In 1973, the first call from a mobile phone was made on a device that had a twenty minute battery life. Today, you can search the internet (do people even make calls anymore?) for almost 15 hours straight on some phones without running out of juice. In this race for higher capacity, longer lasting batteries the sustainability and safety of the materials hasn’t always been the focus. As the pressure to create and use sustainable materials increases, academic researchers and companies alike are investing more in greener energy storage technologies.
With the July reveal of improvements to the Tesla Model S, better batteries have been all the rage. But even Tesla’s batteries aren’t perfect; the car battery is still the size of a mattress and requires a variety of metals. According to the National Academy of Engineering, these blends limit the risk of thermal runaway reactions, but may cut the battery lifespan short.
Although lithium ion batteries are commonly used, their challenges include the risk of explosion during transportation or use - as in the case of a popular gift last year - and the manufacturing poses health concerns for workers. Additionally, because of the potential for explosion, lithium ion battery production is expensive. This limits the viability for their incorporation into electric cars and other large devices. The environmental cost of mining these materials also leaves something to be desired.
Here’s where green chemistry comes in. These challenges only reveal the plethora of opportunities for innovation. Chemists the world over have been diligently working to develop solutions for better energy storage. In the last year there have been publications ranging from batteries that can be folded like origami to graphene-based supercapacitors.
The most common approach to new, more sustainable battery development has been fairly straightforward: replace lithium with a similar, but less hazardous material like sodium. The dual benefits of sodium are its greater abundance and lower risk of explosion when compared to lithium for battery use. In the world of start-ups, developing new batteries is a promising field for those seeking investment. U.K.-based Faradion’s sodium ion battery technology is just one example of entrepreneurship that has caught the attention of the press and researchers alike.
Of course, sodium and lithium have differences, so scientists at the University of Texas, Austin are working on an eldfellite cathode to allow for more efficient diffusion of sodium ions. Although it requires tweaking our current battery model, the appeal of making sodium work for batteries is high; it is hugely abundant and inexpensive to process. Sodium has also been used in new flow batteries with aqueous electrolytes, like those with nearly 100% efficiency being developed at the Pacific Northwest National Laboratory. Other metals being explored as alternatives to lithium include aluminum, iron and calcium.
Teams funded by the Advanced Research Projects Agency-Energy (ARPA-E) take a wide range of innovative approaches to advance high-impact energy technologies. The agency will provide up to $400 million in funding for energy technologies in 2016. Promising start-ups receiving funding from ARPA-E include a small business called 24-M that is working to combine lithium ion with nanotechnology. They hope to significantly reduce cost while eliminating the need for organic solvents and improving recyclability. As new batteries are developed, such a degree of focus on design is key to ensuring safety and sustainability.
At the Jet Propulsion Laboratory (JPL), a collaboration between NASA and the California Institute of Technology, big things are happening in metal hydride/air technology. In addition to using fewer non-renewable metals, reducing our dependence on petroleum products is an important driver for many research groups. To promote adoption of electric vehicles, an ARPA-E supported project in progress at the JPL seeks to develop a new aqueous, low cost battery. A different motivation for similar technology - wearable electronics like this flexible zinc-air battery that uses a non-precious metal catalyst - are creating another push for better battery development.
Other research groups are moving away from traditional battery models altogether. A paper to be published in Green Chemistry, “Biomass-derived binderless fibrous carbon electrodes for ultrafast energy storage” hints a very different future for batteries. Perhaps instead of metal-dependent batteries, the key to sustainable energy storage is in renewable, biobased materials. This route could address many of the challenges associated with traditional batteries, like eliminating the need for and environmental impact of mining associated with battery materials.
With ever-increasing demand for longer lasting, less expensive batteries it’s impossible to say which energy storage technology will take the lead. While it may be one of these ideas currently in development, with green chemistry-inspired innovation batteries in the future could make our lithium ion-powered cell phones seem as ridiculous as the shoebox-sized phones of the 1970’s seem now.
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