Stress-Relieved Nanowires by Silicon Substitution for High-Capacity and Stable Lithium Storage

摘要

Silicon is promising as a high energy anode for next-generation lithium-ion batteries. However, severe capacity fading upon cycling associated with huge volume change is still an obstacle for silicon toward practical applications. Herein, the authors report that Si-substituted Zn-2(GeO4)(0.8)(SiO4)(0.2) nanowires can effectively suppress volume expansion effect, exhibiting high specific capacity (1274 mA h g(-1) at 0.2 A g(-1) after 700 cycles) and ultralong cycling stability (2000 cycles at 5 A g(-1) with a capacity decay rate of 0.008% per cycle), which represents outstanding comprehensive performance. The superior performance is ascribed to the substitution of Si atom that imparts to the nanowires not only high reactivity and reversibility, but also the unique stress-relieved property upon lithiation which is further confirmed by detailed density-functional theory computation. This work provides a new guideline for designing high-performance Si-based materials toward practical energy storage applications.