Solid-state batteries are the thing everyone in the EV and energy storage world keeps promising is just around the corner. Higher energy density, better thermal behavior, fewer of the catastrophic failure modes that make lithium-ion packs occasionally turn into Roman candles. The catch is that the highest-performing chemistry being chased right now — sulphide-based electrolytes — has a small problem where it can generate hydrogen sulphide gas, which is the kind of thing factory safety officers tend to have strong opinions about.
So when a small ASX-listed outfit says it has cooked up a sulphur-free electrolyte that benchmarks against sulphide-class materials on the metrics that matter, it’s worth a look. Critical Resources just put out benchmarking results — its own lab numbers, measured at the South Dakota School of Mines & Technology and compared against published peer-reviewed literature — saying its amorphous solid-state electrolyte hit room-temperature ionic conductivity of 3.2 mS cm⁻¹ and activation energy of 0.27 eV on the first-pass composition. That’s more than three times the ~1 mS cm⁻¹ threshold the industry treats as the practical floor for solid-state operation, and it’s matching activation energy numbers the field has historically reserved for sulphide chemistry.
The company is careful to flag this is early-stage lab work, not a commercial product. But the numbers are notable enough that it’s worth understanding what they actually mean, and why a tiny critical minerals explorer is suddenly publishing battery chemistry benchmarks.
Why sulphur-free matters here
Sulphide-class solid-state electrolytes are the current performance leader in the lab. The transport efficiency is genuinely impressive, which is why companies like Toyota and Samsung have been pouring money into the chemistry for years. The problem is industrial. Sulphide materials are reactive with moisture, and when they react with water — or just humid air — they can release hydrogen sulphide. That’s the rotten-egg gas that’s toxic at low concentrations and lethal at higher ones, and it shows up in OSHA reports for a reason.
You can manage that risk with dry rooms, inert atmosphere handling, and very expensive manufacturing controls. You can’t make it go away. Which means scaling sulphide-based solid-state batteries to gigafactory volumes is a manufacturing problem as much as it is a chemistry problem.
Critical Resources’ pitch is straightforward: skip the sulphur, keep the performance. The company’s amorphous solid-state electrolyte (ASE) is being developed with the team of Dr Alevtina Smirnova — the CEPS director and battery inventor now advising the company — at the South Dakota School of Mines & Technology, inside the US National Science Foundation-supported Centre for Solid State Electric Power Storage framework. The headline number — 3.2 mS cm⁻¹ at room temperature — beats the practical operation threshold by a comfortable margin and outperforms common oxide benchmarks like LLZO and NASICON, which have been the main sulphur-free alternatives until now.
What the numbers actually say
Ionic conductivity is how easily lithium ions move through the electrolyte. Higher is better, because it determines how fast you can charge and discharge the cell without melting the battery. The ~1 mS cm⁻¹ figure isn’t arbitrary — it’s the rough floor below which a solid-state battery struggles to compete with conventional liquid-electrolyte lithium-ion on practical performance.
Activation energy is the other half of the story. It’s the energy barrier lithium ions have to clear to move through the material, and lower numbers mean the electrolyte holds its performance across a wider temperature range. The 0.27 eV figure CRR is reporting is in the territory traditionally associated only with sulphide-class materials. That matters for anything that has to operate in the cold or in environments where you can’t perfectly thermally manage the pack — which is most real-world applications outside a climate-controlled data center rack.
Managing director Tim Wither, quoted in the Proactive report on the benchmarking results, said the exercise “reveals a performance position that is a result of years of combined research by Dr Smirnova and the SDM team.” He added that “being competitive on ionic conductivity — and matching sulphide-class activation energy — from an initial composition is a strong starting point.”
Wither also explicitly cautioned the program remained at early laboratory validation and did not imply commercial readiness. Which is the honest framing, and a refreshing one in a sector where every press release tends to promise revolutionary batteries are six months away.
Where this fits in the broader solid-state race
The solid-state battery market is one of those forecasts that gets cited so often it starts to feel like wishful thinking. CRR’s release points to third-party estimates suggesting the global market could grow from roughly US$1.1 billion–1.4 billion in 2024–25 to as much as US$22 billion–27 billion by 2034. Whether that lands depends entirely on whether any of the current chemistry candidates can actually be manufactured at scale without the bill of materials going through the roof.
The companies furthest along — Toyota, Samsung SDI, Solid Power — are mostly betting on sulphide or hybrid sulphide approaches, with the manufacturing headaches that implies. (QuantumScape, the other big name, runs a proprietary ceramic-oxide chemistry instead.) Industry reporting has tracked repeated timeline slips across the sector as those manufacturing problems prove harder to solve than the chemistry ones. Oxide-based alternatives like LLZO have lower toxicity risk but historically lag on conductivity, which is why a sulphur-free electrolyte hitting sulphide-class numbers is interesting if it holds up.
The applications CRR is pointing at — defence, aerospace, AI-linked data center infrastructure, industrial systems — are not consumer EV. Those are higher-margin, lower-volume sectors where the safety and thermal advantages of solid-state command a price premium, and where the manufacturing constraints of sulphide chemistry are particularly painful. The US Department of Energy’s vehicle battery program has flagged similar applications as the likely early adopters for solid-state, before the chemistry trickles down to mass-market EVs. It’s the same critical-minerals-to-cell logic now driving US efforts to re-shore the battery supply chain.
The bit about it being an ASX-listed explorer
Here’s the part that needs the most context. Critical Resources is not a battery company in the way Solid Power or QuantumScape are battery companies. It’s primarily a critical minerals explorer with the Mavis Lake Lithium Project in Ontario, a gold portfolio in New Zealand, and base metals interests. The battery technology work is a relatively recent expansion, sitting alongside its Dry Supersonic Deposition (DSD) manufacturing workstream focused on solvent-free, low-temperature battery fabrication.
That’s not a knock — plenty of useful battery research has come out of small partnerships with academic labs rather than the big incumbents. But it does mean the path from a benchmarked lab result to a commercial cell is long, expensive, and historically littered with companies whose first-pass numbers didn’t survive contact with full-cell testing.
The next steps CRR has flagged — coin-cell testing on a 48-channel Arbin cycler at SDM, electrolyte optimisation, interface stability testing, compression pathway assessment, and progressive full-cell evaluation — are the right ones. They’re also the steps where a lot of promising electrolytes have run into trouble. Interface stability between the electrolyte and the electrodes is where amorphous materials in particular have historically struggled, and full-cell performance is where the gap between a 3.2 mS cm⁻¹ lab disk and a working battery tends to show up.
What to make of it
The honest read is that this is a genuinely encouraging benchmark from an early-stage program. The numbers are real, they were measured in an NSF-supported research framework and benchmarked against peer-reviewed literature, and they hit a target — sulphide-class transport without sulphide chemistry — that the field has been chasing for years. The framing from CRR’s own management is appropriately cautious, which is a better signal than the breathless announcements that usually come out of this sector.
What it isn’t, yet, is a battery. The road from a first-pass electrolyte composition with good ionic conductivity to a working solid-state cell that can be manufactured at industrial scale is the part where most of these stories end. If CRR’s interface stability and full-cell numbers hold up over the next year or two of testing, this becomes a real contender in the sulphur-free solid-state conversation. If they don’t, it joins a fairly crowded list of promising lab results that didn’t translate.
For now, it’s worth keeping the company on the radar without putting it on the pedestal.
