Nature Energy article on Ultrafast Ion Transport at a Cathode–Electrolyte Interface

We are proud co-authors of an article in Nature Energy on “Ultrafast ion transport at a cathode–electrolyte interface and its strong dependence on salt solvation”. In this work, Bohua Wen from Prof Yet-Ming Chiang’s group at MIT performed electrodynamic measurements on single electrode particles to show that Li intercalation into NMC333 cathodes is primarily impeded by interfacial kinetics when using a conventional LiPF6 salt. Electrolytes containing LiTFSI salt, with or without LiPF6, exhibit about 100-fold higher exchange current density. Zhi Deng from the Materials Virtual Lab carried out MD simulations to show that TFSI preferentially solvates Li+ compared to PF6-, while still yielding a lower Li+ binding energy, explaining the observed ultrafast interfacial kinetics. Check out this work at this link.

Complex Strengthening Mechanisms in Multi-Principal Element Alloys, aka High-Entropy Alloys

Xiangguo’s excellent paper on “Complex strengthening mechanisms in the NbMoTaW multi-principal element alloy” has just been published on npj Computational Materials. Refractory multi-principal element alloys (MPEAs) have exceptional mechanical properties, including high strength-to-weight ratio and fracture toughness, at high temperatures. Here we elucidate the complex interplay between segregation, short-range order, and strengthening in the NbMoTaW MPEA using a machine learning interatomic potential. We show that the single crystal MPEA exhibit greatly reduced anisotropy in the critically resolved shear stress between screw and edge dislocations compared to the elemental metals. In the polycrystalline MPEA, we demonstrate that thermodynamically driven Nb segregation to the grain boundaries (GBs) and W enrichment within the grains intensifies the observed short-range order (SRO). The increased GB stability due to Nb enrichment reduces the von Mises strain, resulting in higher strength than a random solid solution MPEA. These results highlight the need to simultaneously tune GB composition and bulk SRO to tailor the mechanical properties of MPEAs. Check out this work at this link.