most common types are based on either lithium-, lead- or nickel systems where lithium is by far the most used as seen in Figure 1 below. No other chemical system comes close to surpassing it. Nevertheless, lead-acid batteries still account for a large portion of the market and are.
And that means lead acid batteries aren't either! The assembly of reliable, high-performance lead-acid batteries for use in automotive, marine and industrial applications, however, poses a significant challenge. The basic application involves welding a series of lead castings or “tombstones” which make up the cores of the individual battery cells.
Which welding techniques can be used for connecting battery cells?
Brass (CuZn37) test samples are used for the quantitative comparison of the welding techniques, as this metal can be processed by all three welding techniques. At the end of the presented work, the suitability of resistance spot, ultrasonic and laser beam welding for connecting battery cells is evaluated.
The findings are applicable to all kinds of battery cell casings. Additionally, the three welding techniques are compared quantitatively in terms of ultimate tensile strength, heat input into a battery cell caused by the welding process, and electrical contact resistance.
Although the practice has declined over the years, lead welding (also, and somewhat erroneously, referred to as lead burning) is commonly used in applications like roofing, pipework and in the manufacture of acid-resistant tanks where conventional steel tanks may be susceptible to corrosion. There are two types of lead found in commercial welding:
Battery cells are most often put into modules or packs when produced for electrically driven vehicles. The variable of greatest influence when welding battery packs is the contact resistance between the cell and the connection tab. It is crucial to minimize this variable as much as possible to prevent energy loss in the form of heat generation.
How does resistance welding affect a battery cell?
4.1.2 Effect on the battery cell Small-scale resistance welding is often the preferred method for joining Li–ion batteries into battery packs. This process ensures strong joints with an almost complete elimination of the heat impact on the joined workpieces during a short time.