Lithium-ion batteries power so many of today's technologies, from our phones and earbuds to the next class of electric vehicles.
The batteries, however, contain cobalt, which must be mined. Only a very small percentage of Li-ion batteries are recycled too, increasing the demand for the metal and other strategic elements.
A team from Texas A&M developed a battery that's metal-free and replaces cobalt with organic elements: a salt electrolyte and polypeptide cathodes and anodes.
The recyclable architecture minimizes dependance on strategic metals and is an important step in sustainable design, according to the team. The all-polypeptide organic battery degrades on demand.
"By moving away from lithium and working with these polypeptides, which are components of proteins, it really takes us into this realm of not only avoiding the need for mining precious metals, but opening opportunities to power wearable or implantable electronic devices and also to easily recycle the new batteries,” said Dr. Karen Wooley , distinguished professor in the Department of Chemistry and holder of the W.T. Doherty-Welch Chair in Chemistry in the College of Science.
The polypeptide batteries are degradable, potentially recyclable, non-toxic, and safer across the board, says Wooley who also worked with Dr. Jodie Lutkenhaus, Axalta Coating Systems Chair and professor in the Artie McFerrin Department of Chemical Engineering, on the project. (The team's research appeared in the May issue of Nature .)
The polypeptides serve as both the anode and cathode materials. The redox-active polypeptides are active and stable during battery operation and subsequently degrade on demand in acidic conditions to generate amino acids, other building blocks, and degradation products.
The degradability of the organic battery, composed of redox-active amino-acid macromolecules, is one of the major breakthroughs of the research, according to Dr. Lutkenhaus.
“The big problem with lithium-ion batteries right now is that they're not recycled to the degree that we are going to need for the future electrified transportation economy,” said Lutkenhaus. “The rate of recycling lithium-ion batteries right now is in the single digits. There is valuable material in the lithium-ion battery, but it's very difficult and energy intensive to recover.”
In a short Q&A with Tech Briefs below, Lutkenhaus explains more about the importance of a recyclable battery, and what will need to happen before organic batteries begin powering our devices.
Tech Briefs: Why do you think it’s so important to develop an alternative chemistry for batteries?
Prof. Jodie Lutkenhaus: Today's lithium ion batteries are not commonly recycled because the recycling process remains challenging and energy-intensive. Developing an alternative battery chemistry allows us to design from first conception recycling or degradation capabilities.
Tech Briefs: What needs to happen for there to be mainstream adoption of these batteries?
Prof. Lutkenhaus: For these batteries to gain mainstream adoption, the battery's capacity and cycle life must be improved. Further, to truly achieve a recyclable battery, the degradation products will need to be isolated and reconstituted.
Tech Briefs: Is the idea that these building blocks can be used again and again?
Prof. Lutkenhaus: If we can isolate the degradation products, then we can re-polymerize them back into active cathodes and anodes. In that way, we could come full circle in the battery's life cycle.
Tech Briefs: How does the energy storage compare to lithium-ion batteries?
Prof. Lutkenhaus: The initial capacity of our battery is about 30% of a lithium-ion battery. However, with long-term cycling our capacity fades to about 10% of a lithium-ion battery.
Tech Briefs: What are the components of the battery, and what is the most significant way that the battery differs from conventional setups? How different does it look?
Prof. Lutkenhaus: The basic architecture of our battery is the conventional combination of cathode, anode, and electrolyte, but we use entirely different materials relative to lithium-ion batteries. We replace the conventional battery materials with polypeptide cathodes and anodes and organic salt electrolyte. (Read Prof. Lutkenhaus's blog post to learn more.)
Tech Briefs: How do you create the kind of acidic environment to degrade the battery on demand?
Prof. Lutkenhaus: To initiate the degradation, we exposed the battery components to an acid. The polypeptide chains were then hydrolyzed and broken down into smaller building blocks.
Tech Briefs: And what inspired you try this kind of build?
Prof. Lutkenhaus: We were inspired to create this type of battery because of the sociopolitical issues affiliated with cobalt mining, as well as potential supply chain pressures.
Tech Briefs: What will you be working on next?
