A Zero-Conductive-Additive Covalent Organic Polymer Cathode for High-Temperature Lithium-Ion Batteries with High Stability

Li-ion batteries (LIBs) capable of sustaining high-temperature cycling are essential for energy storage; however, building cathode materials with stable cycling for long term at high temperatures remains a significant challenge. Organic cathode materials have significant applied implications for LIBs; however, they are limited by low electronic conductivity, which requires a large amount of inactive conductive carbon for electrode fabrication, leading to a significant decrease in energy density. Herein, we demonstrated that a π-conjugated covalent organic polymer (COP) cathode, coupled with ether-based electrolytes containing 2 wt % LiNO3 additives, could act as an ultra-stable conductive-additive-free organic cathode for lithium storage at room and high temperatures. Typically, at 60 °C, the conductive-additive-free COP cathode could deliver a high initial reversible capacity (374 mAh g–1), an unprecedented cyclability for 5000 cycles (0.01% capacity decay per cycle), and a promising rate capability. The π-conjugated framework of this COP promises enhanced electronic conductivity with high mechanical and chemical stability. The ether-based electrolyte shows favorable compatibility with the cathode and yields a stable cathode–electrolyte interface (CEI) with LiF as an ionic-conductor component to facilitate Li+ transport.