Electrolyte solution additive containing isocyanate and sulfamide structural groups and application thereof

Abstract

An isocyanate electrolyte solution additive containing a sulfamide structural group has a structure of formula I: ##STR00001##
where R.sub.1 and R.sub.2 are identical or different, R.sub.1 and R.sub.2 are each independently selected from methyl, ethyl, butyl, methoxy, methanesulfonyl, ethanesulfonyl, fluorosulfonyl, trifluoromethanesulfonyl, perfluoroethylsulfonyl, benzenesulfonyl, alkyl-containing benzenesulfonyl, cyano/fluorobenzenesulfonyl and alkoxy-containing benzenesulfonyl, and R.sub.1 and R.sub.2 can be linked to form one of five-membered ring or six-membered ring.

Claims

1. An electrolyte solution additive containing isocyanate compound and sulfamide structural groups, wherein the electrolyte solution additive is one or a mixture of two or more selected from a group consisting the following structural formulas: ##STR00016## ##STR00017## ##STR00018## ##STR00019##

2. A lithium ion battery, wherein the electrolyte solution additive containing the isocyanate compound and sulfamide structural groups according to claim 1 is applied to the lithium ion battery, the lithium ion battery comprises an anode, a cathode, a diaphragm arranged between the cathode and the anode and an electrolyte solution.

3. The lithium ion battery according to claim 2, wherein the electrolyte solution comprises a solvent, an electrolyte lithium salt and an additive, and the additive at least comprises the electrolyte solution additive containing the isocyanate compound and sulfamide structural groups.

4. The lithium ion battery according to claim 3, wherein a content of the electrolyte solution additive containing the isocyanate compound and sulfamide structural groups is 0.01wt %-5wt % of a total weight of the electrolyte solution.

5. The lithium ion battery according to claim 3, wherein the electrolyte lithium salt is one or more selected from a group consisting of LiPF.sub.6, LiCIO.sub.4, LiBF.sub.4, LiBOB, LiODFB, LITDI, LiTFSI and LiFSI; a content of the electrolyte lithium salt is 10wt %-20wt % of a total weight of the electrolyte solution.

6. The lithium ion battery according to claim 3, wherein the solvent is any one or a combination of two or more selected from a group consisting of ethylene carbonate, propylene carbonate, butylene carbonate, ethylene fluorocarbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, ethylmethyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, methylpropargyl carbonate, 1,4-butylrolactone, methyl propionate, methyl butyrate, ethyl acetate, ethyl propionate, propyl propionate and ethyl butyrate.

Description

DETAILED DESCRIPTION OF THE EMBODIMENTS

(1) To make the above objective, features and advantages of the present disclosure more clear and understandable, specific embodiments of the present disclosure will be described in detail below. The following description explains many specific details so as to sufficiently understand the present disclosure. However, the present disclosure can be implemented in many other ways different from the description herein. Similar modifications can be made by those skilled in the art without departing from the spirit of the present disclosure, and therefore the present disclosure is not limited by specific embodiments disclosed hereinafter.

(2) Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the technical field of the present disclosure. The terms used in the specification of the present disclosure in this document are only for the purpose of describing the specific embodiments, and are not intended to limit the present disclosure.

Battery Examples

(3) Formulations of lithium ion battery non-aqueous electrolyte solutions listed in battery examples 1-8 and comparative examples 1-5 are shown in Table 1.

(4) TABLE-US-00001 TABLE 1 Formulations of lithium ion battery non-aqueous electrolyte solutions listed in battery examples 1-8 and comparative examples 1-5 Ethylene Isocyanate carbonate: additive dimethyl provided by carbonate:methyl Cathode material of the present Electrolyte ethyl carbonate Number battery disclosure Other additives lithium salt (weight ratio %) Example 1 LiNi.sub.0.8Co.sub.0.1Mn.sub.0.1O.sub.2 0.75% SN02 / 13.5% 30:40:30 LiPF.sub.6 Example 2 LiNi.sub.0.8Co.sub.0.1Mn.sub.0.1O.sub.2 0.5% SN03 / 13.5% 30:40:30 LiPF.sub.6 Example 3 LiNi.sub.0.8Co.sub.0.1Mn.sub.0.1O.sub.2 1.0% SN11 / 13.5% 30:40:30 LiPF.sub.6 Example 4 LiNi.sub.0.8Co.sub.0.1Mn.sub.0.1O.sub.2 0.5% SN19 13.5% 30:40:30 LiPF.sub.6 Example 5 LiNi.sub.0.8Co.sub.0.1Mn.sub.0.1O.sub.2 0.5% SN02 13.5% LiPF.sub.6 30:40:30 Example 6 LiNi.sub.0.8Co.sub.0.1Mn.sub.0.1O.sub.2 0.1% SN03 13.5% LiPF.sub.6 30:40:30 Example 7 LiNi.sub.0.8Co.sub.0.1Mn.sub.0.1O.sub.2 0.25% SN11 0 13.5% LiPF.sub.6 30:40:30 Example 8 LiNi.sub.0.8Co.sub.0.1Mn.sub.0.1O.sub.2 0.75% SN19 13.5% LiPF.sub.6 30:40:30 Comparative LiNi.sub.0.8Co.sub.0.1Mn.sub.0.1O.sub.2 / / 13.5% 30:40:30 example 1 LiPF.sub.6 Comparative example 2 LiNi.sub.0.8Co.sub.0.1Mn.sub.0.1O.sub.2 / 13.5% LiPF.sub.6 30:40:30 Comparative example 3 LiNi.sub.0.8Co.sub.0.1Mn.sub.0.1O.sub.2 / 13.5% LiPF.sub.6 30:40:30 Comparative example 4 LiNi.sub.0.8Co.sub.0.1Mn.sub.0.1O.sub.2 / 13.5% LiPF.sub.6 30:40:30 Comparative example 5 LiNi.sub.0.8Co.sub.0.1Mn.sub.0.1O.sub.2 / 13.5% LiPF.sub.6 30:40:30

