Enhanced Electrochemical Properties of KTiOPO<sub>4</sub>–rGO Negative Electrode for Sodium and Potassium Ion Batteries
P. Ramesh Kumar, Kei Kubota, Daisuke Igarashi, Shinichi Komaba
Abstract
Potassium titanyl phosphate (KTiOPO4) is a well-known material for nonlinear optical device applications, but its electrochemical properties are not yet well understood. This study investigates sodium and potassium storage properties of KTiOPO4 using alkali metal fluorosulfonyl amide based nonaqueous electrolytes and a higher stiffness sodium alginate binder. The prepared KTiOPO4-reduced graphene oxide (rGO) composite electrode delivers stable desodiation and depotassiation capacities of 97 and 123 mAh g–1, respectively, at 0.075 C (10 mA g–1) over 70 cycles. The potassium cells demonstrate excellent cycle stability and high rate capability performances. Operando and ex situ XRD measurements confirm the multiple structural changes by potassiation/depotassiation and the high reversibility of the phase evolution.