Battery stability is a hot topic literally, with daily news of damaged lithium-ion batteries catching fire, and even exploding. We can’t recommend folding, spindling, or mutilating any battery, unless it is a particular lithium-sulfur prototype from University of Electronic Science and Technology of China. American Chemical Society confirms that their scientists could fold or cut this battery, and it kept working. Although we definitely do not suggest you try this out.
The Problem to Solve and a Possible Solution
Sulfur is becoming a strong contender for replacing lithium in lithium-ion batteries in some applications, on account of lower cost. However, battery scientists are still battling to stabilize sulfur at high temperature, according to American Chemical Society..
One option could be to separate the iron-sulfide cathode and lithium-metal anode with a carbonate-based electrolyte. However, the cathode sulfide dissolves in the electrolyte, and forms an impenetrable barrier degrading the battery.
Then Prof Liping Wang and colleagues at University of Electronic Science and Technology of China had a brainwave. Could they add a layer between the cathode and the electrolyte to reduce this corrosion, they wondered, without reducing battery functionality and rechargeability.
Building a Lithium-Sulfur Battery That Folds and Cuts
The team coated their iron-sulfide cathode with a variety of polymers to prevent the sulfide dissolving. They found that polyacrylic acid worked best. Although we very much doubt they intended to fold or cut the battery at this stage.
Prof Liping Wang and colleagues then assembled their modified lithium-sulfur battery with a carbonate-based electrolyte. Plus they added a lithium metal foil as an ion source, and a graphite-based anode to complete their pouch cell.
The team must have been delighted to observe no significant capacity storage loss after 100 charge-discharge cycles. Their novel innovation retained 72% capacity after 300 cycles, even after they folded it, or cut it in half as in our image.
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