Lithium difluoro(bisoxalato) phosphate-based multi-salt low concentration electrolytes for wide-temperature lithium metal batteries: Experiments and theoretical calculations

Wang, Yueda; Zheng, Hao; Liu, Hong; Jiang, Fuyang; Liu, Yongchao; Feng, Xuyong; Zhou, Rulong; Sun, Yi; Xiang, Hongfa

doi:10.1016/j.cej.2022.136802

Cited by 27 publications

(15 citation statements)

References 62 publications

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“…It is well recognized that the SEI on electrodes is dominated by the solvation structure of the electrolytes, making electrolyte engineering a pragmatic approach to enable achieving LMBs. ,,, In regular concentration electrolytes (i.e., ∼1 M), Li + is normally solvated by strongly solvating solvents (e.g., DME) with most anions being excluded from the solvation sheath. , Such a solvation structure would lead to solvent-derived interfacial chemistry, whose SEI is enriched with lithium alkoxy species (ROLi). The SEI dominated by these organic components is not robust enough to accommodate the volume changes as well as to prevent the growth of Li dendrites during Li plating/stripping, causing a low CE and battery failure. , Increasing the salt concentration to above 3 M [i.e., high-concentration electrolytes (HCEs)] could significantly increase the anion-to-solvent ratio in the electrolyte, which allows the anions to enter the primary solvation sheath to form contact ion pairs (CIPs) or aggregates (AGGs). ,,− Such a solvation structure would contribute to the anion-derived interfacial chemistry that is enriched with inorganic components (i.e., LiF), the SEI of which is more conductive and robust to suppress the Li dendrite formation and improve the CE of Li-metal anodes dramatically.…”

Section: Introductionmentioning

confidence: 99%

“…7−10 It is well recognized that the SEI on electrodes is dominated by the solvation structure of the electrolytes, making electrolyte engineering a pragmatic approach to enable achieving LMBs. 1,5,6,11 In regular concentration electrolytes (i.e., ∼1 M), Li + is normally solvated by strongly solvating solvents (e.g., DME) with most anions being excluded from the solvation sheath. 6,12 Such a solvation structure would lead to solvent-derived interfacial chemistry, whose SEI is enriched with lithium alkoxy species (ROLi).…”

Section: Introductionmentioning

confidence: 99%

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Tuning the Solvent Alkyl Chain to Tailor Electrolyte Solvation for Stable Li-Metal Batteries

Ding

Peng

et al. 2022

ACS Appl. Mater. Interfaces

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1,2-Dimethoxyethane (DME) has been considered as the most promising electrolyte solvent for Li-metal batteries (LMBs). However, challenges arise from insufficient Li Coulombic efficiency (CE) and poor anodic stability associated with DME-based electrolytes. Here, we proposed a rational molecular design methodology to tailor electrolyte solvation for stable LMBs, where shortening the middle alkyl chain of the solvent could reduce the chelation ability, while increasing the terminal alkyl chain of the solvent could increase the steric hindrance, affording a diethoxymethane (DEM) solvent with ultra-weak solvation ability. When serving as a single solvent for electrolyte, a peculiar solvation structure dominated by contact ion pairs (CIPs) and aggregates (AGGs) was achieved even at a regular salt concentration of 1 m, which gives rise to anion-derived interfacial chemistry. This illustrates an unprecedentedly high Li||Cu CE of 99.1% for a single-salt single-solvent (non-fluorinated) electrolyte at ∼1 m. Moreover, this 1 m DEM-based electrolyte also remarkably suppresses the anodic dissolution of Al current collectors and significantly improves the cycling performance of high-voltage cathodes. This work opens up new frontiers in engineering electrolytes toward stable LMBs with high energy densities.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Tuning the Solvent Alkyl Chain to Tailor Electrolyte Solvation for Stable Li-Metal Batteries

Ding

Peng

et al. 2022

ACS Appl. Mater. Interfaces

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“…Such a high areal capacity at À 40 °C outperforms many previous works about LIBs at low temperatures (Figure 5e). [40][41][42][43][44][45][46][47][48][49][50][51][52][53]…”

Section: Resultsmentioning

confidence: 99%

Low‐Temperature and High‐Areal‐Capacity Rechargeable Lithium Batteries enabled by π‐Conjugated Systems

