Electrochemical Performance of Ti3C2Tx/MnO2 Cathode in Aqueous Zinc Ion Batteries

Owing to the advantages of large specific capacity, high work potential, rich reserves, and low price, man. ganese dioxide (MnO2) material has become the most potential material for the cathode in aqueous zinc batteries (AZBs). However, it still has problems with poor structural stability and complex electrochemical storage mecha. nism. Herein, a kind of Ti3C2Tx/MnO2 composite material based on bract. liked structural of MnO2 deposited on Ti3C2Tx was prepared by a two. step method, and the structure, composition, and morphology of the composite were characterized by X. ray powder diffraction (XRD), X. ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and high. resolution transmission electron microscopy (HRTEM). The zinc storage performance of Ti3C2Tx/MnO2 cathode were evaluated in different aqueous electrolyte (2 mol.L-1 ZnSO4, 2 mol.L-1 ZnSO4+ 0.1 mol.L-1 MnSO4, 30 mol.L-1 tetraethylammonium triflate (TEAOTf)+1 mol.L-1 ZnCF3SO3 (ZnOTf), 3 mol.L-1 ZnOTf), respectively. As a result, Ti3C2Tx/MnO2 cathode displayed two obvious discharge platforms in 2 mol.L-1 ZnSO4 and 2 mol.L-1 ZnSO4+0.1 mol.L-1 MnSO4 solution, which is attributed to the co. insertion of H+ and Zn2+ due to the weak acidic electrolyte. The initial platform region at 1.0 V occurred in the first step is the insertion of H+, and the subse. quent reaction is the insertion of Zn2+ into Ti3C2Tx/MnO2 electrode. However, in the neutral of 3 mol.L-1 ZnOTf and 30 mol.L-1 TEAOTf+1 mol.L-1 ZnOTf electrolyte, the insertion of H+ into the Ti3C2Tx/MnO2 cathode hardly appears, and the obtained discharge capacity may mainly come from the intercalation of Zn2+. Moreover, the utilization of ultra-high concentration electrolyte could not only improve the reversibility of Ti3C2Tx/MnO2 electrodematerial but also effectively inhibit the dissolution of electrode material in the cycling process (78.2% capacity retention after 100 cycles at 0.2 A.g(-1)).