High-capacity batteries could have a huge impact on products ranging from smart phones to electric cars, if only they weren't so prone to fractures and cracks. Now researchers at Stanford have developed a self-healing battery that mends itself on every charge cycle, dramatically extending its life.
Above: Images acquired with a scanning electron microscope show how charging the self-healing battery causes cracks to form in its electrode (top image). The bottom image shows how the cracks in the electrode – a mixture of silicon microparticles and a self-healing polymer – begin to seal within five hours of charging. Image credit Cui et al.
Tech Review's Katherine Bourzac explains (emphasis added):
The self-healing battery's negative electrode, or anode, combines silicon with polymers that act like chemical zippers, healing cracks that form when the battery is used and recharged.
The self-healing battery electrode has so far been tested with pure lithium metal as the positive electrode, because its storage capacity is much greater than that of any conventional cathode. The self-healing electrode itself has eight times the storage capacity of the carbon anodes found in a conventional rechargeable lithium-ion battery. If paired with a conventional cathode, it would create a battery that stored about 40 percent more energy. If paired with a correspondingly high-capacity cathode, total energy storage would be doubled or tripled.
While previous silicon batteries could only be discharged and recharged 10 times before breaking down, the self-healing battery weathers 100 charging cycles. But that's still not enough, acknowledges Stanford materials scientist Yi Cui. "We need to go to 500 cycles for portable electronics, and a few thousand for electric vehicles," Cui says.
According to Cui, whose findings are published in the latest issue of Nature Chemistry, he and his colleagues are only "just starting" to work on self-healing solutions that could allow for batteries to go through even more charge cycles before giving up the ghost. To read more about what his and other teams are up to, head on over to Tech Review.