From The Drive, January 19:
As promising as this sounds for next-gen EV batteries, it still needs a reality check.
Harvard University claims to have invented a new battery chemistry that could finally realize solid-state battery technology. The results of its experiments so far seem promising, but it's worth remembering how many obstacles stand in the way of even paradigm-shifting batteries' propagation, and the timeline such a change would unfold on.
Solid-state batteries are viewed as the next big evolution for battery tech, and therefore as the next big step forward for EVs. Compared to today's gold standard of lithium-ion batteries, solid-state cells offer higher energy capacity, lower weight, quicker charging, longer lifespans, and greater safety. The tech is only in its infancy though, and is still years from commercialization even by its biggest proponents. But the Harvard John A. Paulson School of Engineering and Applied Sciences thinks it has cracked the code with its new lithium-metal solid-state battery.
Lithium-metal differs from lithium-ion in that it uses lithium in its anode, or positive side, while lithium-ion uses a lithiated metal oxide in its cathode, or negative side. We'll get to what that means for the battery in a second; we should first understand why we're trying to move past lithium-ion.
Lithium-ion batteries tend to degrade during use due to the internal growth of dendrites. These are tiny spikes that grow off the anode and can penetrate the barrier to the cathode, causing an internal short-circuit that can reduce energy capacity or even cause a fire. Harvard says it has figured out how this happens, explaining dendrites form when ions "plate" unevenly onto the anode during charging. Discharging strips this layer back off, but can still leave thick and thin areas. Gradually, these become dendrites.
But by separating anodes and cathodes with extra layers of new materials, Harvard researchers say they've found a solution that controls dendrite formation. By adding a layer of micron-sized silicon particles to the anode's surface, it results in more even plating, and basically stops dendrites before they start.
"In our design, lithium metal gets wrapped around the silicon particle, like a hard chocolate shell around a hazelnut core in a chocolate truffle," said Xin Li, Associate Professor of Materials Science....
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