Gel‐Polymer Electrolytes Based on Organophosphorus Polyurethanes for Lithium Power Sources

ABSTRACT Lithium‐ion batteries with gel polymer electrolytes (GPE) are the promising approach to create next‐generation energy storage devices. Along with the use of a lithium anode, important is the creation of effective cathode materials that would have good compatibility with the polymer electrolyte. In this work, we continued the development of a gel electrolyte composition compatible with the lithium salt, the tetraazapentacene derivative (cathode material LiOTAP). In this regard, polyurethane (AEPA‐PU) gel electrolytes based on branched amino ethers of ortho‐phosphoric acid (AEPA) were synthesized and studied. To enhance the ionogenicity of AEPA‐PU and increase the ionic conductivity by 4 times, a carboxyl‐containing fragment was introduced by using succinic acid (SA). The upper limit of the electrochemical stability window (relative to Li + /Li) of GPE based on AEPA‐SA‐PU reaches 4.95 V. The Li/GPE/LiOTAP cell with a cathode based on the lithium salt of the tetraazapentacene derivative demonstrated its operability during 100 charge–discharge cycles. The discharge capacity during the first 30 formation cycles changed from 350 to 140 mA∙h∙g −1 with subsequent stabilization. Also, at this number of cycles, a 1.4 times increase in the average cell potential was observed, which indicates a more favorable path for the redox reaction in the cathode material LiOTAP.