What should be paid attention to in spot welding of lithium battery

1. Ultrasonic metal spot welding of lithium ion battery

Because the positive plate of the electric lithium-ion battery cell is made of aluminum strip, tin can not be directly welded, so it is necessary to add nickel strip. Ultrasonic metal spot welding method is usually used: high frequency oscillation occurs by ultrasonic, which makes the friction between two metal plates heated locally, resulting in fusion connection. Frequency: 20K ~ 35kHz, time: about 0.3 seconds. Pay attention to the selection of suitable welding equipment for metal ultrasonic welder. Pay attention to the proper welding parameters. Prevent excessive welding of positive aluminum strip, otherwise it is easy to break. Prevent bad welding of positive aluminum bar, otherwise it is easy to cut off the battery;

2. Tin welding connection of lithium ion battery

Important principle: the welding tin wire is melted by heating the soldering iron to make the tin material adhere to the welding part and connect after cooling.

1) Classification of soldering iron:

A. Internal heating type and external heating type, internal heating type iron heating quickly.

Ordinary soldering iron, warm soldering iron, antistatic constant warm soldering iron

2) Soldering iron power: 30W, 35W, 40W, 50W, 55W, 60W, 65W, etc.

3) Soldering iron temperature: set according to tin area and tin dosage. If the temperature is too low, the tin wire will not melt quickly, which will affect the welding speed. If the temperature is too high, the solder joint will not be smooth. The temperature of soldering iron is generally set at 36010

4) Welding posture: generous and natural, sitting upright.

5) Welding process: there are two methods: holding pen and direct holding.

6) Welding angle: the welding angle of the pen holding method is between 30 and 60, and the best angle is 45 between the iron head and the object to be welded.

7) Soldering composition: tin (TIN) 60 ~ 63%, lead (lead) 40 ~ 37%, rosin 1.0% ~ 1.2%, some existing companies began to use lead-free soldering tin

8) Welding time: less than 3S

9) Method: first put the soldering iron on the welding part, and then put the tin wire in the gap between the welding head and the welding part.

10) Welding quantity: the right amount of tin can be used to wrap the object to be welded 10) welding quality: the welding spot is bright and uniform, firm, Wuxi, missed welding, false welding, no porosity, no delamination. The size of solder joint is related to the heat of tin contact

3. Super welding process and requirements of lithium ion battery shell

1) The package connection of the shell generally adopts the ultrasonic plastic welding method.

2) Working principle: the high-frequency oscillation of ultrasonic wave causes friction between the upper and lower shells, and the local temperature rises sharply, resulting in high heat. The plastic flow of materials will occur between the two bonding parts, which will solidify under the action of pressure to form uniform welding.

3) Choose the right ultrasonic welding machine,

4) Use appropriate welding parameters: power factor: force speed, force including pressure (air pressure) and descent speed. Rate includes frequency and amplitude, energy = power, time, frequency: 20kHz, welding time and holding time.

5) Special attention should be paid to the size matching in the design of shell and protection plate to prevent over range or over tightening.

6) The thickness of the protective plate and the arrangement of the components should fully consider the influence of ultrasonic wave to prevent the components from being shaken loose.

7) Welding effect: plastic materials, welding design, mold, etc. 8) Over welding quality: no excessive damage, no melt glue, no ultra-high, even welding wire, tight welding. The sample falls on the board of 1m high, and falls on the X, y and z plane once (six times in total), which meets the requirements.