Chemical Stability of Lithium 2-Trifluoromethyl-4,5-dicyanoimidazolide, an Electrolyte Salt for Li-Ion Cells

Shkrob, Ilya A.; Pupek, Krzysztof; Gilbert, James A.; Trask, Stephen E.; Abraham, Daniel P.

doi:10.1021/acs.jpcc.6b09837

Cited by 18 publications

(17 citation statements)

References 55 publications

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“…With the LiTDI electrolyte (Figure 4b), a rather long reduction plateau is observed at ca. 0.8 V and the ohmic drop at C/10 is very high, even in the first cycle, most likely due to a thick and resistive SEI formed as reported in carbonate mixtures without additives [59] and the capacity drops dramatically with cycling. All the other salts appear to allow graphite electrode operation, although with moderate rate capability.…”

Section: This Contrasts To What Was Reported In Ec-based Electrolymentioning

confidence: 77%

Towards practical sulfolane based electrolytes: Choice of Li salt for graphite electrode operation

Zhang

Porcher

Paillard

2018

Journal of Power Sources

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Abstract:Sulfolane (tetramethylene sulfone, SL) is known for leading to Li-ion electrolytes with high anodic stability. However, the operation of graphite electrodes in alternative electrolytes is usually challenging, especially when ethylene carbonate (EC) is not used as co-solvent. Thus, we study here the influence of the lithium salt on the physico-chemical and electrochemical properties of EC-free SL-based electrolytes and on the performance of graphite electrodes based on carboxymethyl cellulose (CMC). SL mixed with dimethyl carbonate (DMC) leads to electrolytes as conductive as state-of-theart alkyl carbonate-based electrolytes with wide electrochemical stability windows. The compatibility with graphite electrodes depends on the Li salt used and, even though cycling is possible with most salts, lithium difluoro-oxalato borate (LiDFOB) is especially interesting for graphite operation.LiDFOB electrolytes are conductive at room temperature (ca. 6 mS cm -1 ) with an anodic stability slightly below 5 V vs. Li/Li + on particulate carbon black electrodes. In addition, it allows cycling graphite electrodes with steady capacity and high coulombic efficiency without any additive. The testing of graphite electrodes in half-cells is, however, problematic with SL:DMC mixtures and, by switching the Li metal counter electrode for LiFePO4, the graphite electrode achieves better practical performance in terms of rate capability.

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Section: This Contrasts To What Was Reported In Ec-based Electrolymentioning

confidence: 77%

Towards practical sulfolane based electrolytes: Choice of Li salt for graphite electrode operation

Zhang

Porcher

Paillard

2018

Journal of Power Sources

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“…Such a decomposition reaction of LiTDI is further supported by the dQ dV −1 curve of the initial cycles of the baseline, 20F1.5M, and 20F1.5M‐1TDI cells shown in Figure S7 in the Supporting Information. As seen, compared to the baseline cell with an EC‐reduction peak located at 2.9 V, the 20F1.5M‐1TDI cell shows the LiTDI‐reduction peak at 2.6 V. [ 46 ] Such a LiTDI‐reduction peak diminishes after the first cycle, which demonstrates an irreversible decomposition of the LiTDI additive. With respect to the cycling performance, although all three cells deliver similar capacities (≈210 mA h g –1 ) after the formation cycles, their capacities fade at different rates during the subsequent cycling.…”

Section: Resultsmentioning

confidence: 99%

“…As LiTDI is also known to decompose severely on graphite anode, these findings seem to imply a synergistic effect of FEC and LiTDI in EC‐free electrolytes similar to previous reports with EC‐containing electrolytes. [ 46 ]…”

Section: Resultsmentioning

confidence: 99%

Ethylene Carbonate‐Free Electrolytes for Stable, Safer High‐Nickel Lithium‐Ion Batteries

