J. Casella; J. Morzy; V. Montanelli; F.C. Mocanu; A. Müller; M.H. Futscher; M.D. Rossell; M.S. Islam; M. Yarema; Y. Romanyuk
Batteries (2025)
Transition-metal fluorides (TMFs) are attracting attention as alternative lithium-
ion battery cathodes, primarily focusing on Fe-based systems. Here, we report chromium
as a previously unexplored transition metal (TM) for TMF cathodes in rechargeable
lithium batteries. Utilizing a thin-film solid-state platform, we mitigate the common
shortcomings of TMF cathodes, such as sluggish kinetics and electrolyte incompat-
ibility. Coevaporation of Cr and LiF produces a heterogeneous thin film of Cr-LiF
with a 1.1:2 stoichiometric ratio, delivering an initial capacity of 435 mAh/g and an
energy density of 0.71 Wh/g at a C/10 cycling rate. Experimental measurements and
first-principles calculations identify CrF2 as the dominant delithiated phase. The cath-
ode maintains a capacity of 208 mAh/g at both 1C and 5C discharge rates after 1500
cycles. Compared to Fe-LiF (FeF2) analogues, Cr-LiF demonstrates a higher rate ca-
pability with 0.255 Wh/g at 3.80 W/g. This work introduces chromium fluorides as a
new high-energy conversion cathode, expanding the options of viable positive electrode
materials for next-generation batteries.