Enhancing interfacial stability of hybrid polymer electrolytes via functional additives for solid-state batteries

초록

Hybrid solid electrolytes (HSEs) combining ceramic fillers and electrolyte functional additives have emerged as an effective strategy to overcome the low ionic conductivity and interfacial instability of PVDF-HFP-based polymer electrolytes. In this study, Li1.3Al0.3Ti1.7(PO4)3 (LATP) was incorporated as a ceramic filler, while different functional additives (LiOH, LiF, and Li2CO3) were introduced to optimize interfacial properties and cycling performance. Electrochemical impedance spectroscopy (EIS) revealed that LiOH triggered a dehydrofluorination reaction during synthesis, initially causing performance deterioration and a temporary increase in bulk resistance. However, X-ray photoelectron spectroscopy (XPS) analyses before and after cycling confirmed that this controlled degradation facilitated the formation of a stable, LiF-rich interphase, which effectively suppressed further polymer decomposition during prolonged operation. In contrast, LiF and Li2CO3, which did not induce such pre-treatment effects, led to continuous polymer degradation and poor interfacial stability during cycling. As a result, Li||HSE-OH||Li symmetric cells achieved remarkable long-term stability, maintaining stable operation for over 1200 h at 0.1 mA cm-2. These findings demonstrate that inducing a predehydrofluorination reaction offers a viable interfacial engineering strategy for HSE systems, enabling the development of stable and high-performance solid-state lithium metal batteries.

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