Clarification of the dispersion mechanism of cathode slurry of lithium-ion battery under effects of both poly vinylidene fluoride/carbon black ratio and mixing time--颗粒学报PARTICUOLOGY

Wang, Z., Zhao, Z., Yang, Y., Zhang, A., Liu, X., Zhao, T., & Cui, Y. (2024). Clarification of the dispersion mechanism of cathode slurry of lithium-ion battery under effects of both poly vinylidene fluoride/carbon black ratio and mixing time. Particuology, 88, 116-127. https://doi.org/10.1016/j.partic.2023.08.020

Clarification of the dispersion mechanism of cathode slurry of lithium-ion battery under effects of both poly vinylidene fluoride/carbon black ratio and mixing time

Zhilong Wang, Zhenzhen Zhao, Ye Yang, An Zhang, Xiayi Liu, Tong Zhao ^*, Yahui Cui

School of Mechanical and Precision Instrument Engineering, Xi'an University of Technology, Xi'an 710048, China

10.1016/j.partic.2023.08.020

Volume 88, May 2024, Pages 116-127

Received 1 August 2023, Revised 20 August 2023, Accepted 24 August 2023, Available online 20 September 2023, Version of Record 6 November 2023.

E-mail: tongzhao@xaut.edu.cn

Highlights

• LiCoO₂ particles are completely coated by mixture of carbon black (CB) and poly vinylidene fluoride (PVDF) in the case of mPVDF:mCB = 5:10.

• A good conductive network structure is formed by coating thinner PVDF–CB double layer around LiCoO₂ when t = 6 min.

• Cathode slurry prepared under conditions of both m_PVDF:m_CB = 5:10 and t = 6 min can improve performance of LIB.

Abstract

This paper presents the effects of both poly vinylidene fluoride (PVDF)/carbon black (CB) ratio (m_PVDF:m_CB) and mixing time t on the dispersion mechanism of the cathode slurry of lithium-ion battery (LIB). The dispersion mechanism is deduced from the electrochemical, morphological and rheological properties of the cathode slurry by using electrical impedance spectroscopy (EIS), scanning electron microscopy and rheology methods, respectively. From the perspective of EIS method, static simulation models are established in the COMSOL Multiphysics software; meanwhile, the simulated results are used to verify the correctness of the electrochemical properties of the cathode slurry. As a result, the following conclusions are able to be obtained. Firstly, in the case of the mass ratio m_PVD_F:m_CB = 5:10, LiCoO₂ particles are completely coated by the mixture of CB and PVDF to form a stable polymer gel structure. Higher or lower mPVDF:mCB leads to the larger impedance and worse dispersion status for the cathode slurry. Secondly, when t = 6 min, a good gel-like conductive network structure is formed by coating the thinner evenly dispersed CB–PVDF double layer around LiCoO₂ particles. Finally, a strategy regarding to both m_PVDF:m_CB and t in experimental scale is proposed, which has the capability of improving the performance of LIB.

Graphical abstract

Keywords

Cathode slurry; Dispersion mechanism; Lithium-ion battery (LIB)

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