Kyle Proffitt
August 26, 2025| The 2025 Advanced Automotive Battery Conference Europe continued with presentations across varied topics around transportation electrification. Collected here are some select discussions about faster charging standards and equipment, planned advances with aircraft electrification, and edging toward competitive lithium-sulfur batteries.
Super-Megachargers
Grivix Founder and CEO Marc-Andre Beck presented on the future of fast-charging and the need for ever-higher volts and amps. He said 14 years ago, when asked about the fastest charging speeds they could want, Daimler and BMW expressed satisfaction with 44 kilowatts. Now, of course, chargers of 250 and 350 kW are commonly available, and megawatt chargers are coming online for big trucks. Grivix is going bigger. Although his focus was on drastically increasing the power of these charging units, Beck made a prediction about this future of electrified vehicles. In comparing charging to filling a vehicle with gas, he said that already with these megawatt solutions, refueling a vehicle with electricity is faster than pumping the equivalent 23 liters of gasoline. “Looking into the future in 12 years, I’m sure we will recharge our vehicles in one minute, and then think how stupid were we to fill these dangerous liquids into our vehicles,” he said.
Beck discussed the megawatt charging standard (MCS), for which he says Grivix has developed ruggedized variants that go up to 4000 amps and 1500 volts, producing 6 MW of charging power. If a compatible 75 kWh EV battery could be safely charged at this rate, the 0-100% charge time would be just 45 seconds, but the primary impetus for multi-megawatt chargers is to make much larger batteries usable. For instance, Beck said compatible MCS inlet units are already being included in Komatsu 930E heavy mining trucks, which are being designed in power-agnostic versions that could operate on diesel, hydrogen, or battery power. But because the batteries will get even bigger to create solutions in shipping, aviation, and elsewhere, he said they are looking to go to “15,000 amps at 4,000 volt, which leads to 60 megawatt.” Beck further quipped that “you just need to pay me enough, and you get a 120 megawatt connector, no problem.”
Ultimately, to reach these levels of power, Beck said increasing the voltage makes the most sense, but we hit a hard limit. At 1500 volts, a device is no longer human operable because of safety concerns. The solution is that “it needs to be operated by machines,” Beck said. Grivix has created robots that use ultrawide band detection and cameras to locate the vehicles, connect, and charge. Integrated cabling, he says, creates efficiencies for necessary cooling. The robotic arm is the cable and cooling apparatus all in one. He noted that “the big problem in the future will be the infrastructure, and that’s a really hard one,” but added that “if somebody starts pointing the fingers, these things really can be solved.”
Flying Buses
As a perfect example of a higher energy vehicle that could benefit from leaps in charging infrastructure, Sora Aviation principal battery engineer Zi Jian Yeo was at the conference to discuss the company’s planned 30-seater electric vertical take-off and landing (eVTOL) aircraft, the S-1, which they think of as a flying bus.
Most often, eVTOL designs are intended to have low occupancy and cover short distances; four-seater air taxis are a common implementation, but Yeo says the cost per passenger of a 15-minute trip on one of these is $160. By increasing the capacity to 30 passengers, he sees this cost falling to $40.
Yeo explained Sora’s interest in this market. “There’s a report published by Roland Berger a few years ago—the estimated global advanced air mobility market could reach $90 billion in 2050, and 50% of it could come from airport shuttle service.” This segment, he says, is their main focus.
eVTOL solutions face several challenges. Among these, they require on-board batteries to release energy quickly and generate high power for both takeoff and landing. The gravimetric energy density is very important, as all of the battery weight must be lifted and carried. The heavier the aircraft and cargo, the more power needed. “For a big 30-seat eVTOL bus, we are talking about a few megawatts to take off the aircraft,” Yeo said. This is the equivalent power of five Tesla S Plaid EVs. Additionally, regular concerns like thermal runaway leave much less room for error, because you can’t just pull your plane over to the side of the road and get out. For the same reason, the battery management system must accurately gauge the state of charge, and everything is calculated with some room for error because the stakes are so high. Unlike EVs that might warrant their batteries for 500 cycles of greater than 70% of original capacity, Yeo says they consider 90% state of health end of life. They want to be really sure the battery can still produce the necessary power.
Sora is designing the S-1 with a tandem wing design. Six tiltable prop rotors—2 on the front wing and 4 on the back—are powered by one battery pack each, installed in the wings. Yeo says this is helpful both in terms of safety, as they are further from passengers, and because the weight of the batteries helps limit wing flex that would otherwise counteract lift force. The aircraft is designed such that if one of the batteries fails, the remaining five are sufficient to continue the trip and land safely. The battery packs are also encased in a lightweight fire containment enclosure, Yeo said.
