New MOF Solid Electrolyte: Li-IL / UIOSLi

Recently, Professor Arumugam Manthiram of the University of Texas at Austin and others have designed a solid electrolyte based on MOF. This solid electrolyte has a unique structure, which can effectively inhibit the polysulfide shuttle and inhibit the growth of lithium dendrites, which is conducive to promotion comprehensive performance of lithium-sulfur battery.

MOF is an important new type of porous material. It has the advantages of high porosity, low density, large specific surface area, pore rules, adjustable pore size, topological structure diversity and tailorability. It is used in lithium battery solid electrolyte, catalysis and sensing, drug delivery and other fields have been widely used.

The MOF solid electrolyte is developed based on a Universitetet i Oslo (UIO) structure. By grafting a lithium sulfonate (‐SO₃Li) group to the UIO ligand, both the ionic conductivity and the polysulfide‐suppression capability of the resulting ‐SO₃Li grafted UIO (UIOSLi) solid electrolyte are greatly improved. After integrating a Li-IL, lithium bis(trifluoromethanesulfonyl)imide in 1‐ethyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide, the resulting Li‐IL/UIOSLi solid electrolyte exhibits an ionic conductivity of 3.3 × 10⁻⁴ S cm⁻¹ at room temperature.

Li-IL/UIOSLi solid electrolyte plays an important role in the operation of lithium-sulfur batteries. First, it can be used as an insulating separator to prevent electrical contact between the negative and positive electrodes. Secondly, it provides an ion pathway for the transportation of Li⁺ to maintain the electrochemical reaction on the two electrodes. Finally, based on its unique structure, Li-IL/UIOSLi solid electrolyte can effectively inhibit the shuttle of polysulfides and inhibit the growth of lithium dendrites.

Lithium–sulfur cells with the Li‐IL/UIOSLi solid electrolyte and a Li₂S₆ catholyte show stable cycling performance that preserves 84% of the initial capacity after 250 cycles with a capacity-fade rate of 0.06% per cycle.

This is not the first solid electrolyte derived from metal organic framework materials (MOF). In recent years, solid electrolytes based on the unique advantages of MOF materials have been developed successively. In the future, with the help of technology development and material research and development, more functional electrolytes will be designed to promote the development and Application of high-performance lithium batteries.

References:

Poramane Chiochan, et al, A Metal Organic Framework Derived Solid Electrolyte for Lithium–Sulfur Batteries, Adv. Energy Mater. 2020, DOI: 10.1002/aenm.202001285