The current traditional slurry process is:
(1) Ingredients:
1. Solution preparation:
a) The mixing ratio and weighing of PVDF (or CMC) and solvent NMP (or deionized water);
b) The stirring time, stirring frequency and times of the solution (and the surface temperature of the solution);
c) After the solution is prepared, check the solution: viscosity (test), degree of solubility (visual inspection) and shelf time;
d) Negative electrode: SBR+CMC solution, stirring time and frequency.
2. Active substance:
a) Monitor whether the mixing ratio and quantity are correct during weighing and mixing;
b) Ball milling: the milling time of the positive and negative electrodes; the ratio of agate beads to the mixture in the ball mill barrel; the ratio of large balls to small balls in the agate ball;
c) Baking: setting of baking temperature and time; test temperature after cooling after baking.
d) Mixing and stirring of active material and solution: stirring method, stirring time and frequency.
e) Sieve: pass 100 mesh (or 150 mesh) molecular sieve.
f) Testing and inspection:
Carry out the following tests on slurry and mixture: solid content, viscosity, mixture fineness, tap density, slurry density.
In addition to the clear production of the traditional process, it is also necessary to understand the basic principles of lithium battery paste.
Colloid theory
The main effect of causing the agglomeration of colloidal particles is the van der Waals force between the particles. To increase the stability of colloidal particles, there are two ways. One is to increase the electrostatic repulsion between colloidal particles, and the other is to create a space between the powders. To prevent the agglomeration of powders in these two ways.
The simplest colloidal system is composed of a dispersed phase and a dispersed medium, where the scale of the dispersed phase ranges from 10-9 to 10-6m. Substances in the colloid must have a certain degree of dispersion ability to exist in the system. According to different solvents and dispersed phases, many different colloidal forms can be produced. For example, mist is an aerosol in which droplets are dispersed in a gas, and toothpaste is a sol in which solid polymer particles are dispersed in a liquid.
The application of colloids abounds in life, and the physical properties of colloids need to be different depending on the disperse phase and dispersion medium. Observing the colloid from a microscopic point of view, the colloidal particles are not in a constant state, but move randomly in the medium, which is what we call Brownian motion (Brownian motion). Above absolute zero, colloidal particles will undergo Brownian motion due to thermal motion. This is the dynamics of microscopic colloids. Colloidal particles collide due to Brownian motion, which is an opportunity for aggregation, while colloidal particles are in a thermodynamically unstable state, so the interaction force between particles is one of the key factors for dispersion.
Post time: May-14-2021