Ultrafast-charging liquid lithium metal battery electrolyte

Abstract

The invention discloses an ultrafast charge liquid lithium metal battery electrolyte, relates to the technical field of lithium ion battery preparation, and aims to solve the problem of poor fast charge performance of a current semi-solid or all-solid battery, the electrolyte is composed of a solvent and a lithium salt, and the total molar concentration is 0.5-2M; wherein the solvent is one or a mixture of two of fluoroacetonitrile and N, N-dimethyl trifluoroacetamide, and the lithium salt is one or a mixture of two of lithium bis (fluorosulfonyl) imide and lithium bis (trifluoromethanesulfonyl) imide. The ultrafast-charging liquid lithium metal battery electrolyte can be matched with a high-nickel positive electrode and a lithium metal negative electrode, is high in energy density and good in rate capability, and can promote the application of a liquid lithium metal battery.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium-ion battery preparation, and more specifically, to an electrolyte for an ultra-fast charging liquid lithium metal battery. Background Art

[0002] As a core component in new energy vehicles, power batteries naturally receive much attention. The explosion of the new energy vehicle industry chain has also driven the upstream lithium-ion power battery industry chain to experience strong growth.

[0003] The energy density of lithium-ion power batteries has been continuously increasing with the growth of the entire industry chain, which benefits from improvements in battery materials and manufacturing processes, etc. In terms of materials, ternary materials / lithium iron phosphate cathodes + graphite anodes are the mainstream materials currently used in power batteries. At present, the upper limit of the energy density of lithium-ion power batteries is approximately 300 - 350 Wh / Kg.

[0004] Continuously promoting the improvement of the energy density of power batteries is the key to solving the range anxiety of new energy vehicles and is also a topic that cannot be avoided at present and in the future for some time.

[0005] The demand for solid-state batteries comes partly from the pursuit of higher energy density in the power battery system. The upper limit of the energy density of lithium-ion power batteries is determined by the currently mainstream graphite anodes and the silicon-carbon anodes that may become mainstream in the future. If higher energy density is desired, such as above 350 Wh / Kg or even up to 500 Wh / Kg, it depends on a new generation of anode materials represented by metallic lithium.

[0006] In the application of lithium metal anodes, currently, the fast charging performance of both semi-solid and all-solid state batteries is not ideal, and the charge-discharge rate is below 1C. Therefore, it is very necessary to develop an electrolyte for a liquid lithium metal battery with ultra-fast charging performance, which can promote the application of lithium metal batteries. Summary of the Invention

[0007] Aiming at the defect of poor fast charging performance of current semi-solid or all-solid state batteries, one of the purposes of the present invention is to provide an electrolyte for an ultra-fast charging liquid lithium metal battery, which can match high-nickel cathodes and lithium metal anodes, has a high energy density and good rate performance, and can promote the application of liquid lithium metal batteries.

[0008] To solve the above technical problems, the present invention provides the following technical solutions:

[0009] A super-fast charging liquid lithium metal battery electrolyte, the electrolyte is composed of a solvent and a lithium salt, and the total molar concentration is 0.5-2M; wherein, the solvent is one or a mixture of two of fluoroacetonitrile (FAN) and N,N-dimethyltrifluoroacetamide (DTA), and the lithium salt is one or a mixture of two of lithium bis(fluorosulfonyl)imide (LiFSI) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). The introduction of FAN can improve the lithium ion conductivity of the lithium salt; the introduction of DTA can promote the stability of the lithium metal negative electrode; the introduction of LiFSI can improve the lithium ion conductivity of the lithium salt; the introduction of LiTFSI can improve the thermal stability of the super-fast charging liquid lithium metal battery electrolyte.

[0010] The super-fast charging liquid lithium metal battery electrolyte of the present invention can match a high-nickel positive electrode and a lithium metal negative electrode, has a high energy density and good rate performance, and can promote the application of liquid lithium metal batteries.

[0011] Preferably, the total molar concentration of the electrolyte is 1.5M.

