Superior lithium-storage properties derived from a high pseudocapacitance behavior for a peony-like holey Co3O4 anodeElectronic supplementary information (ESI) available: The XPS survey spectrum and BET data of peony-like Co3O4; CV curves after 800 cycles and electrochemical performances at extreme temperature and pseudocapacitive contribution of peony-like Co3O4; the EIS results, equivalent circuit diagram and fitted kinetic parameters of peony-like Co3O4 and commercial Co3O4; the SEM and cycle

Transition metal oxides have shown extraordinary potential for lithium storage to date. Herein, a peony-like holey Co 3 O 4 architecture has been elaborately designed and successfully prepared via a solvothermal process followed by annealing treatment. The as-obtained peony-like Co 3 O 4 material showed an ultra-large reversible capacity of 1880 mA h g −1 at 500 mA g −1 after 800 cycles when it acted as the anode. More importantly, it also afforded a remarkable high-rate capability, i.e. , an excellent capacity of 1141 mA h g −1 at a current density of 10 A g −1 . Such an impressive performance could be ascribed to improved kinetics originating from ultrathin 2D nanosheets with ample pores and a high pseudocapacitive contribution. Therefore, the peony-like Co 3 O 4 material was considered as a promising candidate for high-performance Li-ion battery anodes. A unique Co 3 O 4 material, with a peony-like architecture assembled with ultrathin porous nanosheets, could display unprecedented rate capabilities when acting as the anode for lithium-ion batteries.