Electrochemical effect and mechanism of adiponitrile additive for high-voltage electrolyte

Properties of Ion Complexes and Their Impact on Charge Transport in Organic Solvent-Based Electrolyte Solutions for Lithium Batteries: Insights from a Theoretical Perspective

“…If a linear influence of co-solvent molecules on the chemical equilibrium and on the chemical potential of the ions is assumed, it follows [42,45,51,144] ∆µ cs = ∆µ 0 − mRTρ 3 (27) with the co-solvent or additive bulk number density ρ 3 , where ∆µ cs can be regarded as a modified difference between the chemical potentials of dissociated and associated ion states due to the presence of co-solvent molecules. A more detailed discussion of the underlying relations and a verification of the approach can be found in Ref.…”

“…which corresponds to a difference in the excess volumes of co-solvent and solvent molecules in close vicinity around the respective ion state [42,43,[147][148][149][150][151][152][153][154][155][156][157]. With regard to different chemical potentials in terms of the individual ion states (ion complex, as denoted by superscript A vs. dissociated ions, as denoted by superscript F), one can define ∆µ cs = µ F cs − µ A cs according to Equation (27), and thus the difference between the dissociated and the associated ion state is given by [158]…”

“…Despite important benefits in terms of relatively low cost, most components of liquid organic electrolyte formulations are highly flammable and their use is restricted to well-defined electrode voltage ranges [5][6][7]16]. Recent research thus focuses on novel electrolyte formulations with lower flammability, higher electrochemical and thermal stability, and the presence of multi-functional molecular groups in regards of improved efficiencies and safeties for next-generation LIBs, LMBs and dual ion batteries (DIBs) [1,3,[6][7][8]16,18,[20][21][22][23][24][25][26][27][28][29][30][31][32].…”

Electrolyte Additives for Lithium Metal Anodes and Rechargeable Lithium Metal Batteries: Progress and Perspectives

“…As a5Vcathode material, aLNMO cathode requires an extremely high oxidation-resistant electrolyte,since the major barriers to its implementation are the instability of traditional carbonate-based electrolytes and dissolution of transitionmetal ions from bulk cathode materials.N itrile-based additives have been extensively studied, such as succinonitrile (SN), [78] glutaronitrile (GLN), [77] and adiponitrile (ADN). [79] Nitriles can react with water under acidic conditions (H + ), as shown in Figure 10 a. Thewater content then decreases,which decreases the decomposition of LiPF 6 into HF.I nt otal, the nitrile-based additives not only eliminate H 2 Oand HF,which would promote Mn/Ni dissolution from the cathode,but also reduce the side reactions arising from the formation of any less electrochemical active amide (RCONH 2 ). Chen et al [78] used succinonitrile (SN) as an HF remover as well as af ilmforming additive on the cathode side.The Li 0 /Li 1.2 Ni 0.2 Mn 0.6 O 2 cell with SN-containing electrolytes showed good thermal stability and improved cycling performance (Figure 10 b).…”

“…Additives such as tris(trimethylsilyl)borate (TMSB), [76] tris(trimethylsilyl) phosphite (TMSP), [75] lithium difluoro-(oxalato)borate (LiDFOB), [79] terthiophene (3THP), [80] 1,10sulfonyldiimidazole (SDM), [81] and quercetin (Qc) were evaluated for Li/LNMO cells.T he additive 3THP [82] is one of the most effective choices for improving the cyclic stability of LNMO.T he use of only 0.25 %3 THP in as tandard (1m LiPF 6 in EC and DMC,1 /2 in volume) electrolyte resulted in the capacity retention of the Li/LNMO cell being improved from 50 %t o9 1% after 350 cycles at 1C (1C = 147 mA g À1 ) with acut-off of 4.9 V. This is among the best results that have been reported, although the weight percentage of 3THP is far lower than those achieved with other additives.T he cathode film formed on LNMO particles in the presence of 3THP can greatly suppress decomposition of the electrolyte and protect the LNMO from structural destruction.…”