Strain-coordination strategy enabling long-cycling all-solid-state lithium-sulfur batteries

All-solid-state lithium-sulfur batteries offer high energy density and enhanced safety. However, their practical application is hindered by high external operating pressure to mitigate mechano-chemical failures at interfaces. Here we show a strain-coordination strategy that leverages the opposite volume changes of electrodes during cycling to reduce electrode-level stress evolution and the external pressure required for stable operation. Using an FeS2 positive electrode and a prelithiated Si negative electrode as a representative system, we modulate the Li-to-Si ratio to achieve a near-zero-strain effect, where the expansion of FeS2 and the contraction of Li2Si partially counterbalance each other. This self-compensated electrode configuration mitigates mechano-electrochemical degradation under reduced pressure. As a result, the all-solid-state lithium-sulfur batteries deliver a discharge capacity of 868.4 mAh g⁻1 at 15 MPa. Under 100 MPa, the cells achieve an areal capacity of 21.7 mAh cm⁻2, and cycle life 4500 cycles at 1 C (60 min) and 140,000 cycles at 15 C (4 min). Furthermore, low-pressure all-solid-state pouch cells achieve stable cycling over 500 cycles at 15 MPa. This strain-coordination strategy provides an approach for enabling stable operation of all-solid-state batteries under reduced external pressure. All-solid-state lithium–sulfur batteries are limited by the high external pressure needed to maintain interfacial stability. Here, the authors develop a strain-coordination strategy that exploits opposing electrode volume changes during cycling to reduce stress buildup and enable stable operation under lower pressure.