Effects of adhesion and cohesion on the electrochemical performance and durability of silicon composite electrodes
Effects of adhesion and cohesion on the electrochemical performance and durability of silicon composite electrodes
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DOI：
10.1016/j.jpowsour.2018.06.103
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发表时间：
2018-09-01
影响因子：
9.2
通讯作者：
Cheng, Yang-Tse
中科院分区：
文献类型：
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作者：
Hu, Jiazhi;Wang, Yikai;Cheng, Yang-Tse
虽然粘合剂的选择在决定硅基电极的电化学性能和耐久性方面至关重要，但潜在的机制（例如，化学与机械）不清楚。在这里，我们报告的粘附性与凝聚力的影响的研究硅纳米粒子/聚合物粘合剂/炭黑（CB）电极上的铜导体的电化学行为，通过多种技术。本研究选择了两种类型的聚合物粘合剂：聚偏氟乙烯（PVDF）和海藻酸钠（SA）。结果表明，由于聚合物和铜集电器之间的足够强的界面，Si/PVDF/CB和Si/SA/CB复合电极层压体都具有与Cu导体的足够的粘合强度，以在剥离测试期间在电极层压体内引起内聚破坏。然而，SA和硅之间的界面强度显著高于PVDF和硅之间的界面强度，导致Si/SA/CB电极内的更强的内聚（例如，Si/SA/CB电极的剥离强度分别为78.3N/m，Si/PVDF/CB电极的剥离强度分别为8.7N/m）。通过更强的粘合剂-硅界面提供更高的内聚强度，确保了Si/SA/CB电极的上级电池性能。氢键可能是导致更强的SA-Si界面的原因，因为根据化学分析，PVDF和SA都不与Si共价键合。
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.