CsFSI {[Cesium bis(fluorosulfonyl)imide], >99.95%} Powder as Electrolyte Additive for Lithium-Ion Battery, 10-50 g/bottle, CLIBEACsFSI

CsFSI (Cesium bis(fluorosulfonyl)imide, {CsN(SO2CF3)2} is an alkali metal imide salt investigated as a functional additive in non-aqueous electrolytes for lithium-metal, lithium-sulfur, and liquid-polysulfide flow batteries. It combines the heavy alkali cation Cs+ with the flexible, weakly coordinating, highly fluorinated TFSI- anion.

Maximum Electrostatic Shielding (Cs+): The Cs+ cation provides an effective Self-Healing Electrostatic Shield (SHES): The standard reduction potential of Cs+ (~ -2.92 V vs. SHE) is slightly less negative than that of Li+ (~ -3.04 V). During fast charging, electric fields concentrate at microscopic peaks/dendrite tips on the lithium anode. Cs+ ions rapidly migrate to these high-field regions and accumulate without being reduced into metallic cesium. This accumulation forms a localized positive electrostatic buffer that repels incoming Li+ ions toward surrounding valleys, driving uniform, planar lithium electrodeposition across the anode surface.

Solid Electrolyte Interphase (SEI) Modification & Polysulfide Interaction: (1) F-Rich & Inorganic Interphases: The FSI- anion decomposes at low potentials to build an inorganic-rich interphase (containing LiF, Li2S, and Li3N species), suppressing continuous solvent breakdown. (2) Polysulfide Compatibility: In lithium-sulfur (Li-S) and lithium-polysulfide (LiPS) flow battery chemistries, the incorporation of CsFSI enhances bulk electrolyte ionic conductivity and boosts Coulombic efficiency during long-term cycling.

Part Number	CLIBEACsFSI (C-LIB-EA-CsFSI)
Chemical Formula	CsN(SO2F)2
Appearance	White Powder
Purity	>99.95% (Battery Grade)
Molecular Weight	314.05 g/mol
Package Size	10 g, 25 g, and 50 g/bottle

Notes: Please store the CsFSI powder in the glovebox due to its sensitivity to humidity and oxygen 

References: 

1. J. Yu, et al. Solvent-Free and Long-Cycling Garnet-Based Lithium-Metal Batteries, ACS Energy Lett. (2023) 8 (3): 1468–1476.
   
2. S. Yan, et al., Molten salt electrolytes with enhanced Li+-transport kinetics for fast-cycling of high-temperature lithium metal batteries, Energy Environ. Sci. (2025) 18 (4): 1696–1706.