New solid-state battery chemistry with glass electrolyte delivers 3 times the capacity
Normally it’s a pretty solid assumption that whatever “revolutionary new battery chemistry” has just hit the news is going to crash and burn — sometimes literally. Maybe the thing uses some outlandishly expensive metal as a catalyst, or it has to be supercooled to be well-behaved, or you have to fastidiously mind the outgassing lest the thing explode. Now there’s a new battery chemistry in town, and it comes from the mind of John B. Goodenough (pictured below): the same guy who came up with the cobalt-oxide cathode that powers the lithium-ion battery chemistry we know and love. Goodenough predicts that the new chemistry will have triple the energy density of lithium-ion cells.
This new chemistry has one important difference from the lithium-ion model: It uses sodium instead of lithium. Sodium and lithium are both alkali metals, with the same +1 charge. But sodium is a whole lot more abundant than lithium, which could make the new battery chemistry less expensive than lithium-ion cells.
Then there’s the exploding. Lithium-ion batteries are plagued by the formation of metallic lithium “dendrites” that “spread like kudzu” between the anode and the cathode, which causes a runaway reaction and shorts out the cell. Bang. To avoid this, Goodenough’s new battery chemistry uses an annealed glass matrix as an electrolyte. This presents several possible advantages over most liquid electrolytes, namely that it won’t splash horrible battery liquid all over you if the casing is somehow breached. The glass mats also defy the formation of dendrites, because the anode never reacts with the mats.
I’m a big fan of glass mats, because they have extremely shiny physical properties. Goodenough and colleagues used fiberglass sheets as the electrolyte matrix, and electroplated them with metallic sodium (or lithium) as the anode. Their build then packed the remaining cavities with carbon. The contact surface between the metallic anode and the glass mat is so tight that it’s actually classified as wetting.
Goodenough is betting that the new battery chemistry will be, well, good enough [I was waiting for this. -Ed]. In his words, a “safe, low-cost, all-solid-state cell with a huge capacity giving a large energy density and a long cycle life suitable for powering an all-electric road vehicle or for storing electric power from wind or solar energy.”
