The Influence of Polyvinylidene Fluoride (PVDF) Binder Properties on LiNi0.33Co0.33Mn0.33O2 (NMC) Electrodes Made by a Dry-Powder-Coating Process

We have investigated the effects of the molecular weight of the polyvinylidene fluoride (PVDF) binder on the electrochemical performance and mechanical integrity of the LiNi0.33Co0.33Mn0.33O2 (NMC) electrodes made by a dry-powder-coating process. The microstructure, binding strength, and electrochemical behavior of the electrodes made with two types of PVDF polymers were compared. We show that a thin PVDF layer can form on the NMC particle surface after heating the PVDF to above its melting point. The microstructure and porosity of the PVDF layer depend strongly on the molecular weight of the PVDFs. With increasing molecular weight, the PVDF layer becomes more porous, improving the high-rate capacity without decreasing binding strength and long-term cycling performance of the electrodes. (c) The Author(s) 2019. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited.