Lithium-ion batteries have become ubiquitous. We rely on them to power almost all of our mobile devices, from phones to laptops. Most electric cars even run on them.
There's good reason for this, of course. They're rechargeable and have a wide application spectrum, and we've perfected the technology such that lithium-ion batteries have been made efficient with relatively long lives.
But there's a problem. Lithium is a limited resource, with a demand that's far too high for the supply, and a growing demand at that. As a result, it's expensive, and could soon become impracticably so.
Needless to say, there's a growing urgency to find an alternative to lithium, and that's where sodium comes in. Sodium, like lithium, is an alkali metal, and therefore it possesses some of the same chemical properties that makes lithium so useful in batteries. Unlike lithium, however, sodium is extremely abundant; our oceans are filled with it (think: sea salt). Sodium-ion batteries would therefore be extremely cheap compared to lithium, reports Science Daily.
You might be wondering why we haven't been using sodium all along. The truth is, it can't be perfectly swapped for lithium. For instance, it has a larger ion size and the chemistry isn't exactly the same. Current materials used in lithium-ion batteries won't work with sodium, and so in some ways we need to retool how we make these batteries before the lithium can be replaced.
Tackling the hurdles
Luckily, researchers at the Nagoya Institute of Technology (NITech) in Japan are on the case. They have demonstrated that a specific compound, Na2V3O7, shows desirable electrochemical performance when paired with sodium, as well as crystal and electronic structures that are sodium-compatible. Even better, sodium-ion batteries constructed with this material have shown remarkable charging speeds of only about six minutes. When has your phone ever charged that fast?
"Our aim was to tackle the biggest hurdle that large-scale batteries face in applications such as electric cars that heavily rely on long charge durations. We approached the issue via a search that would yield materials efficient enough to increase a battery's rate performance," wrote the researchers.
There are a few hurdles to overcome before sodium-ion batteries can compete with lithium-ion performance. Most urgently, researchers found that Na2V3O7 underwent deterioration in the final charging stages, which significantly limits its practical storage capacity. That's a problem, but one that scientists are optimistic they can overcome with more research.
With a little luck, it may not be long before lithium-ion batteries become relics of the past, when charging speeds took much longer and our devices were much more expensive.