Improving Energy Storage and Nickel Manganese Cobalt Oxide Cathode Lifetime via a Tannic Acid/Iron (III) Metal Phenolic Network Coating

Abstract Surface coating lithium‐ion battery cathodes is a promising strategy to improve performance and mitigate cathode degradation. The coatings studied to date focus on either electronically or ionically conducting layers, which have been introduced to enhance the redox reactions of cathode particles, or oxide‐based physical protection layers limiting surface degradation. Such coatings require high‐temperature, time‐consuming synthesis processes, along with uncertainty in the specific interactions between these coatings and lithium ions. Here, metal‐phenolic network coated LiNi 0.6 Mn 0.2 Co 0.2 O 2 (NMC) cathodes are, produced using naturally occurring polyphenols via a rapid one‐step assembly, improve cathode electrochemical performance. The performance improvement arises from the interaction between lithium ions and the coated layer, which enhances the lithium‐ion transport to the cathode. In half‐cell 1C rate cycling conditions, the modified cathode displays a 20% reduction in overpotential and a 54% decrease in interfacial resistance compared to the uncoated cathode. In a full‐cell format, the modified cathode exhibits a 10% increase in capacity and a 54% increase in lifespan for constant current cycling; in addition to a 5% increase in capacity and a 25% increase in lifespan for constant current‐constant voltage (CCCV) cycling. This work paves the way for improving cathode materials via eco‐friendly lithium‐ion attraction strategies.