Advanced Salts—Fluoroborates and -Phosphates

Lithium salts with tetraaUcylborate anions are highly soluble in dioxolane (up to 3 M) [157], This is due to the poorly coordinating tetraalkylborate anions which lack donor atoms with electron lone-pairs for LL cation coordination [158], Thus, solvent molecules readily displace the anions in the LL cation coordination shells. This also accounts for the poor chemical stability of the salts [159] lithium 

The anions from conjugate Brpnsted-Lewis superacids represent the core lithium salts used for commercial lithium batteries (i.e., LiPFg and LiBp4). The acidity order determined from QC calculations is as follows HBF4 (287.7) HPFe (276.6) HTaFe (268.3) HA1C14 (257.4) HSbFe (255.5) (DFT-calculated AG dd 

LiAlCLi has been widely used for Li/S02Cl2 batteries [178] (as has LiGaCU [179-186]), but LiAlCLt has also been studied for use with intercalation cathodes. For example, an electrolyte composed of LiAlCLf3S02 was used for a Li/LiCo02 cell [187, 188]. This electrolyte has a very high conductivity (70-80 mS cm at 0-20 °C), but the salt undergoes a degradation side reaction to produce CI2 which then reacts with Li metal to form LiCl [187,188]  

Lithium salt (anion) Conductivity (mS cm ) Lithium salt (anion) Conductivity (mS cm ) 

Lithium trifluoroalkoxyborate salts (Fig. 1.17j) are liquid at room tanperature with a neat salt conductivity on the order of 10 S cm- [202]. Carbonate-based electrolytes (EC PC DMC 1 1 3 v v v) with these salts have a conductivity 3 mS cm at 20 °C (higher than comparable electrolytes with LiBF4) [202]. 

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