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• Significant reduction of surface residual lithium due to the reaction between alumina and residual lithium to form LiAlO 2. • Enhanced charge transfer kinetics with LiAlO 2 modification. • Significant increase in energy density of full cells with the addition of modified samples. The active lithium ions loss during the initial charge and discharge process of lithium ion batteries seriously hampers its increasement of energy density. Pre-lithiation, involving the pre-storage of active lithium ions prior to cycling, emerges as a promising and effective strategy to offset this loss. Li 6 CoO 4 has been identified as a candidate capable of releasing adequate lithium ions to compensate for such loss. However, its poor air stability renders it susceptible to side reactions in the atmosphere, leading to the formation of residual lithium and consequently affecting its electrochemical performance. In this study, we propose application of a lithium aluminate (LiAlO 2) coated onto the surface of lithium cobalt oxide (Li 6 CoO 4) to mitigate the presence of residual lithium. Meanwhile, with decreasing of residual lithium, the rate capability is also enhanced. The research results demonstrate that samples treated with this coating layer exhibit an enhanced energy density in the full cell, indicating the efficacy of this approach in optimizing the electrochemical performance of prelithiation additives. [ABSTRACT FROM AUTHOR]

The graphene/silicon oxide/polypyrrole (G/SiOx/PPY) material was prepared in this paper. The G/SiOx/PPY material has good electrochemical performances including high capacity and cyclic stability. It has 2068/2130 mAh g − 1 of capacity after 100th charge/discharge cycle at 200 mA g − 1 of current density and 575/569 mAh g − 1 of capacity after 100th charge/discharge cycle at 2000 mA g − 1 of current density when G/SiOx molar ratio is 1:5. Its capacity increases but its cyclic stability decreases with G/SiOx molar ratio decreasing from 1:1 to 1:3 and 1:5. The electrochemical performance improvement of the G/SiOx/PPY material is due to the synergetic effect of graphene and polypyrrole, which improve the conductivity of SiOx and prevent its dropping from the surface of the electrode caused by the stress due to the volume expansion and shrinkage in charge/discharge cycles. In the current study, G/SiOx/PPY material was prepared successfully and the G/SiOx molar ratio on its electrochemical performance and microstructure was studied. It was observed that the G/SiOx/PPY material had capacity increase but cyclic stability decreases when G/SiOx molar ratio changed from 1:1 to 1:3 and 1:5. The microstructure analysis confirmed that G and PPY had synergetic effects to improve the conductivity of SiOx and prevent its dropping from the surface of the electrode caused by the stress due to the volume expansion and shrinkage in charge/discharge cycles. [ABSTRACT FROM AUTHOR]

To overcome the limited reversible capacity, unstable cycling performance and poor electrical conductivity of pure ZnFe2O4 as the anode for lithium-ion batteries, graphene oxide-coated ZnFe2O4 hollow spheres have been designed and synthesized by a simple self-assembled strategy. The retractable hollow structure, coupled with the uniformly wrapping GO with high electrical conductivity, ensures a high reversible capacity, remarkable cycle stability (829 mA h g−1 at a current density of 200 mA g−1 even after 500 cycles) and excellent rate performance (463 mA h g−1 at the high current density of 1000 mA g−1). [ABSTRACT FROM AUTHOR]

A hollow silicon oxide coated with cuprous oxide and polyaniline (hSiOx/Cu2O/PANI) was prepared via Stober method, magnesium reduction and chemical oxidative polymerization. The hSiOx/Cu2O/PANI (SiOx 62 wt.%, PANI 33 wt.%, Cu2O 5 wt.%) presented charge/discharge capacities of up to 2000 mAh g − 1 after 60 cycles at 0.2 A g − 1 current density and higher than 880 mAh g − 1 at 8 A g − 1 current density. Microstructural analysis demonstrated that the improvement was due to the nanostructure of hollow SiOx sphere coated with Cu2O and PANI, which could release high stress caused by volume expansion during the lithiation/delithiation process and had little damage to electrode materials. Cycle voltammetry (CV) and electrochemical impedance spectroscopy (EIS) results further confirmed that Cu2O and PANI dual-coating improved reversibility and conductivity of hSiOx and prevented it to drop from the electrode surface. A hollow silicon oxide coated with PANI and Cu2O was prepared, which exhibited a good electrochemical performance. The quantitative value of oxygen in hSiOx ranged in 1–1.5. The improvement was due to the synergy of hollow structure, PANI and Cu2O. [ABSTRACT FROM AUTHOR]

