RU2823038C1 - Method of preparing active mass of positive electrode of lithium-ion battery - Google Patents

Abstract

FIELD: various technological processes.

SUBSTANCE: invention relates to technologies for producing a positive electrode of lithium-ion accumulators (LIA) and can be used in LIA production. In the method of preparing the active mass of a positive electrode of LIA, dried lithium-cobalt dioxide, conductive carbon black Super R, graphite KS-6 are mixed with polyvinylidene fluoride in a vacuum mixer for 30 minutes at speed of 15 rpm with grinding at speed of 200 rpm, NMP is added to obtained mixture in proportion of 80–85% of its total amount, stirring in a vacuum mixer for 30 minutes at speed of 20 rpm with grinding at speed of 900 rpm, stirring is continued at speed of 65 rpm with grinding at 2,250 rpm in a vacuum mixer for 2 hours at a vacuum pressure of 0.08–0.1 MPa, then the remaining amount of NMP is added and mixed at speed of 65 rpm with grinding at 2,250 rpm in a vacuum mixer at a vacuum pressure of 0.08–0.1 MPa for 30 minutes, then the obtained mass is passed through a nickel mesh with mesh size of 0.100 mm.

EFFECT: shorter time for preparation of the active mass, which affects the efficiency of preparation.

1 cl

Description

The invention relates to technologies for producing the positive electrode of lithium-ion batteries (LIB) and can be used in the production of LIB.

A polymer lithium-ion battery is known (patent RU 193504 U1), containing in the positive electrode,%: lithium cobalt dioxide 94.2, polyvinylidene fluoride 2.8, carbon 2, graphite 1, having an increased discharge capacity. The useful model makes it possible to stabilize the process of intercalation and deintercalation in repeating electrical charge-discharge cycles.

The disadvantage of this useful model is the lack of information about the methods and modes of mixing the active mass of the positive electrode, which complicates its practical use.

The technology for preparing the active mass of the positive electrode is known (“Preparation of the active mass of the positive electrode for polymer lithium-ion batteries.” Technological instructions of PJSC Energia, adopted as a prototype), including the following operations. To prepare the active mass of the positive electrode of a lithium-ion battery, conductive black super P carbon, KS-6 graphite, lithium cobalt dioxide and polyvinylidene fluoride are dried at a temperature of 80-120°C for 5 hours, an adhesive solution is prepared by mixing N-methyl-2 pyrrolidone (NMP) and polyvinylidene fluoride in a vacuum mixer MSK-SFM-9 for 2 hours at a speed of 105 rpm. with grinding 1960 rpm. at a vacuum pressure of 0.08-0.1 MPa. The number of components is taken from the calculation, mass. %: polyvinylidene fluoride 2.8, NMP 43. Conductive carbon black Super R, graphite KS-6 are added to the resulting adhesive solution and mixed at a speed of 120 rpm. with grinding 1960 rpm. for 30 minutes without vacuum, then for 2 hours at a vacuum pressure of 0.08-0.1 MPa. The number of components is taken based on mass. %: conductive carbon black Super R 2, graphite KS-6 1. Then lithium cobalt dioxide is added to the resulting mixture and mixed in a vacuum mixer at a speed of 75 rpm. with grinding 1400 rpm. for 30 minutes without vacuum, then for 3 hours at 105 rpm. with grinding 1960 rpm. at a vacuum pressure of 0.08-0.1 MPa, then another 30 minutes at a speed of 90 rpm. with grinding 1680 rpm. at a vacuum pressure of 0.08-0.1 MPa. The amount of lithium cobalt dioxide is taken at the rate of 94.2 mass. %. The preparation time for the active mass is 9 hours.

The disadvantage of this method of obtaining the active mass is a long cycle lasting at least 9 hours, which is why it is necessary to interrupt it at the stage of the conductive adhesive solution and knead and apply the mass for 2 working days. The main component - lithium cobalt dioxide is added on the second day, because The finished active mass cannot be stored.

The problem with technologies for preparing the active mass of the positive electrode is the long production cycle, which reduces the overall productivity of production, since the time for preparing the active mass exceeds the duration of the shift, which creates additional time costs for this production area associated with organizational and production reasons.

