Facile Redox Synthesis and Surface Engineering of Porous Silicon from Zintl Compound for High-Performance Lithium Ion Battery Anodes.

Abstract

Porous silicon (pSi) is considered a promising candidate for next-generation high-energy-density lithium-ion battery (LIB) anodes due to its ability to mitigate volume expansion stress. However, the lack of efficient preparation methods and severe side reactions due to its large specific surface area have hindered its commercial development. This study leverages the redox reaction between the Zintl compound Mg2Si and SiO2 at certain temperatures, using intermediate products as templates, and incorporates CVD deposition to create carbon-coated porous silicon (pSi@C) composite anode materials with excellent electrochemical performance. This approach enables pSi to achieve a high specific capacity, high rate performance, and long lifetime. Additionally, a prelithiation process effectively addresses the issue of low initial Coulombic efficiency (ICE) in pSi electrodes. In half-cell tests, the pSi@C electrode delivered a reversible specific capacity as high as 1500 mAh g-1 and outstanding rate performance (over 500 mAh g-1 at a high current density of 5 A g-1). After repeated charge/discharge 1000 times at 1 A g-1, the reversible capacity remained at 555 mAh g-1. Full-battery assembly with NCM811 cathodes also demonstrated the potential of pSi@C as a promising anode candidate. This work aims to expand the preparation methods for pSi materials and provide guidance for their application in high-energy-density LIBs.