ZnxMnO2/PPy Nanowires Composite as Cathode Material for Aqueous Zinc-Ion Hybrid Supercapacitors

Abstract

Over the past decade, the extensive consumption of finite energy resources has caused severe environmental pollution. Meanwhile, the promotion of renewable energy sources is limited by their intermittent and regional nature. Thus, developing effective energy storage and conversion technologies and devices holds considerable importance. Zinc-ion hybrid supercapacitors (ZISCs) merge the beneficial aspects of both supercapacitors and batteries, rendering them an exceptionally promising energy storage method. As an important cathode material for ZISCs, the tunnel structure MnO₂ has poor conductivity and structural stability. Herein, the Zn_xMnO₂/PPy (ZMOP) electrode materials are prepared by hydrothermal method. Doping with Zn²⁺ is used to enhance its structural stability, while adding polypyrrole to improve its conductivity. Therefore, the fabricated ZMOP cathode presents superb specific capacity (0.1 A g⁻¹, 156.4 mAh g⁻¹) and remarkable cycle performance (82.6%, 5000 cycles, 0.2 A g⁻¹). Furthermore, the assembled aqueous ZISCs with ZMOP cathode and PPy-derived porous carbon nanotube anode obtain a superb capacity of 109 F g⁻¹ at 0.1 A g⁻¹. Meanwhile, at a power density of 867 W kg⁻¹, the corresponding energy density can achieve 20 Wh kg⁻¹. And over 5000 cycles at 0.2 A g⁻¹, the cycle performance of ZISCs maintains at 86.4%, which exhibits excellent cycle stability. This suggests that ZMOP nanowires are potential cathode materials for superior-performance aqueous ZISCs.