Pan

Cui

et al. 2022

Advanced Energy Materials

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highly oxidized transition-metal (TM) ions, particularly Ni. [6,10] This process not only leads to the generation of protons that can further induce a decomposition of lithium hexafluorophosphate (LiPF 6 ) to form hydrofluoric acid (HF), [11][12][13] but also causes the formation of spinel-like and rock salt-like phases at the cathode/electrolyte interphase (CEI). [14][15][16][17][18] Moreover, the generated TM ions and HF can crossover and exert side effects on the performance of Gr anodes. [19][20][21] In addition, EC molecules can also easily react with the oxygen released from high-Ni cathodes at elevated temperatures, leading to a catastrophic heat release and eventual safety hazards. [5,22] This problem is exacerbated when high-Ni cathodes are involved since they tend to release more oxygen at lower temperatures compared to low-Ni cathodes. [23] Consequently, much effort has been devoted to searching for new electrolytes that are compatible with high-Ni LIBs in the past years through an exploration of new electrolyte additives and the development of novel electrolyte systems, such as high concentration electrolytes (HCEs), localized HCEs (LHCEs), and EC-free electrolytes. [9,[24][25][26][27][28][29][30][31][32][33][34][35] Among these approaches, removing the EC from the state-ofthe-art EC-containing electrolytes to make EC-free electrolytes is of particular interest, since it solves the stability and safety issues from the root, and is also considerably more straightforward and cost-effective compared to other approaches. In early studies, Dahn and co-workers demonstrated that a significantly improved cycling stability and a mitigated cell impedance growth could be achieved by removing EC from a conventional electrolyte (i.e., 1 m LiPF 6 in EC:ethyl methyl carbonate (EMC), 3:7 by weight, with 2 wt% vinyl carbonate, VC) and adding a small amount of "enablers," such as VC and fluoroethylene carbonate (FEC). [9,36] However, these reports were focused on low-Ni cathodes (e.g., LiNi 0.4 Mn 0.4 Co 0.2 O 2 and LiNi 0.5 Mn 0.3 Co 0.2 O 2 ) with nonoptimized electrolyte compositions and limited mechanistic insights. [9,36] More recently, our group reported that with an optimized EC-free electrolyte (Gen 1, 1.0 m lithium bis(fluorosulfonyl) imide-0.5 m LiPF 6 in EMC with 3 wt% VC), the electrochemical performance and safety features of a high-Ni (LiNi 0.94 Co 0.6 O 2 ) cell were significantly enhanced owing to the stabilized electrode/electrolyte interphases (EEIs) and the reduced chemical reactivity of the electrolyte toward the cathode. [5] Advanced Ethylene carbonate (EC) is an important component in state-of-the-art electrolytes for lithium-ion batteries (LIBs). However, EC is highly susceptible to oxidation on the surface of high-nickel layered oxide cathodes, making it undesirable for next-generation high-energy-density LIBs. In this study, a simple, yet effective, EC-free electrolyte (20F1.5M-1TDI) is presented by adding 20 wt% fluoroethylene carbonate (FEC) and 1 wt% lithium 4,5-dicyano-2-(trifluoromethyl)im...

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“…123 Consequently, they enhanced the cycling electrochemical performance toward higher operation voltages. The fluorinated [124][125][126] or phosphorus-based 127,128 additives (lithium 2-trifluoromethyl-4,5-dicyanoimidazole, tris (hexafluoroisopropyl)phosphate, etc.) were also applied to minimize the impedance on the cathode side because of its lower oxidation state, hence extending the full cell lifetime.…”

Section: Discussionmentioning

confidence: 99%

Stabilization of a High-Capacity and High-Power Nickel-Based Cathode for Li-Ion Batteries

Zeng

Zhan

Lü

et al. 2018

Chem

152

118

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High-capacity and high-power nickel-based cathode materials have become the principal candidates for a lithium-ion energy storage system powering electrified transportation units. With high nickel content, the cathodes are of great interest for delivering the desired specific energy and energy density. However, the cells still suffer from fast capacity decay and low thermal-abuse tolerance to high voltage. At the highly delithiated state, the damage in the cell is mainly from severe parasitic reactions, including the oxygen evolution reaction in the cathode and oxidization of the organic electrolyte. These side reactions rapidly weaken the system's rate capacity and cyclability. Solutions are being sought to provide safe operation and practical application. Three strategies have proven to be encouraging choices: surface coating, a core-shell structure, and a concentration gradient structure. For each strategy, the material architecture, fabrication procedure, operation principle, advances, and challenges are discussed in this review. The prospects for further developments are also summarized.

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Chemical Stability of Lithium 2-Trifluoromethyl-4,5-dicyanoimidazolide, an Electrolyte Salt for Li-Ion Cells

Cited by 18 publications

References 55 publications

Towards practical sulfolane based electrolytes: Choice of Li salt for graphite electrode operation

Towards practical sulfolane based electrolytes: Choice of Li salt for graphite electrode operation

Ethylene Carbonate‐Free Electrolytes for Stable, Safer High‐Nickel Lithium‐Ion Batteries

Stabilization of a High-Capacity and High-Power Nickel-Based Cathode for Li-Ion Batteries

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