Synergistic Optimization of Cathode Composite Architecture and Stack Pressure for High‐Performance All‐Solid‐State Chloride‐Ion Batteries

ABSTRACT Chloride‐ion batteries (CIBs) represent a promising post‐lithium energy storage platform combining high theoretical energy density with elemental sustainability. However, All‐Solid‐State CIBs (ASS‐CIBs) remain hindered by limited ionic transport and interfacial instability. Here, we demonstrate a high‐performance VOCl/CsSn 0 . 9 In 0 . 067 Cl 3 (CSIC)/In system wherein systematic optimization of the cathode composite identifies an optimal 30:60:10 (VOCl/CSIC/C) ratio, delivering an initial specific capacity of 169 mAh g − 1 . X‐ray diffraction (XRD) with Rietveld refinement and field‐emission scanning electron microscopy (FESEM) confirmed phase purity and uniform particle distribution, while increasing stack pressure from 130 to 400 MPa markedly enhanced interfacial contact and active material utilization. The optimized configuration sustained stable cycling over 500 cycles at 0.1 mA cm − 2 with nearly 100% Coulombic efficiency. Time‐resolved electrochemical impedance spectroscopy (EIS), analyzed using the distribution of relaxation times (DRT) method, identified the VOCl–CSIC cathode interface as the dominant resistance contributor, while the In–CSIC anode remained comparatively stable. Ex situ XRD and focused ion beam–scanning electron microscopy (FIB‐SEM) corroborated these findings, revealing reversible phase transitions alongside structural breathing, particle cracking, and void formation. This work provides a kinetically and structurally rationalized design strategy toward durable ASS‐anionic shuttle batteries based on powdered electrode architectures.