In-SituGrowth of Sandwich-Like Ultrathin MnO₂/Carbon/MnO₂ Composite for Fast and Stable KineticProcess of Lithium Storage

Abstract

The conversion-type anode materials for lithium-ion batteries due to inferior kinetic activity, higher reaction activation energy, low electrical conductivity, and poor ion diffusivity greatly restrict the electrochemical properties. To alleviate the above challenges, an ultrathin sandwich-like structure is structured by two layers of MnO₂ and one layer of carbon film (labeled as MnO₂/C/MnO₂) by controlling the time parameters. The ultrathin sandwich-like structure maintains the structural stability and accelerates the kinetic reaction process maximally. The middle layer of carbon improves the ionic/electronic conductivity and leads to structural specificity. Thanks to a unique structure, the MnO₂/C/MnO₂ indicates a topmost capacity of 515 mA h g^–1 at the current density of 1 C and keeps a stabilized capacity of about 400 mA h g^–1 after 500 cycles. Besides, we further show this mechanism of better electrochemical performance by atomic scale and suggest it can be used in other fields.