(5) A method for preparing a lithium ion button battery by using the lithium ion battery non-aqueous electrolyte solutions in battery examples 1-8 and comparative examples 1-5 is as follows:

(6) (1) Preparation of Cathode Plate

(7) Cathode LiNi.sub.0.8Co.sub.0.1Mn.sub.0.1O.sub.2 powders, carbon black (particle size: 1000 nm), polyvinylidene fluoride (PVDF) and N,N-dimethyl pyrrolidone (NMP) were mixed to prepare uniform slurry, the slurry was evenly coated onto an aluminum foil (15 m) current collector, and then dried and rolled, so as to obtain a LiNi.sub.0.8Co.sub.0.1Mn.sub.0.1O.sub.2 cathode material. After drying for 12 hours at 120 C., in the dried electrode plate, LiNi.sub.0.8Co.sub.0.1Mn.sub.0.1O.sub.2 accounted for 94% of a total coating material, a binder accounted for 4% of the total coating material, and carbon black accounted for 2% of the total coating material. Then, the obtained electrode plate was cut into a wafer with a diameter of 8 mm as a cathode.

(8) (2) Preparation of Anode Plate

(9) An artificial graphite anode material was taken as an example: artificial graphite, polyvinylidene fluoride (PVDF) and N-methylpyrrolidone (NMP) were mixed to prepare uniform slurry, and the slurry was evenly coated onto a copper foil (15 m) current collector, and then dried and rolled to obtain a carbon anode material. After drying for 12 hours at 120 C., in the dried electrode plate, the graphite accounted for 96.4% of a total coating material, a binder accounted for 3.6% of the total coating material. Then, the obtained electrode plate was cut into wafer with a diameter of 8 mm as an anode.

(10) (3) Preparation of Electrolyte Solution

(11) In an argon atmosphere glove box containing <1 ppm of water, a lithium salt was dissolved into a solvent, then novel phosphine isocyanate was added, and then the above materials were evenly mixed to obtain the electrolyte solution.

(12) (4) Preparation of Lithium Ion Battery

(13) A CR2430 button battery was assembled by using the materials described in the above steps (1) and (2) as working electrodes, and a Celgard 2400 membrane (Tianjin) as a diaphragm. From the anode to the cathode, the assembling sequence was as follows: an anode shell, a spring piece, a gasket, an anode plate, an electrolyte solution, a diaphragm, a cathode plate, a cathode shell, and then a sealing machine was used for sealing. These operations were all completed in a pure argon glove box, and subsequently the CR2430 button battery was subjected to electrochemical performance test after standing for 6 hours.

Performance Test of Lithium Ion Battery

(14) Test I: stability test of electrolyte solution: the lithium ion battery electrolyte solutions prepared in examples 1-8 and comparative examples 1-5 were respectively put into sealed aluminum bottles, the aluminum bottles were vacuum encapsulated with aluminum-plastic films, and electrolyte solution samples were simultaneously stored in incubators with a set temperature of 45 C. Before storage and after storage for 30 days, the samples were taken from the glove box to detect the acidity and chroma values of the electrolyte solutions. The acidity was measured by a potentiometric titrator. The acidity value is converted into HF, unit: ppm. The chroma is determined by platinum-cobalt colorimetry, unit: Hazen. The test results are shown in Table 2.

(15) TABLE-US-00002 TABLE 2 Influence of additive on acid value and chroma of electrolyte solution Chroma (Hazan) Acidic value (ppm) Before Store for Before Store for Number storage 30 days storage 30 days Electrolyte solution 10 18 7.6 12.1 in example 1 Electrolyte solution 10 12 7.3 10.4 in example 2 Electrolyte solution 10 20 8.0 13.2 in example 3 Electrolyte solution 10 15 7.6 11.6 in example 4 Electrolyte solution 10 31 8.1 17.2 in example 5 Electrolyte solution 10 23 9.2 18.7 in example 6 Electrolyte solution 10 29 8.2 18.8 in example 7 Electrolyte solution 10 34 5.9 18.7 in example 8 Electrolyte solution 10 83 7.3 38.3 in example 9 Electrolyte solution 10 251 8.1 178.6 in comparative example 2 Electrolyte solution 10 280 7.4 199.1 in comparative example 3 Electrolyte solution 10 73 6.9 59.2 in comparative example 4 Electrolyte solution 10 68 7.8 67.3 in comparative example 5

