ERI: Unravel Charge Transfer Mechanisms in the Bulk and at Interphases and Interfaces of Ionogel Solid Electrolytes for High-Power-Density All-Solid-State Li Metal Batteries

Kennesaw State University Research And Service Foundation, Kennesaw GA

Investigators

Abstract

This is an NSF Engineering Research Initiation award. All-solid-state batteries utilizing solid state electrolytes along with Li-metal anode are notable for their improved safety and potential to achieve simultaneously high energy, power, and longevity. Ionogels, formed by confinement of ionic liquids within ionic conductive polymers and/or ceramics, show a unique combination of favorable properties as solid electrolytes. However, their achievable power density and cycling stability remains notably inferior, owing primarily to the lack of understanding of Li-ion transport mechanisms. The project will develop a series of designed three-phase ionogel systems where each phase will be modified to promote fast Li-ion transport. The mechanistic understanding will elucidate the true Li-ion transport path and tortuosity, guiding the design of structure and chemistry of ionogel-based solid electrolytes and interlayers for high performance solid-state batteries. In addition, this project will integrate research and education for fostering interdisciplinary learnings in STEM areas. Education in Energy Storage and Conversion technology will raise more awareness of carbon neutrality and inspire younger generations to explore technical solutions for a more sustainable future. The goal of this proposal is to elucidate the local Li-ion transport mechanisms influenced by the interaction of different lithophilic environments within ternary ionogel solid electrolytes. The lithophilic molecular environments will be created through ternary ionogel platforms composed of ionic liquid where moving anions can coordinate with Li-ions, polymer scaffolds functionalized with different lithophilic groups which weakly coordinate with Li-ions for rapid Li-ion transport across and along the polymer phase, as well as ceramic nanofillers grafted with lithophilic ligands for facile Li-ion transport along the ceramic phase. These mechanistic understandings will elucidate a) the types of association and dissociation between Li cations and lithophilic anions and the competitive or cooperative interaction between them; b) the true Li-ion dissociation and Li-ion transport at different intrinsic interphases, which will determine the efficient Li-ion transport pathways and tortuosity within the ternary ionogel solid electrolyte featuring diverse intrinsic interphases; and c) the conversion from bi-ion conducting to single-ion conducting systems through effective immobilization of anions by the functional ligands grafted to the ceramic phase. The mechanistic insights will provide the design principles for regulating and accelerating Li-ion transport at various interphases and interfaces through the design of favorable lithophilic molecular environments. The research has potentially transformative impact for offering crucial insights and steering future research efforts toward scalable production of ionogel solid electrolytes and interlayers for high-power-density and high-energy-density all solid-state batteries. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.