1,4-Dialkoxybenzene additives are commonly used as redox active shuttles in lithium-ion batteries in order to prevent runaway oxidation of electrolyte when overcharge conditions set in. During this action the shuttle molecule goes through a futile cycle, becoming oxidized at the cathode and reduced at the anode. Minimizing parasitic reactions in all states of charge is paramount for sustained protective action. Here we demonstrate that recently developed bis- annulated 9,10- bis (2-methoxyethoxy)-1,2,3,4,5,6,7,8-octahydro-1,4:5,8-dimethano-anthracene shuttle molecule (that yields exceptionally stable radical cations) survives over 120 cycles of overcharge abuse with 100% overcharge ratio at C /5 rate. Equally remarkably, in the presence of this additive the cell impedance becomes significantly lower compared to the control cells without the additive; this decrease is observed during the formation, normal cycling, and even under overcharge conditions. This unusual dual action has not been observed in other redox shuttle systems, and it presents considerable practical interest. [ABSTRACT FROM AUTHOR]

Many works have focused on building an improved solid electrolyte interface (SEI) film by consuming additives during the first several cycles. However, the effects of electric double layers (EDLs) on interface chemistry are often overlooked. Here in, experimental and calculated results have proved the anion-building EDLs have a stronger electric field than the one by Li+ ions, resulting in more generation of protective Li x PF y O z compounds. Specifically, the small volume anions to the benefit of improving the electric field of EDLs. Based on this finding, the electrolyte additive of LiCl with the property of small molecular volume is introduced to stabilize SEI films. As expected, it strengthens the electric field, facilitates the self-decomposition of PF 6 − anions, contributes to a moderate increase in the quantity of Li x PF y O z product, and improves the cycle stability of Li-ion batteries. We expect that the method which adjusts the interfacial property by introducing non-consumed small anions provides a new trail in screening and designing electrolyte additives for advanced batteries. [Display omitted] [ABSTRACT FROM AUTHOR]

TiO-B nanowires with remarkable mesoporous structure via a template-free low-temperature hydrothermal fabrication route have been prepared by employing titanium glycolate (TG) as a precursor. The formation of mesopores in TiO-B nanowires is caused by the evolvement of vacancies derived from the chains of TG. The product is characterized by X-ray diffraction, Raman spectroscopy, nitrogen adsorption-desorption, and electron microscopy. The lithium-ion storage capacity of mesoporous TiO-B nanowires is evaluated by galvanostatic measurements. The initial discharge-charge capacities of the material are 310 and 231 mAh g at a current density of 50 mA g, respectively. A discharge capacity of 198 mAh g is still retained when charge-discharge at 1.0 A g for 50 cycles, demonstrating the high-rate performance and good cycle ability. The large reversible capacity, high-rate performance, and good cycle ability of the material are attributed to unique mesoporous structure and intrinsic properties of the TiO-B nanowires. The mesoporous TiO-B nanowire synthesized from TG is promising for use as an anode material for lithium-ion batteries with high power and energy densities. [ABSTRACT FROM AUTHOR]

The dissolution, migration, and deposition of transition metal (TM) ions are the main reasons for the capacity degradation of lithium-ion batteries, which significantly affect their comprehensive electrochemical performance and safety. In this work, the effects of different TM ions (Mn2+, Co2+, and Ni2+) on the electrochemical performance of lithium/mesocarbon microbeads half-cell were compared, and the mechanism was discussed. It is found that Mn2+ ions inhibit the decomposition of lithium salt and promote the decomposition of solvents, resulting in the crack of electrode material and solid electrolyte interface (SEI) film and the increase of capacity degradation. In contrast, Ni2+ ions promote the decomposition of lithium salts to a certain extent, thus inhibiting the excessive damage to the SEI film and electrode material. This study can provide theoretical support and research direction for the design of the electrolytes that can alleviate the damage of TM ions to the anode and the SEI film. [Display omitted] [ABSTRACT FROM AUTHOR]

