Elevated sulfide all-solid-state battery performance enabled by boron and phosphorus doping in nano silicon anodes

Sulfide all-solid-state batteries (ASSBs) using high-capacity silicon (Si) anodes and high‑nickel ternary cathodes offer a promising route to realize high energy density and safety simultaneously. However, the low inherent electronic conductivity of Si constrains its further application in ASSBs. Importing element doping is an available strategy to improve intrinsic electronic conductivity of raw Si anodes. Herein, the effects of N-type (phosphorus doped) and P-type (boron doped) Si anodes were systematically studied in ASSBs. The doping type and doping contents determined the anodic performances. It is unraveled that the doping element with low content will migrate away from the Si matrices during the initial lithiation and amorphization process of the Si anode, forming low conductivity elemental phases. These low conductivity doping elements hinder internal Li⁺ migration through Si particles and deteriorate the electrochemical performance. In contrast, the high content element doping remains stable conductive ionic network inside the Si particles. In addition, the N-type Si with phosphorus formed conductive Li₃P help to increase the lithium utilizations. Therefore, after prelithiation, matching with Li(Ni_0.83Co_0.11Mn_0.06)O₂ (NCM811) cathode, the capacity retention of the high content doped N-type Si ASSBs is 76.24 % after 100 cycles at 0.5C, whereas the capacity retention of the raw Si ASSBs is only 70.61 %.