High-Resolution Nanoanalytical Insights into Particle Formation in SnO2/ZnO Core/Shell Nanowire Lithium-Ion Battery Anodes

Tinoxide (SnO2)/zinc oxide (ZnO) core/shell nanowiresas anode materials in lithium-ion batteries (LIBs) were investigatedusing a combination of classical electrochemical analysis and high-resolutionelectron microscopy to correlate structural changes and battery performance.The combination of the conversion materials SnO2 and ZnOis known to have higher storage capacities than the individual materials.We report the expected electrochemical signals of SnO2 andZnO for SnO2/ZnO core/shell nanowires as well as unexpectedstructural changes in the heterostructure after cycling. Electrochemicalmeasurements based on charge/discharge, rate capability, and electrochemicalimpedance spectroscopy showed electrochemical signals for SnO2 and ZnO and partial reversibility of lithiation and delithiation.We find an initially 30% higher capacity for the SnO2/ZnOcore/shell NW heterostructure compared to the ZnO-coated substratewithout the SnO2 NWs. However, electron microscopy characterizationrevealed pronounced structural changes upon cycling, including redistributionof Sn and Zn, formation of similar to 30 nm particles composed of metallicSn, and a loss of mechanical integrity. We discuss these changes interms of the different reversibilities of the charge reactions ofboth SnO2 and ZnO. The results show stability limitationsof SnO2/ZnO heterostructure LIB anodes and offer guidelineson material design for advanced next-generation anode materials forLIBs.

Automated summary

The SnO2/ZnO core/shell nanowires, as anode materials in LIBs, were studied using electrochemical analysis and electron microscopy to understand the relationship between structural changes and battery performance. The combination of SnO2 and ZnO showed higher storage capacities, but cycling caused significant structural changes and loss of mechanical integrity. This study provides insights into the stability limitations of SnO2/ZnO heterostructure LIB anodes and offers guidance for the design of next-generation anode materials.