Cleaning Battery Terminals before Welding

Is it necessary to clean battery terminals before welding? This is a common question for those focused on battery production processes.

Author Jerry Wan

Laser cleaning of terminals is a critical step in the assembly of battery modules. It effectively removes surface impurities and creates optimal conditions for laser welding, which in turn enhances product quality and production yield.

To understand the cleaning process, it’s important to first recognize the role of the Module CCS (Cell Contact System). Also known as the integrated busbar or wiring board assembly, the CCS is a key structural and functional component. It consists of signal collection elements (such as FPC, PCB, or FFC), plastic structural parts, and copper or aluminium busbars.

The terminal acts as a “bridge” between the cell electrodes and the external circuit. Its welding quality with the CCS parts directly affects the performance of the entire battery module. Poor welding can lead to increased contact resistance, excess heat during charge-discharge cycles, reduced energy efficiency, and potential safety hazards such as overheating. Inconsistent conductivity may also disrupt current distribution, impair performance, and shorten battery life.

Skipping the cleaning step introduces serious risks. During production, handling, and storage, terminals accumulate contaminants like dust, oil, and oxides. These can cause:

• False welding: contaminants inhibit proper metal fusion, leading to weak joints. Studies show uncleaned terminals can result in over 30% false welding rates.
• Weak weld strength: under vibration or impact, poor welds may crack, compromising structural integrity.
• Poor conductivity: oxides and insulating residues increase electrical resistance, generate excess heat, reduce efficiency, and may even cause thermal runaway.

Laser cleaning terminals significantly improves welding outcomes. Laser cleaning uses high-energy beams to vaporize contaminants without damaging the terminal. This process ensures a clean surface for uniform soldering, improves shear strength by 20-30%, and enhances electrical stability. In applications like EV or ESS, cleaned terminals support stable long-term performance and reduce safety risks.

Real-World Examples

One mid-sized battery producer compared two production lines—one with thorough terminal cleaning and one without.

In another case, an EV maker faced recalls and performance issues due to inadequate terminal cleaning.

Conclusion

Terminal cleaning is not just a recommended step—it’s essential for ensuring welding quality, module stability, and overall safety in lithium battery systems.

See also: Terminal Welding, Welding, Cell Joining Techniques