Strengthened negative Poisson's ratio in Cu-regulated Ti₂B₂ enables strain-tolerant Li-CO₂ electrocatalysis

Mechanical stress from Li₂CO₃ accumulation severely limits Li-CO₂ battery life. We report that the strengthened negative Poisson's ratio (NPR) in flexible Cu-regulated Ti₂B₂ enables stable and durable catalytic Li₂CO₃ formation/decomposition. Under ±3% strain, CO₂ redox overpotential fluctuates by merely 0.09 V. This strain resistance in NPR materials provides an intriguing insight into resolving volume expansion and sluggish kinetics in metal-air batteries.