The exploration for post-carbon electrode materials for lithium-ion batteries has been a crucial way to satisfy the ever-growing demands for better performance with higher energy/power densities, enhanced safety, and longer cycle life. Transition metal oxides have recently received a great deal of attention as very promising anode materials due to their high theoretical capacity, good safety, eco-benignity, and huge abundance. The present work reviews the latest advances in developing novel transition metal oxides, including FeO, FeO, CoO, CoO, NiO, MnO, MnO, MnO, MnO, MoO, CrO, NbO, and some binary oxides such as NiCoO, ZnCoO, MnCoO and CoMnO. Nanostructuring and hybrid strategies applicable to transition metal oxides are summarized and analyzed. Furthermore, the impacts of binder choice and heat treatment on electrochemical performance are discussed. [ABSTRACT FROM AUTHOR]

Abstract: This work introduces an effective, inexpensive, and large-scale production approach to the synthesis of Fe2O3 nanoparticles with a favorable configuration that 5nm iron oxide domains in diameter assembled into a mesoporous network. The phase structure, morphology, and pore nature were characterized systematically. When used as anode materials for lithium-ion batteries, the mesoporous Fe2O3 nanoparticles exhibit excellent cycling performance (1009mAhg−1 at 100mAg−1 up to 230cycles) and rate capability (reversible charging capacity of 420mAhg−1 at 1000mAg−1 during 230cycles). This research suggests that the mesoporous Fe2O3 nanoparticles could be suitable as a high rate performance anode material for lithium-ion batteries. [Copyright &y& Elsevier]

Abstract: A novel lysine-assisted hydrothermal process is first developed to produce hierarchically porous Fe2O3 microspheres assembled by well-crystalline nanoparticles. The fabrication process is very simple, without employing any surfactants or templates. A possible growth mechanism of the nano/microspherical superstructure is further discussed. The contribution of lysine to the formation of the unique microspheres is also tentatively proposed. Furthermore, as an anode electrode material for rechargeable lithium-ion batteries, the Fe2O3 microsphere displays excellent electrochemical performance. It also exhibits the feature of capacity increase upon cycling and shows a stable and reversible capacity of 705 mA h g−1 after 430 cycles. The outstanding electrochemical performance of the Fe2O3 microsphere can be attributed to the hierarchical porosity, ordered microstructure, good electron pathways and easy penetration of the electrolyte. [Copyright &y& Elsevier]

Abstract: Unique hollow Fe3O4 spheres are prepared by a simple template-free solvothermal reaction. In the reaction, ethylene glycol (EG) and polyvinylpyrrolidone (PVP) serve as the reducing agent and surface stabilizer, respectively. NH4Ac plays the role of the structure-directing agent, which combines with the Ostwald ripening process, resulting in the favored formation of hollow structures. The morphologies and structures are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The hollow Fe3O4 spheres exhibit excellent cycling and rate performance as anode material for lithium-ion batteries, delivering reversible specific capacities of 870mAhg−1 even after 50 cycles at 100mAg−1 and 836mAhg−1 at 500mAg−1. The excellent electrochemical performance can be attributed to their hollow nanostructure and excellent structural stability. [Copyright &y& Elsevier]

Abstract: A simple approach is proposed to prepare C-SiO2 composites as anode materials for lithium ion batteries. In this novel approach, nano-sized silica is soaked in sucrose solution and then heat treated at 900°C under nitrogen atmosphere. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis shows that SiO2 is embedded in amorphous carbon matrix. The electrochemical test results indicate that the electrochemical performance of the C-SiO2 composites relates to the SiO2 content of the composite. The C-SiO2 composite with 50.1% SiO2 shows the best reversible lithium storage performance. It delivers an initial discharge capacity of 536mAhg−1 and good cyclability with the capacity of above 500mAhg−1 at 50th cycle. Electrochemical impedance spectra (EIS) indicates that the carbon layer coated on SiO2 particles can diminish interfacial impedance, which leads to its good electrochemical performance. [Copyright &y& Elsevier]

