IT’S THE ERA OF SUPERCHARGED LITHIUM-ION BATTERIES

In 2011, Gene Berdichevsky founded Sila Nanotechnologies to build a better battery. His secret ingredient is nanoengineered particles of silicon, which can supercharge lithium-ion cells when they’re used as the battery’s negative electrode, or anode.

Today, Sila is one of a handful of companies racing to bring lithiumsilicon batteries out of the lab and into the real world, where they promise to open new frontiers of form and function in electronic devices ranging from earbuds to cars.

By this time next year, Berdichevsky plans to have the first lithium-silicon batteries in consumer electronics, which he says will make them last 20 percent longer per charge.

When a lithium-ion battery is charging, lithium ions flow to the anode, which is typically made of a type of carbon called graphite. If you swap graphite for silicon, far more lithium ions can be stored in the anode, which increases the energy capacity of the battery. But packing all these lithium ions into the electrode causes it to swell like a balloon; in some cases, it can grow up to four times larger.

The swollen anode can pulverize the nanoengineered silicon particles and rupture the protective barrier between the anode and the battery’s electrolyte, which ferries the lithium ions between the electrodes. Over time, crud builds up at the boundary between the anode and electrolyte. This both blocks the efficient transfer of lithium ions and takes many of the ions out of service. It quickly kills any performance improvements the silicon anode provided.

One way out of this problem is to sprinkle small amounts of silicon oxide—better known as sand—throughout a graphite anode. This is what Tesla currently does with its batteries. Silicon oxide comes pre-puffed, so it reduces the stress on the anode from swelling during charging.

At NanoGraf, Researchers are boosting the energy of carbon-silicon batteries by embedding silicon particles in graphene, graphite’s Nobel Prize-winning cousin.

But to push that number into the 40 to 50 percent range, you have to take graphite completely out of the picture. Scientists have known how to make silicon anodes for years, but they have struggled to scale the advanced nanoengineering processes involved in manufacturing them.