The Impact of Absorbed Solvent on the Performance of Solid Polymer Electrolytes for Use in Solid-State Lithium Batteries.

Mickaël Dollé,Nina Verdier,David Aymé-Perrot,Arnaud Prébé,David Lepage,Gabrielle Foran,Denis Mankovsky

doi:10.1016/j.isci.2020.101597

Mickaël Dollé, Nina Verdier + Show 5 more

Open Access

https://doi.org/10.1016/j.isci.2020.101597

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Journal: iScience	Publication Date: Sep 21, 2020
Citations: 50	License type: cc-by

Affiliation: Université de Montréal, Total (France)

Abstract

SummaryThe effects of solvent absorption on the electrochemical and mechanical properties of polymer electrolytes for use in solid-state batteries have been measured by researchers since the 1980s. These studies have shown that small amounts of absorbed solvent may increase ion mobility and decrease crystallinity in these materials. Even though many polymers and lithium salts are hygroscopic, the solvent content of these materials is rarely reported. As ppm-level solvent content may have important consequences for the lithium conductivity and crystallinity of these electrolytes, more widespread reporting is recommended. Here we illustrate that ppm-level solvent content can significantly increase ion mobility, and therefore the reported performance, in solid polymer electrolytes. Additionally, the impact of absorbed solvents on other battery components has not been widely investigated in all-solid-state battery systems. Therefore, comparisons will be made with systems that use liquid electrolytes to better understand the consequences of absorbed solvents on electrode performance.

Highlights

Battery performance depends on the solubility and mobility of lithium cations in an electrolyte medium (Wegner, 2006)
The lack of information surrounding the solvent content of these materials is not ideal as polymer electrolytes are often prepared via solvent casting, which, like the absorption of water during atmospheric exposure or the absorption of other solvents during glovebox storage, provides a medium through which the dry polymer, and associated lithium salt, can absorb solvents such as acetonitrile and dimethylformamide (DMF) (Bhattacharja et al, 1986; Sun et al, 2015; Andrews et al, 2018; Ohno et al, 2020)
Due to the experimental complexities associated with quantifying electrochemical failure in all-solid-state batteries being outside of the scope of this work, the electrode section of this review focuses on comparing the electrochemical properties of batteries based on their solvent content along with a discussion of how increased solvent content can contribute to battery failure

Summary

INTRODUCTION

Battery performance depends on the solubility and mobility of lithium cations in an electrolyte medium (Wegner, 2006). Examples of deliberate water addition to polymer electrolytes can be found in the work of Donoso et al (1995) and Johansson et al (1995) who exposed lithium salt doped PEO to D2O in order to track changes in cation mobility using nuclear magnetic resonance (NMR) spectroscopy In both cases, sample D2O content was determined by mass. In addition to decreasing the strength of the bond between the lithium salt and the polymer, interactions with water have been shown to change the mechanism of salt complexation in solid polymer electrolytes This phenomenon was demonstrated by Yang and Huo (2013) who doped PEO films with MgCl2 and its hydrated analogs: MgCl2.4H2O and MgCl2.6H2O. As water absorption by the salt has been shown to impact complexation between the polymer and salt components of the electrolyte, more widespread measurement of water content would be beneficial for better understanding the relationship between salt loading and electrolyte crystallinity

IMPACT OF ACETONITRILE ABSORPTION ON THE PROPERTIES OF POLYMER ELECTROLYTES

Findings

CONCLUSION