[Display omitted] • The N-Li 2 CO 3 cathode prelithiation additive enriched with GBs was synthesized. • The Σ(0 0 1) GBs in the N-Li 2 CO 3 exhibit enhanced Li-ion and electronic conductivity. • The ∼100 % capacity utilization of the N-Li 2 CO 3 (724 mAh/g) is obtained. • The improved energy density and lifetime of the Si-based full cells are achieved. Due to high theoretical capacity, Si anodes have attracted tremendous attention. Nevertheless, huge volume change during cycling together with large lithium loss substantially hinders their large-scale application. Prelithiation has emerged as a highly attractive strategy to compensate for the loss of active lithium. Li 2 CO 3 , which is ambient stable and delivers more than 5 times the theoretical capacity of the existing cathode materials, serves as an excellent cathode prelithiation additive. However, the practical application of Li 2 CO 3 is limited by its sluggish charge transport and high critical decomposition potential. Herein, we report a facile route to fabircating nanosized Li 2 CO 3 (N-Li 2 CO 3) materials enriched with grain boundaries (GBs). First-principles investigations reveal that the Li-ion transport behavior is dependent on the concentration of GBs. The Σ(0 0 1) GB model exhibits higher Li-ion and electronic conductivities compared to those of the bulk counterpart. As a result, the ∼ 100 % capacity utilization of N-Li 2 CO 3 with a delithiation capacity of 724 mAh/g is obtained, which is much higher than that of commercial Li 2 CO 3 (115 mAh/g), greatly enhancing the reversible capacity, energy density and lifetime of the LiNi 0.5 Co 0.2 Mn 0.3 O 2 //Si-graphite full cell. These findings provide valuable understanding of the role of GBs and the correlation between microstructure engineering and performance optimization. [ABSTRACT FROM AUTHOR]

Highlights: [•] An acetylene reduction route is designed to synthesis uniformly dispersed Sn-MnO@C nanocomposite. [•] Synchronously formed Sn and MnO nanocrystalline are uniformly dispersed in the amorphous carbon matrix. [•] The composite shows a reversible capacity of 684mA h g−1 after 280 cycles. [•] Fine electrochemical performance attributes to uniformly dispersed nanoparticles, porous structure and carbon matrix coating. [Copyright &y& Elsevier]

Abstract The adoption of lithium metal anodes, which are ideal for constructing batteries with high specific energy, is limited by dendrite growth and poor cycle performance. Herein, an anion-regulated solid polymer electrolyte based on in-situ-polymerized poly(ethylene glycol ether acrylate) is prepared for dendrite-free lithium metal batteries. According to the space-charge theory, the growth of lithium dendrites is effectively inhibited by the improved electric field of solid polymer electrolyte on the lithium anode side. And this solid system achieves a lithium transfer number of 0.63, excellent ionic conduction on 2.16 × 10−5 S cm−1 at room temperature), a wide electrochemical stable window (4.8 V vs. Li+/Li) and excellent cycle performance. The flexible batteries (LiFePO 4 cathode/solid polymer electrolyte/lithium metal) are assembled to power a light-emitting diode at room temperature. We highlight the anion regulated polymer solid electrolyte, which shows great potential for solid lithium metal batteries and flexible batteries. Graphical abstract Image 1 Highlights • Anion-regulated PEGPEA based solid polymer electrolyte(PSPE)is developed. • Lithium dendrite is inhibited by the PSPE. • The lithium-ion transfer number is up to 0.63. • PSPE has a wide operating window of 4.8 V. [ABSTRACT FROM AUTHOR]

Abstract Poly(acrylic acid) (PAA) is widely used as a polymer binder for high capacity silicon (Si) anodes in Li-ion batteries. When used, the carboxyl (CO 2 H) groups of PAA can be partially lithiated (known as pre-lithiation treatment), which is believed to facilitates lamination process, especially for production on a large scale. However, such treatment impacts numerous physico-chemical properties of the PAA binder that affect the cycling performance of the electrode. Here we seek to quantify the pre-lithiation treatment effect on Li-ion cells containing Si-graphite composite electrodes. The electrochemical cycling results indicated that such pre-lithiation treatment of PAA can undermine the cycling performance, as more capacity loss was observed when pre-lithitated PAA binders were used. On the other hand, the same pre-lithiation practice is indeed beneficial for the lamination process, as it increases the viscosity of aqueous slurries at low shear rates (slows down sedimentation) and prompts the shear thinning (so that the slurries can be more easily mixed). Thus, there is an uneasy balance between the electrochemical performance that suffers from the pre-lithiation of PAA and the quality of slurry processing which benefits from the same practice. An alternative approach to slurry treatment would be desired to achieve better cycling performance without undermining the stability of slurry suspensions. Graphical abstract Image 1 Highlights • Pre-lithiation treatment of PAA binder was conducted by titration with LiOH. • The treatment affords enhanced viscosity and shear-thinning but less cohesion. • Cycling results indicated the pre-lithation can undermine the cell performance. • The treatment balances the opposing trends in the cycling and slurry stability. [ABSTRACT FROM AUTHOR]

