High‐Power Lithium Metal Batteries Enabled by High‐Concentration Acetonitrile‐Based Electrolytes with Vinylene Carbonate Additive

Abstract

To enable next‐generation high‐power, high‐energy‐density lithium (Li) metal batteries (LMBs), an electrolyte possessing both high Li Coulombic efficiency (CE) at a high rate and good anodic stability on cathodes is critical. Acetonitrile (AN) is a well‐known organic solvent for high anodic stability and high ionic conductivity, yet its application in LMBs is limited due to its poor compatibility with Li metal anodes even at high salt concentration conditions. Here, a highly concentrated AN‐based electrolyte is developed with a vinylene carbonate (VC) additive to suppress Li+ depletion at high current densities. Addition of VC to the AN‐based electrolyte leads to the formation of a polycarbonate‐based solid electrolyte interphase, which minimizes Li corrosion and leads to a very high Li CE of up to 99.2% at a current density of 0.2 mA cm‐2. Using such an electrolyte, fast charging of Li||NMC333 cells is realized at a high current density of 3.6 mA cm‐2, and stable cycling of Li||NMC622 cells with a high cathode loading of 4 mAh cm‐2 is also demonstrated.

Moving beyond 99.9% Coulombic efficiency for lithium anodes in liquid electrolytes

“…3c) totalling 17% porosity for the carbonate-based electrolyte. The high amounts of isolated References not cited elsewhere in the text are collected here: [105][106][107][108][109][110][111][112][113][114][115][116][117][118][119][120][121][122][123][124] .…”

“…d, Correlation between exchange current density, Li + diffusivity and CE 71,72 . Calculations for Li + diffusivity values are shown in Supplementary Data and references used are aggregated here: 24,28,30,32,71,73,109,118,121,[125][126][127][128][129][130][131][132] .…”

Non‐Flammable Liquid and Quasi‐Solid Electrolytes toward Highly‐Safe Alkali Metal‐Based Batteries

“…[64] The electrolyte composed of 10 m LiFSI in AN:VC (10:1 by volume) possessed a high oxidative stability of 5.5 V, and the Coulombic efficiency reached more than 99.2% when applied in a Li||Cu cell. [65] A smooth and compact Li deposition was detected, confirming the synergetic optimization effect of high salt concentration and SEI-forming additive. Stable cycling of 4.5 V Li metal batteries (e.g., Li||NMC111, Li||NMC622 batteries) with a high cathode areal loading (>2 mAh cm −2 ) was achieved by using this electrolyte, which demonstrates the application potential of nitrile-based electrolytes in long-term high-energy Li metal batteries.…”

High‐Rate Lithium‐Ion Cycling in Electrodeposited Binder‐Free Thin‐Film Vanadium Oxide Cathodes with Lithium Metal Anodes in Ionic Liquid and Polymer Gel Analogue Electrolytes

“…[18] We utilised carbonate additives in the butyl-methylpyrrolidinium-based ILs to investigate if it suppresses the growth of Li dendrites to enable enhanced cycle life with metallic lithium anodes as previously reported for typical organic-based electrolytes. [19] The use of VC is also investigated to develop a more stable cathode electrolyte interface (CEI) layer at the V 2 O 5 . Finally, long-term cycling analysis is shown up to 400 cycles with increasing C-rates, such as 50 cycles at 5 C, with both the IL and polymer gel electrolytes to determine the long-term stability of the V 2 O 5 /Li metal cell.…”