This problem is solved by the proposed method for preparing the active mass of a positive electrode, aimed at increasing the productivity of preparing positive electrodes.

The technical result of the invention is to reduce the preparation time of the active mass, which affects the preparation productivity.

A method for preparing the active mass of the positive electrode of a lithium-ion battery, consisting of drying conductive carbon black super P, KS-6 graphite, polyvinylidene fluoride and lithium cobalt dioxide at a temperature of 80-120 ° C for 5 hours, mixing with grinding lithium cobalt dioxide, carbon black Super R, graphite KS-6 and polyvinylidene fluoride in NMP solution in a vacuum mixer with the following ratio of components, mass. %: lithium cobalt dioxide 94.2, conductive carbon black Super R 2, graphite KS-6 1, polyvinylidene fluoride 2.8, and NMP 43% of the sum of the masses of dry components, with dried lithium cobalt dioxide, conductive carbon black Super R, graphite KS-6 is mixed with polyvinylidene fluoride in a vacuum mixer for 30 minutes at 15 rpm. with grinding at a speed of 200 rpm, NMP is added to the resulting mixture in a proportion of 80-85% of its total amount, mixed in a vacuum mixer for 30 minutes. at a speed of 20 rpm. with grinding at a speed of 900 rpm, continue mixing at a speed of 65 rpm. with grinding 2250 rpm. in a vacuum mixer for 2 hours at a vacuum pressure of 0.08-0.1 MPa, then add the remaining amount of NMP and mix at a speed of 65 rpm. with grinding 2250 rpm. in a vacuum mixer at a vacuum pressure of 0.08-0.1 MPa for 30 minutes, then pass the resulting mass through a nickel mesh with a cell size of 0.100 mm.

Mixing with grinding of lithium cobalt dioxide, conductive carbon black Super R, graphite KS-6 and polyvinylidene fluoride in a dry state allows you to obtain a homogeneous mixture, since with this method of mixing the result is not affected by a significant difference in the density of the materials, and also clumping of the binder, polyvinylidene fluoride is eliminated with the subsequent addition of an aqueous solution of the polymer anionic dispersion. The mixing speed is selected in such a way as to eliminate the loss of conductive carbon of black Super P due to dust and entrainment into the vacuum system. At the selected grinding speed, disintegration of polyvinylidene fluoride powder particles occurs without heating the mixture. Studies have shown that with a dry mixing time of less than 30 minutes, heterogeneous fragments remain in the mixture, and with a mixing time of more than 30 minutes, the mixture no longer changes its homogeneity. When the mixing speed is less than 15 rpm. the homogeneity of the mixture is not ensured; at higher speeds, the entrainment of black Super R carbon begins. At a grinding speed of less than 200 rpm. Large agglomerates of polyvinylidene fluoride powder remain in the mixture; the high grinding speed leads to partial agglomeration of lithium cobalt dioxide. The subsequent addition of NMP in an amount of 80-85% of the total mass of the mixture, together with mixing and grinding, provides a viscosity that prevents the components from separating by density with a larger amount of NMP and the appearance of lumps in the mixture with a smaller amount. Mixing speed 20 rpm. within 30 min. with grinding 900 rpm. helps to obtain a suspension of components with a uniform distribution throughout the volume. At higher mixing speeds, most of the unmixed mixture remains on the walls of the bowl and subsequently leads to the formation of lumps. Grinding speed 900 rpm. prevents the agglomeration of carbon particles of black Super R and lithium cobalt dioxide due to their interaction with gradually swelling polyvinylidene fluoride. High grinding speed leads to unwanted overheating of the mixture. Subsequent mixing at 65 rpm. with grinding 2250 rpm. at a vacuum pressure of 0.08-0.1 MPa for 2 hours is necessary for uniform distribution of polyvinylidene fluoride throughout the volume of the mixture, and the grinding speed is 2250 rpm. prevents coagulation of the colloidal system with polyvinylidene fluoride. At higher mixing and grinding speeds, unacceptable heating of the mixture begins, and at lower grinding speeds, partial coagulation may occur. A time of 2 hours is optimal, ensuring the necessary viscosity and homogeneity of the mixture. The use of stirring at a vacuum pressure of 0.08-0.1 MPa prevents the formation of air bubbles in the mixture, which prevents its quality mixing. Adding the remaining amount of NMP after mixing ensures a decrease in viscosity, which is necessary for applying the active mass to the conductor. Mix with the remaining amount of NMP at 65 rpm. with grinding 2250 rpm. in a vacuum mixer at a vacuum pressure of 0.08-0.1 MPa for 30 minutes. is carried out to ensure uniform density and viscosity of the active mass and the absence of air bubbles in the mass. The given parameters ensure uniformity of the active mass without overheating.

