Enhancing Interfaces in Solid Polymer Electrolyte-Based Flexible Lithium-Ion Batteries



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Portable electronics is one of the most rapidly growing industries, accompanied by a high demand for portable energy storage devices. Among all types of energy storage devices, batteries occupy the majority of market due to their high energy density and efficiency. With the expanding need for smaller, lighter weight and safer product from consumer, flexible Lithium-ion battery (LIB) has become a promising energy source to satisfy the requirements of wearable electronic devices. Biomaterials are safe, environmentally friendly and promising solutions to enhancing the properties of materials especially applicable to batteries. In this dissertation, a soy-based solid polymer electrolyte was introduced to improve the solid-state lithium-ion battery performance. The resultant composite electrolytes with 0.5wt% Tryptone Soy Broth (TSB) show about two orders of magnitude enhancement in ion conductivity. The soy-based material causes better interfacial properties between cathode and solid polymer electrolyte, thus, leading to a significant battery performance improvement. With further study of protein’s surface and interfacial properties, a casein tryptone solid polymer electrolyte was fabricated to be used in a thin-film flexible lithium-ion battery. An amount of 2 wt% pure Casein Tryptone was blended with polymer electrolyte. By providing higher ionic conductivity and surface interaction properties, our thin-film flexible lithium-ion battery can reach 0.15 mAh/cm2 cycling capacity at bent position. To investigate the interfacial properties between cathode and solid polymer electrolyte inside the flexible lithium-ion battery, a phase-field model accompanying by experimental work were used to predict the diffusion in polyethylene oxide (PEO) based cathode-electrolyte interface system. Based on outcome of this study, blended polymer electrolyte and innovative current collector are proposed as promising material solutions for higher performance flexible lithium-ion battery.



Flexible batteries, Batteries, Lithium-ion batteries (LIB), Solid polymer electrolyte