The carmaker said Feb. 4 it was acquiring 45.9 million shares in Maxwell Technologies in an all-stock transaction which values the firm at $218 million. At $4.75 per share, the deal represents a 55 percent premium on Maxwell Technologies' stock price, which closed at $3.07 on Feb. 1, according to CNBC.

Under the agreement, subject to regulatory approval, Maxwell Technologies will become a wholly owned subsidiary of Tesla.

"We are always looking for potential acquisitions that make sense for the business and support Tesla's mission to accelerate the world's transition to sustainable energy," the EV firm said in a statement.

Based in San Diego, Maxwell Technologies develops "ultracapacitor" technology which can store and rapidly deliver electricity for use in industry, transport, renewable energy and information technology. The firm claims its patented manufacturing methods can "create a breakthrough technology that can be applied to the manufacturing of batteries."

Franz Fink, president and CEO of Maxwell Technologies, described Tesla as a "well-respected and world-class innovator," and said the two companies shared a common goal of "building a more sustainable future.

"We believe this transaction is in the best interests of Maxwell stockholders and offers investors the opportunity to participate in Tesla's mission of accelerating the advent of sustainable transport and energy," he said.

It came as car giant Volkswagen announced plans (PDF) to buy and install more than 100 battery recharging stations from Telsa across the United States this year. VW is making the purchase through Electrify America, its $2 billion venture to install EV infrastructure across the country over the next 10 years.

Meanwhile, facing growing competition from the United States and China, European policymakers and industry players have moved to boost the continent's battery expertise.

The European Commission last week launched Batteries Europe, a new technology and innovation platform it hopes will improve the European battery sector's ability to compete with overseas rivals.

Europe's battery market could be worth $281 million per year from 2025 onwards, according to the EU Commission.

Green energy innovation engine InnoEnergy has been appointed to lead the platform, together with the European Energy Research Alliance (EERA) and the European Association for Storage of Energy (EASE).

Over the next three years, the $1.13 million project will bring together public and private partners involved in battery R&D activities, coordinating events, meetings and networking opportunities, according to InnoEnergy CEO Diego Pavia.

"Energy storage is the linchpin technology for the clean energy system of the future, from grid storage to electric vehicles and cordless tools," he said. "It is essential that research and innovation agendas are closely aligned with those in industry to make a seamless transition from concept to reality."