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

Abstract

AbstractMetal‐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 3CO2 + 4K ⇋ 2K2CO3 + 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.