Marrying Ester Group with Lithium Salt: Cellulose-Acetate-Enabled LiF-Enriched Interface for Stable Lithium Metal Anodes

The practical applications of high-energy-density lithium (Li) metal batteries (LMB) have been hindered by the formation and growth of Li dendrites. Homogenizing the Li-ion flux to suppress Li dendrites by regulating the solid electrolyte interphase (SEI) originating from electrolyte degradation is necessary but still challenging. Herein, ion-affiliative cellulose acetate (CA) with functional Li salts is prepared to generate the SEI with fast Li+ diffusion kinetics. First, the correlations between the functional ester group and LiN(CF3SO2)(2) (LiTFSI) are theoretically and experimentally identified, where C(sic)O strongly adsorbed N(CF3SO2)(2)(-) through electrostatic interaction to enhance the charge-transfer-promoted decomposition of LiTFSI. Furthermore, the CA with ex situ doped LiTFSI amplifies this fluorinated degradation effect, and the LiF-enriched SEI nanostructure is consequently established in situ, as confirmed by cryogenic transmission electron microscopy. As a result, the dendritic Li growth during cycling is efficiently suppressed, and the lifespan is prolonged by more than six times at a high current density of 3 mA cm(-2). This study provides insights into the interphase design for realizing ultrastable LMB.

Automated summary

This study investigates the use of ion-affiliative cellulose acetate and functional Li salts to suppress dendritic Li growth in high-energy-density lithium metal batteries. The SEI structure with fast Li+ diffusion kinetics efficiently prevents the formation of Li dendrites, extending battery lifespan at high current densities.