Polystyrene-Based Single-Ion Conducting Polymer Electrolyte for Lithium Metal Batteries

Lithium metal batteries are one of the more promising replacements for lithium-ion batteries owing to their ability to reach high energy densities. The main problem limiting their commercial application is the formation of dendrites, which significantly reduces their durability and renders the batteries unsafe. In the present work, we used a single-ion conducting gel polymer electrolyte based on a poly(ethylene-ran-butylene)-block-polystyrene (SEBS) block copolymer, which was functionalized with benzenesulfonylimide anions and plasticized by a mixture of ethylene carbonate and dimethylacetamide (SSEBS-Ph-EC-DMA), with a solvent uptake of 160% (similar to 12 solvent molecules per one functional group of the membrane). The SSEBS-Ph-EC-DMA electrolyte exhibits an ionic conductivity of 0.6 mSm center dot cm(-1) at 25 degrees C and appears to be a cationic conductor (TLi+ = 0.72). SSEBS-Ph-EC-DMA is electrochemically stable up to 4.1 V. Symmetrical Li|Li cells; further, with regard to SSEBS-Ph-EC-DMA membrane electrolytes, it showed a good performance (similar to 0.10 V at first cycles and <0.23 V after 700 h of cycling at +/- 0.1 mA center dot cm(-2) and +/- 0.05 mAh center dot cm(-2)). The LiFePO4|SSEBS-Ph-EC-DMA|Li battery showed discharge capacity values of 100 mAh center dot g(-1) and a 100% Coulomb efficiency, at a cycling rate of 0.1C.

Automated summary

Lithium metal batteries show potential as replacements for lithium-ion batteries, but dendrite formation limits their commercial application. This study introduces a new electrolyte with good ionic conductivity and electrochemical stability to address this issue.