Pronounced Role of Lithium-Controlling Polymer in Water-Processable/Halogen-Free All-Solid-State Electrolytes for...

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Conventional liquid electrolytes in energy storage devices pose safety risks like fires and leakages.
• Development of safer, environmentally friendly alternatives is crucial for advancing energy storage technologies.

Purpose of the Study:

• To demonstrate water-processable, halogen-free polymeric solid-state electrolytes (SSEs) for safer energy storage.
• To investigate the effect of poly(4-styrene sulfonic acid) (PSSA) molar ratio on ion conductivity and supercapacitor performance.

Main Methods:

• Synthesized polymeric SSEs using branched poly(ethylene imine) (bPEI), lithium hydroxide (LiOH), and PSSA in aqueous solutions.
• Fabricated asymmetric supercapacitors utilizing the developed SSEs with graphite anodes and ITO counter electrodes.
• Evaluated ion conductivity, operating potential, and cycling stability of the supercapacitors at varying PSSA concentrations.

Main Results:

• Achieved high ion conductivity (≈6 mS cm⁻¹) in bPEI:LiOH:PSSA (PLP) SSEs, with optimal performance at 40 mol% PSSA.
• PLP SSEs enabled supercapacitors to reach a high potential of 2.24 V (at 40 mol% PSSA) compared to 1.64 V (at 0 mol% PSSA).
• Supercapacitors demonstrated excellent stability, retaining 96.2% capacitance over 5000 cycles and 80% at 80 °C.

Conclusions:

• PSSA concentration is critical for controlling Li⁺ transport pathways and enhancing ion conductivity in PLP SSEs.
• The developed water-processable SSEs offer a promising pathway for high-safety, high-performance supercapacitors and batteries.
• These findings support the practical application of halogen-free polymeric SSEs in next-generation energy storage devices.