[0012] Preferably, the solvent is a mixture of fluoroacetonitrile (FAN) and N,N-dimethyltrifluoroacetamide (DTA), and the volume ratio of the two is 1:1, which can not only ensure the lithium ion conductivity in the liquid solvent, but also form a stable interfacial structure on the surface of the lithium metal negative electrode.

[0013] Preferably, the lithium salt is a mixture of lithium bis(fluorosulfonyl)imide (LiFSI) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and the molar ratio of the two is 1:0.5-1:2, which can not only ensure the lithium ion conductivity in the liquid solvent, but also improve the thermal stability of the super-fast charging liquid lithium metal battery electrolyte.

[0014] Preferably, the ionic conductivity of the electrolyte at 25°C is greater than 10 mS / cm.

[0015] The second object of the present invention is to provide a super-fast charging liquid lithium metal battery, including a positive electrode sheet, a negative electrode sheet, a separator and the above-mentioned electrolyte; wherein, the positive electrode sheet is lithium nickel cobalt manganese oxide, the negative electrode sheet is a lithium metal, a graphite negative electrode and a carbon nitride negative electrode, and the separator is a ceramic separator, and the separator is a ceramic separator.

[0016] Preferably, the positive electrode sheet is an NCM811 positive electrode material.

[0017] The third object of the present invention is to provide an application of the above-mentioned super-fast charging liquid lithium metal battery electrolyte in a liquid lithium metal battery with a charge-discharge rate greater than 1C.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: The ultra-fast charging liquid lithium metal battery electrolyte of the present invention can match the high-nickel cathode and the lithium metal anode, has a high energy density and good rate performance, and can promote the application of liquid lithium metal batteries. Detailed implementation manners

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0020] The test materials and reagents used in the following embodiments can be obtained from commercial channels without special instructions. For those not specifying specific technologies or conditions in the embodiments, they can be carried out according to the technologies or conditions described in the literature in the field or according to the product specifications.

[0021] An ultra-fast charging liquid lithium metal battery includes a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte; wherein, the positive electrode sheet is lithium nickel cobalt manganese oxide, the negative electrode sheet is lithium metal, the separator is a ceramic separator, and the electrolyte is composed of a solvent and a lithium salt with a total molar concentration of 0.5-2M, and the ionic conductivity of the electrolyte at 25°C is greater than 10 mS / cm; wherein, the solvent is one or a mixture of two of fluoroacetonitrile (FAN) and N,N-dimethyltrifluoroacetamide (DTA), and the lithium salt is one or a mixture of two of lithium bis(fluorosulfonyl)imide (LiFSI) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). The introduction of FAN can improve the lithium ion conductivity of the lithium salt; the introduction of DTA can promote the stability of the lithium metal negative electrode; the introduction of LiFSI can improve the lithium ion conductivity of the lithium salt; the introduction of LiTFSI can improve the thermal stability of the ultra-fast charging liquid lithium metal battery electrolyte.

[0022] Example 1

[0023] This example provides an ultra-fast charging liquid lithium metal battery, which includes a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte; wherein, the positive electrode sheet is NCM811 positive electrode material, the negative electrode sheet is lithium metal, the separator is a ceramic separator, and the composition of the electrolyte is 0.5L of FAN, 0.5L of DTA, 0.75M of LiFSI, and 0.75M of LiTFSI. As shown in Table 1, the cycle performance test of the ultra-fast charging liquid lithium metal battery was carried out.

[0024] Example 2

[0025] This embodiment provides a super-fast charging liquid lithium metal battery, which includes a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte; wherein, the positive electrode sheet is made of NCM811 positive electrode material, the negative electrode sheet is lithium metal, the separator is a ceramic separator, and the composition of the electrolyte is 0.5L of FAN, 0.5L of DTA, 1M of LiFSI, and 0.5M of LiTFSI. As shown in Table 1, the cycle performance of this super-fast charging liquid lithium metal battery was tested.

