Chain engineering of carbonyl polymers for sustainable lithium-ion batteries

The ever-growing demand for energy and the excessive consumption of fossil fuels, accompanied with the rising environmental issues, has brought about an urgent requirement to seek high efficiency and green energy techniques. Lithium-ion batteries (LIBs) employing inorganic electrode materials have dominated such markets over the past decades. However, inorganic materials are being faced with their inherent limitations in specific capacities, mineral resources, and mechanical fragileness as well as eco-sustainability and cost-efficiency. In the last years, carbonyl polymers as electrode alternatives for LIBs have attracted considerable attention due to their high capacities, fast redox kinetics, chain designability, abundant resources, processing compatibility, and mechanical flexibility. Herein, a timely and comprehensive overview of the state-of-the-art knowledge is thoroughly summarized. Particular attention lies on the work principles, chain engineering strategies, carbonyl utilization, and electrochemical activities of carbonyl polymers. The structure-to-performance relationships concerning microstructures, topologies, and composites with nanocarbons are also scrutinized. Current challenges and future perspectives are finally proposed. This Review aims to provide an in-depth insight into the emerging topic of developing redox polymers for the next generation of high-performance batteries, in response to the imperative for the sustainable development of economy and society.