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Open AccessArticle

Mechanical Integrity of Conductive Carbon-Black-Filled Aqueous Polymer Binder in Composite Electrode for Lithium-Ion Battery

by Kehua Peng 1,2,†, Yaolong He 1,2,†, Hongjiu Hu 1,2,*, Shufeng Li 1,2 and Bao Tao 1,2
1
Shanghai Institute of Applied Mathematics and Mechanics, School of Mechanics and Engineering Science, Shanghai University, Shanghai 200072, China
2
Shanghai Key Laboratory of Mechanics in Energy Engineering, Shanghai 200072, China
*
Author to whom correspondence should be addressed.
Both authors have contributed equally to the work.
Polymers 2020, 12(7), 1460; https://doi.org/10.3390/polym12071460
Received: 18 May 2020 / Revised: 26 June 2020 / Accepted: 29 June 2020 / Published: 30 June 2020
The mechanical stability of aqueous binder and conductive composites (BCC) is the basis of the long-term service of composite electrodes in advanced secondary batteries. To evaluate the stress evolution of BCC in composite electrodes during electrochemical operation, we established an electrochemical–mechanical model for multilayer spherical particles that consists of an active material and a solid-electrolyte-interface (SEI)-enclosed BCC. The lithium-diffusion-induced stress distribution was studied in detail by coupling the influence of SEI and the viscoelasticity of inorganic-filler-doped polymeric bonding material. It was found that tensile hoop stress plays a critical role in determining whether a composite electrode is damaged or not—and circumferential cracks may primarily initiate in BCC, rather than in other electrode components. Further, the peak tensile stress of BCC is at the interface with SEI and does not occur at full lithiation due to the relaxation nature of polymer composite. Moreover, mechanical damage would be greatly misled if neglecting the existence of SEI. Finally, the structure integrity of the binder and conductive system can be effectively improved by (1) increasing the carbon black content as much as possible in the context of meeting cell capacity requirements—it is greater than 27% and 50% for sodium alginate and the mixtures of carboxy styrene butadiene latex and sodium carboxymethyl cellulose, respectively, for composite graphite anode; (2) reducing the elastic modulus of SEI to less than that of BCC; (3) decreasing the lithiation rate. View Full-Text
Keywords: structure integrity; aqueous polymer binder; conductive carbon black; composite electrode; lithium-ion battery structure integrity; aqueous polymer binder; conductive carbon black; composite electrode; lithium-ion battery
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MDPI and ACS Style

Peng, K.; He, Y.; Hu, H.; Li, S.; Tao, B. Mechanical Integrity of Conductive Carbon-Black-Filled Aqueous Polymer Binder in Composite Electrode for Lithium-Ion Battery. Polymers 2020, 12, 1460.

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