Facile synthesis of high tap density ZnO microspheres as advanced anode material for alkaline nickel-zinc rechargeable batteries

Sphere-Confined Reversible Zn Deposition for Stable Alkaline Aqueous Batteries

The practical applications of alkaline zinc-based batteries are challenged by poor rechargeability with an insufficient zinc utilization ratio. Herein, a sphere-confined reversible zinc deposition behavior from a free-standing Zn anode is reported, which is composed of bi-continuous ZnO-protected interconnected and hollowed Zn microspheres by the Kirkendall effect. The cross-linked Zn network with in situ formed outer ZnO shell and inner hollow space not only inhibits side reactions but also ensures long-range conductivity and accommodates shape change, which induces preferential reversible zinc dissolution-deposition process in the inner space and maintains structural integrity even under high zinc utilization ratio. As a result, the Zn electrode can be stably cycled for 390 h at a high current density of 20 mA cm-2 (60% depth of discharge), outperforming previously reported alkaline Zn anodes. A stable zinc-nickel oxide hydroxide battery with a high cumulative capacity of 8532 mAh cm-2 at 60% depth of discharge is also demonstrated.

Phase-transition tailored nanoporous zinc metal electrodes for rechargeable alkaline zinc-nickel oxide hydroxide and zinc-air batteries

Secondary alkaline Zn batteries are cost-effective, safe, and energy-dense devices, but they are limited in rechargeability. Their short cycle life is caused by the transition between metallic Zn and ZnO, whose differences in electronic conductivity, chemical reactivity, and morphology undermine uniform electrochemical reactions and electrode structural stability. To circumvent these issues, here we propose an electrode design with bi-continuous metallic zinc nanoporous structures capable of stabilizing the electrochemical transition between metallic Zn and ZnO. In particular, via in situ optical microscopy and electrochemical impedance measurements, we demonstrate the kinetics-controlled structural evolution of Zn and ZnO. We also tested the electrochemical energy storage performance of the nanoporous zinc electrodes in alkaline zinc-nickel oxide hydroxide (NiOOH) and zinc-air (using Pt/C/IrO2-based air-electrodes) coin cell configurations. The Zn | |NiOOH cell delivers an areal capacity of 30 mAh/cm2 at 60% depth of discharging for 160 cycles, and the Zn | |Pt/C/IrO2 air cell demonstrates 80-hour stable operation in lean electrolyte condition.

ZIF-derived ZnO/Sb composite scaffolded on carbon framework for Ni-Zn batteries

Ni-Zn, Zn-MnO₂, and Zn-air batteries have the advantages of inflammability, material abundance, and high specific energy. However, their applications are limited by the poor rechargeability of zinc anodes, which are related to shape changes, dendrite growth, corrosion, passivation, dissolution, etc. In this study, we developed a zeolitic-imidazolate framework (ZIF)-based route to construct a novel ZnO/Sb composite anode. The resultant zinc anode is scaffolded on carbon cloth (CC) and then encapsulated by carbonized resorcinol-formaldehyde resins. Such a carbon-framed ZnO/Sb anode shows the excellent rate and cycling properties because Sb suppresses the corrosion and improves interparticle conductivity, and the ZIF-derived carbon frame accommodates the shape changes, blocks the zinc dissolution, and accelerates the charge transfer. This work demonstrates the effectiveness of anti-corrosion and carbon-framed structure design on pouch and cable-like Ni-Zn batteries.

A Flexible Quasi-Solid-State Nickel-Zinc Battery with High Energy and Power Densities Based on 3D Electrode Design

A flexible quasi-solid-state Ni-Zn battery is developed by using tiny ZnO nanoparticles and porous ultrathin NiO nanoflakes conformally deposited on hierar chical carbon-cloth-carbon-fiber (CC-CF) as the anode (CC-CF@ZnO) and cathode (CC-CF@NiO), respectively. The device is able to deliver high performance (absence of Zn dendrite), superior to previous reports on aqueous Ni-Zn batteries and other flexible electrochemical energy-storage devices.