Fluorine-doped carbon quantum dot interfacial layer on stockade-like etched copper foil for boosting Li-ion storage

The interface engineering of anode electrodes in lithium-ion batteries (LIBs) is a key strategy in improving the Li-ion storage kinetics and interface stability to achieve outstanding ultrafast cycling capacities and cycling stabilities of LIBs. However, despite extensive research on the interfacial engineering of electrode materials, studies on the interface design between the electrode and current collector to improve the ultrafast cycling performance are rare. In this study, we designed a novel interface architecture for a fluorine-doped carbon quantum dot (F-CQD) interfacial layer on a stockade-like etched Cu foil via electrochemical modification and a spray coating process. The anode electrode assembled with the resultant Cu foil showed enhanced adhesion, high reaction kinetics, and excellent interface stability between the electrode and Cu foil due to the F-CQD interfacial layer on the stockade-like etched Cu foil, leading to an improved ultrafast cycling performance. Consequently, the novel architecture of a Cu foil having stockade-like etching patterns with an F-CQD interfacial layer showed an increased ultrafast cycling capacity of 82.9 mAh g⁻¹ and excellent ultrafast cycling stability of 94.1% after 500 cycles under ultrafast cycling conditions. These improved ultrafast cycling performances are due to the high contact area between the electrode and Cu foil, excellent reaction sites, and superb corrosion resistance.