A prelithiation pathway with high-release efficiency and self-enhanced interface chemistry to achieve stable Li-ion full cells

First-cycle irreversible lithium loss critically limits lithium-ion battery capacity. This study proposes the design of unique cathode prelithiation material, carbon sphere-composited lithium squarate (FSL-CS). Among them, the three-dimensional conductive network fabricated through chemical precipitation significantly enhances both electronic conductivity and structural stability. Electrochemical characterization reveals that FSL-CS delivers a compensation capacity of 390.8 mAh·g −1 during initial charging, achieving 92 % efficiency in lithium release, which have high-release efficiency. Compared to unmodified one, the composite demonstrates reduced kinetic barriers with a lowered delithiation plateau voltage of 3.97 V (vs. 4.16 V for pristine material). In situ/ex situ analyses confirm the carbon sphere composite strategy establishes self-enhanced interface chemistry. This optimizes interfacial charge transfer, boosting the Li + diffusion coefficient by an order of magnitude and continuously inducing in-situ formation of a gradient organic-inorganic composite cathode electrolyte interphase. Full-cell evaluations show that NCM811||Graphite batteries with 5 % FSL-CS maintain 87.3 % capacity retention after 400 cycles at 1C, while pouch cells retain 70.2 % capacity after 1000 cycles. Theoretical calculation reveals that FSL-CS exhibits a lower lithium migration energy barrier (0.65 eV) compared to conventional Li 2 NiO 2 (1.00 eV). This work provides new design principles for stable organic prelithiation systems featuring high-release efficiency, self-enhanced interfaces, and low-voltage operation.