Tesla Accuses Supplier of Stealing 4680 Battery Tech

A high-stakes legal dispute over Tesla’s Dry Battery Electrode (DBE) technology has spilled into public view. Following a recent arbitration ruling, former supplier Matthews International issued a press release claiming a legal victory over Tesla.

Tesla Vice President Bonne Eggleston promptly responded on X, dismissing Matthews’ assertions.

The Arbitration Spin

The public clash stems from a February 13, 2026 interim arbitration decision regarding an ongoing trade secret dispute between the two companies.

In its press release, Matthews International said the arbitrator reaffirmed its right to develop and sell its proprietary DBE solutions.

Matthews claimed the arbitrator denied Tesla’s requests for broad injunctive relief, instead issuing only a narrow injunction preventing Matthews from using certain parts in its machines.

The company downplayed the impact, saying it already had replacement parts and that the injunction would not materially impede operations or sales.

Tesla Fires Back

Tesla disputed that portrayal. Shortly after Matthews published its press release, Eggleston, a VP involved in the 4680 battery program, posted a rebuttal on X.

Buyer beware: Matthews International stole Tesla's DBE technology and is now subject to an injunction and liable for damages.

During our work with Matthews, we caught them red-handed copying our technology—including proprietary software and sensitive mechanical designs—into… https://t.co/Toc8ilakeM

— Bonne Eggleston (@BonneEggleston) March 10, 2026

Eggleston contradicted Matthews’ framing of the injunction, saying Tesla caught the supplier copying its technology, including proprietary software and sensitive mechanical designs, into products for other customers.

He further alleged that Matthews lied about the theft for three years while continuing to ship Tesla’s technology to competitors.

Billion-Dollar Background

The arbitration is part of a broader legal battle that began in June 2024, when Tesla sued Matthews in the U.S. District Court for the Northern District of California.

Tesla initially partnered with the Pittsburgh-based company in 2019 to refine its DBE manufacturing processes, a breakthrough aimed at reducing the cost, physical footprint, and energy consumption of producing 4680 battery cells.

According to Tesla’s original lawsuit, Matthews violated non-disclosure agreements by sharing highly confidential information with competitors and attempting to claim the inventions as its own in patent filings. Tesla estimated the resulting damages to exceed $1 billion.

While Matthews maintains the recent injunction will not affect its sales, Eggleston said Tesla intends to enforce the ruling and pursue substantial financial restitution.

“Suppliers who exploit customer IP through theft or deception have no place in Tesla’s ecosystem—or in any ethical supply chain,” Eggleston concluded.