The FeF₃ cathode shows some promising potentials for lithium-ion batteries (LIBs) because of its high theoretical capacity induced by conversion reactions, but the poor electrical conductivity and inferior reaction kinetics severely limit battery performance. Herein, the FeF₃ nanoparticles embedded in double Fe/graphitized carbon (GC) matrices (FeF₃/Fe/GC) are fabricated using low-temperature fluorination, where the spongy structure originates from the unique self-expanding process. It was found that the pseudocapacitive contribution of the optimized FeF₃/Fe/GC nanocomposite is as high as 98%, which contributes to a high specific capacity of 151.2 mA h g⁻¹ at a high rate of 10 C after 1000 cycles, with a capacity decay rate of only 0.03% per cycle. Surprisingly, even at an ultra-high rate of 100 C, the composite cathode still delivers a discharge capacity as high as 106.7 mA h g⁻¹, which is superior to those reported in the previous studies. The excellent cycle stability and ultra-high rate performance can be attributed to the intimate contact between double Fe/GC matrices and ultrafine FeF₃ nanoparticles, which can effectively reduce the diffusion barrier of ions and electrons to enhance the redox pseudocapacitive process. It has been demonstrated that optimizing the pseudocapacitive behavior may be a simple yet effective strategy to obtain the cathode materials with ultra-high rate capability.

FeF ₃正极显示出用于锂离子电池 (LIB) 的一些有前途的潜力，因为它由转化反应引起的高理论容量，但不良的导电性和较差的反应动力学严重限制了电池性能。在此，嵌入双 Fe/石墨化碳 (GC) 基质 (FeF ₃ /Fe/GC) 中的 FeF ₃纳米颗粒是使用低温氟化法制备的，其中海绵状结构源自独特的自膨胀过程。结果发现，优化后的 FeF ₃ /Fe/GC 纳米复合材料的赝电容贡献高达 98%，这有助于实现 151.2 mA h g ^{−1的高比容量}在 1000 次循环后以 10 C 的高速率，每次循环的容量衰减率仅为 0.03%。令人惊讶的是，即使在 100 C 的超高倍率下，复合阴极仍可提供高达 106.7 mA h g ^-1的放电容量，这优于之前研究中报道的那些。优异的循环稳定性和超高倍率性能可归因于双Fe/GC基体与超细FeF ₃纳米颗粒之间的紧密接触，可有效降低离子和电子的扩散势垒，增强氧化还原赝电容过程。已经证明，优化赝电容行为可能是获得具有超高倍率性能的正极材料的一种简单而有效的策略。