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Abstract Layered LiNi 1/3 Co 1/3 Mn 1/3 O 2 (LNCM) cathode has received extensive attention because of its high specific capacity at high voltage (4.5 V). While the unsatisfactory electrochemical performance at high voltage hinders its practical application in next generation lithium ion batteries. Herein we demonstrate that simply application of lithium difluorophosphate (LiPO 2 F 2) electrolyte additive significantly improves the electrochemical performance of high voltage LNCM/Li cell, at room and low temperature (−10 °C). Capacity retention of high voltage LNCM/Li cell with 3 wt. % LiPO 2 F 2 additive achieves 89% after 250 cycles at room temperature and 94% after 200 cycles at low temperature in comparison with that of 61% and 10% without additive. Even discharging at 10 C, the LNCM/Li cell with 3% LiPO 2 F 2 still delivers an initial capacity of 144 mAh g−1 and maintains at 69 mAh g−1 after 1000 cycles at room temperature. While the one without additive drops to 0 mAh g−1 after about 350 cycles. The improved cyclic stability and rate capability of high voltage LNCM is mainly ascribed to the steady low impedance cathode electrolyte interphase (CEI) film created by 3% LiPO 2 F 2 additive, which greatly hinders the subsequent electrolyte oxidation, electrode structural destruction and increase of electrode polarization during cycling. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

A novel electrolyte additive 3-sulfolene (3SF) for graphite anode is proposed in this work according to the DFT calculation. The calculated electron affinity energy of the investigated solvents and additives reveals that 3SF shows the highest reductive activity, which is further confirmed by the cyclic voltammetry test. The characterization results from charge/discharge cycle, scanning electron microscope, transmission electron microscope and elemental mapping demonstrate that the preferential reduction of 3 wt% 3SF additive generates a thin and uniform SEI film on the graphite surface, which effectively suppresses the continuous co-insertion and reduction of PC-based electrolyte, resulting in high cyclic stability of Li/graphite cell in PC-based electrolyte. Importantly, the ability of 3SF on improving the interfacial stability of graphite/PC-based electrolyte is better than that of the prop-1-ene-1,3-sultone which is believed to be the most promising candidates to alternate vinylene carbonate. [ABSTRACT FROM AUTHOR]

The facile synthesis of chiral materials is of paramount importance for various applications. Supramolecular preorganization of monomers for thermal polymerization has been proven as an effective tool to synthesize carbon and carbon nitride‐based (CN) materials with ordered morphology and controlled properties. However, the transfer of an intrinsic chemical property, such as chirality from supramolecular assemblies to the final material after thermal condensation, was not shown. Here, we report the large‐scale synthesis of chiral CN materials capable of enantioselective recognition. To achieve this, we designed supramolecular assemblies with a chiral center that remains intact at elevated temperatures. The optimized chiral CN demonstrates an enantiomeric preference of ca. 14 %; CN electrodes were also prepared and show stereoselective interactions with enantiomeric probes in electrochemical measurements. By adding chirality to the properties transferrable from monomers to the final product of a thermal polymerization, this study confirms the potential of using supramolecular precursors to produce carbon and CN materials and electrodes with designed chemical properties. [ABSTRACT FROM AUTHOR]

The facile synthesis of chiral materials is of paramount importance for various applications. Supramolecular preorganization of monomers for thermal polymerization has been proven as an effective tool to synthesize carbon and carbon nitride‐based (CN) materials with ordered morphology and controlled properties. However, the transfer of an intrinsic chemical property, such as chirality from supramolecular assemblies to the final material after thermal condensation, was not shown. Here, we report the large‐scale synthesis of chiral CN materials capable of enantioselective recognition. To achieve this, we designed supramolecular assemblies with a chiral center that remains intact at elevated temperatures. The optimized chiral CN demonstrates an enantiomeric preference of ca. 14 %; CN electrodes were also prepared and show stereoselective interactions with enantiomeric probes in electrochemical measurements. By adding chirality to the properties transferrable from monomers to the final product of a thermal polymerization, this study confirms the potential of using supramolecular precursors to produce carbon and CN materials and electrodes with designed chemical properties. [ABSTRACT FROM AUTHOR]

Influence of two Si-containing electrolyte additives, tris(trimethylsilyl)borate (TMSB) and tris(trimethylsilyl)phosphate (TMSP), on the cyclic stability of high voltage LiNi 0.5 Mn 1.5 O 4 electrode has been systematically studied in this work. The capacity retention of LiNi 0.5 Mn 1.5 O 4 cycling in STD (1M LiPF 6 /EC: EMC = 3:7), TMSB- and TMSP-containing electrolytes is 23%, 85% and 71% after 600 cycles at 1C rate, respectively, revealing that the ability of TMSB on improving the cyclic performance of LiNi 0.5 Mn 1.5 O 4 is superior to that of TMSP. Experimental and theoretical characterizations show that the preferential reaction of both TMSB and TMSP generates thin and uniform film on LiNi 0.5 Mn 1.5 O 4 surface, which effectively suppress the continuous oxidation reaction of electrolyte. While the film generated from TMSB, which contains B and Si-rich compounds, shows better ability on restraining the growth of interfacial resistance during cycling, resulting in better cyclic stability of LiNi 0.5 Mn 1.5 O 4 than that of TMSP. [ABSTRACT FROM AUTHOR]

Self-discharge behavior of layered lithium-rich oxide as cathode of lithium ion battery in a carbonated-based electrolyte is understood, and a simple boron-containing compound, trimethyl borate (TMB), is used as an electrolyte additive to suppress this self-discharge. It is found that layered lithium-rich oxide charged under 4.8 V in additive-free electrolyte suffers severe self-discharge and TMB is an effective electrolyte additive for self-discharge suppression. Physical characterizations from XRD, SEM, TEM, XPS and ICP-MS demonstrate that the crystal structure of the layered lithium-rich oxide collapses due to the chemical interaction between the charged oxide and electrolyte. When TMB is applied, the structural integrity of the oxide is maintained due to the protective cathode film generated from the preferential oxidation of TMB. [ABSTRACT FROM AUTHOR]

In this work, dimethylacetamide (DMAc) was investigated as an electrolyte film-forming additive to improve the cyclic stability of high voltage Lithium-rich layered nickel manganese cobalt oxide (LLO) cathode at room (25 °C) and elevated (55 °C) temperature. At 0.5C rate, addition of 1% DMAc slightly decreases the initial discharge capacity of LLO from 187 to 179 mAh g −1 at room temperature and 255 to 246 mAh g −1 at elevated temperature, while significantly improves the capacity retention of LLO from 65.8% to 80.2% after 200 cycles at room temperature and from 21.1% to 66.7% after 150 cycles at elevated temperature. The mechanism of DMAc improving the cyclic stability of LLO was investigated via theoretical calculation and experimental characterizations, which demonstrated that DMAc oxidized preferential to the STD (1.0 M LiPF 6 in a mixed solvent of ethylene carbonate/ethyl methyl carbonate/diethyl carbonate) electrolyte, generating a thin and uniform film on the LLO surface. This film effectively suppresses the subsequent decomposition of STD electrolyte and further degradation of spinel phase converted from the layered structure of LLO, resulting in improved cyclic stability of LLO at room and elevated temperature. [ABSTRACT FROM AUTHOR]

