Structural and defect engineering of cobaltosic oxide nanoarchitectures as an ultrahigh energy density and super...

The key challenges of aqueous Zn-based batteries (ZBBs) are their unsatisfactory energy density and poor lifespan, mainly arising from the low capacity and irreversibility of the cathode materials. Herein, a three-dimensional (3D) ordered mesoporous nanoarchitecture cobaltosic oxide (M-Co₃O₄) with rich oxygen vacancies (M-Co₃O_4- ) is reported as a new promising advanced cathode material for rechargeable ZBBs. The experimental results and DFT calculations reveal that the energy storage capacity is significantly enhanced by the synergistic effect of mesopores and oxygen vacancies. Benefiting from the merits of a substantially fast ion diffusion channel, high electrical conductivity, large active surface area, strong OH^- adsorption capacity and stable structure, the fabricated M-Co₃O_4- //Zn battery delivers a remarkable capacity of 384 mA h g^-1 at 1.0 A g^-1 which even rises up to 420 mA h g^-1 after cycling activation with an ultrahigh energy density of 722.4 W h kg^-1 (based on the weights of the cathode active material), which outperforms most of the previously reported aqueous ZBBs. More impressively, the M-Co₃O_4- //Zn battery exhibits extraordinary cycling stability, both at 1 A g^-1 and 10 A g^-1 without any decay of capacity after 6000 and 60 000 cycles, respectively, and such high cycling stability is reported for the first time in ZBBs. The ultrahigh energy and superlong lifespan of aqueous ZBBs could make it satisfy some practical energy demands.