Lifetime Optimization of Amorphous Silicon Thin-Film Anodes for Lithium-Ion Batteries

Silicon has emerged as a highly promising anode materialfor lithium-ionbatteries (LIBs) owing to its high specific capacity and low voltage.However, previous research on silicon-based anodes has not adequatelyaddressed inherent issues, leading to limited commercial applicationson a large scale. Therefore, further scientific investigation is necessaryto uncover the lithiation/delithiation process in silicon materialsand understand the influence of electrode potential and charge stateon the kinetic process during charge and discharge. This understandingwill be instrumental in gradually enhancing the performance of siliconmaterials. Herein, amorphous silicon films were prepared for LIB anodesusing the magnetron sputtering method. Molecular dynamics simulationswere conducted to investigate the microstructure and volumetric changesof the sputtered amorphous silicon anode during the lithiation anddelithiation processes. Additionally, electrochemical characterizationtechniques such as a galvanostatic intermittent titration technique,electrochemical impedance spectroscopy, and galvanostatic charge-dischargetest were employed to explore the electrochemical properties of siliconelectrodes. Electrochemical analysis techniques, such as the differentialcapacity method and distribution of relaxation times, were also usedto investigate the deterioration mechanisms of the electrochemicaland conversion properties of amorphous silicon anodes. Results revealedthat the lithium-ion content in Li x Si,determined through the set cutoff voltage during charge/dischargecycling, considerably affected the volume change of the silicon anodeand the composition and integrity of the solid electrolyte interfaceafter cycling. The optimum discharge cutoff voltage was found to be0.08 V for the amorphous silicon electrode, leading to an optimumcycle life with a capacity retention of 87.17% after 100 cycles.

Automated summary

Silicon has great potential as an anode material for lithium-ion batteries due to its high capacity and low voltage. However, previous research has not fully addressed the issues with silicon-based anodes, limiting their commercial applications. Further scientific investigation is needed to understand the lithiation/delithiation process in silicon materials and how electrode potential and charge state affect the kinetic process. This understanding will help improve the performance of silicon materials.