This section starts based on our native 'Ionic Systems' experience and deals with electrolytes / electrolyte salts / additives for Li-Ion-, Li-Sulfur- and Li-Metal-Batteries.
Low Ion-Pairing Conducting Salt for LIS: The detrimental polysulfide shuttle associated with Li-S batteries is alleviated (without the addition of LiNO3) through the combined use of a non-polar sulfonamide solvent and low-ion pairing salt as the electrolyte. This combination transforms to a sparingly solvating electrolyte at 50 °C and sustains close to theoretical capacity at rates of C/5 with a coulombic efficiency of 99.7 %.
Novel WCA-based Conducting Salts…? The difluorophosphato ligand (O2PF2) was used for the synthesis of borates and aluminates of the [M(O2PF2)x]y–-type in order to generate new weakly coordinating anions. The preparation and characterization of the [B(O2PF2)4]– anion with various different counterions as well as Li3[Al(O2PF2)6] and Al(O2PF2)3 is described.
Li[AlX4] (X = Cl, Br) as Conducting Salts: The lithium salts
of the bromo- and chloro-aluminates were tested and fully characterized for application as electrolytes for Lithium-ion and Lithium-sulfur batteries in conventionally used solvents as well as
o-difluorobenzene as possible alternative. Li[AlBr4]
had very high conductivties in this latter solvent. The lattice enthalpies of these salts were also investigated.
Conducting Salt for Li-Batteries…? Li[B(OTfe)4] (OTfe = OCH2CF3) was synthesized as a water and thermally stable lithium ion electrolyte salt. The electrochemical stability in EC/DMC and in DME lies outside the limits of the solvents. As electrolyte salt, it exhibits good conductivities in many solutions. It was tested in LiSB-Batteries and showed good performance.
Coordination-Polymer based Gel-Electrolytes: The lithium bis(fluoroalkyl)phosphates (1) and (2) were used to prepare novel coordination-polymer based gel-electrolytes that hold conductivity records (see picture). A first performance testing of a cell with addition of 0.25 mol L–1 of (2) proved them to be stable for the application in Lithium-ion batteries (NCM 111 cathode) with some hints that they may also induce formation of a high voltage SEI layer.