Novel Polymer Electrolyte for Greener and Safer Solid State Batteries

Lithium-ion batteries became the most widely used energy storage systems due to their high energy density, power, robustness, and reversibility and are playing a key role for the energy transition towards renewable sources. However, the current commercial batteries contain electrolyte solutions with flammable organic solvents, raising not only safety and reliability concerns but also environmental issues ^[1]. Novel Li-ion technology involves developing solid-state batteries that enhance energy density and safety, making them ideal for the next generation of high-performance batteries ^[2].<br/>Polymer electrolytes (PEs) provide several benefits compared to liquid and inorganic solid electrolytes, including better resistance to electrode volume changes during charging and discharging, enhanced safety features, excellent flexibility, and ease of processing. Additionally, under certain conditions, solvent-free polymer electrolytes can minimize or even prevent dendrite growth ^[3].<br/>Alternative polymer matrices and single ion conducting salts are highly sought after to reduce the crystallinity of the conventional PEO electrolytes and bring about homogenous Li deposition respectively. Based on our previous research , a flowable jeffamine based polymer electrolyte was reported to have appreciable ionic conductivity. However, these polymers lacked mechanical stability and single ion conducting property thereby limiting its role as buffer layers on Li metal. Herein we report the stable operation of a flowable polymer electrolyte (FPE), by incorporating novel functionalised ethyl cellulose as filler that renders mechanical stability resulting in a self-standing polymer electrolyte. The addition of functionalized fillers in addition to mechanical stability renders appreciable ionic conductivity and single-ion conducting properties without the addition of a lithium salt.<br/><br/>[1] D. Zhou et al., <i>Polymer Electrolytes for Lithium-Based Batteries: Advances and Prospects</i>, Chem, 2019, 5, 2326 - 2352<br/>[2] J. C. Barbosa et al., <i>Toward Sustainable Solid Polymer Electrolytes for Lithium-IonBatteries</i>, ACS Omega, 2022, 7, 14457 - 14464<br/>[3] H. Wang et al., <i>Reviewing the current status and development of polymer electrolytes for solid-state lithium batteries</i>, Energy Storage Materials, 2020, 33, 188 - 215