Long-Lived and Mechanical-Abuse-Tolerant Semisolid Slurry Batteries

Semisolid slurry batteries (S 3 -batteries) can eliminate energy-intensive manufacturing but are hindered by particle sedimentation and rapid capacity fade. Here we report long-lived, abuse-tolerant S 3 -batteries enabled by a biomimetic ethyl cellulose (EtC) stabilization strategy. EtC forms entangled polymer networks within slurry electrodes, eliminating solid–liquid phase separation and suppressing electrolyte volatilization while maintaining processable rheology. Embedded three-electrode diagnostics in pouch cells identify lithium plating as the primary degradation mechanism. Guided by this diagnosis, we combine N/P capacity ratio fine-tuning with cathode prelithiation to eliminate anode Li plating and compensate for active Li loss, delivering exceptional full-cell stability over 500 cycles and setting a new benchmark for slurry batteries. Prototype pouch-type full cells further demonstrate outstanding mechanical-abuse tolerance while retaining electrochemical function without hazardous failure. Successful adaptation to sodium-ion battery chemistry confirms the versatility of these principles, offering a promising pathway for next-generation, sustainable energy storage technologies.