4305661

Development strategy for high-performance porous Si anodes for lithium-ion batteries

Date
August 18, 2025

Silicon (Si) has been regarded as a promising anode for Li-ion batteries due to its high theoretical capacity (4200 mAh/g) compared to graphite anode (372 mAh/g). However, it undergoes significant volume changes (~ 300%) during lithiation and delithiation, leading to particle pulverization and continuous electrolyte decomposition on Si surface, which hinders its practical application. Herein, we investigated two cost-effective strategies for Si anode to enable high performance Si-based Li ion batteries. First, we developed an organic solvent assisted HF etching process to prepare porous Si as an anode for Li ion batteries. In conventional approach, porous Si was obtained by etching in hydrogen fluoride (HF) to accommodate the volume changes and improve the overall performance of silicon anodes. However, HF etching is highly corrosive, leading to the generation of excess heat and bubbling, lower yields, and difficult to scale-up. In this work, organic solvent (such as benzene) was added in the etching solution of saturated HF/water solution to form a protection layer to protect the surface of Si/SiO2 particles, enabling controllable etching of Si/SiO2 matrix, and avoids safety concern such as excessive heat/gas generation. This etching method enables Si anode to have an expansion of only ~15 % even after long-term cycles. Second, we investigated effective pre-lithiation strategies for Si anode to increase its initial Coulombic efficiency. Although various pre-lithiation methods have been developed for commercial applications, most of them are complicated and costly. Our simple pre-lithiation approach is easier to be adopted for the production process. The various process parameters for pre-lithiation such as pre-lithiation time, temperature etc have been optimized to improve the initial coulombic efficiency and electrochemical performance of the Si anode. Further, the Si anode with our pre-lithiation process show enhanced the initial Coulombic efficiency and stable cycling performance in a Si||Li(Ni0.6Co0.2Mn0.2)O2 (NMC622) full cell.

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