In today’s rapidly electrifying energy and transport sectors, lithium-ion batteries offer unmatched energy density and scalability. However, this widespread adoption is not without risk. Thermal runaway – where battery cells fail catastrophically – remains one of the most pressing lithium-ion safety challenges facing manufacturers and regulators alike.
Addressing this issue is 24M, a US-based battery technology company with a growing European footprint led by Ulrik Grape. Its latest innovation, the Impervio separator, introduces a proactive safety design that tackles failure at the cell level.
Thermal runaway has long been an issue in the world of energy storage, particularly as battery adoption surges. Grape points to a rise in incidents across applications – stationary systems, e-mobility platforms and, increasingly, passenger vehicles. In most cases, the trouble starts not outside the battery but inside the cell itself.
“External causes like crashes or punctures certainly pose risks,” Grape says, “but we noticed a pattern of failures where the initiating event was internal – caused by dendrite growth and/or contamination issues from the cell manufacturing process.”
Dendrite blocker
Dendrites – metallic structures that form during charging – can silently grow within cells, eventually piercing the separator that divides the anode and cathode. This leads to internal short circuits, and often, instantaneous thermal runaway — a critical lithium-ion safety failure mode.
Impervio addresses this risk where it starts. By treating a conventional separator with a proprietary layer, 24M engineered a barrier that deflects and dissolves dendrites as they form. More than passive protection, it is a circular defence that manages dendrite activity in real time.
What sets Impervio apart is its multi-functionality. First, it blocks dendrites with a specialised treatment layer. According to Grape, dendrites that would normally breach and short the separator are turned sideways instead, dissolved and rendered harmless.
Second, Impervio enables continuous monitoring. Integrating with battery management systems, it allows manufacturers to detect abnormalities before they trigger failure. If necessary, cells can be safely discharged and taken offline – preventing escalation before it begins.
Finally, the system supports precision recalls. Instead of pulling entire product lines from shelves, manufacturers can isolate problematic cells using Impervio’s built-in tracking. This could save companies millions while boosting public trust and advancing lithium-ion safety standards.
Impervio works across chemistries: conventional lithium-ion, lithium metal, and 24M’s proprietary LiForever cells. The chemistry-agnostic design makes it a versatile safety layer for a broad range of applications.
Testing the limits
With any new lithium-ion safety innovation, lab validation is key. 24M pushed Impervio through some of the industry’s harshest abuse tests and Grape says that the results were remarkable.
In one trial, the team deliberately introduced 1% contamination using stainless steel particles. “That’s an extreme scenario,” Grape admits. “Far beyond typical production conditions.”
While control cells failed within a handful of cycles, those with Impervio separator continued with operational stability for over 800 cycles with minimal capacity loss.
The company also conducted a nail penetration test, where a sharp object is driven into the cell to simulate traumatic damage and internal short circuit, and observed zero thermal runaway. In an aggressive overcharge test, Impervio cells were pushed to 200% charge capacity – a scenario designed to stress lithium-ion safety thresholds. Conventional separators combusted within 38 minutes but Impervio’s remained stable, with minimal heat rise.
Compatibility
One of Impervio’s greatest strengths is its drop-in nature. Manufacturers don’t need to overhaul production lines or commit to disruptive changes as the separator is compatible with current cell designs, making integration smoother and quicker.
Though bound by NDAs, Grape confirms that OEMs across multiple sectors – including automotive, consumer electronics, power tools, and stationary storage – are actively testing the technology. Evaluation programmes span Europe, the US and Asia, with particularly strong traction in electrified transport.
“We’re not talking about niche use cases,” he says. “This is cross-industry tech that can be applied wherever batteries pose thermal risks.”
While still in the pre-commercial phase, Impervio is already being produced in substantial volumes – hundreds of metres of separator material are available for trials.
According to Grape, the development timeline has been fast and focused, with work beginning just under two years ago.
Full-scale deployment, however, will take time. Automotive OEMs, for example, require multi-phase qualification cycles, including sample testing, performance verification, and regulatory compliance. Grape estimates the first commercial rollouts by 2027, with broader volume integration by 2028.
“Our goal is not just to introduce a new separator,” he explains. “It’s to evolve how battery safety is fundamentally approached – starting at the cell level.”
Sustainability synergy
Beyond immediate safety benefits, Impervio may play a role in longer-term sustainability. When cells fail less frequently and operate more reliably, their usable life increases, reducing waste and lowering the environmental footprint.
This effect amplifies when paired with 24M’s LiForever technology which is a recycling-friendly chemistry platform that makes recovery of LFP and aluminium economically viable. In current systems, these materials are often discarded due to low salvage value. With LiForever, the economics shift, supporting a more circular battery lifecycle.
“Safer cells mean longer-lasting ones. When you can recycle them affordably, you’re solving both ends of the sustainability equation”, Grape says.
Safety isn’t just a design consideration, it’s becoming a regulatory mandate. As energy density climbs, so does the risk of catastrophic failure. Grape points out that today’s cells hold nearly five times the energy of their 1990s predecessors, packed into increasingly compact footprints.
“Increasing energy density means increasing the consequences when things go wrong,” he says. “OEMs are realising this, and regulators are starting to demand more robust safety measures.”
Social media amplification and consumer awareness mean that even isolated incidents can ripple quickly across markets. Public perception of battery safety was once niche but is now headline news. Impervio, in that context, is not only a technical solution but a reputational safeguard.
Safety design
One issue Grape returns to is the tendency to treat safety as a secondary concern. While efforts like pack-level fire containment systems are valuable, they can’t prevent initial failure inside the cell.
“Propagation barriers help once a cell ignites,” he says. “But they don’t stop it from igniting in the first place. Impervio does.”
Grape is calling for stronger collaboration between manufacturers, integrators and regulators – especially in aligning standards and accelerating sample testing. 24M is part of safety advocacy networks such as Recharge, working to shift industry mindsets toward proactive safety design.
With fires still making headlines and energy systems growing more complex, Grape’s message resonates across the industry: it’s time to stop fires before they start.
