Enhancing Lithium-Ion Battery Performance with Photoactive LiFePO4/CsPbBr3 Quantum Dots Composite Cathodes

The advancement of photo-assisted lithium-ion batteries (LIBs) relies on developing suitable photoactive Li+ storage materials and understanding their energy storage/conversion mechanisms. A novel composite material, LiFePO4/CsPbBr3 quantum dots (LFP/CPB QDs) is presented, created by embedding CPB QDs onto LFP nanoparticles. This composite exhibits dual functionalities of photoelectric conversion and storage in LIBs. Under simulated light, the composite demonstrated significant enhancements in charge and discharge capacities, with increases of 16.8% and 16.4% at 3C, respectively. Remarkably, the coulombic efficiency exceeded 100%, reaching 115.2% when charged in the dark and discharge under light. The LFP/CPB QDs cathode also maintained 93.9% capacity retention after 200 cycles at 0.5C. Analyses with synchronous-illumination X-ray photoelectron spectroscopy, cyclic voltammetry, and electrochemical impedance spectroscopy confirmed photo-induced charge transfer at the composite interface. Under sunlight, CPB QDs transfer photogenerated electrons to LFP, promoting the transition of Fe3+ to Fe2+ and enhancing Li+ reaction kinetics. These findings offer valuable insights for designing electrode materials for photo-assisted battery applications.