Triethylborate (TEB) is used as an electrolyte additive to improve the electrochemical performances of LiNi 1/3 Co 1/3 Mn 1/3 O 2 (LNCM) upon cycling at 4.5 V vs. Li/Li + . Charge/discharge tests demonstrate that the cyclic stability of LNCM at room and elevated temperature can be improved effectively by TEB. With addition of 10 wt. % TEB into STD electrolyte (1.0 M LiPF 6 /EC:EMC:DEC), LNCM achieves a capacity retention of 99.8% after 150 cycles and 94.7% after 120 cycles at room and elevated temperature, respectively, comparing to that of 68.9% and 68.8% of STD electrolyte. In addition, 10 wt. % TEB also improves the rate capability of LNCM at room temperature. Physical and electrochemical characterizations from XRD, SEM, TEM, XPS, ICP-MS, LSV, CA, and EIS reveal that the preferential oxidative reaction of TEB generates a thin, uniform and low interfacial resistance film on the LNCM surface. This film not only suppresses the subsequent decomposition of STD electrolyte, but also prevents the dissolution of transition metal ions from LNCM, resulting in improved cyclic stability and rate capability of LNCM. [ABSTRACT FROM AUTHOR]

Trimethyl borate (TB) is used as an electrolyte additive to improve cyclic stability and rate capability of a layered cathode, LiNi 1/3 Co 1/3 Mn 1/3 O 2 (LNCM), under 4.5 V (vs. Li/Li + ). Charge/discharge tests demonstrate that the cyclic stability and rate capability of LNCM can be improved significantly by adding TB into a standard (STD) electrolyte, 1.0 mol L −1 LiPF 6 in ethylene carbonate/ethyl methyl carbonate/diethyl carbonate (3/5/2, in weight). After 200 cycles at 0.5C between 3.0 and 4.5 V, LNCM exhibits a capacity retention of 89% in 10% TB-containing electrolyte, but only 48% in STD electrolyte. Unlike other additives, which usually decrease the rate capability when they are used for the cyclic stability improvement of LNCM, the discharge capacity of LNCM at 6C is enhanced from 78 mAh g −1 in STD electrolyte to 102 mAh g −1 in 10% TB-containing electrolyte. Physical and electrochemical characterizations demonstrate that these improvements result from the preferential oxidation of TB compared to the STD electrolyte and the formation of a stable and low impedance film on LNCM cathode surface, which suppresses concurrently the decomposition of electrolyte and the dissolution of transition metal ions from LNCM. [ABSTRACT FROM AUTHOR]

In this work, we propose a novel electrolyte additive phenyl trifluoromethyl sulfide (PTS) to improve the interfacial stability of high voltage lithium nickel manganese oxide (LiMn 1.5 Ni 0.5 O 4 ) cathode/electrolyte. At 1C rate, addition of 0.5% PTS improves the capacity retention of LiNi 0.5 Mn 1.5 O 4 from 65% to 84% after 450 cycles at room temperature, and from 64% to 95% after 100 cycles at evaluate temperature. Density functional theory calculation and experimental characterization demonstrate that PTS oxidizes preferentially to the carbonate base electrolyte, generating a SEI film, which effectively suppresses the continuous decomposition of carbonate base electrolyte and the structural destruction of LiMn 1.5 Ni 0.5 O 4 . [ABSTRACT FROM AUTHOR]

Trimethylboroxine (TMB) is used as electrolyte additive to improve the cyclic stability of LiCoO 2 /graphite full cell under high voltage. It is found that capacity retention of LiCoO 2 /graphite cell at 0.3C rate after 200 cycles between 3.0 ∼ 4.5 V is improved from 29 % to 66 % by applying 0.5 % (by weight) TMB in EC-based electrolyte. Charge-discharge tests on graphite/Li and LiCoO 2 /Li half cells demonstrate that the improvement in cyclic stability of the full cell results from the contribution of TMB to the enforced stability of LiCoO 2 cathode. Cyclic voltammogram shows that TMB is oxidized preferentially to the EC-based electrolyte, while physical characterizations, from SEM, TEM, FTIR and XPS, indicate that TMB helps build a thin but protective film on LiCoO 2 , which improves the interfacial stability of high voltage electrode/electrolyte. [ABSTRACT FROM AUTHOR]

Tris(trimethylsilyl)borate (TMSB) is used as an electrolyte additive for high voltage lithium-rich oxide cathode of lithium ion battery. The interfacial natures of Li[Li 0.2 Mn 0.54 N i0.13 Co 0.13 ]O 2 /carbonate-based electrolyte are investigated with a combination of electrochemical measurements and physical characterizations. Charge/discharge tests show that the cyclic performance of Li[Li 0.2 Mn 0.54 N i0.13 Co 0.13 ]O 2 in a mixed carbonate electrolyte is significantly improved by using TMSB. After 200 cycles between 2 V and 4.8 V (vs. Li/Li + ) at 0.5 C rate, the capacity retention of Li[Li 0.2 Mn 0.54 N i0.13 Co 0.13 ]O 2 is only 19% in the blank electrolyte, while it is improved to 74% when 0.5% TMSB is applied. The results from physical characterizations demonstrate that this excellent cyclic performance is attributed to the improved interfacial stability of Li[Li 0.2 Mn 0.54 N i0.13 Co 0.13 ]O 2 /electrolyte due to the thin and protective film generated by TMSB. [ABSTRACT FROM AUTHOR]

In this work, 4-(Trifluoromethyl)-benzonitrile (4-TB) is used as a novel electrolyte additive for LiNi 0.5 Mn 1.5 O 4 cathode of high voltage lithium ion battery. Charge–discharge tests show that the cyclic stability of LiNi 0.5 Mn 1.5 O 4 is significantly improved by using 0.5 wt.% 4-TB. With using 4-TB, LiNi 0.5 Mn 1.5 O 4 delivers an initial capacity of 133 mAh g −1 and maintains 121 mAh g −1 after 300 cycles with a capacity retention of 91%, compared to the 75% of that using base electrolyte (1 M LiPF 6 in ethylene carbonate(EC)/dimethyl carbonate(DMC)). The results from linear sweep voltammetry, density functional theory calculations, electrochemical impedance spectroscopy, scanning electron microscope, energy dispersive spectroscopy, Fourier transform infrared, and inductively coupled plasma, indicate that 4-TB has lower oxidative stability than EC and DMC, and is preferentially oxidized on LiNi 0.5 Mn 1.5 O 4 forming a low-impedance protective film, which prevents the subsequent oxidation decomposition of the electrolyte and suppresses the manganese dissolution from LiNi 0.5 Mn 1.5 O 4 . [ABSTRACT FROM AUTHOR]

