# How Chipmakers Are Using On-Chip Batteries for Energy Storage

An episode of [The Hardware Podcast with Fexingo: Chips, Devices, and Electronics Engineering Conversations](https://invisiblenetwork.ai/podcast/1896799982), 3 Jul 2026, 11 min.

Audio: https://audio.fexingo.com/business/the-hardware-podcast/episode-0089.mp3

Episode 89 explores how chipmakers are integrating tiny on-chip batteries directly into silicon to provide local energy storage for power-hungry applications like IoT sensors, medical implants, and edge AI devices. Lucas breaks down the technical challenge of building a battery on a chip — using solid-state electrolytes, thin-film deposition, and nanoscale electrodes — and why this could eliminate external power supplies for billions of devices. Luna questions the energy density trade-offs and lifespan concerns. The hosts look at a real prototype from imec and discuss what this means for wearable electronics and autonomous sensors. A deep dive into a quiet revolution in on-chip power that could reshape system design. #OnChipBatteries #EnergyStorage #Semiconductors #ChipDesign #SolidStateBattery #ThinFilmBattery #IoT #EdgeAI #MedicalImplants #WearableTech #imec #Nanoscale #PowerManagement #Technology #Hardware #FexingoBusiness #BusinessPodcast #HardwarePodcast Keep every episode free: buymeacoffee.com/fexingo

