Effect of polysulfide-containing electrolyte on the film formation of the negative electrode

Insertion Electrode Materials for Rechargeable Lithium Batteries

“…Due to the low melting point of metallic Li (about 180 C) the local overheat can trigger a disastrous thermal runaway. [216,219±221] Several approaches have been pursued to improve the rechargeability and reliability of the metallic lithium electrode: i) by using liquid electrolytes that are less reactive toward lithium (e.g., highly purified or ªadditive-stabilizedº electrolytes); [96,153,157,158,164,222±234] ii) by using polymer electrolytes; [49,50,114±118,163,217,235] iii) by adding surface active agents such as hydrocarbons, quarternary ammonium salts, and others that level the regrowth of metallic lithium; [208,209,215,227,228,236±239] iv) by controlling the properties of the metal surface and of the SEI using additives such as CO 2 , [151,164,240±249] N 2 O, [240] S x 2± , [240,250] HF, [162,251±255] and H 2 O [164,243,256] (the additives may influence both the film formation and lithium plating process); v) by coating the lithium with a lithium-ion conducting membrane; [257±260] vi) by adding scavengers to the electrolyte that dissolve the dendritic lithium filaments; [148,180] vii) by using mechanical pressure to suppress dendritic lithium growth; [46,261,262] and viii) by ªlow-temperature pre-cyclingº. [263,264] However, all of the above attempts brought only partial improvements to the cycle life of the lithium electrode.…”

“…[97,370,371,382,433,442±447,462,500±512] Significant improvements have been achieved by adding inorganic components to the base electrolyte, for example CO 2 , [240,433,435,436,513±516] N 2 O, [240] SO 2 , [97,517±520] and S x 2± . [240,250] The additives promote the formation of more compact and probably thinner inorganic films, which allow the selective penetration of unsolvated Li + cations. Films formed from organic decomposition compounds are supposed to be penetrated by organic solvent molecules rather easily.…”

The formation and stability of the solid electrolyte interface on the graphite anode

“…Inorganic solvent additives of carbon dioxide [2,16,105] react with Li þ to form a passive film of Li 2 CO 3 on graphite intercalation compounds (GICs) to suppress solvent co-intercalation and electrolyte decomposition in PC electrolytes. Sulfur compounds such as ethylene sulfite, sulfur dioxide, and propylene sulfite electrolyte additives have also been employed to improve the properties and qualities of the SEI layer especially in PC-containing electrolytes systems [121,123,124]. These sulfur compounds are reduced at potential 2 V vs. Li þ /Li to form the passivation layers which hinder PC solvent cointercalation into the graphite layers.…”

Reversible Graphite Anode Cycling with PC-Based Electrolytes Enabled by Added Sulfur Trioxide Complexes

“…4,5 In order to use PC based electrolytes an electrolyte additive is required to assist with SEI formation. 6 One type of additive which frequently stabilizes the SEI are sulfur-based compounds, 7 including SO 2 , 8,9 CS 2 , 10 polysulfides S x 2− , 11,12 cyclic alkyl sulfites, such as ethylene sulfite, 13 propylene sulfite, 14 and aryl sulfites, 14 propane sultone, 15 butyl sultone, 16 functionalized sulfones, 17 and sulfates. 18 All of these sulfur compounds are soluble in the organic electrolytes, but anodic unstable at high potential.…”