Hierarchically structured silicon–carbon anodes: Achieving high-performance all-solid-state Li-ion batteries via chemical pre-lithiation and in-situ polymerization

Abstract

Silicon has emerged as a highly promising contender to replace graphite anodes in the next generation of lithium-ion batteries, primarily owing to its exceptional specific capacity. Nevertheless, due to its huge volume expansion and the continuous generation of a solid electrolyte interface layer during lithiation, silicon-based anodes are difficult to apply directly in all-solid-state lithium-ion batteries. In this work, a triple strategy including a double-layer carbon wrapping, a chemical pre-lithiation method and an in-situ polymerization technology is used jointly to design the all-solid-state Li-ion battery with high stability and excellent coulombic efficiency. The Si@C@C composites are obtained by embedded Si nanoparticles in citric acid and ZIF-8 derived bilayer carbon. Finite element simulation proves that the stress concentration caused by the lithiation of silicon has been significantly alleviated by the double-layer carbon strategy. Moreover, a chemical pre-lithiation method is introduced to compensate the irreversible loss of Li ions of the Si@C@C electrode in the first cycle, and as a result enables an increased first efficiency. Finally, an in-situ polymerization technology is developed to achieve the all-solid-state battery, in which the PDOL-SN polymerization system utilizing LiPF₆ as the initiator and SN as a key additive features exceptional ionic conductivity and high oxidation potential. The as-assembled NCM811|PDOL-SN|Si@C@C-10 % all-solid-state battery shows high ICE (79.5 %) and excellent cycling stability (capacity retention: 82.4 % after 300 cycles). The methodology may be useful in designing the silicon-based all-solid-state lithium-ion battery with the purpose to address those bottleneck issues brought by the silicon negative electrode for its practical application.