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EP-4280331-B1 - CARBONATE-BASED ELECTROLYTE, METHOD FOR MAKING THE SAME, AND LITHIUM METAL BATTERY

EP4280331B1EP 4280331 B1EP4280331 B1EP 4280331B1EP-4280331-B1

Inventors

  • CHEN, Wei-chao
  • WANG, PIN-HAN
  • LAI, Hong-zheng
  • Chang, Tseng-Lung

Dates

Publication Date
20260506
Application Date
20230510

Claims (15)

  1. A carbonate-based electrolyte comprising: a carbonate; an ether; a lithium salt; a lithium nitrate; and a planar macrocyclic compound, wherein a concentration of the planar macrocyclic compound is in a range from 0.5 millimolar concentration to 4 millimolar concentration.
  2. The carbonate-based electrolyte of claim 1, wherein a volume ratio of the carbonate to the ether is in a range from 1:2 to 2:1.
  3. The carbonate-based electrolyte of claim 1, wherein a weight percentage of the lithium nitrate is in a range from 0.5wt. % to 5wt. %.
  4. The carbonate-based electrolyte of claim 1, wherein the carbonate is a cyclic carbonate or a chain carbonate.
  5. The carbonate-based electrolyte of claim 4, wherein the cyclic carbonate is ethylene carbonate, propylene carbonate, or combination thereof; the chain carbonate is dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, or a combination thereof.
  6. The carbonate-based electrolyte of claim 1, wherein the planar macrocyclic compound is porphyrin, phthalocyanine, crown ether, cyclodextrin, calixarene, or a combination thereof, or a metal derivative of porphyrin.
  7. The carbonate-based electrolyte of claim 1, wherein the ether is dimethoxymethane, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, or a combination thereof.
  8. The carbonate-based electrolyte of claim 1, wherein the lithium salt is lithium bis(trifluoromethanesulfonyl)imide, lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium tetrafluoroborate, lithium bis(oxalate)borate, lithium difluoro(oxalato)borate, or a combination thereof.
  9. The carbonate-based electrolyte of claim 1, wherein a weight ratio of the planar macrocyclic compound, the lithium nitrate and the lithium salt is 1:15~45:400~500.
  10. A method of making a carbonate-based electrolyte comprising: mixing a carbonate and an ether in a certain volume ratio and stirring, to obtain an electrolyte base solution; adding a lithium salt to the electrolyte base solution, and stirring; adding a lithium nitrate after the lithium salt is dissolved, and stirring, wherein a weight percentage of the lithium nitrate is in a range from 0.5wt. % to 5wt. %; and adding a planar macrocyclic compound after the lithium nitrate is dissolved, wherein the planar macrocyclic compound has a concentration of 0.5 millimolar concentration to 4 millimolar concentration.
  11. The method of claim 10, wherein the certain volume ratio of the carbonate to the ether is in a range from 1:2to 2:1.
  12. The method of claim 10, wherein the planar macrocyclic compound is porphyrin, phthalocyanine, crown ether, cyclodextrin, calixarene, or a combination thereof, or a metal derivative of porphyrin.
  13. The method of claim 10, wherein a weight ratio of the planar macrocyclic compound, the lithium nitrate and the lithium salt is 1:15~45:400~500.
  14. A lithium metal battery comprising: a positive electrode, wherein a material of the positive electrode is a high-voltage positive electrode material; a negative electrode, wherein the negative electrode is lithium metal; an electrolyte comprising a carbonate, an ether, a lithium salt, a lithium nitrate, and a planar macrocyclic compound, wherein in the electrolyte, a concentration of the planar macrocyclic compound is in a range from 0.5 millimolar concentration to 4 millimolar concentration; and a separator.
  15. The lithium metal battery of claim 14, wherein a cut-off voltage of the high-voltage positive electrode material is greater than 4.2V.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims all benefits from the Chinese Patent Application No. 202210556715.X, filed on May 20, 2022, in the China National Intellectual Property Administration. BACKGROUND 1. Technical Field The present application relates to a carbonate-based electrolyte, a method for making the carbonate-based electrolyte, and a lithium metal battery using the carbonate-based electrolyte. 2. Discussion of Related Art With the continuous progress of society, the demand for various electric vehicles and portable electronic products continues to increase, and the energy density of traditional lithium-ion batteries has reached to its theoretical energy limit, which is not enough to meet the growing demands of the consumers. Therefore, research on rechargeable batteries with higher energy density has become a research focal point. Lithium metal has the highest theoretical gram capacity (3860mAh/g) and relatively low electrochemical reduction potential (-3.04V), thus the lithium metal gained the most research attention as a candidate for negative electrode material. However, in practical applications, due to the charging/discharging behavior of lithium metal and carbonate-based liquid electrolyte, the lithium dendrite is easily generated, resulting unusable lithium rapidly accumulated, and the coulombic efficiency and the battery cycle life are reduced. Therefore, how to effectively inhibit the growth of lithium dendrite and dead lithium, prolong its cycle life in liquid electrolyte, and obtain the high-capacity lithium metal negative batterie is a very important topic in the research field. To solve the above problems, the most effective way at present is to promote the formation of an inorganic solid electrolyte interface (SEI) layer by adding an additive to the electrolyte. There is a very weak force between the SEI layer and the lithium metal, which can accelerate the conduction of the lithium ion between interfaces and simultaneously inhibit the formation of the lithium dendrite. The lithium nitrate has been shown to be an effective and critical electrolyte additive with high solubility in ether electrolytes. However, conventional ether-based electrolyte cannot be used with high-voltage positive electrode material due to its narrow electrochemical window. The carbonate-based electrolyte has a wider electrochemical window than the ether-based electrolyte, and is often used in a combination of the high-voltage positive electrode material and the lithium metal negative electrode, however the solubility of the lithium nitrate in the carbonate electrolyte is very low. Addition of lithium nitrate in the carbonate electrolyte has great potential in realizing high-energy batteries. Therefore, there is room for improvement in the art. CN 113131000A discloses a carbonate-based electrolyte comprising fluoroethylene carbonate, ethylene carbonate, diethyl carbonate; dimethoxyethane, LiPF6; lithium nitrate, and 12-crown-4. BRIEF DESCRIPTION OF THE DRAWINGS In order to illustrate the technical solutions of the embodiments of the present application more clearly, the accompanying drawings in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be seen as the limiting the scope. Implementations of the present technology will now be described, by way of embodiments, with reference to the attached figures, wherein: FIG. 1 shows a flowchart of a method for making a carbonate-based electrolyte in one embodiment.FIG. 2 shows a schematic view of a lithium metal battery in one embodiment.FIG. 3 shows a schematic view of a button-type battery in one embodiment.FIG. 4 shows charging/discharging results of a first lithium metal battery.FIG. 5 shows charging/discharging results of a second lithium metal battery.FIG. 6 shows charging/discharging results of the button-type battery illustrated in FIG. 3.FIG. 7 shows specific capacity results of the button-type battery at different charge/discharge rates. DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS It will be appreciated that for simplicity and clarity of illustration, where appropriate, reference numerals have been repeated among the different figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein can be practiced without these specific details. In other instances, methods, procedures, and components have not been described in detail so as not to obscure the related relevant feature being described. The drawings are not necessarily to scale, and the proportions of certain parts may be exaggerated better illustrate details and features. The description is not to be considered as lim