Laser surface preparation for adhesion & corrosion resistance in battery tabs
Project challenges
Welding and bonding are critical manufacturing processes for battery manufacturing. Avocet battery materials manufacture copper and aluminium tabs which are a significant part of battery pouch cells. To ensure a proper seal a small polymer strip is bonded to the tab to act as an interface to the pouch, the bond strength and chemical resistance of the polymer/tab bond are critical for both safety and longevity.
Business challenge
Process Innovation
Sector
Electrification
Technology or capability
Automation & Robotics
Laser Processing
MTC developed and demonstrated a laser surface treatment for enhancing the adhesion and corrosion resistance of polymer to aluminium and copper tabs used in the manufacture of pouch cells. The laser process replaces a chrome treatment which is banned in Europe, improving sustainability and giving Avocet Battery Materials a USP.
The Challenge
Welding and bonding are critical manufacturing processes for battery manufacturing. Avocet battery materials manufacture copper and aluminium tabs which are a significant part of battery pouch cells. To ensure a proper seal a small polymer strip is bonded to the tab to act as an interface to the pouch, the bond strength and chemical resistance of the polymer/tab bond are critical for both safety and longevity.
Predominantly tabs are manufactured in Asia and to ensure high bond strength and good chemical resistance, are currently treated using a hexavalent chromium (Cr(VI)) surface treatment, which is banned under EU Restriction of Hazardous Substances (RoHS) regulations. An alternative, environmentally friendly surface treatment is required to onshore tab manufacture to the UK.
MTC's Solution
- MTC built on its work in laser surface engineering to propose a chemical-free alternative to Cr treatments produced using an industrial laser system.
- MTC conducted laser surface treatment trials on both aluminium and copper tabs which then underwent polymer bonding, electrolyte exposure and peel testing.
- Peel strength was compared between chrome plated tabs and laser treated tabs.
- A scale-up model was produced to understand the rate capability of the process for production of battery tabs at high-volume (up to 2M/year).
Avocet have been working with MTC for over 18 months developing our technology. Their expertise in the field of laser surface treatments has been instrumental to the project, and we have achieved greater results than we were hoping, surpassing performance results for current state-of-the-art components. We have embarked on a new programme to commercialise this technology, and working with MTC on this has streamlined the process and enabled us to fast-track our route to market
Martyn Brown, R&D Lead, Avocet Materials Group
The Outcome
- Laser surface treatment offers a highly controlled and repeatable, selective treatment of the tab surface with an accuracy of a few microns.
- Laser surface treated tabs show superior adhesion and corrosion resistance (up to 2x higher) than chrome plated tabs.
- The laser surface treatment is chemical-free, reducing the environmental burden and allowing ABM to on-shore manufacture to the UK.
- Scale-up modelling predicts that the laser surface treatment is capable of achieving a TAKT time of <10s, compatible with a high-throughput manufacturing line.
Benefits to the Client
- The demonstrated laser process improved bond strength which translates to longer battery lifetimes for ABM’s customers and a USP for ABM tabs.
- The laser treatment process reduces the cost of manufacture by up to 10x compared to off-shore Cr(VI) treatment, enabling ABM to compete with global tab manufacturers in Asia.
- Off the back of this work, ABM and MTC secured ca. £900,000 of funding from the Faraday Battery Challenge for the scale-up and industrialisation of the laser treatment process.
