In situ anchoring of MnO nanoparticles into three-dimensional nitrogen-doped porous carbon framework as a stable anode for high-performance lithium storage

Although transition metal oxides have the advantages of large theoretical capacity, low cost and eco-friendliness, their application as anodes for lithium-ion batteries (LIBs) is still limited due to their undesirable electrical conductivity and large volume expansion. Herein, a novel two-step rapid freeze-drying-calcination strategy was applied to prepare highly dispersed nano-MnO-anchored three-dimensional nitrogen-doped porous carbon framework composites (MnO@3D N-PCF). Compared with MnO and undoped MnO@3D PCF, the MnO@3D N-PCF anode exhibits superb cycle stability, remarkable specific capacity and impressive high-rate performance (1037.0 mAh g-1 over 100 cycles at 0.1 A g-1 and 760.9 mAh g-1 over 500 cycles at 5 A g-1), mainly due to its well-designed 3D nanoarchitecture. It is found that 3D nitrogen-doped carbon networks can act as stable conductive bridges to facilitate electron transport and sufficient diffusion channels for Li ions. The MnO nano-particles obtained by rapid lyophilization and calcination technology are highly dispersed in the porous 3D carbon skeleton, which can buffer volume expansion and preserve the stability of the electrode. It is expected that this simple and green synthesis strategy will open the door for the development of transition metal oxide/ carbon three-dimensional nanocomposites with high stability and excellent electrochemical properties.