Building A Better Battery
How new advances in engineering and science are creating a new generation of longer-lasting, faster-charging, more efficient batteries
By Christopher Castellaw
It’s a situation we’re all familiar with, right at the moment when you most need to use your cell phone, tablet, or laptop, the battery light begins flashing and you find yourself wishing you’d plugged it in before you needed to complete some critical task. With our increased dependence on the technological marvels that have become part of our ever day lives, we’ve also developed a dependence on the batteries that power them. Even now this article is being written on a laptop that, while it features battery life that couldn’t have been imagined in previous generations of technology, is completely dependent on the battery that powers it.
The overwhelming majority of the rechargeable modern electronics we use rely on one specific type of battery; the Lithium-ion battery, commonly referred to as Li-ion batteries. These batteries are capable of charging all of the electronics we use on a daily basis, from cell phones to laptops to gaming systems, and are able to hold their charge even when they are not in use. Increasingly, Li-ion batteries are even showing up in hybrid and electric cars, such as the batteries that power Tesla’s fleet of all-electric vehicles.
For all of the benefits that these batteries provide us, they also come with drawbacks that limit their power and range of applications when it comes to day-to-day use. To counteract these drawbacks and provide us with a new generation of faster and longer-lasting devices, scientists and engineers from all around the globe are working to develop a new generation of Li-ion batteries that will provide more powerful, faster-charging power for our electronic devices.
Memory Loss
One of the most common drawbacks of Li-ion batteries, and one that almost anyone who owns a cell phone will be familiar with, is known as “memory effect”. Memory effect occurs when a battery loses the ability to hold as long of a charge due to being regularly recharged before the battery has been completely drained; this is the reason why when you buy a new cell phone the instructions tell you to drain it completely before fully charging it again. Scientists such as Petr Novák, who serves as the Head of Electrochemical Energy Storage Section at the Paul Scherrer Institute in Switzerland, along with his team have been doing research on why this memory effect occurs, and ways in which software could provide better battery management in our mobile devices and, increasingly, our vehicles.
In a study published in the journal Nature Materials, Novák and his fellow researchers Tsuyoshi Sasaki and Yoshio Ukyo showed that, contrary to what had been assumed by many people, Li-ion batteries share the same flaw of memory effect that previous generations of batteries such as nickel-cadmium and nickel-metal-hydride had. Their research showed that even after one cycle of recharging a Li-ion battery before it had been fully discharged, the amount of charge held by the battery during subsequent recharge cycles would be diminished. This research is especially important given the increasing numbers of electric vehicles on the roads around the world; the environmental benefits of using electric, rather than internal combustion-powered vehicles, may not be as appealing to consumers when see that their new electric car lasts for increasingly shorter lengths of time with subsequent charges. Their study found that with innovative uses of software regulation in the battery management systems of Li-ion powered devices of all sorts, this memory effect could be negated and possibly eliminated altogether, leading to batteries that hold their charge longer without the diminished storage capacity over time found with other types of batteries.
Harder, Better, Faster, Stronger
Another common problem with current Li-ion batteries that is being taken on by the scientific community is the length of time required to fully charge current batteries. As anyone who has tried to get a few minutes of charge on their electronic device before a long flight has seen, many of the electronic devices we use today charge at an often painfully-slow rate. While some newer cell phones have quick-charge technology that allows them to gain a decent charge in as little as 15-20 minutes, many of today’s rechargeable devices require an hour or more of being plugged in to gain a reasonable amount of electric charge. As with their work on the issue of memory effect, researchers at the Paul Scherrer Institute are also providing new insights in how to effectively and quickly charge Li-ion batteries. A team led by Petr Novak, along with Michael Hess, Tsuyoshi Sasaki, and Claire Villevielle are giving us new insights into how Li-ion batteries charge at the basic levels and how we can possibly develop new, fast-charging Li-ion batteries going forward.
Li-ion batteries charge by moving lithium ions back and forth between two electrodes within the battery, one a positively charged cathode and the other a negatively charged anode; the higher the charging voltage the faster the battery will charge, with a converse effect at lower voltages. According to research published by the Paul Scherrer Institute researchers in the journal Nature Communications, by increasing the voltage at which the batteries are charged, the lithium ions are able to more freely travel between layers with less build-up of ions on one half of the electrode, which results in faster charging. Using x-rays to monitor changes in the electrodes during charging, known as an operando XRD-electrochemical impedance spectroscopy, the team found that when these ions are able to travel with less impedance, the charging time can be drastically reduced. While this particular study was focused on lithium iron phosphate batteries, an offshoot of Li-ion technology, the team believes that these findings can also be applied to other types of Li-ion batteries and can be used to increase their charging times as well. So in the next few years you might find the time it takes to go from a single bar of power to a full charge before hopping on a flight changing from a matter of hours to a matter of minutes.
