Difunctional lithium metal battery electrolyte and application thereof

A lithium metal battery and electrolyte technology, applied in lithium batteries, electrolytes, secondary batteries, etc., can solve the problem of not being able to meet the stability and high-voltage performance of lithium negative electrodes at the same time, and achieve improved conductivity and electrode wettability. High commercial Value, the effect of strong bonding ability

Inactive Publication Date: 2021-12-28
ANHUI UNIVERSITY OF TECHNOLOGY
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] The purpose of the present invention is to solve the problem that the current lithium metal battery electrolyte cannot satisfy the stability and high-voltage performance of the lithium negative electrode at the same time, and develops a dual-functional lithium metal battery electrolyte and its application. Designing lithium salt composition, solvent composition, and additive composition realizes a dual-functional electrolyte that enables lithium metal batteries to cycle stably under high voltage conditions. Compared with traditional electrolytes, it can not only form a film on the positive electrode to prevent electrolyte Decomposition under high pressure and destruction of the positive electrode structure, and also has excellent stability to the lithium negative electrode, so as to obtain a bifunctional lithium metal battery electrolyte that is resistant to high pressure and stable to the lithium negative electrode, which has great application value

Method used

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  • Difunctional lithium metal battery electrolyte and application thereof
  • Difunctional lithium metal battery electrolyte and application thereof
  • Difunctional lithium metal battery electrolyte and application thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0042] Monoether electrolyte (1.5M LiBF 4 in DME, v / v=1), monoester electrolyte (1.5MLiBF 4 in FEC, v / v=1) and bifunctional ether ester mixed electrolyte (1M LiBF 4 in FEC / DME, v / v=1), using the above electrolyte, lithium sheets, copper sheets, and separators to assemble a lithium-copper half-cell, and at 1mA cm -2 The Coulombic efficiency test is carried out under the current density, such as figure 1 As shown, in the monoester electrolyte control group, the lithium negative electrode can only cycle stably for 20 weeks, while in the monoether electrolyte control group, the lithium negative electrode cannot cycle normally after several cycles of charging and discharging. In contrast, in the bifunctional electrolyte experimental group, the Li anode can be cycled stably for more than 100 cycles with high average Coulombic efficiency. This example shows that the bifunctional electrolyte proposed by the present invention has excellent performance when used in lithium metal batt...

Embodiment 2

[0044] Monoether electrolyte (1.5M LiBF 4 in DME, v / v=1), monoester electrolyte (1.5MLiBF 4 in FEC, v / v=1) and bifunctional electrolyte (1M LiBF 4 in FEC / DME, v / v=1), use the above electrolyte, lithium sheet, 622 positive electrode sheet, and separator to assemble a Li-622 battery, and perform charge and discharge tests on it. The charge and discharge curve of the first cycle is as follows: figure 2 As shown, the Li-622 battery cannot be charged and discharged normally with the monoether electrolyte control group, but the Li-622 battery can be cycled normally with the monoester electrolyte and the bifunctional electrolyte, and the bifunctional electrolyte experimental group’s pole The oxidation is smaller than that of monoester electrolyte. This example shows that the performance of the bifunctional electrolyte proposed by the present invention is better than that of other monoether monoester electrolytes, and the cycle of lithium metal batteries is more stable.

Embodiment 3

[0046] Separately configure four kinds of dual-functional electrolytes composed of different solvents, each of which is 1.5M LiBF 4 in DEC / DOL(v / v=1), 1.5M LiBF 4 in DEC / DME(v / v=1), 1.5M LiBF 4 in FEC / DOL(v / v=1), 1.5M LiBF 4 inFEC / DME (v / v=1), to explore the effect of different ether-ester mixed solvent compositions on battery performance. Use the above electrolyte, lithium sheet, 622 positive electrode sheet, and diaphragm to assemble a Li-622 battery, and conduct charge and discharge tests on it. Cyclic curves such as image 3 As shown, the cycle stability of the Li-622 battery assembled by the bifunctional electrolyte experimental group using FEC / DME (v / v=1) is the best. This example shows that the use of FEC and DME as solvents in the bifunctional electrolyte proposed by the present invention has more excellent performance.

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Abstract

The invention discloses a difunctional lithium metal battery electrolyte and application thereof, and belongs to the field of secondary batteries. The electrolyte contains single fluorine-rich lithium salt, ether ester mixed solvent for dissolving the lithium salt and an additive, and has the effect of stabilizing a high-voltage positive electrode and a lithium metal negative electrode at the same time; the ester solvent capable of forming a film on the positive electrode is introduced, so that the high-voltage positive electrode can be stabilized; by introducing the ether solvent, on one hand, the viscosity of the electrolyte is improved, and the conductivity and the electrode wettability are effectively improved, so that the high and low temperature performance of the electrolyte can be improved; on the other hand, the stability of the lithium negative electrode can be enhanced; the adopted single fluorine-rich lithium salt can be effectively combined with the ether solvent to inhibit the decomposition of the ether solvent, and can form a film at the lithium negative electrode to further enhance the stability of the lithium negative electrode; and the introduction of the ether solvent can significantly improve the solubility of the electrolyte, so that an efficient additive which cannot be dissolved in a traditional ester electrolyte can be introduced, and the performance of the battery is improved again.

Description

technical field [0001] The invention relates to the technical field of secondary batteries, and more specifically relates to a bifunctional lithium metal battery electrolyte and its application. Background technique [0002] Due to the increasing demand for portable electronics and electric vehicles, safe, energy-dense and rechargeable batteries are constantly being pursued. Lithium metal is considered as a promising anode for further enhancing the energy density of batteries due to its high theoretical specific capacity (3860 mAh / g) and lowest redox potential (−3.04 V vs. standard hydrogen electrode). However, the large-scale application of lithium metal batteries is facing severe challenges. On the one hand, the uneven deposition and unstable interface of the lithium anode during cycling will lead to a limited cycle life of the anode; Instability, the structure will be destroyed, resulting in a continuous loss of active substances. [0003] The electrolyte is in contact ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M10/0567H01M10/0568H01M10/0569H01M10/052
CPCH01M10/0567H01M10/0568H01M10/0569H01M10/052H01M2300/0037Y02E60/10
Inventor 李永涛莫季生姜智鹏张庆安
Owner ANHUI UNIVERSITY OF TECHNOLOGY
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