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Lithium‐sulfur batteries utilizing sulfide solid electrolytes hold considerable potential for achieving both high energy density and enhanced safety. However, the substantial volume changes experienced by sulfur during cycling result in mechanical stress accumulation, leading to mechanical degradation and thereby degrading overall electrochemical performance. In this study, a stress‐buffer strategy is proposed to address this challenge by engineering a mechanically resilient crosslinked structure for the composite sulfur cathode. This structure is accomplished through the integration of a highly flexible thermoplastic elastomer (ethylene vinyl acetate, EVA), which enables stress release during sulfur volume variations by the repeated stretching and shrinking of EVA, thereby maintaining stable ionic/electronic diffusion channels within the electrode. By virtue of the mechanically stable architecture, the stress evolution experienced by the entire sulfur electrode is substantially reduced, witnessing a remarkable decrease of ≈33.7%. Consequently, the S‐EVA composite cathode demonstrates exceptional electrochemical performance, especially cycling stability. Notably, the S‐EVA composite cathode, with a high loading of 7.5 mg cm−2, exhibits stable cycling performance close to 3.0 mAh cm−2 within 50 cycles. This work not only offers novel insights into mitigating the mechanical stress within the electrode but also paves the way for developing durable high‐performance all‐solid‐state batteries. [ABSTRACT FROM AUTHOR]

Electrode microstructure is one of the primary factors determining the electrochemical properties of all‐solid‐state batteries (ASSBs). However, the key principles of electrode design to realize fast ionic/electronic transport pathways are not well elucidated. Herein, the correlation between electrode microstructure and electrochemical behaviors is studied through different electrode design in terms of energy‐density‐related electrode composition and Ni‐rich layered oxides particle size distribution. A positive relation between particle size and mass fraction in electrode design is revealed, that is, as the particle size increases, more cathode materials are required to enable the fast reaction kinetics. The well interconnected active particles and solid electrolytes construct the highly percolated ionic/electronic transfer networks, which determines the overall electrochemical properties. The findings in this work give a new insight into electrode design to promote the development of high‐energy and high‐power ASSBs. [ABSTRACT FROM AUTHOR]