Ultrathin porous MnO2@C nanosheets for high-performance lithium-ion battery anodes

Engineering ultrathin porous two-dimensional (2D) MnO2/C composites is regarded as an efficient way to achieve high performance of MnO2 anode for lithium-ion batteries (LIBs) because of existence of many features such as shortened ion diffusion pathways and larger surface-controlled capacitance contribution, but they are difficult to prepare because of complex structures. Herein, we contribute a facile strategy for preparing ultrathin porous MnO2/C nanosheets and confirm that the introduced tetraethyl orthosilicate (TEOS) raw material plays a key role in formation of thus MnO2/C nanosheets. The as-prepared MnO2/C composite consists of ultrathin porous conformal carbon coated MnO2 nanosheets whereby integrates the advantages of 2D nanostructure, porous structure and superficial conformal carbon coating so as to improve lithium storage. As a result, this composite exhibits impressive performance, showing high capacity, long cycle life and improved rate capability, with 747.6 mA h g-1 after 400 cycles at 200 mA g-1 and 542.6 mA h g-1 after 420 cycles even at 1000 mA g-1. Based on systematic material and electrochemical characterizations we confirm that the outstanding performance of the as-prepared MnO2/C composite benefits from its well-designed nanostructure. Besides, we believe that this work can enlighten researchers to synthesize other 2D metal oxide/carbon composites for energy storage or other applications.