Suitably designed organic compounds are promising renewable electrode materials for lithium ion batteries (LIBs) with minimal environmental impacts and no CO 2 release. Herein we report a series of polycarbonyl organic compounds with different number of hydroxyl groups, which can be obtained from renewable plants, as cathode materials for LIBs. Density functional theory (DFT) calculations based on the natural bond orbital (NBO) reveal a positive correlation between the reduction potentials and the number of hydroxyl groups, which is borne out experimentally. Anthraquinone (AQ) with three or four -OH groups has the structural advantages for improving the discharge plateaus. Mechanistic studies show that AQ containing neighbouring carbonyl groups and hydroxyl groups facilitates the formation of six or five-membered rings with lithium ion. Charge/discharge tests show that AQ, 1,5-DHAQ, 1,2,7-THAQ, and 1,2,5,8-THAQ can achieve initial discharge capacities of 215, 190, 186 and 180 mAh g -1 at a current density of 20 mA g -1 , corresponding to 84%, 85%, 89% and 91% of their theoretical capacities, respectively. [ABSTRACT FROM AUTHOR]

Highlights: [•] Influence of lithium salts on the anodic stability of sulfolane has been investigated. [•] Oxidation decomposition mechanisms of LiPF6/Sulfolane electrolyte have been well understood by theoretical and experimental methods. [•] Decomposition products of the electrolyte can be found on the electrode surface and in the interfacial electrolyte. [Copyright &y& Elsevier]

Abstract: The effect of anions, PF6 − and ClO4 −, on the oxidation decomposition mechanism of electrolyte solvent ethylene carbonate (EC) for lithium ion battery has been investigated by using density functional theory at B3LYP/6-311++G(d) level, in both gas phase (dielectric constant ɛ = 1) and solvent (dielectric constant ɛ = 20.5). It is found that the presence of PF6 − and ClO4 − anions significantly reduces EC oxidation stability and changes the order of the oxidation decomposition paths. The primary oxidation decomposition products of EC, EC–PF6 − and EC–ClO4 − are CO2 and acetaldehyde radical. The formation of CO is highly improbable in the decomposition reaction of EC with and without PF6 − or ClO4 −. [Copyright &y& Elsevier]

Abstract: In this work, we proposed a new solution to the instability of LiNi0.5Mn1.5O4 cathode for lithium ion battery by simply controlling discharge end-off voltage. The morphology and the crystal structure of LiNi0.5Mn1.5O4 before and after cycling at elevated temperature were characterized with XRD and SEM, and its performances as cathode of lithium ion battery were investigated by cyclic voltammetry and galvanostatic charge–discharge tests. It is found that the cyclic stability of LiNi0.5Mn1.5O4 at elevated temperature is significantly improved by changing the end-off discharge voltage from 3.5V to 4.0V (vs. Li+/Li). After 500cycles with 1C rate at 55°C, the capacity retention rate of LiNi0.5Mn1.5O4 is only 16.8% for the end-off discharge voltage of 3.5V, but improves to 84.9% for 4.0V. The improved stability is attributed to the limitation of the reduction of Mn4+ to Mn3+ that causes the primary particle separation of LiNi0.5Mn1.5O4. [Copyright &y& Elsevier]

Abstract: The reduction mechanism of ethylene sulfite (ES) in propylene carbonate (PC) based electrolyte is investigated using density functional theory in gas phase. Based on the electron affinity energy and lowest unoccupied molecular orbital (LUMO) energy, it can be known that free ES is reduced most easily compared with ES-Li+ and ES-Li+-PC, generating SO2 and propanal. However, the binding energy of ES-Li+ and ES-Li+-PC is quite negative, indicating that both of them are more possible in electrolyte solution than the free ES. The reductive decomposition products of ES-Li+ and ES-Li+-PC are OSO2Li, OSO2Li-R and ethylene. OSO2Li and OSO2Li-R are the main compositions of the solid electrolyte interphase film on the anode of lithium ion battery, which inhibits the reductive decomposition of PC. These calculations provide a detailed explanation on the experimental phenomena. [Copyright &y& Elsevier]

The effect of substituents on the oxidation potential for the one-electron reaction of 1,4-dimethoxybenzene was understood with a theoretical calculation based on density functional theory (DFT) at the level of B3LYP/6-311+G(d). It is found that the oxidation potential for the one-electron reaction of 1,4-dimethoxybenzene is 4.13 V (vs Li/Li+) and can be changed from 3.8 to 5.9 V (vs Li/Li+) by substituting electron-donating or electron-with drawing groups for the hydrogen atoms on the aromatic ring. These potentials are in the range of the limited potentials for the lithium ion batteries using different cathode materials, and thus the substituted compounds can be selected as the redox shuttles for the overcharge prevention of these batteries. The oxidation potential of 1,4-dimethoxybenzene decreases when the hydrogen atoms are replaced with electron-donating groups but increases when replaced with electron- withdrawing groups. The further oxidation of these substituted compounds was also analyzed on the basis of the theoretic calculation. [ABSTRACT FROM AUTHOR]

A novel electrolyte additive, 3, 3, 3‐trifluoropropylmethyldimethoxysilane (TFPMDS), is first proposed to modify both the cathode and the anode of lithium‐ion batteries at the same time. Charging/discharging tests demonstrate that the electrolyte with 1 wt% TFPMDS not only greatly improves the capacity retention of LiNi0.5Mn1.5O4 (LNMO)//Li cell (29.6%→90.8%) and graphite//Li cell (68.1%→98.3%), but also successfully ensures the long‐term cycle stability of LNMO//graphite pouch cell at 4.9 V. Further electrochemical measurements combining with spectroscopic characterization and theoretical calculations indicate that TFPMDS additive displays three principal functions: 1) Be preferentially oxidized to build a robust cathode electrolyte interphase (CEI) enriched in F/Si species with F‐rich nature of strong oxidation‐resistance. 2) Be able to scavenge the hazardous HF, F−, and H+ through its strong binding with these species and thus to protect LNMO at high‐voltage. 3) Be preferentially adsorbed on the graphite surface to form a "framework", and to co‐construct an elastic solid electrolyte interphase (SEI) after the reduction of ethylene carbonate. Importantly, the Si─O group within TFPMDS is especially important for constructing a "molecular bridge" at the CEI/SEI interphase coupling the inorganic and organic species to improve its compatibility, stability, and elasticity. [ABSTRACT FROM AUTHOR]

4.8 M LiFSI FEA/DMC + 1 % LiPF 6 electrolyte with an ultra-low melting point of −93 °C is developed, which enables outstanding electrochemical performances of graphite cathode in a wide working temperature range from −30 °C to 25 °C. The FEA solvent lowers the melting point of the electrolyte, while DMC additive increases the available capacity and LiFP 6 inhibits corrosion of the Al current collector. [Display omitted] • Dual-ion battery with 4.8 M LiFSI FEA/DMC + 1 %LiPF 6 electrolyte was designed. • Fast charge/discharge are achieved with capacity of 108 mAh g−1 at 10 C at 25 °C. • The battery exhibits a capacity retention of 91.5 % at 5 C after 2000 cycles at 25 °C. • The battery can be operated down to −30 °C. • Electrolyte with LiFSI salt shows better low-temperature performance than LiPF 6. The design of electrolyte suitable for low-temperature use is of great significance to expand the applications of energy storage devices. Dual-ion battery (DIB) with fast ion transport kinetics is expected to be a nascent battery system that can deliver high power density both at room temperature and low temperatures. In this work, we design a 4.8 M lithium bis(fluorosulfonyl)imide in 2,2,2-trifluoroethyl acetate/dimethyl carbonate (LiFSI FEA/DMC) + 1 % LiPF 6 electrolyte with a low melting point of about −93 °C, enabling graphite cathode in a DIB to achieve excellent fast charge/discharge capability with a high capacity of about 108 mAh g−1 and 80 mAh g−1 at 10 C at 25 °C and 0 °C, respectively. Even at −30 °C, the graphite cathode can still give a capacity of 69.2 mAh g−1 at 0.5 C. The graphite||Li DIB with 4.8 M LiFSI FEA/DMC + 1 % LiPF 6 electrolyte also exhibits a stable cycle life with a capacity retention of 91.5 % at 5 C after 2000 cycles at 25 °C. The electrolyte forms a uniform cathode electrolyte interface film on the graphite surface, as confirmed by transmission electron microscopy and X-ray photoelectron spectroscopy, which enables the outstanding electrochemical performance of the graphite cathode in a wide working temperature range from −30 °C to 25 °C. [ABSTRACT FROM AUTHOR]

