(John B. Goodenough Award of The Electrochemical Society) Oxide Revolution in Energy Storage

Abstract

Lithium-ion batteries have become an integral part of our daily life. The triumph of lithium-ion batteries is due to their much higher energy density compared to the other rechargeable battery systems. The high energy density along with superior cycling stability became possible because of the use of oxide cathodes in lithium-ion cells. There are only three families of cathodes for practical lithium-ion cells, and all the three of them are oxides: layered, spinel, and polyanion oxide cathodes.As we move forward with vehicle electrification and renewable energy storage, multiple parameters, such as cost, energy density, power density, cycle life, safety, and environmental impact, need to be balanced. Among them, cost along with sustainability and supply chain issues is at the forefront. Cathode is the most expensive component in the cell. The oxide cathodes will still dominate the field, but with fierce efforts to reduce or eliminate less abundant and expensive metals in the cathode. This presentation will focus on eliminating the most expensive cobalt from layered oxide cathodes, then reducing the next expensive nickel in oxide cathodes, and finally replacing/eliminating lithium with sodium in oxide cathodes.Reducing or eliminating cobalt in layered oxide cathodes by increasing the nickel content helps to increase the energy density and reduce the cost, but cathodes with high nickel contents are plagued with cycle, thermal, and air instabilities along with severe scale-up challenges. This presentation will focus on overcoming these challenges with controlled compositional and synthesis designs along with a profound understanding of the intricacies involved with the aid of advanced characterization methodologies. Particularly, issues, such as what different dopants really do, which dopant does what, and which is critical between surface reactivity and crack, in stabilizing high-nickel cathodes will be discussed. The dependence of surface reorganization/degradation pathways on electrolytes and the importance of electrolyte composition and high-voltage stability in stabilizing the cathode-electrolyte interphase will be presented with both graphite and lithium-metal anodes.Finally, elimination of both cobalt and lithium while reducing the nickel content much further down will be described with sodium batteries based on layered oxide cathodes. Tailored electrolyte designs that provide long-life sodium cells with suppressed dendrites and enhanced safety will be presented.