A Lewis acid-base interactive solid-state electrolyte mediating highly stable lithium deposition and long-cycling solid-state batteries

Abstract

Solid-state lithium metal batteries (SSLMBs) are promising for next-generation energy storage but suffer from lithium dendrite growth and interfacial instability. To tackle these issues, we developed the novel solid-state electrolytes (SSEs) by incorporating lithium carboxymethyl cellulose (CMC@Li) into a polyethylene glycol dimethyl ether (PEGDME) matrix (CMC@Li-PEGDME). The ether-oxygen groups in PEGDME act as Lewis bases, dynamically coordinating with Li⁺ (Lewis acid) from CMC@Li to form a solvation structure that enhances Li⁺ transport and stabilizes the solid-electrolyte interphase (SEI). The X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (TOF-SIMS) confirmed the formation of a stable LiF-rich/Li₃N SEI layer. As a result, Li-Li symmetric batteries assembled with designed SSEs achieved stable cycling for over 7200 h with a low overpotential of 125  mV (0.1 mA cm⁻², 0.1 mAh cm⁻²). Even at a higher areal capacity of 1 mAh cm⁻², it still cycled stably for more than 3500 h with a low overpotential of around 153  mV. Moreover, in Li-LFP pouch cells, it delivered 159.9 mAh g⁻¹ initial capacity at 0.2C with 98.21 % average Coulombic efficiency over 100 cycles. This work introduces a Lewis acid-base coordination strategy incorporating a renewable, bio-derived component that simultaneously improves Li⁺ kinetics and interfacial stability, providing a viable path toward high-performance SSLMBs.