Potassium-doped hydrated manganese dioxide nanowires-carbon nanotubes on graphene for high-performance rechargeable zinc-ion batteries.

Aqueous rechargeable Zn-ion batteries (ARZIB) are promising candidates for next-generation batteries because of their high safety, low cost, and relatively high capacity. In this study, we developed hydrated and potassium-doped manganese dioxide (MO) nanowires mixed with carbon nanotubes (CNT) on a graphene substrate (hydrated KMO-CNT/graphene) for ARZIB. A simple polyol process using poly(ethyl glycol), KMnO 4 , CNT, and graphene was utilized to fabricate hydrated KMO-CNT/graphene. MnO 2 nanowires with diameters of 15–25 nm possess a high specific capacity with a short diffusion path. The intercalated K ions and hydrates in the layered MnO 2 nanowires maintained the MO structure during the charge and discharge processes, whereas carbon nanomaterials (CNT and graphene) enhanced the conductivity of the material. Consequently, hydrated KMO-CNT/graphene demonstrated good ARZIB performance. A high capacity of 359.8 mAh g–1 at 0.1 A g–1, and at a high current density of 3.0 A g–1, a capacity of 129 mAh g–1 with 77% retention after 1000 cycles, were achieved. • Hydrated and potassium-doped MnO 2 mixed with CNT on graphene substrate is synthesized. • Polyol process was conducted with PEG, KMnO 4 , CNT and graphene. • MnO 2 has a high capacity, intercalated K and H 2 O keep the structure of MnO 2 and CNT/graphene provide conductivity. • The hydrated KMO-CNT/graphene delivers high specific capacities of 359.8 mAh g–1 at 0.1 A g–1 and 129 mAh g–1 at 3.0 A g–1 with 77% retention. • The performance of ZIB reaches a high energy density of 410.36 Wh kg–1 at 109.93 W kg–1. [ABSTRACT FROM AUTHOR]