Spider silk inspired polymer electrolyte with well bonded interface and fast kinetics for solid-state lithium-ion batteries

Due to their superior safety and stability, solid-state electrolytes (SSEs) are a promising alternative to flammable liquid electrolytes in lithium-ion batteries. However, the poor solid–solid contact at the SSEs/electrodes interface remains a significant challenge. To address this issue, inspired by spider silk, we develop a composite polymer electrolyte (SPLZO), which is highly adhesive due to the designed rich hydrogel bond network, containing a supramolecular poly (urethane-urea) (SPU), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and Li_6.5La₃Zr_1.5Ta_0.5O₁₂. The abundant hydrogen bonds mainly enabled inherently strong adhesion to ensure intimate electrolyte–electrode contact with low interfacial impedance. Besides, the soft polymer segments facilitate Li⁺ transport, and the hard components enhance the LiTFSI dissociation and accelerate Li⁺ motion, resulting in a high ionic conductivity of 1.67 × 10⁻⁴ S cm⁻¹. The significantly improved interface contact and high ionic conductivity lead to a decent capacity and cycling performance of the fabricated solid-state lithium-ion batteries. Moreover, the designed SPLZO electrolyte exhibits remarkable deformability, and the flexible lithium-ion battery demonstrates outstanding mechanical flexibility and stability with negligible capacity loss when subjected to various dynamic deformations. This adhesive SSE design strategy opens new possibilities for promoting interfaces in solid-state batteries.

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