Borate-Water-Based 3D-Slime Interface Quasi-Solid Electrolytes for Li- ion Batteries

Y Shiratori and K Watanabe and K Saito and R Sato and Y Okuno and S Yasui, ADVANCED MATERIALS, 37 (2025).

DOI: 10.1002/adma.202505649

The development of solid-state batteries (SSBs) that do not use hazardous materials as electrolytes and are not flammable is progressing rapidly, however the production of sulfide-based SSBs requires strict low-dew-point control due to their high reactivity with atmospheric moisture and the concern of generating hydrogen sulfide, and several issues remain in terms of the cost and recyclability. Thus, low-cost facile materials and low-CO2-emission processes are necessary. With regard to oxide-type SSBs, which are attracting attention for their safety, there are issues with manufacturing suitability, as high- temperature sintering of oxide solid electrolyte particles is required. A new quasi-solid-state (QSS) electrolyte with 3D-ionic conduction and adhesive interfaces by combining amorphous Li2B4O7 and water (3D-Slime Interface Solid Electrolyte: 3D-SLISE) is synthesized without stringent dew point control and sintering. Electrode and electrolyte slurries containing 3D-SLISE are applied to current-collecting foils in air, naturally dried, and used to construct battery laminates. 3D-SLISE-QSSBs (LiCoO2 cathode/3D-SLISE with 7 wt.% bound-water/Li4Ti5O12 or TiNb2O7 anodes) maintain several hundred cycles of charge/discharge as a 2.35 V lithium-ion battery. The 3D-SLISE-QSSB technology can promote the use of safe and low-cost batteries, eliminate the need for a dry room during manufacturing, and enable direct recycling of active materials.

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