Low-cost melamine and 2-thenaldehyde were assembled into N, S-enriched polymers supporting on commercially carbon nanotubes (CNTs) by one-pot synthesis method. The direct carbonization of this composite precursors harvested the metal-free carbons with synergistic doping of N and S atoms without post-treatment. Abundant large-pore mesopores were formed in the derived N–S–Cs with higher surface area. Higher graphitization degree of N–S–Cs endow it with the low resistance and fast electron conductivity. As a result, the N–S–Cs-900 exhibited as an efficient cathode catalyst for oxygen reduction reaction (ORR) especially in alkaline electrolyte, with positive ORR half-wave potential and higher limiting current density. In addition, the metal-free N–S–C materials also had better performance in Zn-air batteries with an initial voltage gap with 1.487 ​V. This work developed a low-cost synthesis strategy to obtain metal-free N–S–Cs with impressive ORR performance. Melamine and 2-thenaldehyde polymers on commercially carbon nanotubes were thermally conversed into N, S-enriched mesoporous carbons with higher graphitization degree and larger surface area. It served as the impressive metal-free catalyst for oxygen reduction reaction in half-cells and Zn-air batteries. Image 1 • Simple one-step synthesis of N and S-doped carbons with low-cost raw materials. • N and S co-dopped mesoporous carbon were supported on CNT wires. • Higher ORR activity and long-time durability of N–S–Cs-900 in half-cells and Zn-air batteries. [ABSTRACT FROM AUTHOR]

Application of film-forming electrolyte additive has been demonstrated to be an effective and economical approach to improve the performances of lithium ion batteries. However, investigations on the influence of electrolyte additives on the performances of sodium ion batteries is very limited. In this work, with vinylene carbonate (VC) as electrolyte additive, the cyclic stability of MoO 2 anode for sodium ion batteries is greatly improved. After 1000 cycles at 300 mAg−1, the capacity retention of MoO 2 electrode achieves 96.5% in comparison with that of 20.1% without additive. The poor long-term cyclic performance of MoO 2 is mainly ascribed to the sever electrolyte reduction reaction during cycling, which results in significantly increase of electrode polarization. The VC-induced solid electrolyte interphase film effectively suppresses the decomposition of baseline electrolyte, and therefore, hinders the increase of interfacial reaction resistance and improves the interfacial stability of MoO 2 electrode. • Sever capacity fading mechanism of MoO 2 anode for sodium ion batteries is understood. • Vinylene carbonate as electrolyte film-forming additive is proposed to greatly improve the capacity stability of MoO 2 anode. • Capacity retention of MoO 2 electrode achieves 96.5% in comparison with that of 20.1% without additive. [ABSTRACT FROM AUTHOR]

Improving the interphasial stability of electrode/electrolyte is crucial to the large-scale applications of lithium-ion battery with high energy density. Herein, a novel electrolyte additive, phenyl trans-styryl sulfone (PTSS), is proposed to reconstruct the interphasial structure and composition of electrode/electrolyte and to improve the cyclic stability of high voltage LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811)/graphite full-cell. Specifically, the cell with PTSS additive maintains 63% of its initial capacity after 100 cycles at 1C, which is about 15% higher than that of baseline electrolyte. Theoretical calculation and experimental characterization reveal that the high electrochemical reactivity PTSS decomposes prior to the baseline electrolyte, generating a protective film on NCM811 cathode and graphite anode surface. The uniform and thin CEI film effectively enhanced the interphasial stability of NCM811 cathode via suppressing electrolyte oxidation and electrode interphasial destruction during long term cycling. In addition, the PTSS induced-SEI film enhances the interphasial stability of graphite anode. • PTSS was proposed as a novel additive to improve the cyclic stability of LiNi 0.8 Co 0.1 Mn 0.1 O 2 /Graphite full-cells. • PTSS generates CEI and SEI film on cathode and anode surface during initial charging. • The uniform and thin CEI effectively improves the interphasial stability of NCM811 cathode. [ABSTRACT FROM AUTHOR]

The application of Li‐metal‐anodes (LMA) can significantly improve the energy density of state‐of‐the‐art lithium ion batteries. Lots of new electrolyte systems have been developed to form a stable solid electrolyte interphase (SEI) films, thereby achieving long‐term cycle stability of LMA. Unfortunately, the common problem faced by these electrolytes is poor oxidation stability, which rarely supports the cycling of high‐voltage Li‐metal batteries (LMBs). In this work, a new single‐component solvent dimethoxy(methyl)(3,3,3‐trifluoropropyl) silane is proposed. The electrolyte composed of this solvent and 3 m LiFSI salt successfully supports the long‐term cycle stability of limited‐Li (50 µm)||high loading LiCoO2 (≈20 mg cm−2) cell at 4.6 V. Experiments and theoretical research results show that the outstanding performance of the electrolyte in high‐voltage LMBs is mainly attributed to its unique solvation structures and its great ability to build a highly stable and robust interphase on the surface of LMA and high‐voltage cathodes. Interestingly, this proposed electrolyte system builds a stable SEI film rich in LiF and Li3N on the surface of LMA by improving the two‐electron reduction activity of FSI− without adding LiNO3, the well‐known additive used for LMBs. The design idea of the proposed electrolyte can guide the development of high‐voltage LMBs. [ABSTRACT FROM AUTHOR]

Abstract Low-cost melamine and 4-formylphenylboronic acid were assembled into new covalent melamine-boroxine frameworks (COFs) with rich content of nitrogen and boron by a simple one-pot synthesis routine. B,N-codoped carbons (B-N-C) could be successfully derived by copper-assisted thermal conversion of this designed plate-like COF. Differ from other microporous carbon plates derived from COFs, the prepared B-N-C here not only showed the unique hollow capsule morphologies, but also demonstrated the dominant mesoporosities. The easy-decomposition melamine-boroxine organic blocks and catalysis and template functions of Cu species including Cu(NO 3) 2 , Cu 2 (NO 3)(OH) 3 and Cu played the vital roles in the formation of hollow B-N-C capsules. The B-N-C capsules exhibited efficient catalytic performance for oxygen reduction reaction (ORR) in wide pH electrolytes, especially in alkaline solution. Its ORR half-wave potential reached 0.85 V in 0.1 M KOH, 20 mV more positive than the best B,N-codoped carbons previously. It also served as an advanced electrode material for supercapacitor with a specific capacitance of 230 F g−1. This research not only developed a novel copper-assisted thermal conversion pathway of melamine-boroxine frameworks for preparing heteroatom-doped carbons with open capsule morphology and large-pore mesoporosities, but also provided a reliable metal-free ORR electro-catalyst and capacitor material with satisfying performance. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

