Rare tellurium has emerged as vital metalloid in next-gen solar, solid-state batteries.

From longer-range electric vehicle batteries to long-lasting solar panels that efficiently charge those EVs with sunshine, tellurium is quietly becoming one of the most important energy metals that most people have never heard of.

"It has flown largely under the radar, even though it's essential for cadmium-telluride solar panels and new lithium-tellurium batteries that could revolutionize energy storage," said Tyrone Docherty, president and CEO of First Tellurium Corp., a company advancing tellurium exploration projects in the United States and Canada.

One of the reasons tellurium has flown under the radar is that it is one of the rarest of the stable elements on the periodic table.

"Most rocks contain an average of about 3 parts per billion tellurium, making it rarer than the rare earth elements and eight times less abundant than gold," United States Geological Survey penned in a report on the metalloid, one of seven elements with properties that fall between metals and non-metals.

Due to this scarcity, most researchers and manufacturers opted to go with silicon, a more abundant semi-metal with similar semiconductor qualities, for photovoltaic solar technologies.

American-made cadmium-telluride (CdTe) thin-film cells, however, are a rising star when it comes to harnessing sunlight to fill the world's growing need for low-carbon electricity.

"Cadmium telluride solar cells have the characteristics of strong power generation capacity, high conversion rate, low temperature coefficient, good weak light effect and high stability," 360 Research Reports penned in a CdTe thin-film solar cell market report.

Ohio-based First Solar Inc., the world's largest CdTe solar panel manufacturer, is responsible for this rise in popularity.

Seeking to bolster this homegrown technology, the U.S. Department of Energy launched the $20 million Cadmium Telluride Accelerator Consortium earlier this year.

This is good news for First Tellurium, which is advancing two North American mineral exploration projects – Klondike in Colorado and Deer Horn in British Columbia – that could offer domestic supplies of this critical metalloid.

"Governments are just starting to understand the importance of tellurium," said Docherty.

DOE accelerates CdTe tech

The U.S. government's interest in tellurium is being underscored by the Cadmium Telluride Accelerator Consortium, an initiative launched by the Department of Energy that brings academia, national laboratories, and the private sector together to identify ways to lower the cost and increase the production of CdTe solar panels.

"DOE is proud to partner with leading solar researchers and companies to chart the future of CdTe technology, which presents an immense opportunity for domestic manufacturers to help ensure our nation's security while providing family-sustaining jobs," said U.S. Secretary of Energy Jennifer Granholm.

Toward the goal of lowering the cost and increasing the efficiency of American-made CdTe solar cells over the next three years, the Cadmium Telluride Accelerator Consortium is designed to:

• Enhance U.S. technology leadership and competitiveness in CdTe photovoltaics.

• Enable cell efficiencies above 24% and module costs below 20 cents per watt by 2025.

• Enable cell efficiencies above 26% and module costs below 15 cents/w by 2030.

• Increase domestic CdTe PV material and module production through 2030.

"While already enjoying great success in the marketplace, recent scientific developments make it clear that CdTe PV has significantly more potential for dramatically higher module efficiency, lower cost, increased lifetime energy, and more rapid production," said Martin Keller, director at DOE's National Renewable Energy Laboratory.

DOE hopes this consortium will ensure that America remains the leader in CdTe thin film solar cells that will bolster the economy while achieving the Biden administration's clean energy goals.

"As solar continues its reign as one of the cheapest forms of energy powering our homes and businesses, we are committed to a solar future that is built by American workers," said Granholm.

Heavy First Solar investments

First Solar, the lead industrial partner in the consortium, is experiencing enormous demand for the CdTe solar panels it manufactures at its six plants – three in Ohio and three in Asia. The company, which has already invested or has committed to spending well over $2 billion into its manufacturing capacity in the U.S., recently announced plans to invest roughly another $1.4 billion over the next three years.

The largest of these investments is $1.1 billion to build a 3.5-gigawatt-per-year solar plant in Alabama.

"The passage of the Inflation Reduction Act of 2022 has firmly placed America on the path to a sustainable energy future," said First Solar CEO Mark Widmar. "This facility, along with its sister factories in Ohio, will form part of the industrial foundation that helps ensure this transition is powered by American innovation and ingenuity."

This American innovation is being bolstered by a $270 million investment by the company to build a 1.3-million-square-foot thin-film solar panel research and development center in Ohio.

