TiP2O7 and Expanded Graphite Nanocomposite as Anode Material for Aqueous Lithium-Ion Batteries

This paper reports a facile sol gel synthesis method to successfully prepare the TiP2O7/expanded graphite (EG) nanocomposite as an advanced anode material for aqueous lithium-ion batteries. The constructed TiP2O7 nanocomposites (50-100 nm) are in situ encapsulated in the pore and layer structure of expanded graphite with good conductivity and high specific surface area. As a consequence, the resulting Tip(2)O(7)/EG electrode exhibits a reversible capacity of 66 mAh g(-1) at 0.1 A g(-1) with an appropriate potential of -0.6 V before hydrogen evolution in aqueous electrolytes, and also demonstrates greatly enhanced cycling stability with 75% capacity retention after 1000 cycles at the current density of 0.S A g(-1). A full cell consisting of TiP2O7/EG anode, LiMn2O4 cathode, and 1 M Li2SO4 electrolyte delivers a specific energy of 60 Wh kg(-1) calculated on the weight of both cathode and anode materials with an operational voltage of 1.4 V. It also exhibits superior rate capability and remarkable cycling performance with a capacity maintenance of 66% over 500 cycles at 0.2 A CI and 61% at 1 A over 2000 cycles.