms. The strategy reports here may open up new prospects for the design and manufacture of high-performance transition metal-based anode materials. Image 1 • Fe 2.8 Sn 0.2 O 4 @C micro/nano composite with uniform carbon coatings is synthesized. • Fe 2.8 Sn 0.2 O 4 nanocrystals is dispersed in 3D carbon skeleton to form the composite. • Gallic acid is used as Fe (III) complexing agent, dispersant, and in-situ carbon source. • Fe 2.8 Sn 0.2 O 4 @C reveals high-performances as an anode material for Li-ion batteries. • The kinetics and Li storage mechanism of Fe 2.8 Sn 0.2 O 4 @C anode are elucidated. [ABSTRACT FROM AUTHOR]

Rechargeable lithium-sulfur (Li-S) batteries, with a theoretical specific energy (2600 ​Wh kg-1) and theoretical specific capacity (1675 ​mAh g-1), are superior to current commercial lithium ion batteries. However, severe capacity fading due to volume breath and polysulfide dissolution greatly hinders the commercialization of Li-S battery. As an attempt to solve the problem, a hollow MnO 2 spheres/porous reduced graphene oxide/S (MnO 2 /RGO/S) composite was synthesized by an one-step hydrothermal method, of which the hollow MnO 2 spheres can effectively restrains the volume expansion/contraction of S 8 and the dissolution of polysulfides during the charge-discharge processes. Furthermore, 3D RGO with high electronic conductivity can facilitates a fast electronic transfer. The initial specific capacity of the MnO 2 /RGO/S composite is 1202.0 ​mAh g-1 and remains 577.0 ​mAh g-1 with the coulombic efficiency of 93.2% at 0.2C after 200 cycles, and the capacity retention remains higher than 61.4% of the initial capacity after 100 cycles at 1C, indicating a synergistic effect of hollow MnO 2 spheres and conductive 3D RGO. The mixture of ethanol suspension containing MnO 2 spheres and GO aqueous solution were added dropwise into H 2 O/CS 2 solution of S 8. After hydrothermal reduction of above mixed solution and subsequent freezing process, MnO 2 /RGO/S composite was obtained, and which successfully improves the electrochemical performance of the Li-S batteries. Image 1 • The MnO 2 /RGO/S with 3D porous structure is prepared via a simple one-step hydrothermal routine. • The MnO 2 /RGO/S composite is used as the high-performance cathode material for Li-S batteries. • Li-S batteries with MnO 2 /RGO/S exhibit enhanced performance by taking advantages of conductive RGO and hollow MnO 2 spheres. [ABSTRACT FROM AUTHOR]

The high cut-off voltage for delivering the high reversible capacity of LiCoO 2 often causes its capacity fading and potential safety hazards. Herein, LiNi 0.45 Al 0.05 Mn 0.5 O 2 is uniformly modified on LiCoO 2 to prepare LiCoO 2 @LiNi 0.45 Al 0.05 Mn 0.5 O 2 via a ball-milling method. In half-cell (or full-cell) tests, the LiCoO 2 @LiNi 0.45 Al 0.05 Mn 0.5 O 2 exhibits the improved cycle stability between 3.00 V and 4.55 V (or 4.48 V). The capacity of LiCoO 2 @LiNi 0.45 Al 0.05 Mn 0.5 O 2 with 1.0% modification content can be up to 161.9 mAh g−1 from 133.3 mAh g−1 of LiCoO 2 after 150 cycles. The cyclability improvement of lithium ion batteries employing LiCoO 2 @LiNi 0.45 Al 0.05 Mn 0.5 O 2 cathode is ascribed to a delay of structure collapse and a decrement of cobalt dissolution. Moreover, LiNi 0.45 Al 0.05 Mn 0.5 O 2 on the LiCoO 2 leads to an increase in the onset temperature of primary exothermic peaks, and a decrease in the maximum rising temperature of thermal shock from 500 °C to 160 °C while LiCoO 2 @LiNi 0.45 Al 0.05 Mn 0.5 O 2 /graphite full cell is charged to 4.48 V. The LiNi 0.45 Al 0.05 Mn 0.5 O 2 improves thermal stability of the LiCoO 2 -based cathode by depressing O 2 evolution and decreasing internal short dots. Image 1 • LNAMO is uniformly modified on layered LCO by a ball-milling method. • LNAMO modifiers improve high-voltage cycling stability of half/full cells. • Thermal shock and overcharge tests clarify the enhanced thermal stability. • LNAMO prevents structure collapse and cobalt dissolution. • LNAMO depresses internal short dot growth and O 2 evolution. [ABSTRACT FROM AUTHOR]

