A high-efficiency pre-lithiation strategy for Li-ion capacitor achieved by the synergistic effect of pre-lithiation and solid electrolyte interface film modification

The cathodic pre-lithiation process, currently considered the most feasible resolution to address the irreversible depletion of Li + in dual carbon-based lithium-ion capacitors (LICs), encounters obstacles in widespread adoption due to its substantial dosage requirement, rising decomposition potential and the damage related to its decomposition residues. Hence, in this study, the successful utilization of Li 2 NiO 2 for LIC pre-lithiation is accomplished, leveraging the synergistic effect between Li 2 NiO 2 and lithium difluoro oxalate borate (LiDFOB). It's noteworthy that the full capacitor, entirely composed of commercial materials (activated carbon/hard carbon) and supplemented with 20 wt% LNO +2 wt% LiDFOB, exhibits remarkable energy densities of 98.53 Wh kg −1 at a power density of 31 W kg −1 and 19 Wh kg −1 at a power density of 4.65 kW kg −1 . Moreover, the full capacitor displays commendable performance, demonstrating superior capacitive behavior and excellent high-current cycling proficiency. Besides, electrochemical evaluations and structural analyses unveil that LiDFOB, via solid electrolyte interface (SEI) modification, enhances the utilization of Li + sourced from Li 2 NiO 2 thus avoiding the abuse of pre-lithiation reagents, while the LNO decomposition products contribute substantially to additional capacitance. The synergistic effect of pre-lithiation reagent and SEI modification underpin the outstanding performance witnessed in the full capacitor.