整合離子通道的負極材料應用於高性能鋰離子電池之研究

Abstract

本文旨在開發一種兼具儲鋰能力與流變穩定性之功能性黏結劑，應用於鋰離子電池石墨負極，以實現更高性能之石墨電池。基於綠色有機鋰儲存材料對新型電源永續發展的重要性，本研究選用可再生有機化合物聚衣康酸(poly(itaconic acid), PIA) 為主體，結合二丁基衣康酸酯 (poly(dibutyl itaconate), PDBIA)、月桂酸丙烯酸酯 (poly(lauryl acrylate), PLA) 與甲基丙烯酸甲酯(poly(methyl methacrylate), PMMA) 等共聚單體，經乳化聚合合成具梯度核殼結構之乳膠粒子。其中，PIA 所提供之雙羧基結構( C(=O)OH ) 可作為活性儲鋰位點，每一 PIA 結構單元可與最多六個鋰離子反應，其中四個為可逆鋰化/脫鋰反應，展現作為鋰電池功能性黏結劑之潛力。 以代表性配方 (IA 含量 15 wt%) 為例，在 0.001–1.8 V (vs. Li/Li⁺) 電壓範圍下，0.1C 的 formation test 首圈可達 385 mAh g⁻¹ ；於 0.3C 下進行 500 次循環後仍維持 376 mAh g⁻¹，PIA的表面含氧官能基有助於降低電荷轉移阻力（Rct），是長期穩定循環的關鍵因素。此外，其在 5C 高倍率測試下亦保有 379 mAh g⁻¹，歸因於 PIA 中含氧官能基與鋰離子形成可逆配位，於界面提供穩定的鋰離子通道，促進鋰脫溶與嵌入石墨層間的反應動力學。 另一方面，為提升漿料加工性與塗佈均勻性，鋰電池電極製程中常以鹼性中和處理改善溶液黏度與流變性能。傳統使用氫氧化鋰（LiOH）中和雖可提升黏度，卻會造成黏合強度降低與界面劣化，削弱黏附性並降低電池循環壽命。本研究創新提出以氨水作為 PIA 黏結劑的可逆中和劑，形成的羧酸銨鹽基團（–COO⁻⋯NH₄⁺）可於乾燥階段熱分解回原始 PIA 結構，提升界面黏著與穩定性。DLM334-IA15 pH4之樣品在0.1C 的 formation test 首圈可達 420 mAh g⁻¹，且400圈時總界面阻抗僅 196.8 Ω。氨水可逆中和製程成功保留鹼性中和的加工優勢，更進一步提升鋰電池的電容量，以及降低電荷轉移阻抗，展現其在高性能鋰離子電池之應用潛力。

This study aims to develop a functional binder that combines both lithium-storage capability and rheological stability, tailored explicitly for graphite anodes in lithium-ion batteries (LIBs) to achieve enhanced electrochemical performance. Considering the significance of green organic lithium-storage materials in the sustainable development of next-generation energy systems, we synthesized gradient core–shell latex particles via emulsion polymerization using renewable poly(itaconic acid) (PIA) as the lithium-active backbone, co-polymerized with poly(dibutyl itaconate) (PDBIA), poly(lauryl acrylate) (PLA), and poly(methyl methacrylate) (PMMA). The dicarboxylic structure (C(=O)OH) in PIA serves as active sites for lithium storage, with each repeating unit capable of reversibly coordinating up to four lithium ions, demonstrating strong potential as a functional binder for LIB applications. A representative formulation containing 15 wt% IA exhibited an initial specific capacity of 385 mAh g⁻¹ at 0.1C (0.001–1.8 V vs. Li/Li⁺), and retained 376 mAh g⁻¹ after 500 cycles at 0.3C. The surface oxygen-containing functional groups on PIA significantly reduced charge transfer resistance (Rct), which is identified as a key factor in sustaining long-term cycling stability. Moreover, even under high-rate testing at 5C, the capacity remained as high as 379 mAh g⁻¹, attributed to the reversible coordination between Li⁺ and oxygenated functional groups that serve as intermediate transport sites at the electrode–electrolyte interface, facilitating Li⁺ desolvation and intercalation kinetics. To improve slurry processability and coating uniformity, alkaline neutralization is commonly used to modify the rheology of the binder in electrode fabrication. However, conventional neutralization using lithium hydroxide (LiOH) often leads to irreversible lithium binding and reduced interfacial adhesion, compromising structural integrity and cycling life. In this work, we introduce ammonia (NH₃) as a reversible neutralizing agent for PIA, forming ammonium carboxylate (–COO⁻⋯NH₄⁺) groups that thermally decompose during drying, restoring the original PIA structure and enhancing interfacial adhesion. The optimized sample (PIA 15 wt%, pH 4) achieved an initial capacity of 420 mAh g⁻¹ and maintained a low total interfacial resistance of 196.8 Ω after 400 cycles. The proposed ammonia-neutralized PIA system successfully retains the processing advantages of alkaline-treated slurries while simultaneously improving capacity and reducing interfacial resistance. This strategy demonstrates promising potential for high-performance lithium-ion battery applications.