Bacteria Absorption-Based Mn2P2O7–Carbon@Reduced Graphene Oxides for High-Performance Lithium-Ion Battery Anodes

The development of freestanding flexible electrodes with high capacity and long cycle-life is a central issue for lithium-ion batteries (LIBs). Here, we use bacteria absorption of metallic Mn2+ ions to in situ synthesize natural micro-yolk–shell-structure Mn2P2O7–carbon, followed by the use of vacuum filtration to obtain Mn2P2O7–carbon@reduced graphene oxides (RGO) papers for LIBs anodes. The Mn2P2O7 particles are completely encapsulated within the carbon film, which was obtained by carbonizing the bacterial wall. The resulting carbon microstructure reduces the electrode–electrolyte contact area, yielding high Coulombic efficiency. In addition, the yolk–shell structure with its internal void spaces is ideal for sustaining volume expansion of Mn2P2O7 during charge/discharge processes, and the carbon shells act as an ideal barrier, limiting most solid–electrolyte interphase formation on the surface of the carbon films (instead of forming on individual particles). Notably, the RGO films have high conductivity and robust mechanical flexibility. As a result of our combined strategies delineated in this article, our binder-free flexible anodes exhibit high capacities, long cycle-life, and excellent rate performance.