Formation of lithium fluoride/metal nanocomposites for energy storage through solid state reduction of metal fluorides

In order to utilize high energy metal fluoride electrode materials as direct replacement electrode materials for lithium ion batteries in the future, a methodology to prelithiate the cathode or anode must be developed. Herein, we introduce the use of a solid state Li3N route to achieve the lithiation and mechanoreduction of metal fluoride based nanocomposites. The resulting prelithiation was found to be effective with the formation of xLiF:Me structures of very fine nanodimensions analogous to what is found by electrochemical lithiation. Physical and electrochemical properties of these nanocomposites for the bismuth and iron lithium fluoride systems are reported.

Graphical abstractMechanically assisted solid state reduction of metal fluorides by Li3N was found to be a rapid, effective and implementable approach for the formation of xLiF:metal nanocomposites on the order of 2–10 nm crystallite size. The solid state prelithiation process resulted in nanocomposites that were similar in both structure and electrochemical performance to that of electrochemical lithiation.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► LiF–Metal 1–20 nm composites enabled by solid state Li3N reaction with metal fluorides. ► Demonstrated for bismuth and iron fluorides. ► Effective prelithiation technique for metal fluoride conversion electrodes. ► High capacity demonstrated in Li metal and Li-ion cells.