Dual-Functional Carbon Dots as Electrolyte Additives for Enhancing Cathode Catalysis and Anode Stability in Li–O2 Batteries

en This link goes to a English section zh This link goes to a Chinese section Li–O 2 batteries garner widespread attention owing to their remarkable theoretical specific capacity. Nevertheless, the feasible implementation of the system is hindered by sluggish cathode reaction kinetics and poor anode stability. Herein, the carbon dots (CDs) with -OH, -NH 2 , and -COOH groups are synthesized and employed as electrolyte additives for Li–O 2 batteries. The CDs are well-dispersed in the electrolyte which promotes the formation of Li 2 O 2 through hydrogen bond-mediated dissolution, whereas their high catalytic activity simultaneously facilitates Li 2 O 2 decomposition, thereby enhancing cathode reaction kinetics. Additionally, CDs can suppress dendrite growth on the Li anode and reduce dead Li accumulation by improving the properties of the electrolyte, including ionic conductivity, raising the Li + transference number, ensuring strong electronic insulation, and altering the Li + solvation structure. Therefore, the introduction of CDs enables the Li–O 2 battery to achieve a discharge capacity of 5422.2 mAh g −1 and maintain stable cycling performance of 700 h at 100 mA g −1 . This work underscores the remarkable efficacy of CDs electrolyte additive in enhancing the performance of the Li–O 2 battery, providing a new direction for addressing existing challenges of the battery. 摘要 en This link goes to a English section zh This link goes to a Chinese section 锂氧电池因其超高的理论比容量而备受关注,但受限于正极反应动力学迟缓、锂负极稳定性差等问题,其实际应用仍面临挑战。为此,本研究合成了羟基、氨基与羧基官能团修饰的碳点,并将其用作锂氧气电池电解液添加剂。该碳点在电解液中分散性良好,能够通过氢键作用促进过氧化锂 (Li 2 O 2 ) 的形成; 同时,其自身优异的催化活性可加速 Li 2 O 2 的分解,从而有效提升正极反应动力学。此外,碳点的引入可优化电解液的多个关键性能,包括提高离子电导率、增大锂离子迁移数、保持良好的电子绝缘性,并调控锂离子溶剂化结构,进而抑制锂负极的枝晶生长、减少死锂积累。基于以上作用,引入碳点的锂氧电池在 100 mA g −1 电流密度下,放电比容量达到 5422.2 mAh g −1 ,并实现了长达700小时的稳定循环。本研究证实了功能化碳点作为电解液添加剂对提升锂氧电池性能的显著作用,为解决该体系现存的关键问题提供了新思路。