(16) It can be seen from Table 2 that the electrolyte solutions in examples 1-8 can be stored for 30 days at the high temperature of 45 C., the acidity and chroma of the electrolyte solution are both lower than those in comparative examples, the acidity and chroma of the electrolyte solution are effectively inhibited even though the novel additive provided by the present disclosure is added into the electrolyte solution systems of ethylene sulfate (DTD) or methylene methane disulfonate (MMDS), so that the acidity and chroma of the electrolyte solution can be effectively inhibited by adding the novel additive provided by the present disclosure. Accordingly, the novel additive provided by the present disclosure can effectively inhibit the increase in the acidity and chroma of the electrolyte solution and improve the stability of the electrolyte solution under high-temperature conditions.

(17) Test II: high temperature cycle performance test and high temperature storage performance test

(18) The prepared batteries respectively underwent the following tests: {circle around (1)} at 45 C., the battery was charged to 4.3 V at a constant current of 0.1 C, and then discharged to 2.7 V at a constant current of corresponding magnification. This was the first cycle; {circle around (2)} after the first cycle was ended, the battery was charged to 4.3 V at a constant current at 1.0 C, and then discharged to 2.7 V at a constant current at the corresponding rate. The tests of 100 and 500 cycles were respectively performed according to the cycle conditions, and the capacity retention rates of the battery after 100 and 500 cycles were calculated respectively. Wherein, the capacity retention rate after the cycle is calculated according to the following formula. Relevant test data obtained from each battery is shown in Table 2;
Capacity retention rate after cycle=(discharge capacity after the corresponding number of cycles/discharge capacity of the first cycle)100%.

(19) High temperature storage internal resistance change rate test: five charge-discharge cycle tests were performed at room temperature at the rate of 1 C for the batteries in examples 1-8 and comparative examples 1-5, and filially charged to the full charge state at the rate of 1 C. The battery internal resistance T was recorded. The fully charged battery was stored at 60 C. for 15 days, the internal resistance TO of the battery was recorded, and the change rate of the internal resistance of the battery and other experimental data were calculated. The results are recorded and shown in Table 3 (the numbers of batteries in example 1-8 are respectively battery 1-battery 8, and the numbers of batteries in comparative examples 1-5 are respectively battery 1#-battery 5#).
Change rate of internal resistance=(TT0)/T100%.

(20) TABLE-US-00003 TABLE 3 Test results of examples and comparative examples Change rate % of Capacity retention rate/% internal resistance Number of 100 500 after storage for 15 battery weeks weeks days at 60 C. Battery 1 93.37 83.49 5.3 Battery 2 94.24 8619 4.4 Battery 3 89.89 82.49 5.3 Battery 4 92.73 84.13 4.9 Battery 5 92.38 83.67 5.1 Battery 6 94.31 82.49 4.3 Battery 7 93.39 86.31 5.0 Battery 8 94.05 85.93 4.8 Battery 1# 68.59 46.39 8.9 Battery 2# 79.69 68.62 7.7 Battery 3# 78.98 67.34 8.1 Battery 4# 86.25 75.25 7.3 Battery 5# 80.32 74.39 7.6

(21) It can be seen from Table 3 that the use of the novel additive of the present disclosure can significantly improve the high-temperature cycle performance and the high temperature impedance performance of the lithium secondary battery. It is proved that by the improvement of the interface property of the anode electrode/electrolyte solution, the novel additive of the present disclosure can reduce the irreversible capacity of the lithium secondary battery during the first charge and discharge and maintain the stability of the interface while reducing the interface impedance, and is helpful to improve the high temperature cycle stability of the lithium secondary battery.

(22) Accordingly, the novel additive of the present disclosure has good thermostability, can play a role in an electrolyte solution stabilizing agent and avoids the high temperature discoloration and the acid value increase of the electrolyte solution. Even though the novel additive provided by the present disclosure patent is applied to the electrolyte system containing ethylene sulfate (DTD) or methylene methane disulfonate (MMDS) that is prone to the increase in the acid value and chroma of the electrolyte solution, it also shows a good electrolyte stabilizing agent effect, thereby effectively inhibiting the discoloration and acid value increase of the electrolyte solution. After the electrolyte solution containing the novel additive provided by the present disclosure patent is applied to the battery, the battery has improved high temperature cycle performance and low impedance, and therefore the additive has a good application prospect.

(23) Various technical features of the above embodiments can be randomly combined. To make the description concise, all possible combinations of technical features in the above embodiments are not described, however, as long as the combinations of these technical features are not contradictory, they should be considered to be included within the scope of the specification.

(24) The above embodiments are only for expressing several embodiments of the present disclosure, the descriptions are more specific and detailed, but cannot be understood as limiting the scope of the disclosure patent. It should be noted that several deformations and improvements can be made by persons of ordinary skill in the art without departing from the idea of the present disclosure, all of which are included within the protective scope of the present disclosure. Therefore, the protective scope of the present disclosure patent shall be subject to the attached claims.