[Display omitted] An effective electrolyte additive, 3-(tert -Butyldimethylsilyoxy) phenylboronic acid (TBPB), is proposed to significantly improve the cycle stability of high voltage LiCoO 2 (LCO) cathode. Experimental and computational results show that TBPB has a relatively higher oxidation activity than base electrolyte, and preferentially constructs a stable cathode electrolyte interphase (CEI) containing B-/Si- components on LCO surface. Theoretical calculation, XPS and NMR data show that TBPB-derived CEI layer contains B-F species and has the function of eliminating HF. The as-formed CEI effectively inhibits the detrimental side reactions from electrolyte decomposition and LCO surface structure reconstruction. The capacity retention of LCO/Li half-cell increases from 38.92% (base electrolyte) to 83.70% after 150 cycles at 1 C between 3.0 V and 4.5 V by adding 1% TBPB. Moreover, TBPB is also reduced prior to base electrolyte, forming an ionic conducting solid electrolyte interphase (SEI) on graphite surface. Benefiting from the synergistic effect between CEI layer on LCO cathode and SEI layer on graphite anode to effectively decrease the electrolyte decomposition, the capacity retention of commercial LCO/graphite pouch cell with 1% TBPB increases from 10.44% to 76.13% after 400 cycles at 1 C between 3.0 V and 4.5 V. This work demonstrates that TBPB can act as an effective film-forming additive for high energy density LCO cathode at high voltage, and provides novel insights for its commercial application from the aspect of synergistically interfacial stability. [ABSTRACT FROM AUTHOR]

Trimethyl borate (TMB) and triethyl borate (TEB) are used as film-forming electrolyte additives for high voltage Lithium nickel manganese oxide (LNMO) cathode. DFT calculation and initial charge curve of LNMO reveal that the oxidation activity of TEB is higher than that of TMB. Addition of 2% TMB and 2% TEB effectively improve the capacity retention of high voltage LNMO from 23.4% to 85.3% and 72.6% after 600 cycles, respectively. The film generated in TMB-containing electrolyte shows better ability on suppressing the LNMO shedding in comparison with that of TEB, resulting in higher capacity retention of LNMO in TMB-containing electrolyte at high voltage. The superior performance of LNMO with TMB-containing electrolyte should be ascribed to its less intense film-forming reaction which generates a denser protective surface film on LNMO surface. However, why LNMO shows catalyzation effect on TEB oxidation but not on TMB is unclear, which needs further intensive investigation. [ABSTRACT FROM AUTHOR]

LiI and LiBr have been employed as soluble redox mediators (RMs) in electrolytes to address the sluggish oxygen evolution reaction kinetics during charging in aprotic Li‐O2 batteries. Compared to LiBr, LiI exhibits a redox potential closer to the theoretical one of discharge products, indicating a higher energy efficiency. However, the reason for the occurrence of solvent deprotonation in LiI‐added electrolytes remains unclear. Here, by combining ab initio calculations and experimental validation, we find that it is the nucleophile IO3- ${{{\rm I}{\rm O}}_{3}^{-}}$ that triggers the solvent deprotonation and LiOH formation via nucleophilic attack, rather than the increased solvent acidity or the elongated C−H bond as previously suggested. As a comparison, the formation of BrO3- ${{{\rm B}{\rm r}{\rm O}}_{3}^{-}}$ in LiBr‐added electrolytes is found to be thermodynamically unfavorable, explaining the absence of LiOH formation. These findings provide important insight into the solvent deprotonation and pave the way for the practical application of LiI RM in aprotic Li‐O2 batteries. [ABSTRACT FROM AUTHOR]

LiI and LiBr have been employed as soluble redox mediators (RMs) in electrolytes to address the sluggish oxygen evolution reaction kinetics during charging in aprotic Li‐O2 batteries. Compared to LiBr, LiI exhibits a redox potential closer to the theoretical one of discharge products, indicating a higher energy efficiency. However, the reason for the occurrence of solvent deprotonation in LiI‐added electrolytes remains unclear. Here, by combining ab initio calculations and experimental validation, we find that it is the nucleophile IO3- ${{{\rm I}{\rm O}}_{3}^{-}}$ that triggers the solvent deprotonation and LiOH formation via nucleophilic attack, rather than the increased solvent acidity or the elongated C−H bond as previously suggested. As a comparison, the formation of BrO3- ${{{\rm B}{\rm r}{\rm O}}_{3}^{-}}$ in LiBr‐added electrolytes is found to be thermodynamically unfavorable, explaining the absence of LiOH formation. These findings provide important insight into the solvent deprotonation and pave the way for the practical application of LiI RM in aprotic Li‐O2 batteries. [ABSTRACT FROM AUTHOR]

A simple boron-containing molecule, tripropyl borate (TPB), is used as an electrolyte additive to stabilize the interface between spinel lithium manganese oxide (LiMn 2 O 4 ) and carbonate-based electrolyte under elevated temperature. Electrochemical measurements indicate that the cyclic stability of LiMn 2 O 4 electrode can be significantly improved by TPB. The capacity retention of LiMn 2 O 4 at 1C after 200 cycles under 55 °C is improved from 47% to 74% by adding 3% TPB into a standard electrolyte (1.0 mol L −1 LiPF 6 -EC/EMC/DEC (3/5/2, in weight)). Most importantly, the self-discharge of LiMn 2 O 4 under 55 °C, which takes place dramatically in the standard electrolyte, is effectively suppressed in 3% TPB-containing electrolyte. Theoretical calculations and physical characterizations demonstrate that a protective cathode electrolyte interface (CEI) film is formed on LiMn 2 O 4 from the preferential oxidation of TPB, which suppresses the oxidation decomposition of the standard electrolyte. Due to the incorporation of boron, the CEI film formed from TPB is beneficial to the rate capability of LiMn 2 O 4 . [ABSTRACT FROM AUTHOR]

Controlling electrode/electrolyte interfacial chemistry is critically important for improved K+ storage, but the influences of binder chemistry on electrolyte decomposition and interfacial properties are still poorly understood. Herein, sodium carboxymethyl cellulose (CMC)‐based, and polyvinylidene fluoride (PVDF)‐based graphite electrodes are introduced as model systems to quantify the electrolyte decomposition, solid electrolyte interphase (SEI) formation, and the corresponding kinetic evolution transition. A noncatalytic electrolyte reduction path on the CMC‐based electrode and a catalytic reduction path on the PVDF‐based electrode are identified, in terms of the reduction overpotential and product selectivity. The electrolyte reduction and/or SEI formation are found to occur in a successive, two‐step manner, starting with the electrochemical reduction at a potential above 0.35 V where no potassiation has happened (step I), and followed by the thermodynamically accelerated electrolyte reduction at a potential below 0.35 V (step II). Kinetics analysis reveals the former is charge transfer‐controlled for both CMC and PVDF‐based electrodes, and the latter involves a kinetic transition to SEI resistance controlled for the PVDF system, while it is charge transfer‐controlled for the CMC system. All these examples, highlight that binder chemistry plays a dominant role in the electrolyte decomposition and electrode/electrolyte interfacial properties, and promote a better fundamental understanding of electrolyte reduction. [ABSTRACT FROM AUTHOR]