Cheng

Sun

Wang

et al. 2022

Batteries & Supercaps

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High mass loading and high areal capacity are essential for lithium-ion batteries (LIBs) with high energy density, but they usually suffer from the sluggish charge-transfer kinetic of thick electrodes, especially at low temperature. Here, organic molecule perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) has been investigated as a feasible cathode for high areal capacity rechargeable LIBs operated at low temperature. Specifically, the charge storage process mainly occurs on the surface redoxactive groups of PTCDA, resulting in a fast kinetics of charge storage. Meanwhile, the delocalization of electrons in the πconjugated systems of PTCDA could enhance the electron transportation prominently. Consequently, the Li-PTCDA battery with a high mass loading of 14.35 mg cm À 2 delivers a high reversible areal capacity of 1.06 mAh cm À 2 at À 40 °C. This work demonstrates a great potential of π-conjugated organic materials for low temperature and high-areal-capacity rechargeable LIBs.

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“…Inspired by the above studies, lithium difluoro(bisoxalato) phosphate (LiDFBOP), a lithium-salt type additive with a bisoxalic chelate structure, was added into the electrolyte to study the cycle performance of Si@Graphite@C/Li half-cells. − To further investigate the effects of this additive on the interfaces of Si@Graphite@C anodes, decomposition reactions of electrolytes and components of SEI were analyzed. By adding LiDFBOP to Si@Graphite@C/Li half-cells, the capacity retention after the 100th cycle was improved from 53% to 71%.…”

Section: Introductionmentioning

confidence: 99%

Improving Toleration of Volume Expansion of Silicon-Based Anode by Constructing a Flexible Solid-Electrolyte Interface Film via Lithium Difluoro(bisoxalato) Phosphate Electrolyte Additive

Wang

Zhang

et al. 2022

ACS Sustainable Chem. Eng.

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The silicon (Si) anode is considered one of the most promising candidates among many novel anode materials in lithium-ion batteries owing to its high theoretical capacity and earth abundancy. Nonetheless, a large volume expansion of Si particles appears with cycling, prompting unceasing breakage/reformation of the solid-electrolyte interface (SEI) and fast capacity degradation in traditional electrolytes. For the purpose of tolerating volume expansion for the Si anode, lithium difluoro(bisoxalato) phosphate (LiDFBOP) was adopted in the standard (STD) electrolyte based on LiPF6. Density functional theory (DFT) calculations, Young’s modulus from atomic force microscopy, potential-resolved in situ electrochemical impedance spectroscopy (PRI-EIS) measurement, and other characterizations proved that the formed SEI can inhibit volume expansion of a Si@Graphite@C anode. In the STD+2% LiDFBOP electrolyte, the solvation structure of Li(EC)2(PF6)1(DFBOP)1 is more likely to be produced, and this kind of solvation structure has stronger reducibility and easily participates in SEI formation. The 2% LiDFBOP additive increases the inorganic LiF component of SEI, which yields great advantages in regulating the uniform diffusion of Li+ ions passing through the SEI. Besides, the organics containing P and F atoms are also abundant in SEI, which has greater flexibility and can tolerate volume expansion of the Si@Graphite@C anode. Therefore, the STD+2% LiDFBOP electrolyte can improve the electrochemical performances of Si@Graphite@C/Li half-cells. This work has practical implications not only for the molecular design of novel lithium salt but also for the constructions of SEI and electrolyte systems compatible with the Si@Graphite@C anode.

show abstract

Lithium difluoro(bisoxalato) phosphate-based multi-salt low concentration electrolytes for wide-temperature lithium metal batteries: Experiments and theoretical calculations

Cited by 27 publications

References 62 publications

Tuning the Solvent Alkyl Chain to Tailor Electrolyte Solvation for Stable Li-Metal Batteries

Tuning the Solvent Alkyl Chain to Tailor Electrolyte Solvation for Stable Li-Metal Batteries

Low‐Temperature and High‐Areal‐Capacity Rechargeable Lithium Batteries enabled by π‐Conjugated Systems

Improving Toleration of Volume Expansion of Silicon-Based Anode by Constructing a Flexible Solid-Electrolyte Interface Film via Lithium Difluoro(bisoxalato) Phosphate Electrolyte Additive

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