Biaxial strain engineering of atomically thin MoS₂ for highly reversible Li–CO₂ batteries

Lithium-carbon dioxide (Li-CO ₂ ) batteries have attracted considerable interest due to their high energy density and significant potential for achieving net-zero carbon emissions. However, the sluggish kinetics of the CO₂ evolution reaction leads to a substantial overpotential and severe energy loss in Li–CO₂ batteries, thereby drastically limiting their reversible cycling capability. Herein, we report the design of a cost-effective, catalytically active, and mechanically stable cathode catalyst for Li-CO ₂ battery by introducing biaxial strain engineering into atomically thin MoS₂. The structurally stable 3D framework can accommodate high-levels of stress and strain at the catalytic sites, as evidenced by the intact structure and the low overpotential maintained after long and stable cycling. Theoretical calculations demonstrate that the synergistically adjusted d-band centers in biaxially strained atomically thin MoS₂ with functional in-plane S-vacancies facilitate orbital hybridization with both CO₂ and Li species. This unique electronic structure promotes reactant adsorption during discharging and enhances Li₂CO₃ decomposition during charging, ultimately leading to a minimized energy barrier for the rate-determining step. The resulting Li-CO₂ battery based on monolayer biaxially strained MoS₂ exhibits a ~ 0.6 V overpotential, ~ 85% energy-efficiency, and nearly 4000 cycles cycle-lifespan at 10 A g⁻¹ for a fixed 2000 mAh g ^− 1 capacity per cycle, surpassing those of previous catalysts under similar conditions. This work provides a strategic pathway for the rational design of advanced catalysts for practical Li–CO₂ batteries.