Lithium ion battery electrolyte for improving low-temperature charging activity and preparation method thereof

Abstract

The invention relates to the technical field of battery electrolytes, and discloses a lithium ion battery electrolyte for improving low-temperature charging activity, which comprises the following formula and proportion: 30% of ethylene carbonate (EC), 30% of dimethyl carbonate (DMC), 30% of methyl ethyl carbonate (EMC), 5% of fluoroethylene carbonate (FEC), 1 mol / L of lithium bis (trifluoromethanesulfonimide) (LiTFSI), 0.1 mol / L of lithium nitrate (LiNO3), 0.1 mol / L of lithium ion battery electrolyte, 0.1 mol / L of lithium ion battery electrolyte and the balance of water. According to the method, the low-temperature performance can be improved, the electrolyte formula and the preparation method contribute to remarkably improving the charging activity of the lithium ion battery in a low-temperature environment, normal charging of the battery can be ensured under a low-temperature condition (such as-20 DEG C and below), the problem of charging difficulty caused by low temperature is reduced, the usability of the battery in a cold environment is improved, and the service life of the battery is prolonged. For example, the method can be applied to outdoor electronic equipment, electric automobiles and the like in cold winter in northern China.

Description

Technical Field

[0001] The invention relates to the technical field of battery electrolytes, in particular to a lithium ion battery electrolyte with improved low-temperature charging activity and a preparation method thereof. Background Art

[0002] Low-temperature charging problem: The viscosity of traditional lithium-ion battery electrolyte increases and the ion conductivity decreases at low temperatures, which makes it difficult to charge the battery in low-temperature environments. This limits the application of lithium-ion batteries in cold areas or low-temperature environments. For example, the range of electric vehicles in high-latitude areas drops significantly in winter, and mobile devices operating outdoors at low temperatures cannot be charged normally.

[0003] Battery life and safety challenges: With the continuous expansion of lithium-ion battery applications, the requirements for battery life and safety are increasing. Problems such as adverse reactions between electrodes and electrolytes and lithium dendrite growth can cause battery capacity decay and safety hazards, such as battery bulging and fire. Therefore, it is necessary to improve the electrolyte formulation and preparation method to meet these challenges. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] In view of the deficiencies in the prior art, the present invention provides a lithium ion battery electrolyte with improved low-temperature charging activity and a preparation method thereof, which has the advantages of improving the charging activity of the lithium ion battery in a low-temperature environment, ensuring normal charging of the battery under low-temperature conditions (such as -20°C and below), and reducing the charging difficulty caused by low temperature. It solves the problem of difficulty in charging the battery in a low-temperature environment, which limits the application of lithium ion batteries in cold areas or low-temperature environments.

[0006] (II) Technical solution

[0007] In order to achieve the above-mentioned purpose of improving the charging activity of lithium-ion batteries in a low temperature environment, the present invention provides the following technical solution: a lithium-ion battery electrolyte with improved low-temperature charging activity, comprising the following formula and ratio: 30% ethylene carbonate (EC), 30% dimethyl carbonate (DMC), 30% ethyl methyl carbonate (EMC), 5% fluoroethylene carbonate (FEC), 1 mol / L lithium bistrifluoromethanesulfonyl imide (LiTFSI), and 0.1 mol / L lithium nitrate (LiNO3).

[0008] Preferably, a method for preparing a lithium-ion battery electrolyte with improved low-temperature charging activity comprises the following specific steps: S1: preparing the environment and equipment: operating in a glove box filled with argon gas, ensuring that the ambient humidity is less than 0.1 ppm and the oxygen content is less than 0.1 ppm;

[0009] S2 Raw material preparation: accurately weigh ethylene carbonate (EC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and fluoroethylene carbonate (FEC) according to the formula ratio, and slowly pour them into a stirring container in sequence;

[0010] S3 preliminary stirring: start the stirring device at a low speed (such as 200-300 rpm) to fully mix the organic solvents;

[0011] S4 adding lithium salt: slowly adding lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and lithium nitrate (LiNO3);

[0012] S5 deep stirring: increase the stirring speed to 500-800 rpm to ensure that the lithium salt is completely dissolved in the mixed organic solvent;

[0013] S6 Filtration and storage: Filter the stirred electrolyte through a polytetrafluoroethylene filter with a pore size of 0.22μm into a storage container and store it in a sealed container.

[0014] Preferably, the step S1 is to prepare the environment and equipment, and prepare clean and dry mixing equipment and storage containers.

[0015] Preferably, the preliminary stirring in S3 is stirring for 30-60 minutes.

[0016] Preferably, the S4 adds lithium salt: its concentration in the mixed organic solvent reaches 1 mol / L and 0.1 mol / L respectively.

[0017] Preferably, the S5 deep stirring: continuous stirring for 2-3 hours.

[0018] (III) Beneficial effects

[0019] Compared with the prior art, the present invention provides a lithium ion battery electrolyte with improved low temperature charging activity and a preparation method thereof, which has the following beneficial effects:

[0020] 1. The lithium-ion battery electrolyte with improved low-temperature charging activity and the preparation method thereof, which can achieve improved low-temperature performance: This electrolyte formula and preparation method help to significantly improve the charging activity of lithium-ion batteries in low-temperature environments. Under low-temperature conditions (such as -20°C and below), it can ensure normal charging of the battery, reduce the charging difficulty caused by low temperature, and improve the battery's usability in cold environments, such as outdoor electronic equipment, electric vehicles and other application scenarios in the cold winter in the north.

[0021] 2. The lithium-ion battery electrolyte with improved low-temperature charging activity and its preparation method, the solution improves battery life: the ingredients in the formula can form a stable interface film on the electrode surface, reduce the side reactions of the electrode material during the charging and discharging process, and inhibit the growth of lithium dendrites, thereby extending the cycle life of the battery and reducing the battery use cost and replacement frequency.

