Researchers from the University of California San Diego (UCSD) and the University of Texas at Austin, with colleagues at the US Army Research Laboratory and Lawrence Berkeley National Laboratory, have developed a thick cobalt-free high voltage spinel (LiNi_0.5Mn_1.5O₄ (LNMO)) cathode material with high areal capacity. The paper on their work is published in the Journal of Power Sources.

Advancing cathode materials with both high energy density and low cost have always been the main objective of battery material research. Developing cobalt-free cathode materials is one of the significant concepts to lower down the price of current LIBs. … It should be noted, the cost and sustainability of lithium-ion batteries are not only limited by the production of Co and Ni but also potentially limited by the lithium element itself.

… The price of Co fluctuates significantly, with the inconspicuous fall of Ni price and continues growing of Li price. It is expected that with the large-scale popularization of electric vehicles and energy storage, the price and consumption rate of lithium resources will be even higher. Developing cathode material with less lithium and cost-effective elements such as Mn/Fe/Al is thus quite imperative.

—Li et al.

(a) Annual price of Li, Mn, Al, Fe, Ni and Co elements; (b) element mass ratios in five common cathode materials; (c) benchmark radar map for five widely used cathode materials. Li et al.

High voltage spinel (LNMO), is one of the most promising candidates yet to be commercialized for novel cathode materials with high energy density, low cost, and improved safety. More importantly, the researchers note, it does not contain expensive cobalt or an excessive amount of lithium—making LNMO cost-effective and suitable for applications in the field of power batteries and large-scale energy storage.

However, the material faces two primary obstacles: inferior electronic conductivity and fast capacity degradation in full cells due to the high operating voltage.

By systematically addressing these limitations, we successfully develop a thick LNMO electrode with areal capacity loadings up to 3 mAh·cm⁻². The optimized thick electrode is paired with a commercial graphite anode at both the coin cell and pouch cell level, achieving a full cell capacity retention as high as 72% and 78%, respectively, after 300 cycles. We attribute this superior cycling stability to careful optimizations of cell components and testing conditions, with a specific focus improving electronic conductivity and high voltage compatibility.

These results suggest precise control of materials quality, electrode architecture and electrolyte optimization can soon support the development of a cobalt-free battery system based on a thick LNMO cathode (>4 mAh·cm²), which will eventually meet the needs of next-generation Li-ion batteries with reduced cost, improved safety, and assured sustainability.

—Li et al.

The University of Texas researchers, led by Arumugam Manthiram, have separately reported a new class of high-energy cathode anchored by high nickel content. (Earlier post.)

Resources

• Weikang Li, Yoon-Gyo Cho, Weiliang Yao, Yixuan Li, Ashley Cronk, Ryosuke Shimizu, Marshall A. Schroeder, Yanbao Fu, Feng Zou, Vince Battaglia, Arumugam Manthiram, Minghao Zhang, Ying Shirley Meng (2020) “Enabling high areal capacity for Co-free high voltage spinel materials in next-generation Li-ion batteries,” Journal of Power Sources, Volume 473, doi: 10.1016/j.jpowsour.2020.228579