High-κ, high-rate: Pseudocapacitive Li+storage in ultrathin BaTiO3 and its composites

초록

This study investigates the intrinsic and composite electrochemical behavior of ultrathin BaTiO3 (BTO) electrodes fabricated via alternating current electrophoretic deposition (AC-EPD). Additive-free BTO films exhibited strong pseudocapacitive charge storage with b-values of 0.87 (anodic) and 0.84 (cathodic), along with high Li+ diffusivity (1.17 × 10−10 to 1.62 × 10−10 cm2/s), underscoring the advantage of an ultrathin, high-dielectric interface. Incorporating poly(vinylidene fluoride) (PVDF) binder alone suppressed performance, reducing capacity and obscuring pseudocapacitive contributions. By contrast, the BTO + carbon black + PVDF composite demonstrated the highest specific capacity and excellent rate performance, rivaling that of additive-free BTO, owing to enhanced electronic conductivity provided by the carbon network. Nevertheless, diffusivity in the composite was lower than in pure BTO, reflecting increased ionic tortuosity and partial masking of active sites. SEM analysis further revealed that additive-free films preserved interfacial stability, while composites experienced greater structural disruption after cycling. These findings highlight the complementary roles of intrinsic BTO pseudocapacitance and conductive additive networks, establishing ultrathin BTO films as both an interface-sensitive platform for probing charge storage and a versatile component for designing high-performance Li-ion battery anodes. © 2026 Elsevier Ltd. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

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