Plate lug connecting method used in process of assembling power soft-packed lithium-ion storage batteries

Abstract

The invention provides a plate lug connecting method used for assembling power soft-packed lithium-ion storage batteries, which has the advantages of tight and firm connection, short operation time and the like. The method overlays positive and negative plate plugs and metal sheets connected by a circuit protective plate lead according to a certain order in a winding mode, and winds the positive and negative plate plugs and the metal sheets together through a special winding device, and finally fixes the positive and negative plate plugs and the metal sheets through a silica gel. The method has the main characteristics of radically avoiding influence on battery cells of high temperature caused by soldering and having simple process.

Description

technical field [0001] The invention relates to a storage battery assembly technology, in particular to a tab connection method used in the assembly process of a power type soft-packaged lithium-ion storage battery. Background technique [0002] When the commonly used power lithium-ion battery cells are connected in series, the tabs are connected by soldering or ultrasonic welding. The soldering method is simple, only need to use simple tools (such as electric soldering iron) to complete the process of welding, solder joint repair, component replacement, re-soldering and other processes. In addition, soldering also has the advantages of low cost and easy automation. At present, the connection of the tabs in the lithium battery assembly process is mainly by soldering. However, this method has the following problems in the application: [0003] 1. During welding, high temperature will be generated on the surface of the tab, and the temperature inside the battery core will a...

AI Technical Summary

Problems solved by technology

High temperature conditions will reduce the stability of the SEI film and the cycle performance of the electrode, thus affecting the capacity of the battery and its cycle performance

Moreover, the high heat generated inside the battery cell will cause part of the electrolyte to vaporize or even decompose, and the increase in the internal pressure of the battery will deform the battery shell, and even increase the temperature of the battery to the point where the material burns to explode;

[0004] 2. During welding, due to the high temperature, an oxide film is formed on the metal surface, which affects the weldability of the material, and also affects the contact resistance and conductivity of the tab;

[0005] 3. The positive tab of the power lithium-ion battery is an aluminum strip, and the negative tab is a nickel strip. For aluminum substrate materials, special soldering flux is required for soldering; in order to avoid this situation, laser spot welding machines or The ultrasonic welding machine welds the aluminum-nickel composite strip on the aluminum strip substrate to facilitate welding with the nickel strip of the negative electrode, which increases the complexity of the operation;

[0006] 4. The flux will volatilize harmful gas when heated, which will cause harm to the operator;

[0007] 5. Since there will inevitably be some oxides and dirt on the surface of the lug, it is easy to cause false welding

[0008] 6. Due to the high input impedance of the MOSFET in the circuit protection board, it cannot withstand a temperature higher than 200°C, otherwise the internal circuit may break down and fail

Therefore, connecting the tabs of the battery core and the wires of the protection circuit module by soldering will have an adverse effect on the circuit protection board

[0009] Ultrasonic metal welding uses high-frequency vibration waves to transmit to two metal surfaces to be welded. Under pressure, the two metal surfaces rub against each other to form fusion between molecular layers. Its advantages are fast, energy-saving, and fusion. High strength, good conductivity, no sparks, close to cold processing; the disadvantage is that the metal parts to be welded should not be too thick (generally less than or equal to 5mm), the solder joints should not be too large, need to be pressurized, and the connection of positive and negative tabs is complicated , can only be Al-Al surface, Ni-Ni surface welding, the welding between different metals needs to reset the parameters, which makes the operation process cumbersome and inefficient

The most important thing is that ultrasonic welding cannot be applied to the connection between the tabs of the battery core and the protection circuit module, and soldering is still required, so it is impossible to avoid the adverse effects of soldering on the inside of the battery core and the circuit protection board

[0010] Therefore, the above two welding methods are not the most ideal way to connect the tabs of lithium-ion power batteries.

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