Low-strain metal–organic framework negative electrode for stable all-solid-state batteries

All-solid-state batteries face critical mechanical challenges, particularly when employing Li-metal, Si-based, or initially anode-free configurations, due to substantial volume changes of the negative electrode within rigid cell architectures during cycling. Such fluctuations generate considerable mechanical stress, which can lead to both bulk and interfacial degradation, posing serious risks to long-term stability. This problem is further amplified in stacked cell configurations, where mechanical integrity is critical. To address this, we investigate metal-organic frameworks as low-strain negative electrodes integrated with the argyrodite Li₆PS₅Cl_0.5Br_0.5 solid electrolyte in sulfide-based all-solid-state batteries. Notably, the Co-based metal-organic framework containing a thiophenedicarboxylic acid linker exhibits high structural reversibility, retaining 82% of its capacity with only 1.04% volume change after 700 cycles at 30 °C (1.5 mA cm^-2). Operando pressure and displacement analysis further confirm negligible mechanical strain during cell operation. Moreover, a pouch-type full cell maintains stable performance for 50 cycles at 30 °C under a low stack pressure of 5 MPa (0.5 mA cm^-2), demonstrating the promise of metal-organic frameworks as low-strain electrodes for durable all-solid-state battery architectures.