Manipulating charge-transfer kinetics and a flow-domain LiF-rich interphase to enable high-performance microsized silicon–silver–carbon composite anodes for solid-state batteries

Silicon (Si) anode with high theoretical specific capacity (3579 mAh g−1) offers great promise for realizing high-energy solid-state batteries (SSBs). However, given Si’s huge volume variations during cycling, sluggish kinetics and unfavorable interface stability with solid-state electrolyte (SSE), its practical potential in SSBs has not been fully exploited. Herein, we propose a design of highly-dense Ag nanoparticles decorated porous microsized Si, which is coated by thin-layer carbon (PS-Ag-C) working as high-performance anode for boosting SSBs performance. Specifically, the mechanical stress at interface, originated from large volume change of Si, can be alleviated by the highly porous architecture. Meanwhile, the continuous charge transfer within Si can be facilitated by the introduction of Ag nanoparticles, thin carbon layer and the as-formed Ag-Li alloys, which contributes to high-rate capability and stable cycling performance. Furthermore, coupled with poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)/Li1.3Al0.3Ti1.7(PO4)3 (LATP) SSE with low mobility, a flow-domain LiF-rich solid-electrolyte-interphase (SEI) is formed, which ensuring desirable interfacial and mechanical stability. Accordingly, the as-fabricated PS-Ag-C anode achieves high reversible capacities of 3030.3 mAh g−1 at 0.2 A g−1with an initial Coulombic efficiency of 90% and 1600 mAh g−1 over 500 cycles at 1 A g−1, respectively. In particular, we observed the highest areal capacity reaches 4.0 mAh cm−2 over 100 cycles at 0.5 A g−1 in Si-based SSBs with organic-inorganic composite SSEs. Moreover, a solid-state full cell assembled with the as-obtained PS-Ag-C anode and LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode demonstrates high capacity and desirable cycling stability. This work provides new insights into developing high-capacity and durable Si anode toward high-performance SSBs.