Toward all-climate high-energy lithium-ion batteries: Nickel-rich cobalt-free layered oxide cathodes and wide-temperature electrolyte engineering

The development of high-energy-density lithium-ion batteries (LIBs) is crucial to advancing electric vehicles (EVs) and large-scale renewable energy storage. Ni-rich cathodes (e.g., LiNi _x Mn _y Co _z O₂), one of the most widely used cathode materials in LIBs, directly determine the overall performance and cost of LIBs. However, due to the scarcity and high price of Co resources, there is an urgent need to develop Ni-rich Co-free cathode materials for LIBs. Despite the many efforts that have been made, Ni-rich Co-free cathodes still face insufficient electrochemical stability and poor adaptability to extreme temperatures. This review provides a comprehensive analysis of the development and synthesis of Ni-rich Co-free oxide cathodes, emphasizing their performance characteristics, existing challenges, and potential future trends. Special attention is given to modification strategies, particularly concentration gradient materials, which offer significant promise in overcoming these challenges. Additionally, this review examines the progress in the development of electrolytes designed for these cathodes in wide-temperature ranges, detailing the influence of temperature factors on their performance and highlighting the associated challenges and opportunities for their practical application in LIBs. This review aims to provide valuable insights for promoting the further application and development of Ni-rich Co-free cathodes under extreme conditions.