theion is developing lithium-sulfur battery technology targeting 500 watt hours per kilogram in their first commercial product—nearly double today's lithium-ion cells at 270-300 Wh/kg—with an ultimate roadmap to 1,000 Wh/kg. By replacing nickel-manganese-cobalt cathodes with crystalline sulfur and graphite anodes with lithium metal, theion aims to deliver three times the energy density at one-third the cost and CO2 footprint of current batteries. In this episode of BUILDERS, we sat down with Dr. Ulrich Ehmes, CEO of theion, to discuss how a production-focused CEO is navigating the journey from TRL 3-4 to pilot line, why they're targeting electric aviation first, and how a 12-year battery industry veteran evaluates what actually constitutes a materials breakthrough.

Topics Discussed:

Why sulfur cathodes and lithium metal anodes enable the performance jump beyond lithium-ion
The critical importance of monoclinic gamma crystalline structure for cycle life
Navigating the transition from coin cells to pouch cells to industrialization
Strategic decision-making on initial market entry for deep tech hardware
Why process innovation in mixing and coating is required to unlock sulfur's full potential
Building a China-independent supply chain using oil refining waste
The 3-year development reality driven by cycling test requirements

GTM Lessons For B2B Founders:

Price your technology against value creation, not cost savings alone: Ulrich's market strategy centers on "markets which will pay a lot of money for super lightweight batteries"—specifically aviation applications where weight reduction directly enables business model viability. For eVTOLs, the constraint isn't battery cost but energy density; current batteries make many routes economically impossible. This is fundamentally different from cost-driven markets like consumer EVs where incremental weight savings have marginal value. Deep tech founders should map which customer segments face hard physical constraints that only your technology solves versus those seeking incremental optimization. The former will pay 3-5x premiums; the latter will demand cost parity from day one.
Match CEO background to the company's primary risk: Ulrich led Leica's 600-person Portugal production facility for a decade before entering batteries, and he frames his value as "I'm a production guy...for me it's very important not to produce only one battery cell in a lab, but millions of cells in highest quality." For a battery company at TRL 3-4 moving toward industrialization, the existential risk isn't the science—it's whether you can manufacture at quality and yield. Many deep tech companies fail because PhD founders remain CEOs through manufacturing scale-up. Ulrich's hire signals that theion's board correctly diagnosed their de-risking sequence. Founders should brutally assess what will kill the company in the next 24 months and ensure the CEO's pattern recognition matches that failure mode.
Seek investors where your technology is infrastructure for their thesis: theion's primary investor is "heavily invested in eVTOLs," making theion's battery technology directly relevant to multiple portfolio companies facing the same energy density constraint. This creates structural alignment on timeline expectations—eVTOL companies won't reach commercial scale before 2027-2028 anyway, matching theion's development cycle. The investor understands that battery development "takes time because always when you change a parameter, you have to cycle again to test the cells." This is radically different from a generalist VC expecting SaaS-like iteration speeds. Hardware founders should explicitly map how their technology unblocks other portfolio companies and use this to negotiate patient capital terms and strategic customer introductions.
Use competitive landscape size as legitimacy signal, not differentiation: When pressed on disrupting incumbents, Ulrich immediately countered: "We are not the only company working on sulfur and this is good...there are 28 other companies out there." He then differentiated on "monoclinic gamma crystalline structure" validated by Drexel University achieving 4,000+ cycles. This is sophisticated category positioning: the 28 competitors validate that lithium-sulfur is a credible next-generation technology, while the specific crystalline approach provides technical differentiation for those who understand the chemistry. Founders should resist the urge to claim they're the only ones solving a problem in nascent categories—it raises "why hasn't anyone else tried this?" concerns. Instead, position within an emerging category and differentiate on technical approach.
Communicate realistic timelines as competence signaling, not weakness: Ulrich states plainly that commercial availability is "at least the next three years" and frames this as doing "first things first and first things right." For sophisticated buyers in aviation and aerospace, compressed timelines signal naivety about certification requirements, manufacturing validation, and qualification testing. A battery company claiming 12-month commercialization would lose credibility with Boeing or Joby Aviation procurement teams who understand the actual development cycles. Deep tech founders should recognize that customer segments accustomed to long development cycles (aerospace, automotive, medical devices) interpret realistic timelines as domain expertise, while consumer/software buyers may interpret them as lack of urgency. Match timeline communication to buyer sophistication.

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How theion's CEO approaches pre-GTM deep tech strategy | Dr. Ulrich Ehmes"