MXene—manganese oxides aqueous asymmetric supercapacitors with high mass loadings, high cell voltages and slow self-discharge

How to achieve high mass loadings while maintaining energy and power densities together with slow self-discharge rates for aqueous asymmetric supercapacitors (AASCs) remains a great challenge. Herein, we tested an AASC using Ti3C2Tz MXene as the negative electrode, mixture of manganese oxides, Mn3O4 MnOOH, positive electrode saturated lithium chloride (14 M LiCl) electrolyte. This device, thicknesses > 100 µm, loading ~ 10 mg cm−2, resulted in density ≈ 30 Wh kg−1 at 0.5 A g − 1, 23 kW 20 open cell voltage 2.3 V, excellent rate capability cycling stability. When allowed 54 h room temperature, ~66% was retained. Crucially, after that time 1.5 V. work opens new opportunity performance, environmentally friendly AASCs, where are combined commercial loadings.