Organic Cathode Materials for Lithium-Ion Batteries: Past, Present, and Future

With the rapid development of energy storage systems in power supplies and electrical vehicles, the search for sustainable cathode materials to enhance the energy density of lithium-ion batteries (LIBs) has become the focus in both academic and industrial studies. Currently, the widely utilized inorganic cathode materials suffer from drawbacks such as limited capacity, high energy consumption in production, safety hazards, and high-cost raw materials. Therefore, it is necessary to develop green and sustainable cathode materials with higher specific capacity, better safety properties, and more abundant natural resources. As alternatives, organic cathode materials possess the advantages of high theoretical capacity, environmental friendliness, flexible structure design, systemic safety, and natural abundance, making them a promising class of energy storage materials. Herein, the development history of the organic cathode materials and recent research developments are reviewed, introducing several categories of typical organic compounds as cathode materials for LIBs, including conductive polymers, organosulfur compounds, radical compounds, carbonyl compounds, and imine compounds. The electrochemical performance, electrode reaction mechanism, and pros and cons of different organic cathode materials are comparatively analyzed to identify the challenges to be addressed. Finally, the future research and improvement directions of the organic cathode materials are also proposed.