High‐energy lithium‐ion batteries (LIBs) can be realized with the use of nickel‐rich materials, however, their reversible operation requires long‐term cathode‐electrolyte interfacial (CEI) stability, especially for high‐temperature applications, but how the CEIs evolves during operation is still a mystery. The unstable CEIs have been recently ascribed to them generating/disappearing/regenerating during Li+ extraction/insertion by in situ Fourier Transform Infrared Spectroscopy spectrum. Herein, a strategy of insoluble CEI is proposed toward addressing the interfacially induced deterioration of cathodes with a focus on Ni‐rich layered oxides. Incorporating unsaturated units (CC/CC) to siloxane as electrolyte additives advances the commercial LiNi0.8Co0.1Mn0.1O2/graphite cells up to around 300 cycles at 60 °C with more than 85% capacity retention, along with the LiCoO2 cells reaching ≈90% capacity retention over 350 cycles under 80 °C. The experimentally and theoretically detailed investigation shows that the higher unsaturation bond with high reactive sites show more polymerization via a 3D topological pathway to form insoluble CEI species, leading to suppression of parasitic reactions, corrosive acid, transition‐metal dissolution, stress corrosive cracking, and impedance growth. The scientific discoveries of this study highlight the pivotal role of electrode–electrolyte interactions and recapitulates the tried‐and‐true "electrolyte" approach for the future development of high‐energy batteries under extreme temperature conditions. [ABSTRACT FROM AUTHOR]

In this work, trimethylboroxine is used as electrolyte additive to improve the electrode/electrolyte interface stability of LiNi 1/3 Co 1/3 Mn 1/3 O 2 (LNCM) cathode for high voltage lithium ion battery. Charge/discharge tests show that addition of 3% TMB is the optimal amount for LNCM. After 300 cycled at 1C rate under the cut-off charge voltage of 4.5 V, the LNCM with 3% TMB achieves a capacity retention of 99%, compared to the 40% of that using STD electrolyte (1 M LiPF 6 in ethylene carbonate/diethyl carbonate /dimethyl carbonate). The results from LSV, EIS and physical characterizations, including SEM, TEM, XPS and ICP–MS, demonstrate that TMB oxidizes preferentially to the STD electrolyte, and catalyzes the decomposition of base electrolyte subsequently, generating a thin and low impedance film on the LNCM surface, which effectively stabilizes the electrode/electrolyte interface by suppressing the continuous oxidation of STD electrolyte and the dissolution of LNCM, and hence, improves the cyclic and rate performances of LNCM under high voltage. [ABSTRACT FROM AUTHOR]

Abstract: In this work, tris (trimethylsilyl) phosphate (TMSP) is used as an electrolyte additive to improve the cycling performance of Li/LiNi0.5Mn1.5O4 cell upon cycling at high voltage, 4.9 V vs. Li/Li+ at room temperature and elevated temperature (55 °C). The effects of TMSP on the cathode interface and the cycling performance of Li/LiNi0.5Mn1.5O4 cell were investigated via the combination of electrochemical methods, including cycling test, cyclic voltammetry (CV), chronoamperometry, and electrochemical impedance spectroscopy (EIS). It is found that cells with electrolyte containing TMSP have better capacity retention than that of the cells without TMSP upon cycling at high voltage at room temperature and elevated temperature. The functional mechanism of incorporation of TMSP to the electrolyte to improve the cycling performance is conducted with ex-situ analysis approaches, including X-ray diffraction (XRD), scanning electron microscope (SEM), thermal gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), transmission electron microscope (TEM) and ICP-MS. The surface analysis results reveal that more stable and more conductive surface layer is formed on the LiNi0.5Mn1.5O4 electrode with TMSP containing electrolyte, which is a leading factor for the enhanced the cycling performance of Li/LiNi0.5Mn1.5O4 cells upon cycling at high voltage at room temperature and elevated temperature. [Copyright &y& Elsevier]

Abstract: 4,5-Dimethyl-[1,3]dioxol-2-one (DMDO) was used as a novel electrolyte additive for lithium-ion batteries. The effect of DMDO on the formation of the solid electrolyte interface (SEI) on anode and cathode of MCMB/LiNi0.8Co0.2O2 cells was investigated via a combination of electrochemical methods, X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations. It is found that cells with electrolyte containing 2% DMDO have better capacity retention than cells without DMDO and this improved performance is ascribed to the assistance of DMDO in forming better SEIs on anode and cathode. DMDO-decomposition products are identified experimentally on the surface of the anode and cathode and supported by theoretical calculations. [ABSTRACT FROM AUTHOR]

The formation mechanism of protective interphases on high voltage cathodes of lithium ion batteries, resulting from phenyl trifluoromethyl sulfide (PTS) as an electrolyte additive, is understood through theoretical calculations, and confirmed by evaluating the cyclic stability of a lithium-rich cathode, Li 1·2 Mn 0·54 Ni 0·13 Co 0·13 O 2 , in the electrolytes with and without PTS. It is found that PTS is oxidized through the transferring of one fluorine atom from methyl to phenyl and the subsequent breaking of bond S–C in phenyl, yielding fluorobenzene and sulfur-contained radical that construct mainly the protective interphase. With this interphase formed from PTS, the cyclic stability of Li 1·2 Mn 0·54 Ni 0·13 Co 0·13 O 2 is significantly improved. The capacity retention of Li 1·2 Mn 0·54 Ni 0·13 Co 0·13 O 2 in 1.0 M LiPF 6 -EC/EMC/DEC (3/5/2 by weight) at 0.5C after 200 cycles is enhanced from 39% to 83% by adding 0.5% PTS. [ABSTRACT FROM AUTHOR]

Although the "water‐in‐salt" electrolyte has significantly expanded the electrochemical stability window of aqueous electrolytes from 1.23 to 3 V, its inevitable hydrogen evolution under 1.9 V versus Li+/Li prevents the practical use of many energy‐dense anodes. Meanwhile, its liquidus temperature at 17 °C restricts its application below ambient temperatures. An advanced hybrid electrolyte is proposed in this work by introducing acetonitrile (AN) as co‐solvent, which minimizes the presence of interfacial water at the negatively charged electrode surface, and generates a thin and uniform interphase consisting of an organic outer layer based on nitrile (CN) and sulfamide (R‐S‐N‐S) species and an inner layer rich in LiF. Such an interphase significantly suppresses water reduction and expands the electrochemical stability window to an unprecedented width of 4.5 V. Thanks to the low freezing point (−48 °C) and low viscosity of AN, the hybrid electrolyte is highly conductive in a wide temperature range, and enables a LiMn2O4/Li4Ti5O12 full cell at both ambient and sub‐ambient temperatures with excellent cycling stability and rate capability. Meanwhile, such a hybrid electrolyte also inherits the nonflammable nature of aqueous electrolyte. The well‐balanced merits of the developed electrolyte make it suitable for high energy density aqueous batteries. [ABSTRACT FROM AUTHOR]

• Holey 2D MnCo 2 O 4 nanosheets were prepared by using GO as sacrificial template. • The unique morphological feature of MnCo 2 O 4 yields an excellent capacity delivery ability. • MnCo 2 O 4 //AC supercapattery delivers high energy and power densities. Two dimensional (2D) nanostructure materials are auspicious for energy storage application due to their excellent electrical conductivity and electrochemical properties. We report a facial synthesis of holey 2D MnCo 2 O 4 nanosheets using bottom-up process and apply the as-synthesized materials as a positive electrode for supercapattery. The fabricated electrode shows an excellent capacity due to the large electrochemical active area and a number of nanoholes in the nanosheets, which allow fast electrochemical redox reaction. The assembled supercapattery coupled with AC negative electrode delivers a specific capacity of 152.7 mAh g−1 at a current density of 5 mA cm−2 with a high specific energy density of 33.8 Wh kg−1 (at a power density of 318.9 W kg−1). Furthermore, the supercapattery shows an excellent cycle stability of ∼85% capacity retention even after 10,000 cycles at a high current density of 30 mA cm−2. The reported simple and versatile fabrication technique allows the synthesis of various metal oxide nanosheets with the 2D structure as well as with porous nature, offering an interest in various electrochemical applications such as electrocatalyses and biosensors. [ABSTRACT FROM AUTHOR]

Abstract Lithium-sulfur battery is one of the most promising next-generation energy storage devices owing to its high energy density and environment friendliness. However, the low electronic conductivity of sulfur and the high solubility of intermediates in electrolyte are the challenges for its wide applications. To address these issues, we report a novel architecture, a coral-like reduced graphene oxide/tungsten sulfide hybrid, as host for sulfur cathode. This hybrid is fabricated by in-situ growing tungsten sulfide nanoflakes on a reduced graphene oxide aerogel, providing not only a 3D network for electronic conductivity, but also a large surface area to entrap chemically the intermediates. As expected, the sulfur cathode based on this hybrid support exhibits a high discharge capacity of 1531 mAh g−1 at 0.05 C and a high sulfur utilization of 91.6%. Even at a high rate of 1 C, an initial specific capacity of 883 mAh g−1 and an extremely low capacity-decay rate of 0.086% per cycle are still achieved. The ability of the resulting hybrid to entrap the intermediates is confirmed by combining physical characterization and theoretical calculations. Highlights • Coral-like rGO/WS 2 hybrid is fabricated as a host for sulfur cathode of Li/S battery. • Coral-like rGO provides a 3D network for electronic conductivity. • The hybrid possesses large surface area to entrap chemically intermediate polysulfides. • The rGO/WS 2 -S cathode exhibits excellent cyclic stability and rate capability. [ABSTRACT FROM AUTHOR]

Abstract: High energy batteries urgently required to power electric vehicles are restricted by a number of challenges, one of which is the sluggish kinetics of cell reactions under low temperatures. A novel approach is reported to improve the low temperature performance of high energy batteries through rational construction of low impedance anode and cathode interface films. Such films are simultaneously formed on both electrodes via the reduction and oxidation of a salt, lithium difluorobis(oxalato) phosphate. The formation mechanisms of these interface films and their contributions to the improved low temperature performances of high energy batteries are demonstrated using various physical and electrochemical techniques on a graphite/LiNi0.5Co0.2Mn0.3O2 battery using 1 m LiPF6‐ethylene carbonate/ethyl methyl carbonate (1/2, in weight) baseline electrolyte. It is found that the interface impedances, especially the one on the anode, constitute the main obstacle to capacity delivery of high energy batteries at low temperatures, while the salt containing fluorine and oxalate substructures used as additives can effectively suppress them. [ABSTRACT FROM AUTHOR]

Abstract: Graphitic carbon nitride (g‐CN) has emerged as a promising material for energy‐related applications. However, exploitation of g‐CN in practical devices is still limited owing to difficulties in fabricating g‐CN films with adjustable properties and high surface area. A general and simple pathway is reported to grow highly porous and large‐scale g‐CN films with controllable chemical and photophysical properties on various substrates using the doctor blade technique. The growth of g‐CN films, ascribed to the formation of a supramolecular paste, comprises g‐CN monomers in ethylene glycol, which can be cast on different substrates. The g‐CN composition, porosity, and optical properties can be tuned by the design of the supramolecular paste, which upon calcination results in a continuous porous g‐CN network. The strength of the porous structure is demonstrated by high electrochemically active surface area, excellent dye adsorption and photoelectrochemical and photodegradation properties. [ABSTRACT FROM AUTHOR]

Abstract: Graphitic carbon nitride (g‐CN) has emerged as a promising material for energy‐related applications. However, exploitation of g‐CN in practical devices is still limited owing to difficulties in fabricating g‐CN films with adjustable properties and high surface area. A general and simple pathway is reported to grow highly porous and large‐scale g‐CN films with controllable chemical and photophysical properties on various substrates using the doctor blade technique. The growth of g‐CN films, ascribed to the formation of a supramolecular paste, comprises g‐CN monomers in ethylene glycol, which can be cast on different substrates. The g‐CN composition, porosity, and optical properties can be tuned by the design of the supramolecular paste, which upon calcination results in a continuous porous g‐CN network. The strength of the porous structure is demonstrated by high electrochemically active surface area, excellent dye adsorption and photoelectrochemical and photodegradation properties. [ABSTRACT FROM AUTHOR]

Electrolyte additives are necessary for the application of high potential cathode in high energy density lithium ion batteries, especially at elevated temperature. However, the electrolyte additives that can effectively suppress the dissolution of transition metal ions from cathode have seldom been developed up to date. In this work, we propose a novel electrolyte additive, trimethylsilylcyclopentadiene (SE), for high temperature application of a representative high potential cathode, lithium nickel manganese oxide (LiNi 0.5 Mn 1.5 O 4 ). It is found that the dissolution of Mn and Ni from LiNi 0.5 Mn 1.5 O 4 can be effectively suppressed by applying SE. With applying 0.25% SE, the dissolved amount of Mn and Ni is decreased by 97.4% and 98%, respectively, after 100 cycles at 55 °C. Correspondingly, the cyclic performance of LiNi 0.5 Mn 1.5 O 4 is significantly improved. Physical characterizations and electrochemical measurements show that SE can be preferentially oxidized and generate a protective film on LiNi 0.5 Mn 1.5 O 4 . The resulting film inhibits the electrolyte decomposition and the transition metal ion dissolution. [ABSTRACT FROM AUTHOR]

