Flexible Li–CO2 Batteries with Boosted Reaction Kinetics and Cyclelife Enabled by Heterostructured Mo3N2@TiN Cathode and Interface‐protected Li Anode

Abstract With theoretically endowing with high energy densities and environmentally friendly carbon neutralization ability, flexible fiber‐shaped Li–CO2 battery emerges as a multipurpose platform for next‐generation wearable electronics. Nevertheless, the ineluctable issues faced by cathode catalysts and Li anodes have brought enormous obstacles to the development of flexible fiber‐shaped Li–CO2 batteries. Herein, a flexible fiber‐shaped Li–CO2 battery based on Mo3N2 cathode coating with atomic layer deposited TiN and Li3N protected Li anode is constructed. Owing to the regulation surface electrons of Mo3N2 by TiN, heterostructured cathode has more delocalized electrons which enable cathodes to stabilize 2‐electron intermediate products Li2C2O4 by electron bridge bonds and avoid disproportionation into Li2CO3. Li3N layers not only accelerate Li+ transportation but also avoid contact between Li and CO2 to form Li2CO3. Thus, the constructed Li–CO2 battery demonstrates a low charge potential of 3.22 V, low overpotential of 0.56 V, outstanding rate capabilities up to 1 A g−1, and excellent long‐term cycling (≈2000 h) with an energy efficiency of ≈80%. The fabricated flexible fiber‐shaped Li–CO2 battery shows an ultrahigh energy density of 14 772.5 Wh kg−1 based on cathodes (340.8 Wh kg−1 based on device mass), and outstanding deformations adaptability, giving it great potential for wearable electronics.