June 13, 2024

New Method Developed for Highly Performing Electrolytes in Multivalent Metal Batteries

In order to meet the increasing demand for electric and hybrid vehicles, researchers are focused on developing battery technologies that are safe, high-performing, and scalable. One promising technology is rechargeable multivalent metal batteries, which use multivalent ions like magnesium (Mg) and calcium (Ca) to achieve high energy densities. However, the development of efficient electrolytes for these batteries has proven challenging, as many proposed electrolytes are difficult to source or require complex synthesis processes.

To address this challenge, a team of researchers from Zhejiang University, the ZJU-Hangzhou Global Scientific and Technological Innovation Center, and Dalian University of Technology have introduced a new method to create highly performing and scalable electrolytes for multivalent metal batteries. Their approach, described in a paper published in Nature Energy, aims to develop affordable and reversible electrolyte systems that can be produced on a large scale.

However, the expensive precursor materials and complex synthesis processes often limit the exploration of cathode electrode/electrolyte interfaces and solvation structures. To overcome these limitations, the research team developed a universal cation replacement method to prepare low-cost and high-reversibility magnesium and calcium electrolytes derived from a zinc organoborate solvation structure.

The method involves several steps. First, the researchers initiated a chemical reaction between an easily attainable Zn(BH4)2 precursor and different fluoroalcohols, resulting in target anions with various branched chains. These anion solvates then reacted with low-cost metal foils with higher metal activity to produce target solvation structures. To ensure stability during battery cycling, the researchers proposed the formation of a passivation layer using two types of calcium solvates.

By adjusting the precursor chain length and F-substitution degree, the research team was able to fine-tune anion participation in the primary solvation shell. This resulted in a completely dissociated magnesium organoborate electrolyte with high current endurance and enhanced electrochemical kinetics, as well as a calcium organoborate electrolyte with a stable solid-electrolyte interphase and high coulombic efficiency due to strong coordination/B–H inclusion.

The researchers have already used their method to create a high-loading battery prototype based on Mg/S, which achieved a promising energy density of 53.4 Wh/kg. The prototype consisted of a 30 μm magnesium anode, a low electrolyte/sulfur ratio (E/S = 5.58 μl/mg), and a modified separator/interlayer. These initial tests demonstrate the potential of the approach to create cost-effective electrolytes for multivalent metal batteries.

In the future, this method could enable the development of various reversible electrolyte systems that rely on more affordable materials and simpler processing strategies. These electrolytes could be used to create scalable and safe multivalent metal batteries with higher energy densities, further advancing battery technologies for electric and hybrid vehicles.

1. Source: Coherent Market Insights, Public sources, Desk research
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