The Impotence of Non-Brownian Particles on the Gel Transition of Colloidal Suspensions.

Samantha Morelly,Nicolas Alvarez,Maureen Tang

doi:10.3390/polym9090461

Abstract

The ability to predict transitions in the microstructure of mixed colloidal suspensions is of extreme interest and importance. The data presented here is specific to the case of battery electrode slurries whereby the carbon additive is reported to form strong colloidal gels. Using rheology, we have determined the effect of mixed particle systems on the critical gel transition . More specifically, we show that the introduction of a high volume fraction of large non-Brownian particles has little to no effect on . Although is unchanged, the larger particles do change the shape of the linear viscoelasticity and the nonlinear yielding behavior. There are interesting similarities to the nonlinear behavior of the colloidal gels with trends observed for colloidal glasses. A comparison of experimental data and the prediction from theory shows that the equation presented by Poon et al. is able to quantitatively predict the transition from a fluid state to a gel state.

Highlights

Coatings of particle–polymer composites are ubiquitous in a myriad of applications, including lithium-ion and other advanced battery technologies that are predicted to play substantial roles in growing concerns over the energy and environmental landscape [1]
Control Sample: A φCB = 0.005 NMP solution in the absence of PVDF was observed as a control
carbon black (CB) Only: Mixtures of CB and PVDF in NMP were observed for 0.004 ≤ φCB ≤ 0.009

Summary

Introduction

Coatings of particle–polymer composites are ubiquitous in a myriad of applications, including lithium-ion and other advanced battery technologies that are predicted to play substantial roles in growing concerns over the energy and environmental landscape [1]. Both material- and device-level limitations play a role in determining battery performance, lifetime, and cost. One of the greatest of these limitations is charge transport. Electrodes must have sufficiently fast electron and ion transport to utilize the electrochemically active material and prevent resistive losses. The rate of transport is determined by material properties, and by the electrode microstructure [2,3]. Recent studies suggest that the final “dry” microstructure is determined by the initial “wet” microstructure of the colloidal slurries formed during electrode processing [4,5,6,7,8,9,10,11,12,13,14,15,16,17]

Methods

Results

Conclusion