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Severe capacity degradation at low temperatures (<−20°С) hampers wide applications of lithium‐ion batteries (LIBs) in consumer electronics and electric vehicles. Existing works are dedicated to electrolyte modification because that electrolyte controls both Li+ transportation and interfacial reaction. However, the efforts on electrolytes are always hard to balance rate performance and low‐temperature capacity due to their high viscosity. Herein, a binary coating layer for Li3V2(PO4)3 cathode material without changing electrolyte formulation is proposed, which significantly improves the high‐rate capability and low‐temperature performance of batteries. YPO4 nanoparticles are in situ formed in the amorphous surface carbon layer under the reaction between Li3V2(PO4)3 and Y(NO3)3 during post‐thermal treatment. The C+YPO4 binary coating reduces the side reactions of Li3V2(PO4)3 at high voltage. In addition, the binary surface coating also improves the interfacial kinetics of the electrode at low temperatures. Benefiting from these advantages, the Li3V2(PO4)3 cathode material can cycle stably at ultra‐high rates up to 50 C. In addition, the capacity retention at −20 and −40 °С are improved to 89.1% and 75.7%, respectively. This binary surface‐coated Li3V2(PO4)3 cathode material shows promising application potential in low‐temperature LIBs. [ABSTRACT FROM AUTHOR]

Fluorinated electrolytes possess good antioxidant capacity that provides high compatibility to high‐voltage cathode and flame retardance; thus, they are considered as a promising solution for advanced lithium‐ion batteries carrying both high‐energy density and high safety. Moreover, the fluorinated electrolytes are widely used to form stable electrolyte interphase, due to their chemical reactivity with lithiated graphite or lithium. However, the influence of this reactivity on the thermal safety of batteries is seldom discussed. Herein, we demonstrate that the flame‐retardant fluorinated electrolytes help to reduce the flammability, while the lithium‐ion batteries with flame‐retardant fluorinated electrolytes still undergo thermal runaway and disclose their different thermal runaway pathway from that of battery with conventional electrolyte. The reduction in fluorinated components (e.g., LiPF6 and fluoroethylene carbonate (FEC)) by fully lithiated graphite accounts for a significant heat release during battery thermal runaway. The 13% of total heat is sufficient to trigger the chain reactions during battery thermal runaway. This study deepens the understanding of the thermal runaway mechanism of lithium‐ion batteries employing flame‐retardant fluorinated electrolytes, providing guidance on the concept of electrolyte design for safer lithium‐ion batteries. [ABSTRACT FROM AUTHOR]

Li3V2(PO4)3 (LVP) has been highlighted as a promising cathode material for lithium ion batteries, but it suffers from poor rate capability and rapid capacity decay due to sluggish electrode kinetics and vigorous electrode/electrolyte side reactions at high voltage. In this study, an inexpensive aqueous lithium poly-acrylic acid (LiPAA) binder was developed to deftly solve the shortcomings of the LVP material by tailoring the functional groups in the binder. The good adhesion and cohesion properties of the LiPAA binder ensured a close linkage between the active LVP particles, conductive additives and current collector, which formed a stable and conductive network in the electrode. In addition, the reversible H+/Li+ exchange in LiPAA effectively assisted the transport of Li+ ions at the electrode interface, which allowed the establishment of a Li+ conductive pathway without considerable degradation of the electrolyte. Due to these advantages, the LVP electrode containing the LiPAA binder exhibited significantly improved electrochemical performance compared to the electrode that employed the traditional polyvinylidene fluoride binder. The new electrode configuration showed a large specific capacity of 107 mA h g−1 at 70C rate and a high capacity retention of 91% was obtained after 1400 cycles at 10C rate, showcasing the great potential of this aqueous binder in lithium ion batteries. [ABSTRACT FROM AUTHOR]

H2V3O8 nanowires wrapped by reduced graphene oxide (RGO) are synthesized successfully through a simple hydrothermal process. The structural properties of the samples are characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman scattering, and X-ray photoelectron spectroscopy. The RGO nanosheets modify the surfaces of the H2V3O8 nanowires through VC linkages. The H2V3O8/RGO composite exhibits a remarkably enhanced electrochemical performance in terms of its reversible capacity, cyclic performance, and rate capability. The material shows high discharge capacities of 256 and 117 mA h g−1 at the current densities of 0.1 and 1 A g−1, respectively, with almost no capacity fading after fifty charge/discharge cycles. Cyclic voltammetry and electrochemical impedance spectroscopy show that the superior electrochemical performance of H2V3O8/RGO can be attributed to the cooperation of RGO, which provides better mechanical flexibility, higher electronic conductivity, and smaller charge-transfer resistance. [ABSTRACT FROM AUTHOR]

The fabrication of silicon (Si) anode materials derived from high silica-containing plants enables effective utilization of subsidiary agricultural products. However, the electrochemical performances of synthesized Si materials still require improvement and thus need further structural design and morphology modifications, which inevitably increase preparation time and economic cost. Here, the conversion of corn leaves into Si anode materials is reported via a simple aluminothermic reduction reaction without other modifications. The obtained Si material inherits the structural characteristics of the natural corn leaf template and has many inherent advantages, such as high porosity, amorphous/crystalline mixture structure, and high-valence SiO x residuals, which significantly enhance the material's structural stability and electrode adhesive strength, resulting in superior electrochemical performances. Rate capability tests show that the material delivers a high capacity of 1200 mA h g -1 at 8 A g -1 current density. After 300 cycles at 0.5 A g -1 , the material maintains a high specific capacity of 2100 mA h g -1 , with nearly 100% capacity retention during long-term cycling. This study provides an economical route for the industrial production of Si anode materials for Lithium-Ion batteries., (© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

H 2 V 3 O 8 nanowires wrapped by reduced graphene oxide (RGO) are synthesized successfully through a simple hydrothermal process. The structural properties of the samples are characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman scattering, and X-ray photoelectron spectroscopy. The RGO nanosheets modify the surfaces of the H 2 V 3 O 8 nanowires through VC linkages. The H 2 V 3 O 8 /RGO composite exhibits a remarkably enhanced electrochemical performance in terms of its reversible capacity, cyclic performance, and rate capability. The material shows high discharge capacities of 256 and 117 mA h g -1 at the current densities of 0.1 and 1 A g -1 , respectively, with almost no capacity fading after fifty charge/discharge cycles. Cyclic voltammetry and electrochemical impedance spectroscopy show that the superior electrochemical performance of H 2 V 3 O 8 /RGO can be attributed to the cooperation of RGO, which provides better mechanical flexibility, higher electronic conductivity, and smaller charge-transfer resistance., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)