A novel LiTi2(PO4)3/MnO2 hybrid supercapacitor in lithium sulfate aqueous electrolyte

Abstract In this work, carbon-coated lithium-ion intercalated compound LiTi 2 (PO 4 ) 3 and MnO 2 have been synthesized and they deliver a capacity of 90 and 60 mAh/g in 1 M Li 2 SO 4 neutral aqueous electrolyte within safe potentials without O 2 and H 2 evolution, respectively. The novel hybrid supercapacitor in which MnO 2 was used as a positive electrode and carbon-coated LiTi 2 (PO 4 ) 3 as a negative electrode was assembled and the LiTi 2 (PO 4 ) 3 /MnO 2 hybrid supercapacitor showed a sloping voltage profile from 0.7 to 1.9 V, at an average voltage near 1.3 V, and delivers a capacity of 36 mAh/g and an energy density of 47 Wh/kg based on the total weight of the active electrode materials. It exhibits a desirable profile and maintains over 80% of its initial energy density after 1000 cycles. The hybrid supercapacitor also exhibit an excellent rate capability, even at a power density of 1000 W/kg, it has a specific energy 25 Wh/kg compared with 43 Wh/kg at the power density about 200 W/kg.