[0026] Example 3

[0027] This embodiment provides a super-fast charging liquid lithium metal battery, which includes a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte; wherein, the positive electrode sheet is made of NCM811 positive electrode material, the negative electrode sheet is lithium metal, the separator is a ceramic separator, and the composition of the electrolyte is 0.5L of FAN, 0.5L of DTA, 0.5M of LiFSI, and 1M of LiTFSI. As shown in Table 1, the cycle performance of this super-fast charging liquid lithium metal battery was tested.

[0028] Example 4

[0029] This embodiment provides a super-fast charging liquid lithium metal battery, which includes a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte; wherein, the positive electrode sheet is made of NCM811 positive electrode material, the negative electrode sheet is lithium metal, the separator is a ceramic separator, and the composition of the electrolyte is 1L of FAN, 1L of DTA, 0.75M of LiFSI, and 0.75M of LiTFSI. As shown in Table 1, the cycle performance of this super-fast charging liquid lithium metal battery was tested.

[0030] Example 5

[0031] This embodiment provides a super-fast charging liquid lithium metal battery, which includes a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte; wherein, the positive electrode sheet is made of NCM811 positive electrode material, the negative electrode sheet is lithium metal, the separator is a ceramic separator, and the composition of the electrolyte is 1L of FAN, 1L of DTA, 1M of LiFSI, and 0.5M of LiTFSI. As shown in Table 1, the cycle performance of this super-fast charging liquid lithium metal battery was tested.

[0032] Example 6

[0033] This embodiment provides a super-fast charging liquid lithium metal battery, which includes a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte; wherein, the positive electrode sheet is made of NCM811 positive electrode material, the negative electrode sheet is lithium metal, the separator is a ceramic separator, and the composition of the electrolyte is 1L of FAN, 1L of DTA, 0.5M of LiFSI, and 1M of LiTFSI. As shown in Table 1, the cycle performance of this super-fast charging liquid lithium metal battery was tested.

[0034] Comparative Example 7

[0035] This embodiment provides a super-fast charging liquid lithium metal battery, which includes a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte; among them, the positive electrode sheet is made of NCM811 positive electrode material, the negative electrode sheet is graphite, the separator is a ceramic separator, and the composition of the electrolyte is 1L of FAN and 1.3M of LiFSI. As shown in Table 1, the cycle performance of this super-fast charging liquid lithium metal battery was tested.

[0036] Comparative Example 8

[0037] This embodiment provides a super-fast charging liquid lithium metal battery, which includes a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte; among them, the positive electrode sheet is made of NCM811 positive electrode material, the negative electrode sheet is lithium metal, the separator is a ceramic separator, and the composition of the electrolyte is 1L of DTA and 1M of LiTFSI. As shown in Table 1, the cycle performance of this super-fast charging liquid lithium metal battery was tested.

[0038] Comparative Example 9

[0039] This embodiment provides a super-fast charging liquid lithium metal battery, which includes a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte; among them, the positive electrode sheet is made of NCM811 positive electrode material, the negative electrode sheet is lithium metal, the separator is a ceramic separator, and the electrolyte is Li6PS5Cl. As shown in Table 1, the cycle performance of this super-fast charging liquid lithium metal battery was tested.

[0040] Comparative Example 10

[0041] This embodiment provides a super-fast charging liquid lithium metal battery, which includes a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte; among them, the positive electrode sheet is made of NCM811 positive electrode material, the negative electrode sheet is lithium metal, the separator is a ceramic separator, and the electrolyte is Li7La3Zr2O 12 . As shown in Table 1, the cycle performance of this super-fast charging liquid lithium metal battery was tested.

[0042] In the above embodiments and comparative examples, the manufacturing processes of all the batteries are the same, and the separators used are the same. The only difference is the positive and negative electrodes and the electrolyte (quality). The detailed formula of the electrolyte (quality) is as follows:

[0043] ① 0.5L of FAN, 0.5L of DTA, 0.75M of LiFSI, 0.75M of LiTFSI;

[0044] ② 0.5L of FAN, 0.5L of DTA, 1M of LiFSI, 0.5M of LiTFSI;

[0045] ③ 0.5L of FAN, 0.5L of DTA, 0.5M of LiFSI, 1M of LiTFSI;

