Developing New Functionalities of Superconcentrated Electrolytes for Lithium-ion Batteries

Abstract

The nature of electrolyte solutions is dominated by the three factors of Li salts, solvents, and their mixing ratios (salt concentrations). Conventionally, the selections of Li salts and solvents have been considered of prime importance for Li-ion battery electrolytes, while the salt concentrations have been always fixed to approximately 1 mol dm −3 based on maximized ionic conductivities. Recently, however, the salt concentrations are increasingly recognized as a key to developing new functionalities for battery electrolytes in the wake of various unusual interfacial/bulk properties discovered in superconcentrated (highly concentrated) electrolytes. For example, highly concentrated electrolytes i) passivate effectively negative electrodes, ii) facilitate rapid Li + intercalation reactions, iii) show high oxidative stabilities, iv) prevent the corrosion of Al current collectors, and v) suppress the dissolution of transition metals from positive electrodes, all of which are beneficial for battery applications. This article discusses those unique functionalities of highly concentrated electrolytes from the viewpoint of their ion-solvent and ion-ion coordination structures.

Safety Issues in Lithium Ion Batteries: Materials and Cell Design

“…Combining ARC and DSC technique, the author concluded that the two cells fail for the oxidation of electrolyte and the formation of LiF, respectively. While as reported in many previous reports, LiF is an important component in the SEI (Wu et al, 2012;Yamada, 2017), moreover, SEI regeneration was also mentioned in several papers (Feng et al, 2018b), therefore, we consider that it is the crosstalk between cathode and anode which influenced the stability of SEI and further lead to this special phenomenon.…”

Anion Coordination Characteristics of Ion-pair Complexes in Highly Concentrated Aqueous Lithium Bis(trifluoromethane- sulfonyl)amide Electrolytes

“…6 Recently, a novel concept for practical LIB electrolyte materials with highvoltage operation has been proposed, i.e., super-concentrated electrolytes. [7][8][9][10][11] This concept has been widely investigated, not only in the field of LIB chemistry/technology, but also for fundamental science at the molecular level (structure and dynamics in the liquid state), both experimentally and theoretically. [12][13][14][15][16][17] Highly concentrated electrolytes can be successfully applied to both non-aqueous [18][19][20][21][22] and aqueous [23][24][25][26] solution systems to enable reversible, stable, and working LIBs with adequate electrode materials.…”

Cation effect on small phosphonium based ionic liquid electrolytes with high concentrations of lithium salt

“…The advantages of using highly concentrated electrolytes for battery applications have been demonstrated not only with ionic liquids but also with many common organic molecular solvents (also known as superconcentrated solvent-based electrolytes or solvent-in-salt electrolyte), which includes organic carbonates, sulfoxides, ethers, nitriles, and so on. [27][28][29][30][31] The differences between highly concentrated solvent-based and ILbased systems largely come from the choice of solvent. From a simulation point of view, different solvents lead to different alkali metal ion coordination geometries.…”