Fundamental insights into the transport of lithium for the design of novel cathode materials and solid state conductors.

The world is going electric. The growth of electrochemical energy storage is projected to reach several TWh of annual production by 2030, driven by electrification of the automotive market and penetration of electrical energy storage into the grid. I will discuss the scientific challenges with two new materials technologies that will drive this electrification: solid state batteries, and novel cation-disordered rocksalt cathodes.
Cobalt and nickel resources used in today's layered NMC cathodes for Li-ion may not be able to keep up with the rapidly growing demand for Li-ion energy storage. Recently developed disordered rocksalt cathodes present a Cobalt and Nickel-free high-energy density alternative. In these novel materials, well-defined Li transport channels are replaced by statistical percolation of low barrier, Li-rich, environments through a cation-disordered landscape. The flexibility of working with a cation-disordered structure creates the option to use a much broader set elements, many of which are abundant and inexpensive. More than a dozen novel cation-disordered cathode materials have been synthesized and tested, most of which contain one or more of either Ti⁴⁺, Nb⁵⁺, Zr⁴⁺, Mo⁶⁺ and a redox active elements from the group of Mn, Fe, V, Ni. While the high-valent cations create short-range order which can destroy Li percolation, we have recently shown that high-entropy systems have reduced short-range order and much high Li transport rates.
Solid-state batteries, in which the liquid electrolyte is replaced with a solid-state Li-ion conductor offer the promise of safe energy storage with very high energy density. While many sulfide systems with high ionic conductivity exist their limited stability and toxicity makes them less suitable in commercial battery applications. I will show how we have systematically investigated the mechanisms that create very high Li-ion conductivity in solids and used it to develop several novel solid electrolytes.