Renewable Energy Global Innovations highlights High-Power and High-Energy Hybrid Rechargeable Battery research

Renewable Energy Global Innovations features the research of Dr. Zhongwei Chen is Canada Research Chair Professor in Advanced Materials for Clean Energy at the University of Waterloo. The research team developed Self-Assembled NiO/Ni(OH)2 Nanoflakes as Active Material for High-Power and High-Energy Hybrid Rechargeable Battery,

 With continuous increase in fuel prices and rising concerns of environmental issues, much research and development efforts have been focused on the advancement of energy conversion and storage systems such as fuel-cells, supercapacitors, and metal-air batteries. In particular, rechargeable zinc-air batteries have recently gained tremendous attention due to their extremely high energy density and flat discharge profile. Additionally, zinc-air batteries are considered highly promising as potential replacements for lithium-ion batteries due to the advantages of low cost, safe operation, and environmental benignity.

With electric drive vehicles emerging in the market, the demand for energy systems to efficiently power them has increased tremendously. Typically, energy systems for electric drive vehicles require generation of both high power and energy densities to provide sufficient acceleration and driving range. To address this, previous hybrid energy systems have been developed by simply connecting multiple energy devices through an external circuitry, or by utilizing multiple active materials to obtain both high power and energy densities. These hybrid systems, however, are usually physically much bulkier and are too costly to generate energy in a cost-competitive manner.

Unlike previous hybrid systems, the present work by Prof. Zhongwei Chen’s group at the University of Waterloo introduces a proof-of-concept of a hybrid rechargeable battery, which combines the electrochemical reactions of nickel-zinc and zinc-air batteries at the cell level to harness both high power and high energy densities without increasing system complexity, physical dimensions, and the number of active materials. The single active material used in the hybrid battery is nickel oxide/nickel hydroxide (NiO/Ni(OH)₂) nanoflakes self-assembled into mesoporous spheres, which is affordable, simple to fabricate, and environmentally benign. This cost-effective non-precious transition metal based active material is capable of exhibiting both Faradaic redox and reversible oxygen electrocatalytic reactions, which provide the driving forces to produce high power and energy densities, respectively. Specifically, the hybrid battery is capable of demonstrating extremely high power density (gravimetric: 2700 W kg^-1, and volumetric: 14000 W L^-1), over five times that of the conventional zinc-air battery obtained based on standard Co₃O₄ air electrode. Simultaneously, it is capable of demonstrating very high energy density of 980 W h kg^-1, far exceeding those of commercial primary zinc-air batteries (~470 W h kg^-1), and lithium-ion batteries (~300 W h kg^-1). 

Read the full story at Renewable Energy Global Innovations