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By Jean-Pierre Joosting
Ligna Energy, headquartered in Norrköping, Sweden, manufactures ultra-thin supercapacitors engineered from the outset to sit inside flexible, compact, and wearable electronics. The company’s flagship product, the S-Power 2S delivers 1.2 F capacity, a 2.7 V rating, a 0.5 Ω Equivalent Series Resistance (ESR), and supports over 250,000 cycles. It provides rapid charging in a pouch-format cell that slips comfortably inside a smart card or a sliver-thin indoor sensor.
Where conventional supercapacitors typically rely on synthetic carbon electrodes, lithium-salt electrolytes, and PFAS-containing binders, Ligna has systematically removed each of those materials. Coconut-derived activated carbon replaces synthetic carbon, and an organic electrolyte takes the place of the more chemically aggressive options on the market. The result is a component that matches the electrical characteristics of its conventional peers while eliminating a raft of substances that make end-of-life disposal costly and environmentally damaging.
“We have taken a fairly standard type of supercapacitor and put it into a different form — a pouch, a thin format — and removed synthetic carbon, lithium salts, and PFAS materials from the electrolyte and binders,” explains John Söderström, Marketing Director at Ligna Energy. “It is a conventional supercapacitor in terms of electrical performance, but we have tried to optimise the material stack to remove a few nasty materials and offer a different alternative for our customers.”
The trade-off is a narrower operating temperature range: the organic electrolyte performs well between -20°C and 65°C in its standard form. For colder Nordic deployments — and specifically for a customer targeting installations in the more extreme parts of Finland — Ligna is introducing a second electrolyte formulation capable of operating down to -40 °C, a variant expected to reach the market later in 2026.
The sustainability argument for Ligna’s supercapacitors is easier to make on paper than in a procurement meeting — but that is changing. In 2025, Ligna published a third-party verified Life Cycle Assessment (LCA) and an Environmental Product Declaration (EPD) for its S-Power range, reporting a cradle-to-gate carbon footprint of just 12 g CO₂e per unit. It is, Söderström believes, a level of transparency that remains rare in the energy storage components sector.
“It is really hard to get these numbers from component manufacturers. We felt that publishing a third-party verified LCA and sharing all the numbers was the right thing to do — just to help system designers bring that into their calculations when they design a system,” says Söderström.
The broader economic case for removing conventional batteries is compelling once all costs are accounted for. A coin cell may have a low unit price, but the total cost of ownership is inflated by service visits to replace exhausted cells, the logistics of hazardous waste disposal, and increasingly stringent regulatory requirements. European CSRD reporting obligations, which began to bite for larger companies in 2025, are starting to force those hidden costs into balance sheets. For building operators managing tens of thousands of sensors across a large estate, the numbers can be significant.
According to Söderström, battery replacement is one of the silent ‘taxes’ embedded in traditional sensor deployments. Remove the battery, and a cascade of downstream costs — service visits, waste handling, regulatory reporting — disappears with it.
The decisive shift in recent years has been the maturing of indoor energy harvesting — particularly organic photovoltaic (OPV) cells that perform efficiently under the diffuse, low-intensity light typical of office environments. Ligna works closely with Swedish OPV specialist Epishine and French counterpart Dracula Technologies, both of whom produce indoor PV cells well matched to the output characteristics of Ligna’s supercapacitors.
“When I started at Ligna five years ago, energy harvesting was not widely adopted in wireless electronics. What has happened since is that light harvesters have increased efficiency to the point where batteries can be removed even in low-light conditions — and a sensor can operate in an office space with essentially no downtime,” says Söderström.
Ligna’s Gwen climate sensor, a battery-free indoor reference design unveiled at Embedded World 2026, has been running continuously in the company’s own office for over a year, measuring temperature and humidity and transmitting via Bluetooth Low Energy (BLE) — without a single interruption. Light harvesting is not the only option: a collaboration with a French fuel-cell company is powering disposable logistics trackers intended to be placed on parcels and discarded after delivery, removing metals and hazardous chemicals from a use case where battery recycling is rarely practical.
For smart card applications, RF harvesting, specifically near-field communication (NFC), is the preferred energy source, where a tap on a reader provides the burst of power needed to execute a transaction or authenticate a user. Ligna is also tracking the evolution of dedicated RF transmission technology, though regulatory constraints in Europe limit some of the more powerful approaches currently being explored in the US market.
Ligna’s pouch format is not merely an aesthetic choice. Smart card standards impose strict dimensional envelopes on every component inside the card, and working within those constraints has given Ligna’s engineering team a forensic understanding of what is possible when a PCB is ruthlessly optimised for thinness and area. That discipline, Söderström argues, translates directly to indoor sensors — a product category that has historically been shaped more by battery geometry than by any deliberate design intent.
“Many customers in the early years claimed that thinness was not a selling point for indoor sensors — they were stuck in the old way of doing sensors, where no one required them to be anything other than bulky and rigid. Gwen was designed to tickle the brains of those projects,” says Söderström.
The Gwen demonstrator proved the point more concretely than Ligna had anticipated. An end customer operating high-end commercial offices in Stockholm — a business whose clients place a premium on unobtrusive interiors — told the company they had been unable to find a sensor that could blend into the spaces they curate. Gwen, at roughly the footprint of a large postage stamp and a thickness comparable to two stacked credit cards, fitted the brief. An OEM is now adapting the design for production.
The argument extends beyond aesthetics. For a building operator deploying 10,000 to 50,000 sensors across an estate, the volume of casing material alone represents a non-trivial environmental and cost burden — especially when that casing exists primarily to accommodate a battery that could, in many straightforward temperature-and-humidity applications, be eliminated altogether. Thin construction also simplifies end-of-life handling: fewer materials, no batteries to segregate, and a smaller overall footprint to manage.
