Flexible Li-CO 2 Batteries with Boosted Reaction Kinetics and Cyclelife Enabled by Heterostructured Mo 3 N 2 @TiN Cathode and Interface-protected Li Anode.

With theoretically endowing with high energy densities and environmentally friendly carbon neutralization ability, flexible fiber-shaped Li-CO 2 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-CO 2 batteries. Herein, a flexible fiber-shaped Li-CO 2 battery based on Mo 3 N 2 cathode coating with atomic layer deposited TiN and Li 3 N protected Li anode is constructed. Owing to the regulation surface electrons of Mo 3 N 2 by TiN, heterostructured cathode has more delocalized electrons which enable cathodes to stabilize 2-electron intermediate products Li 2 C 2 O 4 by electron bridge bonds and avoid disproportionation into Li 2 CO 3 . Li 3 N layers not only accelerate Li + transportation but also avoid contact between Li and CO 2 to form Li 2 CO 3 . Thus, the constructed Li-CO 2 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-CO 2 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.