Plant Power
As we continue to put Li-ion batteries in more and more devices, one common critique against the technology is the negative environmental impact that the production, storage, and disposal of these batteries have. Even as the use of Li-ion batteries has continued to soar over the past decade, there are constant reports from government and private researchers showing that the environmental and health impacts of these devices are not something to be taken lightly. In a 2013 report from the United States Environmental Protection Agency (EPA) entitled Application of Life-Cycle Assessment to Nanoscale Technology: Lithium-ion Batteries for Electric Vehicles, the EPA listed a number of serious concerns about the negative impacts of the widespread use of these types of batteries, specifically as it applied to electric vehicles,
In their report the EPA showed that, by 2050, the battery demand in the United States will consist of nearly 60,000 tons of contained lithium annually, with only slightly over 40,000 tons of that material being available for recycling. That leaves us with 20,000 tons of lithium ending up in landfills, roughly 1.5x the daily mass of trash produced in New York City. Needless to say, this has the potential to have a huge negative impact on the environment. With nearly 20 different input flows of materials making up the chain that leads to the production of Li-ion batteries, from minerals such as bauxite, sodium chloride, and copper ore, to fossil fuels such as coal, natural gas, and crude oil, the production of Li-ion batteries leaves a heavy toll on the natural world. With current production methods, roughly 12% of the energy used by Li-ion batteries for vehicles is in the process of materials extraction and processing, as well as component, product, and materials manufacturing. On top of this, the production of batteries for vehicles has shown large rises in the potential for ecological and human health-related toxicity according to the EPA study.
In response to the economic, environmental, and human costs associated with the increased production and use of Li-ion batteries, researchers are now beginning to look for ways to make batteries that are more environmentally friendly and that take advantage of readily-available recyclable materials for battery production. Two of the most interesting examples of this come from the work of researchers from the School of Materials Science and Engineering at Beihang University, who propose using cornstalks as a source for anodes for Li-ion batteries, and researchers in Singapore supported by the Singapore Natural Research Foundation who have examined how disposable bamboo chopsticks could serve the same purpose. While there will still be negative environmental impacts related to the extraction and creation of Li-ion batteries, changing even one area of battery production can have a huge effect when it comes to make “greener” batteries.
Currently, the anodes within Li-ion batteries are traditionally made from graphite due to its superior electric properties. The researchers from Beihang University and Singapore are examining how using plant materials, which have a similar carbon makeup as graphite, could provide a more economical and environmentally friendly building block for these batteries. In China, over 200 million tons of cornstalks are produced annually as part of food production, with the vast majority of these either ending up burned or buried in landfills. According to the researchers at Beihang, these cornstalks could instead be transformed into carbon nanofibers for use in the battery industry. After undergoing treatment in a chemical bath to remove some of the plant material, the cornstalks are heated to 800 degrees Fahrenheit in a nitrogen environment, causing the carbonized remains of the stalks to take on many of the same properties as graphite.
In a similar method to their counterparts in China, the researchers from Singapore have shown that it is possible to change the chemical structure of disposable bamboo chopsticks in such a way that they can be made into viable anodes for use in Li-ion batteries for electric vehicles. In Japan alone, over 24 billion pairs of bamboo chopsticks are tossed away each year, the equivalent of what the Singapore study calls “millions of cubic meters of timber”. Much like the cornstalks in China, the majority of these will end up either burned or buried in landfills. The chopsticks undergo a similar process to the preparation of the cornstalks, first undergoing a chemical treatment to distribute the cellulose evenly and then being placed under high heat in order to carbonize the remaining material. These recycled carbonized materials exhibit the same sorts of electrically conductive properties of other reclaimed plant fibers and graphite itself. The widespread adoption of the techniques being pioneered by these two groups of researchers could not only result in a vast decrease in the amount of plant-based material ending up in landfills worldwide each year, but also provide a much more environmentally-friendly way to manufacture some of the key components of Li-ion batteries, reducing the environmental impacts that result from their manufacture.
Moving Forward
Batteries, and especially Li-ion batteries, are a technology that looks to become an increasingly common and necessary part of the lives of all us as technology continues to advance in the years to come. While there have been great strides over the past several decades in the efficiency and reliability of this technology, it is becoming more and more evident that the current status quo isn’t sustainable from the perspectives of battery life, storage capacity, and environmental and health impacts on society as a whole. This is why this new generation of scientists and engineers are working day and night to make these miraculous devices that literally power so many aspects of our everyday life smarter, more powerful, and greener so that, next time you’re minutes away from that flight you won’t have to scramble to find a power outlet, your device will have plenty of clean power to keep it going.