Battery-free operation places demanding constraints on the rest of the system. Every component — microcontroller, sensor, radio — must be optimised for the smallest possible quiescent current, and the architecture must be rethought from scratch rather than adapted from a battery-powered design. The trend in the wider semiconductor industry is, fortunately, running in the right direction.
Bluetooth Low Energy is currently Ligna’s most common radio protocol, partly because the ecosystem of BLE-capable low-power silicon is mature and partly because the power budgets involved are well understood. The Gwen sensor uses BLE to transmit its climate readings at intervals calibrated to keep consumption within what the indoor harvester can sustainably supply.
LoRaWAN is the protocol Söderström is watching most closely for future growth. Its low data-rate, long-range characteristics and growing network coverage — near-complete across Sweden and expanding rapidly across Europe — make it well suited to applications where sensors need to report infrequently over large distances. At Embedded World 2026, Ligna co-exhibited a LoRa mesh sensor developed in collaboration with Mdish and Dracula Technologies, pointing toward a future in which the same battery-free, energy-harvesting architecture can serve both the dense indoor sensor networks of smart buildings and the sparse, wide-area deployments of agriculture and industrial parks.
“I am interested in LoRa because it brings some freedom. Bluetooth is more restricted in the way we can use it. The coverage of LoRa in Sweden is almost complete, and I think for the more developed countries it is really attractive,” says Söderström.
The practical power budget for LoRaWAN in Ligna’s typical use cases is manageable with current harvesting technology, and the protocol’s infrequent transmission pattern — a position update every twenty minutes, a humidity reading twice a day — maps neatly onto the charge-and-discharge profile of a small supercapacitor coupled to an indoor PV cell.
Ligna’s appearance at Embedded World 2026 in Nuremberg centred on Gwen, presented as a reference design rather than a finished product — a set of building blocks that OEMs and system providers can adapt to their own industrial designs. The sensor harvests ambient light, stores energy in Ligna’s S-Power 2S supercapacitor, measures temperature and humidity, and transmits over BLE, all without a primary battery and, in principle, without any scheduled maintenance for the operational life of the device.
The show demonstrated something that datasheets cannot: real-world longevity. The Gwen reference design used as an internal demonstrator had been running in Ligna’s office for over a year without interruption at the time of Embedded World, providing a degree of evidence that lab-rated lifetimes translate to field conditions — a reassurance the industry badly needs. Söderström is candid that Ligna, as a young company, cannot yet present ten years of field data, but accelerated testing is underway alongside the launch of full industrial production in early 2026, and more comprehensive lifetime evidence is expected to be published during the year.
The company targets an operational lifespan of eight to ten years for its supercapacitors — a figure grounded in the physics of the pouch format, where the integrity of the seals around the connecting tabs is the limiting factor. A useful rule of thumb in the industry holds that each additional centimetre of pouch perimeter adds roughly one year of life, which means that customers requiring longer lifespans need to accommodate a correspondingly larger footprint.
Scale is where many promising sustainable technologies falter. Ligna’s answer is a roll-to-roll manufacturing process — a continuous coating and assembly line analogous in concept to a high-speed printing press, though the chemistry involved is rather more demanding. Ligna holds patents on a process step that keeps the assembly in the roll-to-roll line for longer than conventional supercapacitor manufacturing, reducing the number of discrete machines required and lowering production complexity. The company produces supercapacitors in Sweden, which carries a cost premium over Asian alternatives but supports the European value-chain credentials that OEMs navigating CSRD disclosure requirements are increasingly keen to demonstrate.
Ligna has also recently been selected as a supplier to OEM Electronics, broadening its distribution reach, and its S-Power 2S supercapacitors are now available through DigiKey — a milestone that signals the product is ready for design-in at volume. The company is additionally collaborating with Altris on the world’s first ultra-thin sodium-ion battery, backed by Swedish innovation agency Vinnova, extending its technology roadmap beyond supercapacitors into a complementary energy storage format that retains the same commitment to non-toxic, recyclable materials.
“We can produce at high volumes and stay in Sweden. We might not be able to compete on costs with some Chinese competitors right now, but we can give something different in terms of form factor and sustainability — and we are working to cut costs further as we scale,” says Söderström.
The vision Ligna is building toward is one in which the coin cell is no longer the default answer for wireless IoT — replaced by a system in which a wafer-thin supercapacitor, a high-efficiency indoor harvester, and a low-power radio protocol together deliver years of maintenance-free operation at a total cost of ownership that, once the hidden taxes of battery management are included, is genuinely competitive.
It is a vision that is already running — in a Stockholm office building, on top of parcels moving through a French logistics network, inside smart cards tapped at building access points across Europe. Gwen at Embedded World was not a prototype of a distant future. It was a working demonstration of a transition already underway.
“Battery-free can be a better product experience. When you remove routine battery swaps, you unlock simpler operations and new possibilities for where sensors can live — including thin or discreet placements where bulky enclosures are a non-starter,” says Söderström. “This also simplifies end-of-life handling by reducing the need to remove, sort, or treat batteries separately when devices are retired.”
For engineers designing the next generation of connected buildings, supply chains, and agricultural networks, the question is shifting from whether battery-free is possible to how quickly the ecosystem of low-power components, efficient harvesters, and transparent, sustainable energy storage can mature to make it the obvious choice.
Based on what Ligna demonstrated at Embedded World 2026, the answer may be sooner than the industry expects.
www.lignaenergy.com
www.oemelectronics.se/en
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