Preparation method of battery pole piece and battery

Abstract

The preparation method of the battery pole piece comprises the following steps: carrying out mixing granulation operation on an active substance, a conductive agent, a binder and pure water to obtainelectrode particles; performing roll-in film laminating operation on the electrode particles and an electrode current collecting net to prepare an electrode laminated sheet; and carrying out baking operation on the electrode lamination sheet to obtain the battery pole piece. Thus, various components are mixed and granulated to obtain the electrode particles instead of conventional slurry, so thatthe non-uniformity caused by subsequent combination with the current collector can be avoided, and the porosity can be improved; and the electrode current collecting net and the electrode particles are adopted to carry out roll-in film laminating operation, so that the electrode particles can be clamped and embedded into the electrode current collecting net, the combination firmness is improved, the powder falling problem is avoided, the use of a binding agent can be reduced, and the discharge performance of the battery pole piece is also greatly improved. In addition, the invention also provides a battery comprising the battery pole piece.

Description

technical field [0001] The invention relates to the technical field of batteries, in particular to a method for preparing battery pole pieces and a battery. Background technique [0002] Usually, when preparing the electrode sheet, the slurry drawing method is adopted, that is, the electrode slurry is coated on the current collector, and then the electrode sheet is obtained through baking, coining and cutting. [0003] However, there are the following disadvantages in the method of drawing pulp: (1) In order to avoid the pulp agglomeration caused by the fibrosis of the binder PTFE, the temperature of the slurry, the mixing time and the stirring speed must be controlled in the pulping process, which will cause the material and bonding (2) The viscosity of the positive electrode slurry is usually ≥60000mPa s, and the slurry with high viscosity is likely to make the thickness consistency and uniformity of the slurry diaphragm poor, and even have a certain degree of delamination...

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Problems solved by technology

[0003] However, there are the following disadvantages in the method of drawing pulp: (1) In order to avoid the pulp agglomeration caused by the fibrosis of the binder PTFE, the temperature of the slurry, the mixing time and the stirring speed must be controlled in the pulping process, which will cause the material and bonding (2) The viscosity of the positive electrode slurry is usually ≥60000mPa s, and the slurry with high viscosity is likely to make the thickness consistency and uniformity of the slurry diaphragm poor, and even have a certain degree of delamination ;At the same time, with the progress of the slurry drawing process, the viscosity of the slurry continues to increase, and it is easy to make the thickness consistency of the front and rear sections of the current collector poor, and even the thickness difference can exceed 0.20mm; the process controllability is poor

(3) After the slurry is formed into a membrane, the surface density of the pole piece is low, and the battery made by this method has a low capacity; (4) The degree of compaction of the pole piece is too large, and the pores inside the particles are forcibly squeezed and deformed. The porosity is too low and the pore distribution is uneven, and the discharge consistency is poor

(5) The depth of discharge in different regions of the pole piece is different, and the expansion situation is also different. During the discharge process, the battery is prone to increase in battery resistance due to the detachment of the active material and the current collector (powder drop), and the final pulse capability drops rapidly; In severe cases, an internal short circuit of the battery may occur due to partial powder falling

(6) Low utilization rate of active material during discharge

(7) The material utilization rate in the process of preparing electrode sheets is low

[0004] Therefore, it is necessary to further improve the problem of poor discharge performance of the battery, especially for the inhomogeneity of the electrode sheet slurry on the current collector, the low porosity, and the low utilization rate of the active material.

However, if the electrode sheet slurry is changed into powder and then pressed onto the current collector, it is easy to cause the powder and the current collector to be unable to adhere firmly, and it is easy to cause the problem of powder removal, and some people are pressing the powder to the current collector Before, a layer of binder was applied on the current collector, and then the powder was pressed together. However, this would easily increase the resistance value of the electrode sheet due to the presence of too much adhesive on the electrode sheet, thereby affecting the discharge performance.

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