[0046] ④ FAN 1L, DTA 1L, LiFSI 0.75M, LiTFSI 0.75M;

[0047] ⑤ FAN 1L, DTA 1L, LiFSI 1M, LiTFSI 0.5M;

[0048] ⑥ FAN 1L, DTA 1L, LiFSI 0.5M, LiTFSI 1M;

[0049] ⑦ FAN 1L, LiFSI 1.3M;

[0050] ⑧ DTA 1L, LiTFSI 1M;

[0051] ⑨ Li6PS5Cl;

[0052] ⑩ Li7La3Zr2O 12 。

[0053] Table 1 shows the test results of the battery discharge cycle performance of Examples 1 - 10

[0054] Lithium metal battery Positive electrode Negative electrode Electrolyte Test conditions Cycling performance Example 1 NCM811 Li metal ① 4C 1500 times Example 2 NCM811 Li metal ② 4C 1350 times Example 3 NCM811 Li metal ③ 4C 1250 times Example 4 NCM811 Li metal ④ 4C 1150 times Example 5 NCM811 Li metal ⑤ 4C 1100 times Example 6 NCM811 Li metal ⑥ 4C 1000 times Comparative example 7 NCM811 Graphite ⑦ 6C 2000 times Comparative example 8 NCM811 Li metal ⑧ 0.5 1000 times Comparative example 9 NCM811 Li metal ⑨ 1C 1000 times Comparative example 10 NCM811 Li metal ⑩ 0.5C 800 times

[0055] The ultra-fast charging liquid lithium metal battery electrolyte of the present invention can match a high-nickel cathode and a lithium metal anode, has a high energy density and good rate performance, and can promote the application of liquid lithium metal batteries.

[0056] The embodiments disclosed in the present invention are preferred embodiments, but are not limited thereto. Those of ordinary skill in the art can easily understand the spirit of the present invention based on the above embodiments and make different extensions and changes. However, as long as they do not depart from the spirit of the present invention, they are within the protection scope of the present invention.

Claims

1. An ultra-fast charging liquid lithium metal battery electrolyte, characterized in that: The electrolyte is composed of a solvent and a lithium salt, and the total molar concentration is 0.5 to 2 M; wherein, the solvent is one or a mixture of two of fluoroacetonitrile and N,N-dimethyltrifluoroacetamide, and the lithium salt is one or a mixture of two of lithium bis(fluorosulfonyl)imide and lithium bis(trifluoromethanesulfonyl)imide.

2. The ultra-fast charging liquid lithium metal battery electrolyte according to claim 1, characterized in that: The total molar concentration of the electrolyte is 1.5 M.

3. The ultra-fast charging liquid lithium metal battery electrolyte according to claim 1, characterized in that: The solvent is a mixture of fluoroacetonitrile and N,N-dimethyltrifluoroacetamide, and the volume ratio of the two is 1:

1.

4. The ultra-fast charging liquid lithium metal battery electrolyte according to claim 1, characterized in that: The lithium salt is a mixture of lithium bis(fluorosulfonyl)imide and lithium bis(trifluoromethanesulfonyl)imide, and the molar ratio of the two is 1:0.5 to 1:

2.

5. The ultra-fast charging liquid lithium metal battery electrolyte according to claim 1, characterized in that: The ionic conductivity of the electrolyte at 25 °C is greater than 10 mS / cm.

6. A super-fast charging liquid lithium metal battery, characterized in that: It includes a positive electrode sheet, a negative electrode sheet, a separator, and the electrolyte according to any one of claims 1-5; wherein, the positive electrode sheet is lithium nickel cobalt manganese oxide, the negative electrode sheet is lithium metal, a graphite negative electrode, and a carbon nitride negative electrode, and the separator is a ceramic separator.

7. The ultra-fast charging liquid lithium metal battery according to claim 6, wherein: The positive electrode sheet is an NCM811 positive electrode material.

8. Use of an ultra-fast charging liquid lithium metal battery electrolyte according to any one of claims 1-5 in a liquid lithium metal battery with a charge-discharge rate greater than 1C.