Highly reversible and rapid charge transfer Zn-MnO2 battery by MnO2 nanosheet arrays anchored nanocellulose-based carbon aerogel

Abstract

Zn-MnO₂ batteries are eco-friendly energy storage devices, but their practical application is hindered by challenges such as low conductivity, sluggish Zn²⁺ diffusion kinetics, and instability in the crystal structure of manganese dioxide (MnO₂) cathode materials during Zn²⁺ insertion/extraction. In this work, a composite nanocellulose-based carbon aerogel@MnO₂ (CA@MnO₂) cathode with enhanced Zn²⁺ insertion/de-insertion kinetics and storage capacity was fabricated by bi-directional freezing, carbonization, and following hydrothermal deposition. The nanocellulose-based carbon aerogels with ordered porous structure and high specific surface area served as the substrate, which facilitated the rapid Zn²⁺ migration and efficient electrode contact interface. In the two-electrode system, the CA@MnO₂ can provide a reversible specific capacity of 480 mAh g⁻¹ at 0.5 A g⁻¹ and a high multiplicative capacity of 160 mAh g⁻¹ at 5 A g⁻¹ with outstanding stability of operation over 3000 cycles. The assembled Zn//CA@MnO₂ batteries attained a remarkable specific capacitance of 397 mAh g⁻¹ at a current density of 0.1 A g⁻¹. This study provides a feasible route for the preparation of high-performance Zn-ion batteries.