Russian doll architecture enables a high-rate and long-life MnCo₂O₄/C-lithium battery

Realizing high capacity at high current densities is one of the challenges for battery electrode materials towards practical applications, especially for metal oxide electrode materials. Designing a specific structure that can alleviate volume expansion and accelerate the diffusion of the ions is an effective way to achieve this goal. Herein, a porous multilayer core-shell structured manganese cobalt oxide/carbon composite (MnCo₂O₄/C) was obtained by using a simple route that combines the hydrothermal method with calcination. The structure is similar to a Russian doll, which is nested with three to four layers of concentric porous shells. The porous multilayer core-shell structures can relieve volume expansion during discharge/charge and reduce the Li-ion diffusion path. Additionally, it can provide a richer activity site, thereby storing more lithium ions. When used as an anode material, the synthesized MnCo₂O₄/C showed a high specific capacity of 978 mAh g^-1 after 800 cycles at a current density of 1 A g^{- 1}. Even at a high current density of 10 A g^-1, the electrode could still deliver a specific capacity of 251 mAh g^-1, which makes it more suitable for powering large equipment such as electric vehicles.