A Low-Cost and High-Capacity SiO x /C@graphite Hybrid as an Advanced Anode for High-Power Lithium-Ion Batteries

Low-temperature electrolytes based on linear carboxylic ester co-solvents for SiO x /graphite composite anodes

Silicon-based anode materials have been applied in lithium-ion batteries with high energy density. However, developing electrolytes that can meet the specific requirements of these batteries at low temperatures still remains a challenge. Herein, we report the effect of linear carboxylic ester ethyl propionate (EP), as the co-solvent in a carbonate-based electrolyte, on SiO _x /graphite (SiOC) composite anodes. Using electrolytes with EP, the anode provides better electrochemical performance at both low temperatures and ambient temperature, showing a capacity of 680.31 mA h g^-1 at -50 °C and 0.1C (63.66% retention relative to that at 25 °C), and a capacity retention of 97.02% after 100 cycles at 25 °C and 0.5C. Within the EP-containing electrolyte, SiOC‖LiCoO₂ full cells also exhibit superior cycling stability at -20 °C for 200 cycles. These substantial improvements of the EP co-solvent at low temperatures are probably due to its involvement to form a solid electrolyte interphase with high integrity and facile transport kinetics in electrochemical processes.

A Low-Cost SiO x /C@Graphite Composite Derived from Oat Husk as an Advanced Anode for High-Performance Lithium-Ion Batteries

Silicon monoxide (SiO _x ), as a promising anode for the next-generation high-power lithium-ion batteries, has some advantages such as higher lithium storage capacity (∼2400 mAh g^-1), suitable working potential, and smaller volume variations during cycling compared with pure silicon. However, its disadvantages such as its inherent low conductivity and high cost impede its extensive applications. Herein, we have developed a low-cost and high-capacity SiO _x /C@graphite (SCG) composite derived from oat husks by a simple argon/hydrogen reduction method. For further practical application, we also investigated the electrochemical performances of SiO _x mixed with different ratios of graphite. As an advanced anode for lithium-ion batteries, the SCG-1 composite exhibits an excellent electrochemical performance in terms of lithium storage capacity (809.5 mAh g^-1 at 0.5 A g^-1 even after the 250th cycle) and high rate capability (479.7 mAh g^-1 at 1 A g^-1 after the 200th cycle). This work may pave the way for developing a low-cost silicon-based anode derived from biomass with a large reversible capacity and long cycle life in lithium-ion batteries.

Control of cyclic stability and volume expansion on graphite–SiOx–C hierarchical structure for Li-ion battery anodes

To increase the energy density of today's batteries, studies on adding Si-based materials to graphite have been widely conducted. However, adding a Si-based material in the slurry mixing step suffers from low distribution due to the self-aggregation property of the Si-based material. Herein, a hierarchical structure is proposed to increase the integrity by using APS to provide a bonding effect between graphite and SiO_x. Additionally, to endow a protection layer, carbon is coated on the surface using the CVD method. The designed structure demonstrates enhanced integrity based on electrochemical performance. The MSG (methane decomposed SiO_x@G) electrode demonstrates a high ICE of 85.6% with 429.8 mA h g⁻¹ initial discharge capacity. In addition, the MSG anode has superior capacity retention (89.3%) after 100 cycles, with enhanced volumetric expansion (12.7%) after 50 cycles. We believe that the excellent electrochemical performance of MSG is attributed to increased integrity by using APS (3-aminopropyltrimethoxysilane) with a CVD carbon coating.

This study demonstrates the increased integrity of graphite–SiO_x–C hierarchical structure using 3-aminopropyltrimethoxysilane (APS). Furthermore, the carbon coating contributes to elec-trode stability.