Stanford Researchers use Carbon nanoparticles to Create Stable Lithium Anode

Jul 28, 2014 05:16 AM EDT

Stanford University researchers have found a way to design a pure lithium anode. The research is expected to make batteries smaller and more efficient.

The team used 20 nanometers-thick carbon nanosphere wall to create lithium anode.

All batteries have three components - an electrolyte that provides electrons, an anode that releases those electrons and a cathode that receives them. Currently, lithium ion batteries that are used in phones and laptops have lithium in the electrolyte, but not in the anode.

A pure lithium anode in a battery would boost its efficiency, researchers said.

'Of all the materials that one might use in an anode, lithium has the greatest potential. Some call it the Holy Grail,' said Yi Cui, a professor of Material Science and Engineering and leader of the research team, according to a news release. 'It is very lightweight and it has the highest energy density. You get more power per volume and weight, leading to lighter, smaller batteries with more power.'

Key component in a lithium ion battery is an anode, which is a negative pole discharging electrons. These electrons move towards the cathode. An electrolyte separates these two poles.

During charging, the positively charged lithium ions in the electrolyte are attracted to the anode and the lithium gathers on the negative pole. Currently, graphite or silicon is used to make the anode in a lithium ion battery.

A major problem in using a lithium anode in these types of batteries is that during charging, lithium ions expand as they accumulate on the anode. The expansion is uneven and results in cracks in the anode. The fissures in the anode could lead to development of hair-like structures called dendrites. These dendrites can short-circuit the battery and reduce its lifespan.

Another problem is that lithium in batteries produces a lot of heat, damaging electronics.

The team at Stanford said that using carbon can help solve several problems associated with lithium batteries. Scientists built a protective layer of interconnected carbon domes on the lithium anode. These structures - nanospheres - resemble honeycombs and are strong and flexible.

Researchers say that the nanospheres don't interfere with the chemical reaction in the battery, but provide mechanical strength to help the battery withstand the expansion of lithium during recharge-discharge cycles.

Researchers say that their study will help make batteries more efficient.

'With some additional engineering and new electrolytes, we believe we can realize a practical and stable lithium metal anode that could power the next generation of rechargeable batteries,' Cui said in a news release.

The study is published in the journal Nature Nanotechnology,

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