Realizing long-cycling silicon-based all-solid-state batteries with near-zero-stress variation.

Silicon anodes present a compelling alternative to lithium metal for all-solid-state batteries (ASSBs), offering high capacity without dendrite risks. However, their application is hindered by incomplete understanding of electro-chemo-mechanical (ECM) failure mechanisms in all-solid-state configurations. Through multiple in situ characterizations combining optical microscopy, atomic force microscopy, and pressure monitoring, this work uncovers fundamental stress-mediated degradation pathways in silicon-based ASSBs. Stress evolution-particularly in-plane strain mismatch and out-of-plane mechanical constraints-governs the dominant failure criterion, superseding traditional volume change metrics. This stress-dominated mechanism arises from the interplay between volume and modulus in constrained all-solid-state systems. Guided by these insights, complementary mitigation strategies were developed, including electrode/electrolyte modulus engineering to reduce interfacial stresses and elastic constraint design to accommodate mechanical fluctuations. The synergistic implementation achieves near-zero stress variation and breakthrough cycling stability (90.1% capacity retention after 5000 cycles). This work establishes a paradigm for high-energy-density batteries, shifting the design focus from volume accommodation to comprehensive stress management in all-solid-state systems.