Charging up: the growing use of 3D printing for battery applications

It always starts with a conversation. This particular one was between Shen J. Dillon and Jennifer A. Lewis, the latter recounts, and was an off the cuff suggestion that, having used 3D printing techniques to produce electronics with very fine features, perhaps they should do similar with lithium-ion batteries.

They talked it through, decided that, in theory at least, it made sense that you could go ‘out of plane’ to pack more energy storage within the same footprint, and decided to get to work. This was almost a decade ago when Lewis was working alongside Dillon at the University of Illinois.

By the time the subsequent paper, ‘3D printing of interdigitated Li-Ion microbattery architectures’, was published in 2013, Lewis had moved to Harvard University where she would welcome the attention of several battery companies. During the research, Lewis and her team demonstrated a 3D printing technique which patterned functional inks in filamentary form with feature sizes as small as 1μm. The composition and rheology of the inks were optimised to ensure they could flow through the deposition nozzles – battery electrodes were printed at thicknesses of around 30 microns – while the materials also required the structural integrity to withstand drying and sintering without delamination or distortion. Having formulated such materials, they had broken new ground.

“We found that we could create a 3D printed battery,” she tells TCT, “that wasn’t a clear outcome from the start. Importantly, we also found the performance was akin to [that of] a bulk battery, so the ability of printing at the micro scale didn’t degrade the performance in any way, it just made it possible to create something that was small. We were printing a functional battery that can be recharged many times within the size of a single grain of sand. It doesn’t seem possible, but it was.”

Some years later, there was another conversation. This one took place in the UK between Dr Sarah Karmel and Paul Holt, the Head of R&D Chemistry and Managing Director of Photocentric, respectively. They too were discussing the energy density within batteries, pondering the efficacy of 3D printing for such an application and reaching out to industry partners. In September 2020, the company set up a division dedicated to 3D printed battery research, with several projects launched to explore the architecture, structure and manufacture of electrodes.

“The concept of thick electrodes has been there for a while; they’re the easiest way to get a battery with a higher energy density,” Dr Karmel says. “The problem is thick electrodes hinder the lithium-ion flow. But you can [address] that by designing porosity and channels for lithium ions to flow and what better way of doing that than by using 3D printing?”

Two years prior to Photocentric launching its own research unit, Lewis had co-authored a paper titled ‘3D printing of customised li-ion batteries with thick electrodes.’ Whereas in the 2013 research, Lewis’ team had proved the ability to print the anode and cathode of a battery, this time they had printed all the battery components. The motivation here was to open up application opportunities.

“With that capability, it goes beyond micro batteries,” Lewis explains. “One of the drivers when we first did this work with 3D printing was thinking about, well you can get coin cell batteries, silt cylinders, thin film batteries, but you don’t have a lot of choices. Battery makers make them in certain form factors, and if you have something like a hearing aid, for example, and you want to have a cavity where you fill up every open space that’s not used for something else in the hearing aid, if you could print a three-dimensional battery that was a different shape, that could be more volumetrically efficient and open up the design space for batteries.”

This was also a key motivation for Photocentric’s step into the battery space. The company is primarily leveraging its LCD Screen 3D printing technology to power its research efforts. While much of the technology is safeguarded by IP, Dr Karmel did outline the company’s LC Maximus machine, with its 920 x 510 x 800 mm build volume and 43-inch LCD screen, is being leaned on, while there is also a prototype machine with a 90-inch LCD screen and another prototype system called LC Nano which can deliver accuracies down to 20 microns. Photocentric will be teaming these machines with a ‘specific type of photopolymer matrix’ which is said to have a very high load of active electrode material.

We’ve only just scratched the surface.

The company is currently participating in three grant-funded projects, the first of which centres on the design of single, dense electrodes for solid-state batteries; the second focuses on electrode architecture and structuring; while the third will explore electrode manufacturing methods. As Photocentric completes these projects, it hopes to have its ‘first big demonstrator’ ready within six months, with small field trials following shortly after. The company’s aim is to develop batteries that can be launched commercially and used at scale. It sees the electric vehicle market as one that is crying out for the benefits that 3D printed batteries can bring.

“If you look into the weight of electric cars,” Dr Karmel says, “they’re two to three tones which is because of the battery pack, so if you can make lighter batteries it’s a huge benefit. You want to have batteries which are better, which have a faster charging capacity, with a higher energy density that allow you a longer range. But it’s not only electric vehicles. If you look at drones, you want to have a battery that will make a much lighter drone which, again, will give it a much longer range. For these kinds of lightweight applications, battery shape would make a very big difference.”

Amid the climate crisis and government initiatives to reduce national carbon footprints, the electric vehicle market is growing fast. By 2030, the EU is targeting at least 30 million zero-emission vehicles on its roads, while the UK announced in October its intentions to phase out the sale of petrol and diesel vehicles by the same year. Photocentric believes its photopolymer 3D printing technology is capable of meeting the desired principles of battery design for markets like this, as well as the steep volumes likely to be required. Lewis, meanwhile, sees another key opportunity: hybrid functionality.

“Right now, all your battery packs are in the floor of your car, they’re not serving any mechanical function. They’re just providing the energy to power but wonder if in the door panels you could have batteries that both had the capability of being energy storage devices and of providing the structural features that you need. That’s one example but there’s a lot of opportunity. If you can replace some structural elements with functional elements that still have mechanical properties, that can be very helpful [in lightweight applications].”

There is research being carried out on this hybrid functionality concept elsewhere. One would think there would certainly be an appetite for such a concept. But through her own experiences, Lewis estimates that the industry is ten years behind academia when it comes to 3D printed batteries and, as with all disruptive technologies, uptake is slow. Yet, Addionics is a commercial battery firm embracing the technology, as are Blackstone and Sakuu Corporation. Then, of course, there’s Photocentric with a roadmap in place and capacity – it says – to scale. There is still work to be done, more conversations to be had, but Lewis believes there is plenty of scope for commercial 3D printed batteries.

“[3D printing] opens up the design space in terms of the shape or form factor of the battery. It affords much more architectural complexity and, if we started to think about using them not only for energy storage but also for a structural element, it allows you to co-print multiple materials together and that even further opens up the design space. There’s the potential benefit for these micro batteries to go out of plane, packing more energy in a small volume. From what I’ve seen not only in my lab but broadly, we’ve only just scratched the surface.”

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