New 'pomegranate-inspired' design could revolutionise battery storage

Researchers have created an electrode designed like a pomegranate- with silicon nanoparticles clustered like seeds in a tough carbon rind- that overcomes several remaining obstacles to using silicon for a new generation of lithium-ion batteries.

"While a couple of challenges remain, this design brings us closer to using silicon anodes in smaller, lighter and more powerful batteries for products like cell phones, tablets and electric cars," lead researcher Yi Cui, an associate professor at Stanford University and SLAC National Accelerator Laboratory, said.

The inventor said that experiments showed their pomegranate-inspired anode operates at 97 percent capacity even after 1,000 cycles of charging and discharging, which puts it well within the desired range for commercial operation.

Silicon anodes could store 10 times more charge than the graphite anodes in today's rechargeable lithium-ion batteries, but they also have major drawbacks: The brittle silicon swells and falls apart during battery charging, and it reacts with the battery's electrolyte to form gunk that coats the anode and degrades its performance.

Over the past eight years, Cui's team has tackled the breakage problem by using silicon nanowires or nanoparticles that are too small to break into even smaller bits and encasing the nanoparticles in carbon "yolk shells" that give them room to swell and shrink during charging.

The study was published in the journal Nature Nanotechnology.