Non-monotonic engineering of isomeric solvents for high-voltage Li-ion batteries with Si/C anodes

Silicon (Si) anode is considered one of the most promising next-generation anodes in high-energy density lithium-ion batteries (LIBs) due to its high specific capacity and abundant reserves. However, its severe volume expansion during cycling leads to rapid capacity degradation. In this work, an isomer engineering strategy is employed to reorganize the electrolyte solvation structure. The unique propyl formate (PF) molecule facilitates the formation of an anion-dominated Li⁺ solvation sheath, thereby constructing a solid electrolyte interphase (SEI) with high ionic conductivity and excellent mechanical compliance on the Si/C anode surface. As a result, Si/C||LiNi_0.8Co_0.1Mn_0.1O₂ full cells with the optimized electrolyte demonstrate impressive cycling stability, with a capacity retention of 83.7% at 0.5C after 400 cycles and 83.9% at 1C after 300 cycles. More notably, a high areal loading of 3 mAh cm^-2 full cell shows remarkable cycling stability retention over 150 cycles. This work provides an effective strategy for extending the cycling life of the Si-based anode by molecular design of electrolytes.