Scientists have developed a new prototype battery inspired by human anatomy. The prototype – which offers up to 5x the energy density of the lithium-ion batteries – uses a lithium-sulphur cell with an intestine-mimicking design that could finally make these energy-dense batteries long-lasting enough for commercial use.
Headed by the University of Cambridge, this research has managed to overcome one of the major drawbacks to lithium-sulphur cells: the fact that they disintegrate very quickly, despite their superior energy density to lithium ions.
When a lithium-sulphur battery discharges, sulphur in the cathode absorbs lithium from the anode. This interaction causes the sulphur molecules to transform into chain-like structures called poly-sulphides.
After the battery goes through numerous charge-discharge cycles, the reaction starts to stress the cathode, leading to bits of the poly-sulphides breaking off and entering the battery's electrolyte, which joins the two electrodes.
When this happens, the battery starts to degrade, as it loses its active material.
Here is where bio-mimicry comes in. Our gut is lined with tiny protrusions called villi, which absorb nutrients during digestion. The villi increase the surface area of the intestines by 30x. Scientists have now developed a nano-structure made of zinc oxides which resembles and act like the villi. These prototype villi will absorb the polysulphides in the electrolyte, slowing down the degradation process of the lithium-sulphur cell.
In testing, after 200 cycles at 1C, the prototype nanostructure saw only 0.05% average capacity loss per cycle, making it almost as stable as lithium-ion – which ranges between 0.025 to 0.048 percent average capacity loss per cycle.