Sandwich-structured carbon nanotubes, silicon oxide, and polyaniline (hereafter denoted as CNTs/SiO x /PANI) were prepared by combining a sol–gel method, magnesiothermic reduction at 250 °C, and chemical oxidative polymerization. The CNTs, SiOx and PANI in the composite was 16 wt%, 51 wt% and 33 wt%, respectively. The CNTs/SiO x /PANI electrodes exhibited excellent cycle and high-rate performance as anodes in Li-ion batteries, including charge/discharge capacities of 1156/1178 mAh g −1 after 60 cycles at 0.2 A g −1 current density and 728/725 mAh g −1 at 8 A g −1 current density. The improvement was due to the synergy between CNTs and PANI. The SiO x scattered on the CNTs core and coated by PANI improved its conductivity and accommodated the volume change during repeated lithiation/delithiation cycles. This simple synthesis provided a scalable route for the large-scale production of CNTs/SiO x /PANI nanostructures, with various applications such as in Li-ion batteries. [ABSTRACT FROM AUTHOR]

Poly(acrylic acid) (PAA) based binders have been widely used for the high capacity silicon anodes of lithium-ion batteries. While numerous promising progress has been reported, there is no general guideline for choosing the right PAA binders for optimized cycling performance. In this report, aiming to optimize the cycling performance of the Si/graphite composite anodes (15 wt% Si), we systemically investigated a series of PAA binders by validating their molecular weights (MWs) and correlating them to the cycling performance of the anodes fabricated with such binders. The gel permeation chromatography (GPC) was used to validate the MWs of six PAA binders (PAA1 to PAA6). Those binders then underwent a series of characterizations, including rheology study, half-cell cycling, scanning electron microscope (SEM), and Fourier-transform infrared spectroscopy (FTIR). It is observed that the MWs of PAA binders not only affected the viscosities of the binder solutions but also impacted the cycling performance, possibly due to the cohesion changes. A range of 24–150 kDa is found to be optimal for minimizing the rate and extent of capacity fade and maintaining the cohesion in the electrode matrix despite the dramatic volumetric changes due to Si alloying. [ABSTRACT FROM AUTHOR]

Lithium-ion batteries (LIBs) suffering from severe performance degradation because of the unstable solid electrolyte interphase (SEI) on the anode at low temperature restricts their practical applications. Herein, lithium difluorophosphate (LiDFP) as the additive is introduced into lithium bis(fluorosulfonyl) imide (LiFSI) based electrolyte to improve the electrochemical performance of graphite/Li half-cells at low temperature. Contrary to the popular perception, we reveal at low temperature that LiDFP attenuates the decomposition of LiFSI by competing the hydrolysis reaction with LiFSI to generate a SEI film rich in LiF and Li 3 PO 4 during prolonged cycling, rather than preferential decomposition. Additionally, the possible reaction equations and the interaction mechanism between LiDFP and LiFSI are proposed by combining in situ electrochemical impedance electrochemical (PRIs-EIS) tests, spectroscopic characterization techniques and density functional theory (DFT) calculations. It is demonstrated that the strong binding energy between LiF (from the decomposition of LiFSI) and LiDFP makes LiDFP easier deposit on the electrode surface. This work demonstrates the synergistic role combining the complementary advantage of film-forming additives and main lithium salts to improve the interfacial stability of LIBs at low temperature. Additionally, it can also pave the new pathway for the design of low temperature electrolytes in LIBs. [Display omitted] • The synergy effect of additive LiDFP and LiFSI improves the interface stability. • The competitive hydrolysis reaction of LiDFP and LiFSI is elucidated. • The strong binding energy between LiF and LiDFP enables LiDFP easier deposit. • The stable and robust interface can avoid the aggregation of organics. [ABSTRACT FROM AUTHOR]

Abstract: Carbon-coated α-FeSe nanoparticles in an average size of 200nm have been prepared by a facile one-pot reaction. As an anode material for lithium batteries, the core-shell α-FeSe@C composites showed a discharge plateau at 1.5V, which could effectively avoid the formation of the lithium dendrites and the solid-electrolyte interface layer. They delivered a sustainable reversible capacity of 340mAhg−1 after 40cycles, which is about twice as much as that of the Li4Ti5O12 (175mAhg−1), thereby indicating its promising applications for lithium storage. [Copyright &y& Elsevier]