Zeta Energy Develops a Process for Double-sided CNT Coating for Lithium-Sulfur Batteries
Zeta Energy announced today that it has created a process for coating both sides of a copper current collector with carbon nanotubes (CNTs) simultaneously, an invention that will save time, money, and space in the production of its lithium-sulfur batteries. This is a significant development because copper is the industry standard current collector for a lithium battery anode: it is an electrochemically stable substrate for the anode, and it is inexpensive.
Zeta's lithium-sulfur batteries use a combination of a proprietary 3D-structured lithium metal anode and a proprietary sulfurized carbon cathode. Zeta's anode hosts lithium metal in vertically aligned CNTs grown directly on a copper current collector. The carpet-like structure of these CNTs prevent the dendrite issues common to lithium metal, making it possible to take advantage of the significantly higher energy density enabled by lithium metal, while avoiding the safety hazards and cycle life problems created by dendrites in other lithium metal anodes.
Zeta Energy pairs this anode with a proprietary sulfurized carbon cathode that suppresses the formation of soluble polysulfides, resulting in sulfur-based batteries that offer unprecedented stability and performance. Together, Zeta's anode and cathode enable long-lasting batteries with extremely high energy density and safety while being significantly lower cost than lithium-ion batteries.
Vertically aligned CNTs on foil, double-sided coating.
As noted by Chief Technology Officer Abdul-Rahman Raji, "We can grow CNTs to the heights we need for the lithium metal anode in less than a minute with greater than 90% uniformity on both sides of the copper current collector. Growing vertically aligned CNTs on copper was a big challenge and growing on both sides was an even greater challenge. But Zeta now does these routinely in a very fast process. Our throughput rate for the anode will be tens of meters per minute – comparable to typical lithium-ion anode production." Raji adds, "This is an exciting development in the way we make batteries! A typical process for coating an anode requires making the active powder, mixing it into a slurry, coating the electrode and then drying it. Our process is much more direct – you deposit the catalyst on the current collector and grow the CNTs. We can control the thickness and density of the CNTs by adjusting the temperature, pressure and time. I believe we are the only company in the world that has achieved large-scale double-sided CNT growth on copper."
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