While copper prices have somewhat stabilized in the weeks since a 50% import tariff on the metal went into effect, the battery energy storage industry is bracing for higher prices and supply chain disruptions in the near future. Though refined copper has been granted a temporary exemption, it might not be enough to shield the market, as semi-finished products are still vulnerable.
Copper features prominently in various battery components like wiring and current converters; the average lithium-ion battery is up to 15% copper by weight. Given that nearly 50% of the U.S.’ copper consumption relies on imports, a squeezed supply chain and climbing costs could leave battery manufacturers scrambling.
But what if those batteries didn’t need copper at all? That’s what Sakuu, a Silicon Valley startup, is betting on: that their printing-based manufacturing process could make mineral price spikes irrelevant.
Sakuu’s additive manufacturing technology couples document printing and 3D printing technologies with polymer-based current collectors to enable metal-free energy storage systems (ESS).
“We’re able to eliminate copper and aluminum foils and replace them with lightweight polymer conductors,” Karl Littau, Sakuu’s CTO, told pv magazine USA, adding that the process removes two of the most expensive, supply-constrained metals from the storage equation.
In practice, he said, the resulting battery functions “just as well as conventional lithium-ion cells” but without any heavy or expensive metals.
“It’s really the cost that it helps,” he explained. “By printing with cheaper materials, we’re taking costs out of the process in a way that’s very unusual in battery technology.”
By using dry-printing methods to build cells layer by layer, Littau explained, the company can construct new battery architectures that bypass traditional metal-based current collectors entirely. Dry-printing eliminates the costly and energy-intensive solvent drying step in conventional cell manufacturing.
“In traditional wet-coating, you have to dry the electrodes, which takes a lot of time and energy and requires enormous ovens,” Littau said, noting that dry-printing can significantly cut the capex and opex for gigafactories. It allows for more flexible designs, as the 3D printers can “bake” structures into the electrodes that can make the cells more energy dense.
The process is also chemistry-agnostic. Littau explained that while many start-ups were working to displace lithium-ion, “no one was working on the manufacturing side.” That’s why the startup opted to do just that.
Rather than staking a claim on any one chemistry, a key part of Sakuu’s development process was ensuring that its manufacturing approach and resulting polymer architecture could apply to various types of batteries.
“Regardless of which chemistry wins,” he said, Sakuu’s processes should be broadly relevant and can help bring overall costs down.
“Not many advanced chemistries actually make batteries cheaper,” Littau noted. “Most are more expensive and will be for a while.”
Beyond cost, the additive manufacturing process can also make batteries safer; unlike copper foils, polymer current collectors can’t overheat or short circuit, which reduces fire risk. Eliminating copper and aluminum also makes it easier to recycle end-of-life batteries since it reduces the temperature needed to recover oxides.
“Moving to polymers potentially allows solvents to be used instead of heat, so you can reclaim cathodes and anodes with far less processing,” Littau noted.
While Sakuu’s still scaling, Littau said that the company borrows and benefits from mature printing technologies in other industries. Document printers can already produce hundreds of pages per minute.
Translating the same principle to battery production could let manufacturers ramp up incrementally, he explained, instead of building billion-dollar gigafactories from day one.
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