Reversible formation of metastable Sn-rich solid solution in SnO2-based anode for high-performance lithium storage

Abstract

Tin dioxide (SnO2) has been considered as a promising anode for high-energy alkali-ion batteries due to its high theoretical specific capacity, but still plagued by the intrinsic issues of Sn coarsening and significant volume change during cycling. Herein, a stable Ti-SnO2 material is tactfully designed and constructed via one-step simple hydrothermal reaction for highly reversible lithium storage. Density functional theory (DFT) calculations and experimental results show that a metastable Sn-rich Sn(Ti) solid solution can be reversibly formed after multiple conversion reaction of the Ti-SnO2 and exhibits high recrystallization temperature of 509–589 K. Then, the solid solution formed by Ti atoms during the cycling leading to the enhanced inhibitory effect on the coarsening of Sn. Therefore, the Sn(Ti) solid solution can maintain a small grain size of 10 nm even after hundreds of cycles. Take an example, the Ti-SnO2 anode displays a stable long life with high Li discharge capacity of 705 mAh g−1 and 95.4% capacity retention (compared to the initial specific discharge capacity) after 700 cycles at 1 A g−1. This work provides a novel and versatile strategy to suppress the coarsening of Sn by inducing a metastable Sn-rich solid solution for all Sn-based compound anodes in alkali-ion batteries.