Reevaluating the Critical Role of Cobalt in Ultra-High Nickel Cathodes: Toward Sustainable and High-Performance Lithium-Ion Batteries

Lithium-ion batteries are extensively employed in electric vehicles and energy storage systems due to their exceptional energy density and operational voltage. However, with the swift expansion of the electric vehicle market, batteries are now confronted with increasingly stringent demands concerning energy density, driving range, and charging efficiency. As the pivotal and determinant component of a battery, the cathode material has a direct impact on the overall performance of the battery. Ultra-high nickel cathodes have emerged as a research focus owing to their superior high capacity and voltage. Despite efforts to reduce or even completely replace cobalt in the pursuit of low-cost and high-performance cathodes, its indispensable role in structural stabilization and charge compensation cannot be overlooked, rendering complete cobalt substitution a formidable challenge. To gain a more profound understanding of the role of cobalt in ultra-high nickel cathodes, this paper delves into the structural characteristics of these cathodes by analyzing their failure mechanisms by means of structural characterization and electrochemical performance evaluation, and comprehensively discussing the role of cobalt in ultra-high nickel cathodes. This comprehensive study aims to provide a reliable theoretical basis for the industrialization of ultra-high nickel cathode materials.