A Li-Mn battery generally refers to a lithium dioxide manganese battery. It is a type of battery in which lithium is used as the negative electrode and manganese dioxide is used as the positive electrode.
The low and medium rate discharge performance of the lithium dioxide manganese battery is good, the price is cheap, and the safety performance is good. It is competitive with conventional batteries, and therefore was the first type of lithium battery to be commercialized.
Using a fully sealed cylindrical winding Li-Mn battery as an example, this article explains the basic manufacturing process for this type of battery, as well as the process flow.
1. Preparation of the manganese dioxide positive electrode
Mix heat-treated electrolytic manganese dioxide powder with acetylene black, polytetrafluoroethylene emulsion, isopropyl alcohol in a certain proportion to form a paste. Then the paste is evenly coated onto a metal collector grid for heat treatment and rolling to form an electrode. Another method is to heat the prepared positive electrode paste and place it on both sides of the metal collector through a rolling machine to produce an electrode. The prepared electrode should be placed in an environment with humidity less than 2%.
2. Preparation of the lithium metal negative electrode
Select lithium strips of the appropriate thickness and width according to the battery model and cut them into the required length. Then, the electrode tabs are cold welded onto the cut lithium strips. The preparation of the negative electrode must be performed in an environment with relative humidity less than 2%.
3. Preparation of the separator
Dry polypropylene separator of the required thickness and width, and store it in an environment with humidity less than 2%. A composite separator that can be closed at 130-160℃ is usually selected.
4. Preparation of the Li-Mn battery core
Wrap two layers of separators slightly wider than the electrodes on both sides of the manganese dioxide positive electrode in an environment with humidity less than 2%, so as to separate the positive electrode from the lithium negative electrode. Then, wind it into a core on a winder and place it in the battery case. The winding structure of the Li-Mn battery core is shown in the figure.
5. Preparation of electrolyte solution
There are different formulae for the electrolyte solutions of different manufacturers. The basic preparation method is to mix dehydrated lithium perchlorate with purified propylene carbonate, ethylene glycol dimethyl ether and other components in a proportion. The preparation of the electrolyte solution should be carried out in a dry air environment with humidity less than 2%.
6. Injection and sealing welding of the electrolyte solution
Firstly, weld the upper cover with glass insulators to the shell with the electrode core installed, and then inject the prescribed amount of electrolyte solution into the battery through the injection hole using an injection machine. Finally, seal the hole with a steel ball by welding.