Here’s an update on some battery news from this week. First, researchers from the University of Ulm and the University of Freiburg reported they have created new anodes for aluminum-ion batteries that significantly improve their performance, while Lyten announced the opening of its pilot battery factory in the United States for lithium-sulfur batteries. Both could have an impact on the future of battery-powered transportation and energy storage.
Anodes For Aluminum-Ion Batteries
The German researchers published a paper entitled “On a high-capacity aluminium battery with a two-electron phenothiazine redox polymer as a positive electrode” in the journal Energy & Environmental Science this month. In it, they say they have developed an anode that consists of an organic redox polymer based on phenothiazine. Why is that important? Here’s in introduction to their findings.
Due to the scarcity of lithium and transition metal oxides used in traditional batteries, there is a strong impetus to develop alternative battery technologies for applications ranging from small devices to large scale stationary storage of electricity. Since aluminium is one of the most widely available elements in the Earth’s crust, Al-based batteries are considered promising candidates for such next generation energy storage devices.
However, to date, it remains a challenge to identify appropriate host electrode materials that reversibly insert (complex) aluminium ions. In this article, we demonstrate a strategy for designing such positive electrode materials. This strategy involves using an organic redox polymer as a positive electrode material, which reversibly inserts two [AlCl4]− ions with a specific capacity that surpasses that of graphite as a positive electrode material. In addition, it shows superior cyclability at fast C-rates. This concept could pave the way towards the development of advanced Al-based batteries and affordable energy storage devices.
Climate change and the increasing demand for electrical energy require the development of novel types of devices for the storage of renewable energy. While classical lithium-ion batteries might benefit from engineered electrode materials, next generation batteries should rely on abundant elements, be safe and of low cost, use non-toxic materials and be easy to recycle.
Aluminium is the most abundant metal in the Earth’s crust and its recycling is easy. Its high volumetric capacity of 8040 mA h cm−3 as a negative electrode material even exceeds that of lithium of 2046 mA h cm−3. In contrast to the latter, it can be reversibly stripped and deposited without forming dendrites, preventing short circuits. Favorably, the ionic liquid electrolytes currently used in Al batteries are non-flammable. Hence, rechargeable Al ion batteries (AIBs) hold great promise as storage devices. Yet, the development of rechargeable AIBs faces fundamental challenges and in particular lacks suitable positive electrode materials, leaving them still in their infancy.
“The study of aluminium-ion batteries is an exciting field of research with great potential for future energy storage systems,” Gauthier Studer, who led the research, told Innovation News Network. “Our focus lies on developing new organic redox-active materials that exhibit high performance and reversible properties. By studying the redox properties of poly(3-vinyl-N-methylphenothiazine) in chloroaluminate-based ionic liquid, we have made a significant breakthrough by demonstrating for the first time a reversible two-electron redox process for a phenothiazine-based electrode material.”
The redox polymer of the aluminium-ion batteries deposits the anions at potentials of 0.81 and 1.65 volts and provides specific capacities of up to 167 mAh/g. By contrast, the discharge capacity of graphite as an electrode material in batteries is 120 mAh/g. The researchers determined that aluminum-ion batteries using the electrodes they developed retain 88% of their capacity at 10C over 5000 cycles. At lower C rates, the observed decrease in performance was negligible.
Birgit Esser, one of the lead researchers, said, “With its high discharge voltage and specific capacity, as well as its excellent capacity retention at fast C rates, the electrode material represents a major advance in the development of rechargeable aluminium-ion batteries. Our concept provides the battery industry with advanced and affordable energy storage solutions.”
Lyten Christens Its Lithium-Sulfur Prototype Factory
Lyten lithium sulfur batteries. Image credit: Lyten
As exciting as the news about aluminum-ion batteries is, the technology exists only in the laboratory at the moment. Lyten is a California company that has been pursuing lithium-sulfur batteries for many years, helped by significant support from the US military. This week it celebrated the commissioning of its first pilot production facility that will be able to produce 200,000 battery cells annually. That’s a drop in the bucket compared to the number of lithium-ion batteries being produced commercially every year, but those prototype cells will be shared with potential customers in the military, the auto industry, and others for them to test and benchmark them for possible future use.
As we reported in September, 2021, the Lyten lithium-sulfur batteries have an energy density of up to 900 Wh/ kg — roughly three times greater than conventional lithium-ion batteries, thanks to a special 3-dimensional graphene that took years to refine. This unique material can be engineered and tuned at the molecular level to specific battery application requirements, the company says. It makes it possible to unlock the performance potential of sulfur by arresting the “poly-sulfide shuttle,” a compromising factor that shortens battery life and has prevented the use of lithium-sulfur batteries in electric vehicles until now. During Department of Defense testing, a LytCell™ prototype design has survived more than 1,400 charge/discharge cycles.
At the opening of the new factory, Celina Mikolajczak, chief battery technical officer for Lyten, said, “Lithium-sulfur is the battery chemistry that has the potential to electrify everything. A projected 50 percent lower cost bill of materials compared to conventional lithium-ion chemistries will enable significantly lower cost automotive battery packs, making an all electric automotive fleet economically achievable. The high energy density of the chemistry will make it appealing for application in heavy vehicles such as delivery vans, trucks, buses, and construction equipment, as well as in aviation and satellites. The raw materials for this chemistry are abundant throughout North America favoring a domestic supply chain and domestic manufacturing, supporting a strong American electrification industry.”
Also in that press release, Keith Norman, chief sustainability officer for the company, said, “Lyten is making a battery with a lower carbon footprint using readily available materials sourced in North America. Lyten’s Lithium-Sulfur battery uses no nickel, cobalt, or manganese (NMC), eliminating key environmental and ethical barriers to ramping up battery production to meet global demand. At scale, we target to produce the lowest carbon footprint EV battery on the market, more than 60 percent lower than best in class lithium ion batteries and more than 40 percent below emerging solid state batteries. For automakers to achieve their net zero commitments, we believe they will require a battery with a fundamentally lower carbon footprint and lighter weight, both features we are delivering with our lithium sulfur battery.”
The Takeaway
Yes, we know. All this happy talk is all well and good, but where are the low cost, long life batteries made with sustainable materials we need today? Patience, grasshopper. They are coming. As we have said many times, the batteries that will power our vehicles and store our electricity in 2030 are not in existence yet, but are being developed in laboratories all around the world. Progress takes time. Do you really want to climb aboard a battery-powered airplane that is using experimental batteries, or drive a car with high energy density batteries that need to be replaced after 6 months?
Of course not. Don’t be silly. Better batteries are coming, and our grandkids will think of NMC lithium-ion batteries the way we think of vacuum tubes. Around CleanTechnica headquarters, the future’s so bright, we gotta wear shades!
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Former Tesla Battery Expert Leading Lyten Into New Lithium-Sulfur Battery Era — Podcast:
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