Lithium-ion battery energy consumption in the production process accounted for about 66% of the energy consumption of lithium-ion batteries, while the drying room between the energy consumption accounted for about 43% of the total production (due to differences between the local natural environment and production processes may Some changes.) As an important step in the production of lithium-ion batteries - liquid injection, mainly in the drying room to complete, so to ensure that the infiltration under the premise of minimizing infiltration time for the reduction of lithium-ion battery production costs of great significance In the past, we could not observe the injection and infiltration process of Li-ion battery in real time. Therefore, the optimization of the injection process is more based on empirical analysis. In recent years, with the maturity of observation methods such as neutron diffraction, Have the opportunity for electrolyte in-cell lithium-ion battery inside the infiltration of real-time observation, for example, we have some time ago in the "cell infusion, infiltration process visualization" (please click on the link) article reported in Germany Bosch WJ Weydanz, who used neutron imaging technology to study the infiltration of electrolyte in lithium-ion batteries, the technical hand The progress of the paragraph let us 'see' to the electrolyte in the lithium-ion battery infiltration process, and infiltration model allows us to understand the principle from the electrolyte infiltration process.
There are many factors which affect the filling and infiltration of Li-ion batteries. For example, liquid injection equipment, battery structure, battery material and liquid injection process all have important impressions on liquid injection and infiltration. The relationship between these factors is often complicated , Interaction and interaction, so how to optimize the infusion and infiltration becomes very subjective, so the optimization effect is often unsatisfactory.Munistry of Technology, Germany, Thomas Knoche and other models through the establishment of a way to clarify the process of injection between the various factors Interaction and causality, providing a powerful analytical tool for optimizing the injection process of Li-ion batteries.
1. Introduction of the model
Thomas Knoche's model structure can be divided into three steps, the first step in building the model is to subdivide the fluid injection process, as shown in the figure below: The factors that influence the fluid injection process can be subdivided into 'product design', 'fluid injection equipment' , 'Process characteristics', 'fluid injection equipment', and 'product quality' and 'process quality' where 'product design' can continue to be subdivided into a few more specific parts, especially when the few parts For example, for lithium-ion battery charging process, the battery design can be divided into two parts: 'battery structure' and 'battery material', where 'battery structure' represents the macro of the battery Structure, 'battery material' represents the physical and chemical characteristics of the battery material 'equipment' and 'process implementation' represents the impact of the production process on the characteristics of the battery 'process phenomenon' is the core of this model, so the 'process Phenomenon "describes the causal relationship between the different parts of the final input factors will eventually be reflected in the output of 'product quality' and 'process quality' on.
The second step in building the model focuses on the causal relationships between the different factors, as shown in the following figure.
The third step in building a model is to model and detail the model based on actual process steps, as shown in the following figure.
2. Model application
2.1 injection process
Lithium-ion battery electrolyte injection and infiltration can be subdivided into multiple steps - injection, sealing and infiltration, as well as between the various steps of preparation work, etc. According to the above method of building a model, lithium-ion battery injection and Infiltration process can be represented by the following figure, the arrow in the figure below shows the causal relationship between the various factors of the injection process can be seen from the figure, the injection process is mainly affected by the injection system and the system pressure of two factors. The system pressure on the battery injection preparation, injection, sealing before infiltration and infiltration after sealing have an impact, showing that the system pressure is the battery system infiltration and infiltration process the most important factor.
The current common injection method is divided into two categories, one is directly through the injection hole liquid injection (the most mainstream way), the other is the battery into the electrolyte into the electrolyte through the battery through Note that the liquid injection method, according to the liquid injection volume can be divided into single injection and multiple injection (by the battery structure and the impact of the batch.) Several ways to promote liquid infiltration measures vary, including Single injection method, through repeated pumping pressure to promote the infiltration of the electrolyte in the cell, and multiple injection method is through the pressure to promote the electrolyte in the cell infiltration, immersion injection is not Promote infiltration measures.
2.2 infusion equipment
Infusion and infiltration of the equipment used, as well as the causal relationship between equipment as shown below.It can be seen that the liquid injection equipment is mainly composed of three parts: 1) liquid injection equipment; 2) pressure control equipment, vacuum equipment and Pressure equipment; 3) battery fixed structure.
2.3 process characteristics
The factors that affect the filling and wetting of the battery are shown in the following figure, with the causal relationship between them as indicated by the arrows.The filling of the lithium-ion battery is mainly influenced by the battery structure, the battery material and the filling process.
2.4 product design
This part of the product design can be divided into two parts: 1) battery material selection; 2) battery structure design. Different materials have different physical and chemical properties, so the lithium ion battery material selection determines the electrolyte infiltration rate, such as Electrolyte viscosity, surface tension, porous materials, porous structure, the electrolyte and the contact angle of the positive and negative materials and other characteristics of the cell infiltration will have an impact on the infiltration of the electrolyte before the battery will be first stored in the lithium-ion battery So the cell structure (square or cylindrical, hard shell or soft bag, laminated or wound) will have an impact on the infiltration of the electrolyte.The causal relationship between these factors is shown in the following figure.
Thomas Knoche, who used modeling analysis, will affect the lithium-ion battery infusing and infiltration process factors, and the impact of these factors more clearly demonstrated in front of us, so that we can more comprehensive analysis Analysis of the impact of the factors that affect the lithium-ion battery electrolyte injection, Li-ion battery for optimizing the injection and infiltration process provides a powerful analytical tools.
