Stanford have created what looks to be the holy grail of lithium-ion batteries architecture and battery life, with the research here lead by Yi Cui. What they have done is work out how to create a rugged lithium electrodes that increase the amount of charge which can be stored by 3-4 times, this could increase the life of your battery, while reducing the size and cost of the battery.
A lithium ions battery capacity is dictated by how many lithium ions can be utilized by the anode while charging. In most lithium ion batteries the anode is constructed from the material known as graphite. Graphite is cheap and long lasting as it can have latterly hundreds of charge cycles, but its useful capacity of charge is quite low, around 350mAh/g.
With lithium being the far best anode material over graphite as it has almost (theoretical) ten times the capacity of graphite with 3,860mAh/g, however the drawback is that this degrades very quickly and isn’t robust. More importantly they have a tendency to explode when in contact with the electrolyte. If somehow these issues could be altered or removed the lithium anode would be extremely efficient.
If these niggling issues could be rectified, a LIB with much higher capacity could be built (not quite 10 times higher though; there are lots of other factors at play that prevent theoretical limits from being hit).
A team at Stanford University led by Yi Cui (who has masterminded other amazing breakthroughs) have found a way of creating lithium anodes which keep their capacity over a period of 150 charge cycles, and they don’t explode. ( which is a bonus)
To read how they did this follow the link below:
[doi:10.1038/nnano.2014.152 – “Interconnected hollow carbon nanospheres for stable lithium metal anodes”]
With a new nano-sphere coating the lithium anodes no longer crack from dendrites.
One of the main problems with lithium is that it expands dramatically when it absorbs ions during charging causing cracks within the metal and the ions then pour out the cracks creating “mossy” metal deposits known a dendrites. Dendrites quickly lower the battery’s efficiency enough so that it becomes useless to use.
To prevent the cracks from forming Stanford has developed a way of depositing a layer nano-spheres on the surface of the lithium anode. As you can see in the photo above.
The nano-spheres on the surface of the lithium create a barrier that is strong enough to maintain the lithium’s structural integrity, whilst still allowing the charge carriers to move though the material. The layer is around 20nm thick and also prevents the lithium from exploding.
Microscopic imagery of Stanford’s carbon nanospheres
This new lithium anode structure has a columbic (Faraday) efficiency of around 99% after a period of 150 charge cycles. Cui says it needs to be 99% so that it can be developed commercially, but they still need to make this efficiency higher for it to truly hit the markets.
“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.”
If this hits the market it could massively increase the battery life of any mobile device, or electric vehicle, with a smaller cheaper battery.