Cosolvent Engineered Phosphaphenanthrene-Based Self-Extinguishing Electrolyte for Safer Lithium-Ion Batteries

Lei, Sheng; Zeng, Ziqi; Wu, Yuanke; Long, Zeyang; Li, Xiaohang; Liu, Mengchuang; Ai, Xiaomeng; Xie, Jia

doi:10.1021/acsaem.2c01007

Cited by 9 publications

(5 citation statements)

References 44 publications

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“…In addition, FB may reach the anode interface more easily than MA molecules, which can reduce the probability of the appearance of MA molecules at the interface, thus resisting the decomposition of MA molecules. [ 32 ] The characteristics of the electrolyte and the electrode interface were further investigated by contact angle and EIS tests. As shown in Figure S15, Supporting Information, the contact angle of LMF145 on the PP separator is 31.1°, which is lower than that of LMF140 (43.2°).…”

Section: Resultsmentioning

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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Section: Resultsmentioning

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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“…In TDEs, TTE serves as a lithiophobic cosolvent to isolate DOPO from other species, preventing damage to the solvation shell and degradation of the interphase (Figure 7c). 49 This optimized electrolyte simultaneously exhibits good graphite compatibility, fire resistance, and cycling stability (Figure 7d).…”

Section: Intrinsic Safetymentioning

confidence: 97%

“…9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) interacts with carbonates by forming P–H bonds in common electrolytes, leading to interphase degradation. In TDEs, TTE serves as a lithiophobic cosolvent to isolate DOPO from other species, preventing damage to the solvation shell and degradation of the interphase (Figure c) . This optimized electrolyte simultaneously exhibits good graphite compatibility, fire resistance, and cycling stability (Figure d).…”

Section: Applications Of Tdesmentioning

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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“…A high content of MA will decompose on the surface of the Li-metal anode, forming a loose and highly resistive SEI. 37 When it comes to charge transfer, according to previous studies, 11,23 the slow desolvation process remains persistent challenges to the performance of LMBs at low temperatures. Regulating Li deposition behavior can be realized by optimizing solvation structure and SEI composition.…”

Section: Introductionmentioning

confidence: 99%

Synergy of Weakly Solvated Electrolyte and LiF-Reinforced Interphase Enables Long-Term Operation of Li-Metal Batteries at Low Temperatures

Tao,

Zheng,

Jia

et al. 2024

ACS Appl. Mater. Interfaces

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Hindered by the high diffusion energy barrier of Li + in graphite anode layers, the low-temperature application of traditional Li-ion batteries is limited. Lithium metal without intercalation and with excellent specific capacity is expected to support battery operation at low temperatures. However, due to the low conductivity, high freezing point, and strong solvation energy of traditional carbonate electrolytes, the application of lithium− metal batteries at low temperatures remains challenged. In this paper, an all-ester-based ternary solvent electrolyte based on fluorinated carbonate and methyl acetate is developed to improve the cyclic efficiency of the Li-metal anode at subzero temperatures. Methyl acetate, with low viscosity and low freezing point, endows Li + with efficient transfer in the bulk phase at low temperatures. Fluorinated cosolvent regulates the solvation structure, thereby facilitating Li + desolvation while forming a LiF-rich solid electrolyte interphase. The electrolyte exhibits good compatibility with the Li-metal anode, as confirmed by the significantly reduced kinetic barrier of Li + diffusion at the interface. The theoretical calculations suggest that anions occupy the dominant positions within the inner solvation sheath. The in situ/ex situ characterizations provide straightforward evidence of a dendrite-free Li-metal electrode during cycling. As a result, the symmetric Li||Li cell is able to cycle stably for thousands of hours at current densities of 0.5 mA cm −2 and 1 mAh cm −2 . When paired with a LiFePO 4 cathode, the battery at 0.2 C (1 C = 170 mA g −1 ) has a capacity retention of 95.4% after 200 cycles at −15 °C and 92.6% after 100 cycles at −20 °C, respectively.

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Cosolvent Engineered Phosphaphenanthrene-Based Self-Extinguishing Electrolyte for Safer Lithium-Ion Batteries

Cited by 9 publications

References 44 publications

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

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

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

Synergy of Weakly Solvated Electrolyte and LiF-Reinforced Interphase Enables Long-Term Operation of Li-Metal Batteries at Low Temperatures

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