Cross-linked K0.5MnO2 nanoflower composites for high rate and low overpotential Li–CO2 batteries

Abstract

Rechargeable Li–CO₂ batteries are deemed to be attractive energy storage systems, as they can effectively inhale and fix carbon dioxide and possess an extremely high energy density. Unfortunately, the irreversible decomposition of the insoluble and insulating Li₂CO₃ results in awful electrochemical performance and inferior energy efficiency of Li–CO₂ batteries. Furthermore, the low energy efficiency will exacerbate the extra waste of resources. Therefore, it is vital to design novel and efficient catalysts to enhance the battery performance. Herein, a facile, one-step strategy is introduced to design cross-linked, ultrathin K_0.5MnO₂ nanoflowers combined with CNTs (K_0.5MnO₂/CNT) as a highly efficient cathode for Li–CO₂ batteries. Impressively, the Li–CO₂ battery based on the K_0.5MnO₂/CNT cathode achieves a low overpotential (1.05 V) and a high average energy efficiency (87.95%) at a current density of 100 mA g⁻¹. Additionally, the K_0.5MnO₂/CNT cathode can steadily run for over 100 cycles (overpotential < 1.20 V). Moreover, a low overpotential of 1.47 V can be obtained even at a higher current density of 1000 mA g⁻¹, indicating the superior rate performance of K_0.5MnO₂/CNT. This strategy offers new insight and guidance for the development of low-cost and high-performance Li–CO₂ batteries.