Prof. Lutkenhaus: Our next tasks are to enhance the capacity and cycle life of the battery so that the batteries can last longer and deliver more energy. We are also looking to adapt these batteries for use in the body to power biomedical devices.
Tech Briefs: How hopeful are you that you can improve the battery’s capacity? And do you envision this kind of battery being used in the next 10-20 years?
Prof. Lutkenhaus: Improving the battery's capacity shouldn't be too difficult. It will require switching out the redox-active groups with more active ones. We will also need to stop dissolution during cycling. I think that a battery following this concept — in which the active materials can be broken down and rebuilt back up — could be used in the next 10-20 years. It will require researchers to redesign the chemistry of the battery from square one, with consideration of not only performance but break-down and reconstitution.
What do you think? Share your questions and comments below.
Transcript
00:00:00 So you’re outside chasing around that rare Squirtle, when BAM--your phone dies! We can’t help you catch Pokémon, but we can give you three hacks for keeping your phone battery juiced. [Splash] Alright before we get into the hacks--here’s how your phone battery works. Smartphones, laptops, and Teslas get their power from rechargeable lithium-ion batteries. All batteries have the same three basic parts: a positive electrode called a cathode, a negative electrode called an anode, and a chemical layer called an electrolyte that lets electrical charge flow between the electrodes. In lithium-ion batteries, the electrode combo is usually a lithium cobalt oxide cathode and a graphite anode.
00:00:43 When you plug in your phone, electrons enter your phone’s battery and cause lithium ions to meet up with them at the anode. Once at the anode, the lithium atoms nestle in sites between the graphite’s carbon layers. When you unplug your phone, the process reverses: lithium atoms at the anode start losing their electrons. The electrons zip through the circuit, providing the current to run your phone. Meanwhile, lithium ions journey through the electrolyte. They reunite with the electrons at the cathode. These processes keep going until all ions reach the cathode, causing that dreaded flashing battery symbol.
00:01:17 Every time you burn through 100% of the battery’s charge, which is called its capacity, you take the battery through one charge cycle. Each cycle inches the battery closer to death by shaving off some of its total capacity. So here’s how to keep your phone’s battery charge and life lasting longer with science. Hack #1: Avoid heat! Heat does nasty things to lithium-ion batteries. And we’re not talking thermonuclear-level heat: we’re talking about when you forgot your phone in a hot car or left it in the sun at the beach. As your phone gets warm, the heat speeds up the chemical reactions that cause a battery to go kaput.
00:01:50 These reactions break down the electrolyte and form products on the anode. This blocks lithium ions from nestling into the graphite. Fewer site means less capacity and you’ll have to charge your phone more often. Even worse, heat can start a “thermal runaway”. Once the cobalt oxide gets hot enough, it starts a cycle of reactions that throw out more and more heat. All this heat starts to boil the liquids in your phone’s battery building pressure until the battery EXPLODES!!! Hack #2: Don’t Let Your Phone Die. Lithium-ion batteries don’t need to be fully discharged before recharging, unlike nickel
00:02:23 batteries. Nickel batteries suffer from the “memory effect”—meaning that unless they’re at 0%, they’ll “forget” part of their capacity when recharged. But lithium-ions never forget, and they loathe a full discharge. When you drained your phone to zero, your phone lost more capacity so your charges won’t last as long. So make sure your phone doesn’t die. If it’s on the verge of death just turn it off. You can tweet us thanks later. Hack #3: Store at 50% charge.
00:02:49 We weren’t kidding about lithium-ions hating it when you let your phone die. If you’re leaving a fully discharged battery alone for a while, it could get unstable. Like, the thermal-runaway-and possibly-blow-up kind of unstable. Fortunately for us, modern batteries trip a self-destruct circuit before destabilizing. Unfortunately for us, self-destructed batteries never work again. So if you’re going on vacation to a foreign country where you won’t be using your phone, make sure the battery is around 50% before turning it off. And if you’re letting it sit for a longer period of time, turn it on about every six months to make sure it’s charged to 50%. This way you avoid both self-destruction and capacity loss.
00:03:29 With our simple hacks, you can keep your current battery in top shape for the next time you go hunting Squirtle. What features do you want to see in your next smartphone? Let us know in the comments and hey, thanks for watching.
