A “tug-of-war” effect tunes Li-ion transport and enhances the rate capability of lithium metal batteries

Zhang, Han; Zeng, Ziqi; Liu, Mengchuang; Ma, Fengwang; Qin, Mingsheng; Wang, Xinlan; Lei, Sheng; Wu, Yuanke; Cheng, Shijie; Xie, Jun

doi:10.1039/d2sc06620c

Cited by 23 publications

(10 citation statements)

References 69 publications

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“…2,20 Furthermore, cosolvents, depending on their distance from Li + , can compress or expand the multilayer Li + solvation shell in space-confined coordination chemistry. 20 Consequently, a superior Li + solvation shell featuring efficient diffusion, facile desolvation, superior stability, and electrochemical compatibility can be obtained by optimizing these ion−dipole and dipole−dipole interactions (Figure 2c). The dipole−dipole interaction between lithiophobic cosolvents and lithiophilic solvents arises due to the inductive effect as exemplified by 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (HFE) (negative F) and triethyl phosphate (TEP) (positive H), which is monitored by vibrational spectra (e.g., Raman and Fourier transform infrared spectra), NMR spectra (Figure 2d), and theoretical calculations.…”

Section: Solvation Chemistrymentioning

confidence: 99%

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Two-Dimensional Electrolyte Design: Broadening the Horizons of Functional Electrolytes in Lithium Batteries

Qin,

Zeng,

Cheng

et al. 2024

Acc. Chem. Res.

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Metrics & MoreArticle Recommendations CONSPECTUS: Since their commercialization in the 1990s, lithium-ion batteries (LIBs) have been increasingly used in applications such as portable electronics, electric vehicles, and large-scale energy storage. The increasing use of LIBs in modern society has necessitated superior-performance LIB development, including electrochemical reversibility, interfacial stability, efficient kinetics, environmental adaptability, and intrinsic safety, which is difficult to simultaneously achieve in commercialized electrolytes.Current electrolyte systems contain a solution with Li salts (e.g., LiPF 6 ) and solvents (e.g., ethylene carbonate and dimethyl carbonate), in which the latter dissolves Li salts and strongly interacts with Li + (lithiophilic feature). Only lithiophilic agents can be functionally modified (e.g., additives and solvents), altering the bulk and interfacial behaviors of Li + solvates. However, such approaches alter pristine Li + solvation and electrochemical processes, making it difficult to strike a balance between the electrochemical performance and other desired electrolyte functions. This common electrolyte design in lithiophilic solvents shows strong coupling among formulation, coordination, electrochemistry, and electrolyte function. The invention of lithiophobic cosolvents (e.g., multifluorinated ether and fluoroaromatic hydrocarbons) has expanded the electrolyte design space to lithiophilic (interacts with Li + ) and lithiophobic (interacts with solvents but not with Li + ) dimensions. Functional modifications switch to lithiophobic cosolvents, affording superior properties (carried by lithiophobic cosolvents) with little impact on primary Li + solvation (dictated by lithiophilic solvents). This electrolyte engineering technique based on lithiophobic cosolvents is the 2D electrolyte (TDE) principle, which decouples formulation, coordination, electrochemistry, and function. The molecular-scale understanding of TDEs is expected to accelerate electrolyte innovations in next-generation LIBs. This Account provides insights into recent advancements in electrolytes for superior LIBs from the perspective of lithiophobic agents (i.e., lithiophobic additives and cosolvents), establishing a generalized TDE principle for functional electrolyte design. In bulk electrolytes, a microsolvating competition emerges because of cosolvent-induced dipole−dipole and ion−dipole interactions, forming a loose solvation shell and a kinetically favorable electrolyte. At the electrode/electrolyte interface, the lithiophobic cosolvent affords reliable passivation and efficient desolvation, with interfacial compatibility and electrochemical reversibility even under harsh conditions. Based on this unique coordination chemistry, functional electrolytes are formulated without significantly sacrificing their electrochemical performance. First, lithiophobic cosolvents are used to tune Li + −solvent affinity and anion mobility, promoting Li + diffusion and electrochemical kinetics of the electroly...

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Section: Solvation Chemistrymentioning

confidence: 99%

Section: Applications Of Tdesmentioning

confidence: 99%

Two-Dimensional Electrolyte Design: Broadening the Horizons of Functional Electrolytes in Lithium Batteries

Qin,

Zeng,

Cheng

et al. 2024

Acc. Chem. Res.

