Enhanced Co3O4 Nanoflakes Reactivity via Integrated Al-Doping and Metal Vacancy Engineering for Large Capacity Li-CO2 Batteries

Rechargeable Li-CO2 batteries are well-regarded for their high-energy, environmental friendliness, and resourceful use of CO2, but suffer from poor cycle reversibility. Herein, Al-doped Co3O4 nanoflakes featuring abundant metal vacancies (V-ACO/CC) were synthesized via a facile approach employing Al ions as both a dopant and sacrificial agents, which serve as high-efficient cathode catalyst for Li-CO2 batteries. Experiment results demonstrate that the incorporation of Al doping and metal vacancies modulates the electronic structure of Co-center and optimizes the growth path of discharge product. The cation vacancies generated by the sacrificed part of the Al atoms change the local charge distribution, strengthen the affinity of CO2 and reaction intermediates and facilitate the reversible decomposition of discharge products. Concurrently, the formation of covalent Al-O bonds by the remaining Al species reinforces the stability of nanostructures. Notably, the V-ACO/CC-based LCBs exhibit enhanced CO2 conversion kinetics, as evidenced by a high specific capacity (12.06 mAh cm−2 at 0.05 mA cm−2), fast rate capability and impressive stability (over 420 cycles under 0.1 mA cm−2).