The S-1 uses a 1000-volt electrical system, which Yeo says reduces electrical system weight and enables megawatt charging. For the batteries, they are targeting “at least 250 Wh/kg to 350 Wh/kg of energy density” and power “between 1000-2000 W/kg,” and Yeo expects that megawatt charging will allow 2-3C fast charge with a 3-MW charger. Taken together, these metrics suggest a total of roughly 1000 kWh of battery. He discussed some of the battery requirements and pointed out that as the power output of a cell increases, the energy density tends to decrease, but some technologies suffer more. As an example, lithium metal cells have some of the highest energy density at low power output, but the density falls off quickly as output approaches 1000 W/kg. In the chart Yeo displayed, silicon oxide anode pouch cells appeared optimal for fulfilling both criteria. Yeo was quick to point out that these are real commercial cells available from suppliers, not undiscovered battery chemistry that they must wait for to continue development.
Although Sora is in a prototype stage, they have secured about $2.8M (£2.1M) of funding from the UK government for associated projects. There’s also a preorder agreement in place with South Korean charter operator Moviation with expectations that these aircraft will be in service in 2031.
Zeta Energy Tackles Lithium-Sulfur
Chief Commercial Officer Michael Liedtke presented for Texas-based Zeta Energy about their fundamental work with lithium-sulfur batteries. He said that from the beginning, cost was a driving force for Zeta, and cheap, abundant sulfur plays nicely.
Lithium-sulfur is not just a cost-cutting measure though; it is also poised to double the energy density available from traditional lithium-ion cells. Zeta takes an approach with similarities to those of Lyten and Coherent, as all three companies use different methods to sequester sulfur in the cathode. Coherent uses electrophilic carbon to bind to sulfur, Lyten stores it in 3d graphene, and Zeta uses what they refer to as “sulfurized carbon”.
Zeta creates their own active materials for cathode and anode and sandwiches those around commercial liquid electrolyte and separator. On the cathode side, Liedtke said that they take sulfur, polymer, and carbon, make little granules, and subject them to pyrolysis at “less than 400 °C for less than 2 hours,” a big improvement relative to typical 700-900 °C and 10-20 hours for NMC. He differentiated their technology from elemental sulfur and solutions such as sulfurized polyacrylonitrile (S-PAN), but they do use polyacrylonitrile derivatives. Their solution is unique, however, in enabling sulfur content of 40-70%, whereas S-PAN is limited to 30-40%. Liedtke explained that in their design, “the sulfur is chemically bonded to this carbon backbone… this way we do not lose the sulfur in the electrolyte during cycling,” referring to the well-known polysulfide shuttle that has stymied Li-S development. With regard to cost, he referenced the mountains of sulfur piled up at refineries. He said with their local supplier, the only processing necessary is to break up the largest chunks using a hammer.
They’ve also made technological improvements on the anode side, where they can coat both sides of copper foil with vertically aligned carbon nanotubes using a chemical vapor deposition method. They pre-lithiate these nanotubes, thus ultimately creating a lithium metal anode, but “we’re using this 3D structure to host the lithium,” Liedtke explained. The nanotubes form a sort of forest, but if you zoom in tightly, you see that it is 98% void space that can host lithium. Liedtke added that these nanotubes are very light, adding only about 2% to the weight of the copper, and they can control both the height and how tightly the nanotubes pack. Too tight and the lithium just sits at the surface, but with appropriate density, the lithium coats the nanotubes.
They performed dynamic stress testing, intended to mimic some of the irregularities associated with driving by varying the charge and discharge speed, and showed >90% capacity retention after 300 cycles. They also ran one unplanned test. A charged cell was mistakenly left on the shelf and discovered five months later. Surprisingly, it showed only ~0.5% capacity loss. “This is a very unusual test result,” Liedtke said, and it will be quite a benefit for leaving your car parked at the airport. Their batteries also showed 83% capacity retention at -20 °C. Liedtke says their cells only swell about 2% with cycling, which he reported as the lowest value of any battery technology, including liquid electrolyte lithium-ion cells.
The talk was a bit light on energy density details, but Liedtke said they are working to increase the currently used 50% sulfur content to 70%, at which point they should be able to achieve density on the order of 450 Wh/kg, a jump from the 300 Wh/kg previously reported using a 20-Ah multilayer pouch cell.
Finally, Liedtke returned to cost, their initial driver. They have a funded joint development agreement with Stellantis, for whom they performed a total cost calculation at scale (based on a 40 GWh factory) and arrived at $50/kWh, with lithium as the most expensive input. This price significantly undercuts NMC while matching or besting LFP.
