3D Quantification of Elemental Gradients within Heterostructured Particles of Battery Cathodes

Heterogenous architectures with elemental gradients tailored within particles have been pursued to combat the instabilities limiting Ni-rich cathode materials for lithium-ion batteries. The growth of different compositional layers is accomplished during the synthesis of hydroxide precursors. However, the extent to which these concentration gradients are modified during high-temperature reactions is difficult to establish in their intact, spherical form. Here, we show the entire three-dimensional structure of a secondary particle can be resolved nondestructively with differential X-ray absorption spectroscopy (XAS) through transmission X-ray microscopy (TXM). The relationship between particle location and elemental content was fully quantified, with high statistical significance, for heterostructures possessing different compositional gradients in the precursors with 90:5:5 Ni:Mn:Co core compositions. Reduced elemental heterogeneity was observed after high-temperature synthesis, but gradients remained. The methodology presented should be used to guide synthesis while assuring that gains in electrochemical performance are linked to precise elemental distributions at the nanoscale

Chemomechanically Stable Ultrahigh-Ni Single-Crystalline Cathodes with Improved Oxygen Retention and Delayed Phase Degradations

The pressing demand in electrical vehicle (EV) markets for high-energy-density lithium-ion batteries (LIBs) requires further increasing the Ni content in high-Ni and low-Co cathodes. However, the commercialization of high-Ni cathodes is hindered by their intrinsic chemomechanical instabilities and fast capacity fade. The emerging single-crystalline strategy offers a promising solution, yet the operation and degradation mechanism of single-crystalline cathodes remain elusive, especially in the extremely challenging ultrahigh-Ni (Ni > 90%) regime whereby the phase transformation, oxygen loss, and mechanical instability are exacerbated with increased Ni content. Herein, we decipher the atomic-scale stabilization mechanism controlling the enhanced cycling performance of an ultrahigh-Ni single-crystalline cathode. We find that the charge/discharge inhomogeneity, the intergranular cracking, and oxygen-loss-related phase degradations that are prominent in ultrahigh-Ni polycrystalline cathodes are considerably suppressed in their single-crystalline counterparts, leading to improved chemomechanical and cycling stabilities of the single-crystalline cathodes. Our work offers important guidance for designing next-generation single-crystalline cathodes for high-capacity, long-life LIBs

Scalable Synthesis of Pt/SrTiO₃ Hydrogenolysis Catalysts in Pursuit of Manufacturing-Relevant Waste Plastic Solutions

An improved hydrothermal synthesis of shape-controlled, size-controlled 60 nm SrTiO3 nanocuboid (STO NC) supports, which facilitates the scalable creation of platinum nanoparticle catalysts supported on STO (Pt/STO) for the chemical conversion of waste polyolefins, is reported herein. This synthetic method (1) establishes that STO nucleation prior to the hydrothermal treatment favors nanocuboid formation, (2) produces STO NC supports with average sizes ranging from 25 to 80 nm with narrow size distributions, and (3) demonstrates how SrCO3 formation and variation in solution pH prevent the formation of STO NCs. The STO synthesis was scaled-up and conducted in a 4 L batch reactor, resulting in STO NCs of comparable size and morphology (m = 22.5 g, davg = 58.6 ± 16.2 nm) to those synthesized under standard hydrothermal conditions in a lab-scale 125 mL autoclave reactor. Size-controlled STO NCs, ranging in roughly 10 nm increments from 25 to 80 nm, were used to support Pt deposited through strong electrostatic adsorption (SEA), a practical and scalable solution-based method. Using SEA techniques and an STO support with an average size of 39.3 ± 6.3 nm, a Pt/STO catalyst with 3.6 wt % Pt was produced and used for high-density polyethylene hydrogenolysis under previously reported conditions (170 psi H2, 300 °C, 96 h; final product: Mw = 2400, Đ = 1.03). As a well-established model system for studying the behavior of heterogeneous catalysts and their supports, the Pt/STO system detailed in this work presents a unique opportunity to simultaneously convert waste plastic into commercially viable products while gaining insight into how scalable inorganic synthesis can support transformative manufacturing