Fast Magnesium Conducting Electrospun Solid Polymer Electrolyte

Abstract

Magnesium Ion based Solid State Batteries (MIBs) are subject of intensive studies due to abundance of magnesium, its advantages in volumetric capacity, and the reduced dendrite growth. Here we report on a true solid polymer electrolyte system without liquid additives or plasticizers that reaches conductivities above 10 À 5 S cm À 1 at room temperature and above 10 À 4 S cm À 1 at 50 °C. An electrospun polymer electrolyte membrane fabricated from a polymer electrolyte featuring a composition of PEO : Mg(TFSI) 2 36 : 1 [where PEO stands for poly(ethyleneoxide) and Mg(TFSI) 2 for magnesium bis(trifluoromethanesulfonyl) imide] was identified as the best performing system. Magnesium transport was substantiated by different methods, and the electrochemical properties including solid electrolyte interface (SEI) formation were investigated. Electrospinning as a preparation method has been identified as a powerful tool to enhance the electrochemical properties beyond conventional polymer membrane fabrication techniques.

Multivalent Cation Transport in Polymer Electrolytes – Reflections on an Old Problem

“…As mentioned in the previous section, different drying conditions play a very important role in the measured values and vastly different transport properties in multivalent systems. Newer studies suggest that the ionic conductivities in these early studies were overestimated, as seen in two recent studies by Park et al [ 33 ] and Walke et al [ 34 ] Both studies found significantly decreased glass transition temperatures between −30 °C and −20 °C for low and intermediate salt concentrations between 10–40 wt.%, which was explained by stronger ionic cross‐linking effects, as compared to monovalent cations. Just above the melting temperature (estimated to 50–65 °C from Figure 3 ), (total) ionic conductivities reached the 10 −4 S cm −1 regime.…”

Recent Research Progress on All-Solid-State Mg Batteries

“…Polymer hosts and Mg salts are dissolved into a solvent and then cast onto a substrate to obtain SPE films. Common host polymers, such as PEO, have been used in Mg 2+ -ion conductive SPEs [83,84]. Different from Li + ion conductive SPEs, water-soluble polymers like PVP and PVA are also used [85][86][87][88].…”

“…To improve the properties of SPEs, a polymer blend, namely, a mixture of two host polymers, was also studied [106][107][108][109][110][111][112][113][114][115][116]. By the blending, the ionic conductivity increases by Common host polymers, such as PEO, have been used in Mg 2+ -ion conductive SPEs [83,84]. Different from Li + ion conductive SPEs, water-soluble polymers like PVP and PVA are also used [85][86][87][88].…”