A Novel Orientation Aliphatic Ketone-Based Liquid Crystal Polymer Electrolyte for High-Voltage Solid-State Lithium Metal Batteries

Abstract

Low room temperature ionic conductivity and interfacial incompatibility severely hinder the further application of polymer electrolytes in lithium metal batteries. Here, a novel shear-oriented (SO) aliphatic ketone-carbonyl-based liquid crystal composite solid polymer electrolyte (FL₇M₃@CSPE_SO) is prepared by in situ thermal-polymerization of liquid crystal monomer (FPZ-LC, FL) and N, N'-Methylenebisacrylamide (MBA, M) on cellulose nanofiber (CNF) in the presence of triethylene-glycol-dimethyl-ether (G₃) and lithium salt (lithium bis(trifluoromethanesulphonyl)imide, LiTFSI). The high polarity of keto-carbonyl groups improves the dissociation ability of lithium salt. The highly oriented liquid crystals provide rapid ion transport channels. Thus, the FL₇M₃@CSPE_SO achieves ionic conductivity of 10⁻⁴ S cm⁻¹ and a lithium-ion transference number (t_Li+) of 0.52 at 30 °C. Besides, in situ formed stable interface layer effectively inhibits the growth of lithium dendrites. The assembled Li/FL₇M₃@CSPE_SO/Li cells operate stably over 5500 h at 0.05 mA cm⁻² (30 °C). Impressively, the assembled Li/FL₇M₃@CSPE_SO/NCM811 cells exhibits a long-term cycle over 1200 h with a capacity retention of 92% under 0.05 C and 4.4 V (−5 °C). This work not only highlights the advantages of the aliphatic keto-carbonyl groups and highly oriented liquid crystal in improving ion transport capacity, but also provides a design strategy for advanced polymer electrolytes suitable for lower temperature and high-voltage solid-state lithium batteries.