## Transcript

Lucas: So we talk a lot on this show about how chips are getting faster, cooler, more efficient. But there is a quiet revolution happening in how chips are powered — specifically, the idea of putting a battery directly on the chip itself.
Luna: An on-chip battery. I've seen some research papers, but I didn't realize it was already at the prototype stage.
Lucas: It is. And I think it's one of those things that sounds almost impossible at first. A battery is a bulk chemical device — electrolyte, anode, cathode, separator. How do you shrink that down to something that fits on a few square millimeters of silicon and is fabricated using semiconductor processes?
Luna: Right, because standard chip fab is all about depositing thin films of silicon, oxide, metal. Batteries need thick layers of active material to store meaningful energy.
Lucas: Exactly. And that's the core challenge. But researchers at imec, the Belgian nanoelectronics R&D lab, have been working on this for years. They recently demonstrated a solid-state thin-film battery that's just a few micrometers thick and can be integrated directly onto a CMOS chip.
Luna: Solid-state being the key. No liquid electrolyte, so no leakage, no flammability issues, and it can be deposited using sputtering or atomic layer deposition.
Lucas: Right. The imec battery uses a lithium-based solid electrolyte — lithium phosphorus oxynitride, or LiPON — with thin-film electrodes. The total thickness is around 10 micrometers. That's about a tenth of a human hair. And it can deliver enough power to run a small sensor or a wireless transmitter for a few seconds to minutes.
Luna: So we're not talking about powering a smartphone. But for IoT sensors that wake up once an hour, take a reading, transmit a packet, and go back to sleep — that could be a game changer.
Lucas: Exactly. And that's the killer app. Right now, billions of IoT devices rely on coin cell batteries or energy harvesting. Coin cells are bulky, they have limited lifespan, and they're not really integrated into the system. An on-chip battery means you can have a self-contained microsystem — sensor, processor, memory, radio, and power — all on one die.
Luna: And it could be recharged wirelessly. So you could have a implantable medical device that never needs a battery replacement surgery.
Lucas: That's exactly the use case that a company like Qualcomm is looking at. They've filed patents for on-chip rechargeable batteries for implantable sensors. But the challenges are still significant. Energy density is the big one.
Luna: How does it compare to a standard lithium-ion coin cell?
Lucas: It's much lower. A typical thin-film battery today has an energy density around 10 to 50 microwatt-hours per square centimeter. A CR2032 coin cell has about 200 milliwatt-hours. So you need a much larger area or you accept very short bursts of power.
Luna: But if you're only powering a tiny sensor that draws a few microwatts, that could still be enough for a few thousand transmissions before recharging.
Lucas: Right. And the recharging can be done wirelessly — inductive coupling or RF harvesting. So the battery acts as a buffer, storing energy from intermittent harvesting and releasing it in bursts.
Luna: That makes me think about edge AI devices. If you have a tiny neural network accelerator that does inference on sensor data, it might need a burst of current for a few milliseconds. An on-chip battery could provide that without needing a big capacitor bank.
Lucas: And that's actually another application. Power integrity. Chips with high transient current demands — like a wireless transmitter or a processor entering turbo mode — can cause voltage droops that mess up logic. A local on-chip battery can act as a decoupling capacitor with much higher energy density than traditional on-chip capacitors.
Luna: So it's not just about replacing the external battery. It's about enabling new architectures where power delivery is distributed across the chip.
Lucas: Exactly. Imagine a chip with multiple voltage domains, each with its own tiny battery that gets recharged wirelessly or from a shared bus. That's a whole new design paradigm.
Luna: What about lifespan? Lithium-ion batteries degrade over charge cycles. If this is on a chip that's supposed to last 10 years in a medical implant, that's a concern.
Lucas: Solid-state thin-film batteries actually have better cycle life than conventional lithium-ion. imec has demonstrated over 10,000 cycles with minimal capacity fade. The main degradation mechanism is interfacial reactions, but with solid electrolytes, that's much slower.
Luna: So the chemistry is actually more stable. That's promising.
Lucas: And because the battery is so thin, it can be encapsulated in a hermetic package that prevents moisture ingress. So shelf life could be decades. That's critical for applications like asset tracking tags that might sit in a warehouse for years before being activated.
Luna: Are there any commercial products yet? Or is it still all lab-scale?
Lucas: There are a few companies. One is Cymbet, which has been making thin-film batteries for about 15 years. Their EnerChip line is available as a surface-mount component about 0.1 millimeters thick. It's not integrated on the same die, but it's close.
Luna: So you could solder it next to your main chip rather than on top of it.
Lucas: Right. But the real goal is monolithic integration — where the battery is deposited directly onto the silicon during fab. imec has shown that you can process the battery after the CMOS layers are done, using a low-temperature process that doesn't damage the transistors.
Luna: And that's the key. If you can add battery fabrication as a back end of line step, it becomes a standard part of the chip. No extra assembly, no bulky packaging.
Lucas: Exactly. And the cost could be very low because you're adding just a few extra mask steps. The material cost for a thin-film battery is negligible — it's just a few nanometers of lithium compounds and metals.
Luna: What about safety? Lithium is reactive. If you have a tiny battery on a chip that gets hot, could it catch fire?
Lucas: Solid-state electrolytes are non-flammable. And the total amount of lithium in a thin-film battery is minuscule — micrograms. Even if it short-circuits, the energy release is too small to cause a fire. That's a big advantage over lithium-ion polymer batteries.
Luna: So it's actually safer than the batteries we use today. That opens the door for medical and automotive applications where safety is paramount.
Lucas: Right. And there are already pilot programs. Imec has partnered with a medical device company to develop a smart contact lens that measures glucose in tears, powered by an on-chip battery that recharges wirelessly from a special glasses frame.
Luna: That's incredible. A contact lens with a battery on the chip itself.
Lucas: It's still in prototype, but it shows the direction. Another application is in RFID tags that can actively transmit data — not just backscatter. With an on-chip battery, you could have active tags that work at longer ranges and can store data even when the reader is off.
Luna: So we're moving from passive to active, without needing a separate battery. That's a huge shift for logistics and supply chain.
Lucas: And for environmental monitoring. Imagine a tiny sensor that's deployed in a forest or ocean, powered by an on-chip battery that recharges from a small solar cell. It could transmit data for years.
Luna: What are the limits? Is there a fundamental ceiling on how much energy you can store in a thin film?
Lucas: There is. The volumetric energy density of thin-film batteries is limited by the thickness of the active layers. To increase capacity, you need thicker films, which take longer to deposit and can cause stress. The current practical limit is around 100 micrometers total thickness, giving maybe a few hundred microwatt-hours.
Luna: So not enough for a phone, but plenty for a sensor.
Lucas: Exactly. And researchers are working on 3D structures — like etching trenches into the silicon to increase surface area, then depositing the battery layers conformally. That could multiply capacity tenfold.
Luna: So we might see on-chip batteries in consumer devices within the next five years.
Lucas: I think so. Especially in wearables and hearables. The Apple AirPods, for example, have a tiny battery that's assembled separately. If that could be integrated into the chip itself, you'd save space and reduce manufacturing complexity.
Luna: That's a compelling business case. And if the cost is low, it's a no-brainer for any device that needs to be small and wireless.
Lucas: And that's where the show comes in. If today's conversation gave you something useful, maybe consider tossing a couple of dollars toward it at buy me a coffee dot com slash fexingo. It genuinely makes a difference in keeping these ad-free and focused on the technology.
Luna: Yeah, a few bucks a month really does help. We don't run ads, so listener support is what keeps the lights on, so to speak.
Lucas: Anyway, back to the tech. I think the next frontier is not just integrating the battery, but integrating the charging circuitry too — so the chip can manage its own power harvesting and distribution.
Luna: So a truly self-powered chip. That's the holy grail.
Lucas: Exactly. And with on-chip batteries, we're one step closer. The pieces are falling into place — solid-state electrolytes, low-temperature deposition, 3D structuring. I think in a decade, most IoT chips will have a tiny battery built right in.
Luna: It's one of those quiet revolutions that changes everything underneath, even if the user never notices.
Lucas: Right. And that's the kind of innovation that makes this show fun to do. So — next time, we'll look at how chips are using on-chip cooling with microfluidic channels. Another way to pack more power into the same space.
Luna: Looking forward to it.

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