Electrolyte Additives for Col Battery Electrolytes

Electrolyte additives are the smallest-volume, highest-leverage component in a battery cell — a few weight percent rewrites the interphase chemistry, the flammability profile, and the high-voltage stability of an otherwise unchanged formulation. This collection groups the additives we stock for lithium-ion, lithium-metal, sodium-ion, and Li-S electrolyte work, and is organized by what each family actually does at the electrode-electrolyte interface.

SEI / CEI film-formers

Reductive film-formers decompose preferentially on the anode during the first cycles to build a flexible, ion-conducting solid electrolyte interphase. Fluoroethylene carbonate (FEC) is the workhorse for silicon and lithium-metal anodes that suffer large volume change; cyclic sulfates and sultones such as DTD (ethylene sulfate) and 1,4-butane sultone (BS) reinforce the SEI on graphite and LTO and contribute to a thin, robust CEI on high-voltage cathodes. Succinic anhydride (SA) is a low-loading anhydride additive used in Li-ion and Na-ion cells to passivate transition-metal cathodes.

Lithium / sodium salt-type additives

Borate and chelated-borate salts deliver B-O-rich interphases. NaBOB (sodium bis(oxalato)borate) is the sodium-ion analogue of LiBOB and is widely used in SIBs to stabilize both the anode SEI and the cathode CEI.

Flame retardants and fluorinated co-solvents

Phosphorus-based and fluorinated species reduce electrolyte flammability without rebuilding the formulation. DMMP (dimethyl methylphosphonate) scavenges combustion-chain radicals; FEMC (fluoroethyl methyl carbonate) raises the flash point and supports high-voltage operation as a co-solvent.

Ionic-liquid co-solvents and additives

Imidazolium-based ionic liquids such as [EMIM][TFSI] and [BMIM][TFSI] are non-flammable, low-vapor-pressure species used as safety-enhancing co-solvents in Li-ion, Li-metal, Na-ion, and supercapacitor electrolytes.

Specialty additives for Li-S and CO2RR

Phenyl disulfide (Ph2S2) acts as a redox mediator and polysulfide "scissor" in Li-S and Li-CO2 chemistries. Cationic surfactants such as CTAB reorganize interfacial water at the cathode in CO2 electroreduction to suppress HER. PSS (poly(sodium 4-styrenesulfonate)) is used as an ionically conductive aqueous binder and as a polyelectrolyte additive — it is a binder/polyelectrolyte rather than a sulfonated PFSA ionomer.

If you are stabilizing silicon or lithium-metal anodes, start with FEC and DTD; for high-voltage NCM or LNMO work, pair a sulfate/sultone with a fluorinated co-solvent; for safety-driven projects, browse the flame-retardant and ionic-liquid families above. For full electrolyte formulations rather than additives, see Electrolytes.