Combinatorial synthesis has proven extremely effective in screening for new battery materials for Li-ion battery electrodes. Here, a study in the Li-Ni-Mn-Co-O system is presented, wherein samples with nearly 800 distinct compositions were prepared using a combinatorial and high-throughput method to screen for single-phase materials of high interest as next generation positive electrode materials. X-ray diffraction is used to determine the crystal structure of each sample. The Gibbs' pyramid representing the pseudoquaternary system was studied by making samples within three distinct pseudoternary planes defined at fractional cobalt metal contents of 10%, 20%, and 30% within the Li-Ni-Mn-Co-O system. Two large single-phase regions were observed in the system: the layered region (ordered rocksalt) and cubic spinel region; both of which are of interest for next-generation positive electrodes in lithium-ion batteries. These regions were each found to stretch over a wide range of compositions within the Li-Ni-Mn-Co-O pseudoquaternary system and had complex coexistence regions existing between them. The sample cooling rate was found to have a significant effect on the position of the phase boundaries of the single-phase regions. The results of this work are intended to guide further research by narrowing the composition ranges worthy of study and to illustrate the broad range of applications where solution-based combinatorial synthesis can have significant impact.

The catalytic performance under simulated transient start-up and shut-down conditions is evaluated for five potential cathode-side catalyst compositions containing Pt, Ir and Ru. Experiments using the rotating disk electrode technique showed that samples containing a solid solution of Ir and Ru on top of a Pt base layer were the most active and the most durable over 1000 simulated start-stop events.

A test protocol to measure catalyst durability and OER activity through multiple simulated fuel cell start-up shut-down pulses has been developed. Data for NSTF-coated glassy carbon disks coated with platinum and platinum with an overlayer of IrRu are presented. A small amount of catalyst with high oxygen evolution activity deposited on platinum leads to a significant reduction in the potential an electrode will see during a transient start-up or shut-down pulses.

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