Facile synthesis of graphene-wrapped porous MnCO3 microspheres with enhanced surface capacitive effects for superior lithium storage

摘要

MnCO3-based materials with high electrochemical activity and good structural stability hold great potential as advanced anode materials for lithium-ion batteries (LIBs). However, the poor Li+/e(-) conductivities and large volume changes during the charge/discharge process greatly hinder the application of MnCO3. In this work, the ingenious 3D architecture of graphene-wrapped porous MnCO3 microspheres is well designed and constructed via a facile and low-cost process without any structure-directing agents nor surfactants. The composites exhibit superior lithium storage capacity (1168 mA h g(-1) after 200 cycles at 500 mA g(-1)) and ultra-long cycling life (595 mA h g(-1) after 1000 cycles at high rate of 3000 mA g(-1)). The results obtained from the systematic electrochemical study demonstrate that the introduction of graphene could not only buffer the volume expansion of MnCO3 and ensure the rapid transportation of Li+/e(-), but also improve the interfacial lithium storage property by enhancing surface capacitive contribution. Furthermore, full cells with the composite as anodes and commercial LiNi0.5Co0.2Mn0.3O2 as cathodes are assembled, which show good cycling stability, suggesting excellent practical adaptability of the composite anodes. This work provides a methodology to design and create composite anodes which could be extended to the synthesis of other graphene coated metal carbonates for lithiumion batteries.