High power lithium-ion hybrid electrochemical capacitors using spinel LiCrTiO4 as insertion electrode

Abstract

We report the synthesis and electrochemical performance of sub-micron size LiCrTiO₄ particles prepared by a solid-state approach. X-ray diffraction and transmission electron microscopic studies are used to analyze the structural and morphological properties, respectively, of the synthesized powders. Electrochemical Li-insertion properties are evaluated in half-cell configurations (Li/LiCrTiO₄) by means of both galvanostatic and potentiostatic modes between 1 and 2.5 V vs. Li. Reversible insertion of almost one mole of lithium (∼155 mA h g⁻¹) is noted at a low current rate of 15 mA g⁻¹ and rendered an excellent cycling profile as well. A non-aqueous Li-ion electrochemical hybrid capacitor (Li-HEC) is fabricated with an optimized mass loading of activated carbon (AC) cathode and synthesized LiCrTiO₄ as anode in 1 M LiPF₆ in ethylene carbonate–diethyl carbonate solution and cycled between 1 and 3 V under ambient conditions. The Li-HEC delivered maximum specific energy and power densities of 23 W h kg⁻¹ and 4 kW kg⁻¹, respectively.