[0022] 3. The lithium-ion battery electrolyte with improved low-temperature charging activity and the preparation method thereof, which enhances battery safety: the addition of ingredients such as lithium nitrate can improve the thermal stability of the electrolyte, reduce the risk of thermal runaway of the battery in a high temperature environment or under abnormal conditions, and ensure safe use. DETAILED DESCRIPTION

[0023] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0024] The present invention provides a technical solution, a lithium-ion battery electrolyte for improving low-temperature charging activity, comprising the following formula and proportion: 30% ethylene carbonate (EC), 30% dimethyl carbonate (DMC), 30% ethyl methyl carbonate (EMC), 5% fluoroethylene carbonate (FEC), 1 mol / L lithium bistrifluoromethanesulfonyl imide (LiTFSI), and 0.1 mol / L lithium nitrate (LiNO3);

[0025] Furthermore, a method for preparing a lithium-ion battery electrolyte with improved low-temperature charging activity comprises the following specific steps: S1 preparing the environment and equipment: operating in a glove box filled with argon gas, ensuring that the ambient humidity is less than 0.1 ppm and the oxygen content is less than 0.1 ppm;

[0026] Among them, S1 prepares the environment and equipment, and prepares clean and dry mixing equipment and storage containers;

[0027] S2 Raw material preparation: accurately weigh ethylene carbonate (EC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and fluoroethylene carbonate (FEC) according to the formula ratio, and slowly pour them into a stirring container in sequence;

[0028] S3 preliminary stirring: start the stirring device at a low speed (such as 200-300 rpm) to fully mix the organic solvents;

[0029] Among them, S3 initial stirring: stirring for 30-60 minutes;

[0030] S4 adding lithium salt: slowly adding lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and lithium nitrate (LiNO3);

[0031] Wherein, S4 adds lithium salt: its concentration in the mixed organic solvent reaches 1 mol / L and 0.1 mol / L respectively;

[0032] S5 deep stirring: increase the stirring speed to 500-800 rpm to ensure that the lithium salt is completely dissolved in the mixed organic solvent;

[0033] Among them, S5 deep stirring: continuous stirring for 2-3 hours;

[0034] S6 Filtration and storage: Filter the stirred electrolyte through a polytetrafluoroethylene filter with a pore size of 0.22μm into a storage container and store it in a sealed container.

[0035] Furthermore, the method can achieve low-temperature performance improvement: the electrolyte formulation and preparation method can help significantly improve the charging activity of lithium-ion batteries in low-temperature environments. Under low-temperature conditions (such as -20°C and below), the normal charging of the battery can be ensured, the charging difficulty caused by low temperature can be reduced, and the availability of the battery in cold environments can be improved, such as outdoor electronic equipment and electric vehicles in the cold winter in the north.

[0036] Furthermore, the solution improves battery life: the ingredients in the formula can form a stable interface film on the electrode surface, reduce the side reactions of the electrode material during the charge and discharge process, and inhibit the growth of lithium dendrites, thereby extending the cycle life of the battery and reducing the cost of battery use and replacement frequency;

[0037] Furthermore, the solution enhances battery safety: the addition of ingredients such as lithium nitrate can improve the thermal stability of the electrolyte, reduce the risk of thermal runaway of the battery in high temperature environments or abnormal conditions, and ensure safe use.

[0038] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A lithium ion battery electrolyte with improved low temperature charging activity, characterized in that: The invention comprises the following formula and proportion: 30% of ethylene carbonate (EC), 30% of dimethyl carbonate (DMC), 30% of ethyl methyl carbonate (EMC), 5% of fluoroethylene carbonate (FEC), 1 mol / L of lithium bistrifluoromethanesulfonyl imide (LiTFSI), and 0.1 mol / L of lithium nitrate (LiNO3).

2. A method for preparing a lithium ion battery electrolyte with improved low temperature charging activity, characterized in that: The method comprises the following specific steps: S1: preparing the environment and equipment: operating in a glove box filled with argon gas, ensuring that the ambient humidity is less than 0.1 ppm and the oxygen content is less than 0.1 ppm; S2 Raw material preparation: accurately weigh ethylene carbonate (EC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and fluoroethylene carbonate (FEC) according to the formula ratio, and slowly pour them into a stirring container in sequence; S3 preliminary stirring: start the stirring device at a low speed (such as 200-300 rpm) to fully mix the organic solvents; S4 adding lithium salt: slowly adding lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and lithium nitrate (LiNO3); S5 deep stirring: increase the stirring speed to 500-800 rpm to ensure that the lithium salt is completely dissolved in the mixed organic solvent; S6 Filtration and storage: Filter the stirred electrolyte through a polytetrafluoroethylene filter with a pore size of 0.22μm into a storage container and store it in a sealed container.

3. A method for preparing a lithium ion battery electrolyte with improved low temperature charging activity according to claim 2, characterized in that: The S1 prepares the environment and equipment, and prepares clean and dry mixing equipment and storage containers.

4. A method for preparing a lithium ion battery electrolyte with improved low temperature charging activity according to claim 2, characterized in that: The S3 initial stirring: stirring for 30-60 minutes.

5. The method for preparing a lithium ion battery electrolyte with improved low temperature charging activity according to claim 2, characterized in that: The S4 adds lithium salt: its concentration in the mixed organic solvent reaches 1 mol / L and 0.1 mol / L respectively.

6. A method for preparing a lithium ion battery electrolyte with improved low temperature charging activity according to claim 2, characterized in that: The S5 deep stirring: continue stirring for 2-3 hours.