Aqueous lithium-ion battery LiTi2(PO4)3/LiMn2O4 with high power and energy densities as well as superior cycling stability

Porous, highly crystalline Nasicon-type phase LiTi2(PO4)(3) has been prepared by a novel poly(vinyl alcohol)-assisted sol-gel route and coated by a uniform and continuous nanometers-thick carbon thin film using chemical vapor deposition technology. The as-prepared LiTi2(PO4)(3) exhibits excellent electrochemical performance both in organic and aqueous electrolytes, and especially shows good cycling stability in aqueous electrolytes. An aqueous lithium-ion battery consisting of a combination of LiMn2O4 cathode, LiTi2(PO4)(3) anode, and a 1 m Li2SO4 electrolyte has been constructed. The cell delivers a capacity of 40 mA h g(-1) and a specific energy of 60 W h kg(-1) with an output voltage of 1.5 V based on the total weight of the active electrode materials. It also exhibits an excellent cycling stability with a capacity retention of 82 % over 200 charge/discharge cycles, which is much better than any aqueous lithium-ion battery reported.