Ionic transport and non-aqueous potassium-ion

Schematic of the K preparation protocol enabling K ion electrolyte transport and thermodynamic property characterisation

Non-aqueous potassium-ion batteries (KIBs) represent a promising complementary technology to lithium-ion batteries due to the availability and low cost of potassium. Moreover, the lower charge density of K⁺ compared to Li⁺ favours the ion-transport properties in liquid electrolytes solutions, thus making KIBs potentially capable of improved rate capability and low-temperature performance - however a comprehensive study of the ionic transport and thermodynamic properties of non-aqueous K-ion electrolyte solutions is not available.

In 'Fundamental investigations on the ionic transport and thermodynamic properties of non-aqueous potassium-ion electrolytes' the authors report on the full characterisation of the ionic transport and thermodynamic properties of a model non-aqueous K-ion electrolyte solution system comprising potassium bis(fluorosulfonyl)imide (KFSI) salt and 1,2-dimethoxyethane (DME) solvent and compare it with its Li-ion equivalent (ie LiFSI:DME) over the concentration range 0.25-2 molal.

Using tailored K metal electrodes, they demonstrate that KFSI:DME electrolyte solutions show higher salt diffusion coefficients and cation transference numbers than LiFSI:DME solutions. They also investigate the K-ion and Li-ion storage properties for KIIgraphite and LiIIgraphite cells using Doyle-Fuller-Newman simulations.