Effects of polymeric binders on. the cracking behavior of silicon composite electrodes during electrochemical cycling

JOURNAL OF POWER SOURCES

卷:438

Article

Wang, Yikai¹  Dang, Dingying¹  Li, Dawei^1,2  Hu, Jiazhi¹  Zhan, Xiaowen¹  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 electrode;    Cracking;    Polymeric binder;    In situ observation;    Adhesion;    Lithium ion battery;   

DOI  :  10.1016/j.jpowsour.2019.226938

来源: Elsevier

【 摘 要 】

Mechanical degradation caused by lithiation/delithiation-induced stress and large volume change is the primary cause of fast capacity fading of silicon (Si)-based electrodes. Although intensive efforts have been devoted to understanding electromechanically induced fractures of electrodes made of Si alone (e.g., Si particles, Si thin films, and Si wafers), the cracking behavior of Si/polymeric binders/carbon black composite electrodes is unclear and poorly understood. Here, we investigate, by in situ and ex situ techniques, the cracking behavior of Si composite electrodes made with different binders, including polyvinylidene fluoride (PVDF), sodium-alginate (SA), sodium-carboxymethyl cellulose (Na-CMC), and Nafion. We found that extensive cracks form during the 1st delithiation process, which periodically open and close during subsequent lithiation/delithiation cycles at the same locations in the Si composite electrodes made with SA, Na-CMC, and Nafion. In contrast, a significantly fewer number of cracks form in the Si/PVDF electrodes after electrochemical cycling. A possible mechanism is proposed to help understand the effects of binders on the cracking behavior (e.g., crack spacing and island size) of Si composite electrodes. We also suggest possible approaches, including reducing the electrode thickness, patterning electrodes, and using highly recoverable binders, to inhibit cracks and improve the mechanical integrity of Si composite electrodes.

【 授权许可】

Free