Poly(vinylidene fluoride-co-hexafluoro-propylene) doped with imidazole-modified silica nanoparticles (Z-SiO 2) is coated in a polyethylene substrate to form a functional composite polymer electrolyte (PVDF-HFP-(Z-SiO 2)/PE-based CPEs) and used for high voltage LiNi 0.5 Co 0.2 Mn 0.3 O 2 cathode lithium-ion batteries (LIBs). The imidazole-based modified SiO 2 nanoparticles are first prepared via a distillation precipitation polymerization. The composite separators with 30 wt% Z-SiO 2 nanoparticles prepared via a dip-coating process exhibits a porous and uniformly dispersed morphology and enhanced performance, including excellent electrolyte uptake (310%), high ionic conductivity of 1.03 mS cm−1, and oxidative decomposition voltage up to 4.75 V. More importantly, a stable cathode electrolyte interphase (CEI) layer can be formed, endowing the Li/PVDF-HFP-(Z-SiO 2)/PE-based CPEs/LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM523) cells superior cycling stability and rate capability (169 mAh g−1, 81.9%) under when the charge cut-off voltage increased to 4.5 V, which is higher than that assembled with PE separator (160 mAh g−1, 40.8%). These results demonstrate that the Z-SiO 2 nanoparticles not only act as the fillers of the CPEs but also are water/acid scavengers in favor of the formation of a stable CEI film, which promotes the cycling performance and rate capability of high voltage NCM523 cathode and reveals promising prospect for practical applications in LIBs at high voltage operation. Image 1 • The Z-SiO 2 was synthesized by a distillation-precipitation polymerization method. • A functional CPEs was prepared by doped with Z-SiO 2. • The Z-SiO 2 as water/acid scavengers in favor of the formation of a stable CEI layer. • Li/CPEs/NCM523 cell exhibits a good cycling stability under high voltage. [ABSTRACT FROM AUTHOR]

Lithium difluorophosphate (LiPO 2 F 2) as a multi-functional additive is added into the carbonate-based electrolyte to enhance the electrochemical performances of 4.4 V LiNi 0.5 Co 0.2 Mn 0.3 O 2 /graphite lithium ion batteries (LIBs). Compared with the baseline electrolyte, the addition of 2% LiPO 2 F 2 can significantly improve the electrolyte stability and enlarge the electrochemical window of about 1 V. At the room temperature and cutoff voltage of 4.4 V, the capacity retention of the batteries with 2% LiPO 2 F 2 is increased from 55% to 93% after 150 cycles. At the high temperature of 45 °C, the capacity retention of the battery with 2% LiPO 2 F 2 additive still keeps 86% after 150 cycles, while the coulombic efficiency of the battery without additive begins to decline sharply after 30 cycles. These positive effects are also reflected in the low temperature discharging at −20 °C, cycling at −10 °C, and rate capability. The enhanced performances are attributed to the excellent interfacial film promoted by the additive, which can reduce the interfacial impedance, suppress electrolyte decomposition, and alleviate the side reactions. It is indicated that LiPO 2 F 2 is a promising multi-functional electrolyte additive for high-voltage NCM/graphite LIBs. [ABSTRACT FROM AUTHOR]