Artificial Solid-Electrolyte Interphase and Bamboo-like N-doped Carbon Nanotube Enabled Highly Rechargeable K-CO2 Batteries

Metal-CO2 (Metal = Li, Na, K) batteries demonstrate an attractive strategy for utilizing the excessively released CO2 emissions into electrochemical energy storage devices. Among them, K-CO2 batteries represent a promising energy storage system owing to high potential (2.48 V), high energy density, and earth-abundant K resources. The cycle stability and electrochemical mechanism are still far beyond satisfactory because of the active potassium metal, although the first rechargeable K-CO2 battery has been reported very recently. Herein, a high-performance K-CO2 battery is fabricated using passivated K anodes with artificial surface film and N-doped carbon nanotubes cathodes. The battery shows high specific full discharge capacity (9436 mAh g(-1)), good rate capability with small overpotential gap (0.81 V at 50 mA g(-1)), and long cycle life (450 cycles or 3100 h with a curtailing capacity of 500 mAh g(-1)). The reaction of 3CO(2) + 4K reversible arrow 2K(2)CO(3) + C reversibly occurs in the charge/discharge processes. Moreover, the assembled fiber-shaped battery demonstrates a long operation time of 57 h and stable output under different bending conditions. This work provides an option for the possible recycling utilization of the CO2 in future space exploration.