Zero-Swelling Flake Graphite/Silicon Composite Anode for Sulfide-Based All-Solid-State Batteries

Silicon (Si) is a promising anode material for sulfide-based all-solid-state batteries (ASSBs) owing to its high theoretical capacity (3,579 mAh g -1 ) and low operating potential (0.4 V vs. Li + /Li), which suppresses lithium dendrite formation. However, severe volume changes during lithiation/delithiation (~300%) disrupt mixed ionic-electronic conduction (MIEC) pathways, leading to rapid electrode degradation. In this work, we propose a flake-type graphite/silicon (Flake Gr/Si) composite anode designed via chemical vapor deposition (CVD) of SiH 4 to address this challenge. The flake graphite substrate allowed uniform deposition of amorphous Si as thin (~15 nm) island-like domains, even at high Si loading (22 wt%). The homogeneously distributed Si on the flake-type Gr keeps MIEC percolation pathway with solid electrolytes during repeated cycling by accommodating the volume expansion within the voids between the islands and maintaining the interparticle contact with the vertical operational stack pressure. The Flake Gr/Si composite anode demonstrates remarkable cycling stability (85.6% capacity retention after 850 cycles), excellent rate performance (92.3% at 1C), and an unprecedentedly low electrode swelling ratio (~3% after 100 cycles). This study provides a new material design principle for mechanically stable Si-based composite anodes in ASSBs by harmonizing volume-change management with continuous MIEC percolation. Figure 1