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“…It is noteworthy that, based on basic understanding at the microscopic scale, the electrolyte plays a key role in several steps during the charging and discharging of LIBs, including the bulk transport of solvated Li + , the desolvation of solvated Li + at the electrode interface, and the crossing of bare Li + through the SEI. 39 Therefore, when designing fast-charging electrolytes, important parameters such as ion conductivity, viscosity, binding energy, 40 and dielectric constant should be considered. Ionic conductivity directly reflects the ability of lithiumion transmission, viscosity is related to lithium-ion mobility, and the desolvation of solvated Li + is affected by the binding energy of solvent to Li + .…”

Section: Challenges and Requirements Of Fast-charging Electrolytesmentioning

confidence: 99%

Fast‐charging of lithium‐ion batteries: A review of electrolyte design aspects

et al. 2023

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Lithium‐ion batteries (LIBs) with fast‐charging capabilities have the potential to overcome the “range anxiety” issue and drive wider adoption of electric vehicles. The U.S. Advanced Battery Consortium has set a goal of fast charging, which requires charging 80% of the battery's state of charge within 15 min. However, the polarization effects under fast‐charging conditions can lead to electrode structure degradation, electrolyte side reactions, lithium plating, and temperature rise, which are highly linked to the thermodynamic and kinetic properties of electrolytes. The conventional nonaqueous electrolytes used in LIBs consist of carbonate and cannot support fast‐charging without compromising performance and lifespan. This review outlines the challenges of fast‐charging LIBs and the requirements of electrolytes suitable for fast‐charging. Additionally, recent developments in fast‐charging electrolytes from four key perspectives: electrolyte additives, low‐viscosity co‐solvents, high concentration or localized high‐concentration electrolytes, and advanced electrolytes are summarized. Furthermore, this review provides insights for the design of fast‐charging electrolytes based on the mechanism of charging process and offers an overview of the current state and future direction of the field.

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“…Recently, our group has found that dipole-dipole interactions between solvents can inhibit solvent cointercalation into graphite anodes from a transfer kinetics perspective. [19][20][21] However, the FB-induced dipole-dipole interactions are too weak to counteract strong interaction of propylene carbonate (PC)-Li + and alter the primary solvation structure, but rather facilitate the de-solvation and inhibit PC cointercalation. In the PC system, the dipole-dipole interaction changes the kinetic stability of the solvent at the interface and rarely involve thermodynamic stability.…”

Section: Introductionmentioning

confidence: 99%

Nonpolar Cosolvent Driving LUMO Energy Evolution of Methyl Acetate Electrolyte to Afford Lithium‐Ion Batteries Operating at −60 °C

Lei

Zeng

Yan

et al. 2023

Adv Funct Materials

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The operation of lithium‐ion batteries (LIBs) at low temperatures (<−20 °C) is hindered by the low conductivity and high viscosity of conventional carbonate electrolytes. Methyl acetate (MA) has proven to be a competitive low‐temperature electrolyte solvent with low viscosity and low freezing point, but its interfacial stability is poor and remains elusive until now. Here, it is revealed thaat the reductive stability of MA‐based electrolytes is fundamentally governed by the anion‐prevailed solvation structure. Based on this framework, fluorobenzene is employed in the electrolyte to promote the entry of anions into the solvation shell via dipole‐dipole interactions and the generation of free MA, thus enhancing the lowest unoccupied molecular orbital energy of MA. The designed electrolyte enables LiCoO2 (LCO)/graphite cells to exhibit excellent cycling performance at −20 °C (90% retention after 1000 cycles at 1 C) and to remain 91% of their room‐temperature capacity at a super‐low temperature of −60 °C at 0.05 C. Thanks to the plentiful free MA, this electrolyte has a high conductivity (2.61 mS cm−1) at −60 °C and allows LCO/graphite cell to charge at −60 °C. This study offers the possibility of practical applications for those solvents with poor reductive stability and provides new approaches to designing advanced electrolytes for low‐temperature applications.

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A “tug-of-war” effect tunes Li-ion transport and enhances the rate capability of lithium metal batteries

Abstract: “Solvent-in-salt” electrolyte (high-concentration electrolyte (HCE) and diluted high-concentration electrolyte (DHCE)) show great promises for reviving secondary lithium metal batteries (LMBs). However, the inherently sluggish Li+ transport of such electrolytes limits...

Cited by 23 publications

References 69 publications

Two-Dimensional Electrolyte Design: Broadening the Horizons of Functional Electrolytes in Lithium Batteries

Two-Dimensional Electrolyte Design: Broadening the Horizons of Functional Electrolytes in Lithium Batteries

Fast‐charging of lithium‐ion batteries: A review of electrolyte design aspects

Nonpolar Cosolvent Driving LUMO Energy Evolution of Methyl Acetate Electrolyte to Afford Lithium‐Ion Batteries Operating at −60 °C

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