Effects of adhesion and cohesion on the electrochemical performance and durability of silicon composite electrodes

JOURNAL OF POWER SOURCES

卷:397

Article

Hu, Jiazhi¹  Wang, Yikai¹  Li, Dawei²  Cheng, Yang-Tse¹ 

[1] Univ Kentucky, Dept Chem & Mat Engn, Lexington, KY 40506 USA

[2] Shanghai Univ, Shanghai Inst Appl Math & Mech, Shanghai 200072, Peoples R China

关键词: Silicon;    Polymer binder;    Binder-silicon interface;    Lithium ion batteries;   

DOI  :  10.1016/j.jpowsour.2018.06.103

来源: Elsevier

【 摘 要 】

Although the choice of binder is crucial in determining the electrochemical performance and durability of silicon-based electrodes, the underlying mechanisms (e.g., mechanical vs. chemical) are unclear. Here, we report a study of the effects of adhesion vs. cohesion on the electrochemical behavior of silicon nanoparticle/polymeric binder/carbon black (CB) electrodes on copper conductor by multiple techniques. Two types of polymeric binders, polyvinylidene fluoride (PVDF) and sodium alginate (SA), were chosen for this study. The results show that because of a sufficiently strong interface between polymer and the copper current collector, both Si/PVDF/CB and Si/SA/CB composite electrode laminates have sufficient adhesive strength with the Cu conductor to cause cohesive failure within the electrode laminate during peel test. However, the interfacial strength between SA and silicon is significantly higher than that between PVDF and silicon, resulting in stronger cohesion within the Si/SA/CB electrode (e.g., peel strength of 78.3 N/m for Si/SA/CB electrode and 8.7 N/m for Si/PVDF/CB electrode, respectively). With a higher cohesive strength provided by a stronger binder-silicon interface, superior cell performance was ensured for Si/SA/CB electrodes. Hydrogen bonding is likely responsible for the stronger SA-Si interface since neither PVDF nor SA bonds covalently with Si according to chemical analysis.

【 授权许可】

Free