Cobalt in high-energy-density layered cathode materials for lithium ion batteries

Lithium-ion batteries are one of the most successful energy storage devices and satisfy most energy storage application requirements, yet, should further lower kWh costs. The application of cobalt in cathodes engenders controversy due to the scarcity and uneven distribution, resulting in environmental and social concerns, including human rights violations and price volatility. However, it is worth re-examining whether cobalt shall be replaced entirely. Herein the roles of cobalt in LiCoO2 and LiNixCoyMn1-x-yO2 cathode materials are discussed. Cobalt makes LiCoO2 presenting the highest volumetric energy density and LiNixCoyMn1-x-yO2 possessing the excellent electronic and ionic conductivity. Complete removal of cobalt may damage the battery performance, and it is difficult to find alternative elements that offer both extraordinary ionic and electronic conductivity as Co at present. The review summarizes some of the current scientific opinions underpinning the role of cobalt in high-energy-density layered cathodes.