Rechargeable LiCO₂ Batteries with Graphdiyne as Efficient Metal‐Free Cathode Catalysts

Abstract A rechargeable LiCO₂ battery is one of the promising power sources for utilizing the greenhouse gas CO₂ in a sustainable approach. However, highly efficient catalysts for reversible formation/decomposition of insulating discharge product, Li₂CO₃, are the main challenge, which can boost the cycle stability. Herein, 2D single‐atom‐thick graphdiyne (GDY) with abundant acetylenic bond sites is prepared by a bottom‐up cross‐coupling reaction strategy and used as metal‐free catalysts for reversible LiCO₂ batteries. The prepared GDY has a rich diacetylenic unit and atomic‐level in‐plane pores in the network, which can chemically adsorb the CO₂ molecules and easily promote the Li⁺ diffusion and thereby resulting in uniform nucleation and reversible formation/decomposition of the discharge product. The GDY hybrid cathodes show a small overpotential gap of 1.4 V at a current density of 50 mA · g⁻¹, a high full discharge capacity of 18 416 mAh · g⁻¹ at 100 mA · g⁻¹, and outstanding long‐term stability of 158 cycles at 400 mA · g⁻¹ with a curtailing capacity of 1000 mAh · g⁻¹. Furthermore, a flexible belt‐shaped LiCO₂ battery is fabricated as a proof of concept with a high gravimetric energy density of 165.5 Wh · kg⁻¹ (based on the mass of the whole device) as well as excellent mechanical flexibility.