Diethyl phenylphosphonite (DEPP) is used as a novel electrolyte additive to improve the cyclability of spinel LiMnO upon cycling at elevated temperature (55 °C). The charge/discharge cycling stability results indicate that capacity retention of Li/LiMnO cell is significantly improved from 40 to 78% at a rate of 1C (1C = 120 mAh g) when 1.0 wt% DEPP is added to the baseline electrolyte (1.0 M LiPF in EC/EMC/DEC (3:5:2, vol.%)) after 450 cycles at 55 °C. This improvement can be attributed to the preferential oxidation of DEPP to that of the baseline electrolyte and the subsequent formation of a protective film on the cathode surface. This passivation film suppresses detrimental electrolyte decomposition and in turn protects LiMnO from further decomposition. Molecular energy level calculations, linear sweep voltammetry, and cyclic voltammetry results confirm that DEPP is oxidized on the cathode surface prior to the oxidation of carbonate solvents. Electrochemical impedance spectroscopy illustrates that the the cathode interfacial film generated from DEPP oxidation is more stable and robust than that of the surface film yielded from the baseline electrolyte's decomposition. Ex situ surface-characterization results further support the claim that DEPP incorporation in the electrolyte suppresses the electrolyte oxidation at elevated temperature and the decomposition of LiMnO cathode material as well. Graphical Abstract: The highest occupied molecular orbital energy of DEPP (−6.75305 eV) is higher than that of EC (−8.73078 eV), EMC (−8.40479 eV), and DEC (−8.36043 eV). Furthermore, the oxidation potential and the ionization energy also demonstrate that DEPP is more easily oxidized than electrolyte solvents. Therefore, DEPP is preferred to be oxidized on the cathode than the baseline electrolyte. [ABSTRACT FROM AUTHOR]

Currently, the application of high voltage cathode is hindered by its instability of electrode/electrolyte interphase. Continuous electrolyte oxidation and products accumulation lead to the increase of electrode polarization, and the degeneration of cycle life, rate capability and low temperature performance. Such interfacial challenge is even more serious for Ni-rich cathode materials, because the high nickel state generated during charging would further aggravate these side reactions. Lithium tetraborate (Li 2 TB), a novel electrolyte film-forming additive is proposed in this work to conduct a high stability and low impedance interphase on the Ni-rich cathode surface. After 300 cycles, the capacity retention of LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM622)/Li half-cell with 2 wt% Li 2 TB increases from 50% to 76%. After 150 cycles at low temperature, the capacity retention with Li 2 TB achieves 99%, compared with 47% for the one without additive. Moreover, the capability of Li 2 TB additive on enhancing the interphasial stability of NCM622 cathode has been further verified in 2 Ah-grade NCM622/graphite pouch cell. Finally, the mechanism of additive is proposed by combining theoretical calculation and experimental results. [Display omitted] • Li 2 TB additive builds a highly stable and conductive CEI film on NCM622 cathode. • The Li 2 TB-derived CEI film is composed of B–O rich oligomer. • The electrochemical performances of high-voltage NCM622 are remarkably enhanced. • The Li 2 TB is successfully applied in the 2Ah-grade NCM622/graphite pouch cell. [ABSTRACT FROM AUTHOR]

• A brand-new all-climate GPE was rationally designed to in-situ engineer interfaces within high-power lithium-ion battery. • The GBL-based GPE endows lithium-ion battery with remarkable all-climate performances. • The high-power pouch cell with the non-flammable GPE exhibit great tolerance under abusive conditions. Lithium-ion batteries (LIBs) with gel polymer electrolytes (GPE) employing highly volatile and extremely flammable linear carbonate solvents still face the safety hazard of fire and combustion. Gamma-butyrolactone (GBL) as electrolyte solvent can greatly improve the safety and all-climate performance of LIBs due to its higher flash point, lower vapor pressure, better thermal stability and wider liquid temperature range than those of the carbonate solvents. However, the application of GBL solvent is hindered by its incompatibility with the most widely used graphite anode. Herein, an all-climate high-power LiMn 2 O 4 + LiMn 0.7 Fe 0.3 PO 4 /graphite pouch cell is achieved by employing non-flammable GBL-based GPE. The interphacial instability of GBL/graphite is solved by introducing three synergistic film-forming additives, including lithium bis(oxalato)borate, 4-vinyl-1,3-dioxolan-2-one and 3-sulfolene. The developed non-flammable GBL-based GPE enables the all-climate high-power LIBs application with great room-temperature rate capability, excellent low-temperature cranking and long elevated-temperature durability. More importantly, the developed pouch cells exhibit excellent cold-cranking performance even at −18 °C and maintain a high-capacity retention of 80 % after 400 cycles at 1C at 25 °C. [ABSTRACT FROM AUTHOR]

The specific capacity of lithium-ion battery with lithium cobalt oxide as cathode depends on the upper limitation voltage for charge/discharge cycling, but this oxide tends to be destructed structurally when it is cycled in carbonate-based electrolyte under high voltage. We report a novel electrolyte additive, fumaronitrile (FN, CN CH CH CN), which can maintain the structural integrity of lithium cobalt oxide. Electrochemical measurements indicate that lithium cobalt oxide exhibits poor cyclic stability when it is cycled under 4.5 V (vs. Li/Li + ) and the charged cathode suffers serious self-discharge in a base electrolyte, 1.0 mol L −1 LiPF 6 in EC/EMC/DEC (3:5:2, by weight). These issues can be overcome effectively by adding 0.5% FN into the base electrolyte. Physical and chemical characterizations demonstrate that the poor cyclic stability and self-discharge of lithium cobalt oxide result from its structural destruction caused by HF formed from electrolyte decomposition, and FN yields a protective cathode interphase film which maintains the structural integrity of lithium cobalt oxide. [ABSTRACT FROM AUTHOR]

We present a novel configuration for stabilizing manganese oxide as anode of high energy density lithium ion battery. Porous Mn 2 O 3 nanocubes were developed with cubic MnCO 3 as precursor and coated with a solid electrolyte interphase (SEI) by applying an electrolyte additive, prop-1-ene-1,3-sultone (PES). Discharge-charge tests demonstrate that the resulting anode exhibits excellent cyclic stability. Electrochemical and physical characterizations indicate that PES is easily reducible on Mn 2 O 3 forming a protective SEI, which maintains the structural integrity of Mn 2 O 3 particles. The porosity of the cubes and the SEI on the particles co-contribute to the improved cyclic stability of the resulting anode. [ABSTRACT FROM AUTHOR]

1,1′-sulfonyldiimidazole (SDM) has been investigated as a novel carbonate-based electrolyte additive for high voltage nickel-rich cathode chemistry, graphite/LiNi 0.5 Co 0.2 Mn 0.3 O 2 cells. Upon cycling at high voltage for 50 cycles, graphite/LiNi 0.5 Co 0.2 Mn 0.3 O 2 cells with SDM containing electrolyte have superior cycling performance than the cells with baseline electrolyte, specifically, 96.9% and 73.1% capacity retention, respectively. Moreover, cells with 0.25 wt. % SDM have lower impedance and better elevated temperature storage performance as well. The functional mechanism of electrolyte containing SDM on improved cycling performance is elucidated with ex-situ analytical techniques, including scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and fourier transform infrared spectroscopy (FTIR), etc. The surface analysis result reveals that SDM has been involved into the surface film forming on the LiNi 0.5 Co 0.2 Mn 0.3 O 2 cathode and graphite anode as well, which can simultaneously provide protection for both cathode and anode upon cycling to high voltage, leading to enhanced cyclability of the high voltage (4.5 V vs. Li/Li + ) graphite/LiNi 0.5 Co 0.2 Mn 0.3 O 2 cells with the presence of SDM. [ABSTRACT FROM AUTHOR]