By the time the Alabama plant comes online, First Solar will have invested more than $4 billion in U.S. solar manufacturing and research, and will employ more than 3,000 people in four states by 2025.

"With a record shipment backlog and consistent demand for our modules, we face the twin challenges of optimizing existing and planned production capacity to deliver on our commitments, while ensuring that our technology roadmap does not lose momentum," said Widmar. "This investment allows us to create an R&D sandbox separate from our commercial manufacturing operations, ensuring that we can accelerate innovation without the cost of taking mission-critical tools offline."

First Tellurium hunt

Increased numbers of CdTe solar panels being shipped out of First Solar plants in Ohio and Alabama means an increased demand for the metalloid First Tellurium was founded to explore for.

"It's clear that North America is going to need a lot more tellurium," said Docherty. "This is why we're on the hunt for new tellurium projects in addition to Deer Horn and Klondike."

The Klondike property in Colorado was previously owned by First Solar, which was looking for a secure domestic supply of the thin-film solar panel ingredient as it was ramping up manufacturing in the U.S.

When the company decided to forego its own tellurium mining venture, First Tellurium Corp. picked up this property where samples with as much as 3.3% tellurium, along with 33.7 grams per metric ton gold, and 364.8 g/t silver, were collected.

"The Klondike property has by far the highest tellurium grades in rock samples of the hundreds of prospects and mines we examined in the U.S. and Canada from 2006 to 2011," said John Keller, the previous mineral exploration manager for First Solar and a current consultant to First Tellurium. "Some samples at Klondike were an order of magnitude higher in tellurium grade than any others we collected in the U.S. or in Canada."

Early in 2022, Keller collected additional samples in preparation for a drill program at Klondike. One of the rocks collected during this sampling contained 1.1% tellurium, 3.76 g/t gold, and 130 g/t silver, along with copper, zinc, and lead.

This was followed up with a soil sampling program to prepare for the drilling aimed at outlining a mineable tellurium-gold-silver deposit at Klondike.

"This program was essential for setting up our planned 2023 drill program," said Docherty. "We had an exceptional team of senior exploration geologists managing the project, all of whom had previously conducted tellurium exploration on behalf of First Solar."

The most advanced project in First Tellurium's portfolio, however, is Deer Horn.

Located in western BC, Deer Horn hosts 93,000 kilograms of tellurium, 100,000 ounces of gold, and 3.3 million oz of silver in the combined indicated and inferred resource categories, making it the only gold-silver project in North America with an industry-compliant NI 43-101 tellurium resource.

This property hosts a number of other targets enriched with bismuth, copper, molybdenum, tungsten, and zinc. Metals that have been deemed critical in Canada and the U.S.

"Canadian and U.S. governments are really pushing new strategies and funding initiatives to address the problem of critical mineral supplies," said Docherty. "North America is just too dependent on foreign sources for the critical metals required for clean energy, defense and other essential needs."

Solid-state tellurium batteries

Tellurium derived from Deer Horn is being used for research into the development of solid-state lithium-tellurium batteries being carried out at the University of British Columbia Okanagan.

Earlier this year, a UBC Okanagan research team published a study that shows adding a dash of tellurium enhanced the lifespan, charging time, safety, and capacity of existing lithium battery technologies.

With high electrical conductivity and volumetric capacity, tellurium is an ideal material for batteries that would allow EVs to travel further without increasing the size of the battery pack.

"All-solid-state, lithium-tellurium batteries enable higher energy output with an improved safety rating inside a smaller form-factor, thereby expanding its possible applications," said Jian Liu, principal research chair in energy storage technologies at UBC Okanagan.

University of British Columbia Okanagan

Lithium-tellurium solid-state battery cells being tested at UBC Okanagan's Advanced Materials for Energy Storage Lab.

Fenix Advanced Materials, a BC-based company that specializes in ultra-high purity metals for the clean energy sector, is supplying the UBC research team with high-quality tellurium derived from Deer Horn.

"The high purity of the tellurium along with the mineral's overall attributes makes it ideal as a rechargeable battery material," said Liu.

Using this material, the team developed a quasi-solid-state lithium-tellurium test battery with a flexible gel polymer electrolyte that allows lithium ions to move between the lithium anode and the tellurium cathode.

"It's possible that tellurium could have the largest single impact on future battery technology over any other critical mineral," said Docherty. "Its properties are unique, the demand is increasing and America's mandate is to source tellurium at home and become less reliant on China is changing the landscape."