Passing the resulting active mass through a nickel mesh with a mesh size of 0.100 mm prevents clots of active mass from getting onto the current conductor, which can lead to defects during subsequent rolling.

An example of the implementation of a method for preparing the active mass of the positive electrode of a lithium-ion battery.

To prepare the active mass of the positive electrode of a lithium-ion battery, conductive black Super P carbon, KS-6 graphite, lithium cobalt dioxide and polyvinylidene fluoride were dried at a temperature of 80-120°C for 5 hours, then lithium cobalt dioxide, black Super P carbon, KS-6 graphite and polyvinylidene fluoride were mixed dry in a vacuum mixer MSK-SFM-9 for 30 minutes at a speed of 15 rpm. with grinding 200 rpm. The number of components was taken from the calculation, mass. %: lithium cobalt dioxide 94.2, black carbon Super R 2, graphite KS-6 1, polyvinylidene fluoride 2.8. NMP was added to the resulting mixture at the rate of 43 wt. % in a proportion of 80-85% of the total amount of the mixture and mixed in a vacuum mixer for 30 minutes. at a speed of 20 rpm. with grinding at a speed of 900 rpm, then at a speed of 65 rpm. with grinding 2250 rpm. at a vacuum pressure of 0.08-0.1 MPa for 2 hours. The remaining amount of NMP was added to the resulting mixture and stirred at the same speed at a vacuum pressure of 0.08-0.1 MPa for 30 minutes. Then the resulting mass was passed through a nickel mesh with a mesh size of 0.100 mm. The preparation time for the active mass was 4 hours.

Thus, the proposed method for preparing the active mass of the positive electrode of a lithium-ion battery reduces the preparation time of the active mass, which allows increasing the productivity of the process.

Claims (1)

A method for preparing the active mass of the positive electrode of a lithium-ion battery, consisting of drying conductive carbon black Super P, KS-6 graphite, lithium cobalt dioxide and polyvinylidene fluoride at a temperature of 80-120 ° C for 5 hours, mixing with grinding lithium cobalt dioxide , carbon black Super P, graphite KS-6, polyvinylidene fluoride in a solution of NMP (N-methyl-2 pyrrolidone) in a vacuum mixer with the following ratio of components, mass. %: lithium cobalt dioxide 94.2, conductive carbon black Super P 2, graphite KS-6 1, polyvinylidene fluoride 2.8 and NMP 43% of the sum of the masses of dry components, characterized in that dried lithium cobalt dioxide, conductive carbon black Super R, graphite KS-6 is mixed with polyvinylidene fluoride in a vacuum mixer for 30 minutes at a speed of 15 rpm with grinding at a speed of 200 rpm, NMP is added to the resulting mixture in a proportion of 80-85% of its total amount, mixed in vacuum mixer for 30 minutes at a speed of 20 rpm with grinding at a speed of 900 rpm, continue mixing at a speed of 65 rpm with grinding at 2250 rpm in a vacuum mixer for 2 hours at a vacuum pressure of 0.08-0 ,1 MPa, then add the remaining amount of NMP and mix at a speed of 65 rpm with grinding 2250 rpm in a vacuum mixer at a vacuum pressure of 0.08-0.1 MPa for 30 minutes, then pass the resulting mass through a nickel mesh with cell size 0.100 mm.