Unraveling superior lithium storage performance of MnO by a three-dimensional structure-memory anode

Abstract

MnO is a promising anode material for high-performance lithium-ion batteries (LIBs) due to its high theoretical capacity and rich resource. However, MnO has low electrical conductivity and suffers from drastic volume changes during cycling, resulting in poor cycling stability and limited rate capability. Here, we demonstrate the elaborate design of a novel three-dimensional structure-memory electrode (3D SME) material consisting of MnO nanoparticles encapsulated in the N-doped carbon (NC) as well as anchored on reduced graphene oxide (RGO) nanosheets. The structures of electrolyte diffusion channels, electrode strain-control layer, and electrode/electrolyte interface are all engineered from the ‘memory’ formed during the wet processes. This delicate design rationally combines the compositional and structural merits of NC and MnO species with RGO framework. Consequently, the 3D SME exhibits high specific capacity (927.5 mAh g−1 at 0.1 A g−1), high rare capability (375.3 mAh g−1 at 5.0 A g−1), and long-term cycling stability (835.7 mAh g−1 after 1000 cycles at 2.0 A g−1). Additionally, the charge storage mechanism of 3D SME is investigated by combining ex situ X-ray photoelectron spectroscopy and cyclic voltammetry, revealing a reversible conversion reaction between Mn species and Li+ ions upon the lithiation/delithiation process. This study reports a delicate design to achieve high-performance MnO/C anodes for LIBs, more importantly, provides significant insight into the reaction mechanism of MnO-based anode.