Commercial lithium-ion batteries have always relied on cathodes that contain cobalt, but the expensive metal’s supply chain is fraught with issues.
A new cobalt-free cathode could provide reprieve (Adv. Mater. 2020, DOI: 10.1002/adma.202002718). What’s more, in lab tests, lithium-ion battery cells made with the new cathode held more energy over hundreds of charge cycles than commercial ones.
Battery cathode materials are layered crystals of lithium metal oxides. The metal is usually a mix of nickel, cobalt, aluminum, and manganese. Nickel alone would give the most energy-dense batteries, meaning cars with longer driving range, but it is unstable and reactive. Cobalt is
key for boosting energy density and battery life because it keeps the layered structure stable as lithium ions get reversibly stuffed into and extracted from the cathode during battery operation.
Most of today’s electric vehicle batteries use nickel-manganese-cobalt cathodes, with 60% nickel and 20% each of cobalt and manganese. Researchers are working on pushing nickel up to 80% and bringing the other metals down to 10% each.
But some carmakers want to eliminate cobalt entirely, given its scarcity and ethical considerations around mining the metal. Around two-thirds of the world’s cobalt mining happens in the Democratic Republic of Congo, where operations are linked to human rights and environmental abuses. Cobalt-free cathodes made so far, though, have lagged in performance and have not been tested in practical cells—until now.
Arumugam Manthiram, a solid state chemist at the University of Texas at Austin, and his colleagues made a high-performance, cobalt-free cathode material that is 89% nickel, with aluminum and manganese comprising the rest. Making a layered crystal with an even distribution of metal ions is key to a good cathode, but without the help of cobalt, it has proven difficult, Manthiram says. “The ions tend to segregate, so you won’t get performance,” he explains.
The UT Austin team was able to get a uniform distribution by carefully controlling their chemical synthesis. They first mix aqueous solutions of nickel, manganese, and aluminum salts. Then they add potassium and ammonium hydroxide to maintain a precise pH and heat to a controlled temperature of 50°C. This forces the metal hydroxides to precipitate out of the solution together, keeping the ions evenly distributed. The precipitate is then filtered, mixed with lithium hydroxide, and heated until it sinters into 12 µm spheres of the final cathode material.
The researchers made battery pouch cells with the new cathode and a commercial graphite anode, and compared it with nickel-manganese-cobalt cathodes. The new cathode battery had higher energy density over 1000 charge cycles. Manthiram and his colleagues have launched a start-up, TexPower, to commercialize the material.
K.M. Abraham, chief technology officer at battery consulting company E-KEM Sciences, says the long-term safety and performance of the new material will need to be assessed using industrial scale cathodes. But he says the work is a very important development. “These investigators appear to have finally achieved the long sought-after cobalt-free cathode,” he says.
By: Prachi Patel
INEOS Styrolution, the global leader in styrenics, has today announced the official opening of a new world-scale ABS facility located in Ningbo, China, together with its joint venture partner SINOPEC. The facility has an annual nameplate capacity of 600,000 tonnes.
The merger of Röhm’s Acrylic Products business unit and SABIC’s Functional Forms business has resulted in the formation of Polyvantis. This new company will offer extruded products in the forms film, sheet, pipe and rod for markets that include building and construction, transportation and aviation, electrical and electronics, automotive and home and garden.
Abu Dhabi National Oil Co. (Adnoc) is considering plans to acquire upstream oil and gas company Wintershall DEA, an affiliate of BASF SE, according to a Bloomberg report citing people with knowledge of the matter. A deal to acquire Wintershall DEA could be worth more than €10 billion, the report said. BASF and Adnoc declined to comment on the report.