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Ionic diffusivity plays a central role in battery performance. A cathode material for lithium-ion (Li-ion) batteries, LiFePO4 (LFP), performs poorly at high current rates due to low Li-ion diffusivity. An increase in ionic diffusivity is essential to enhance battery performance for high-power-density applications such as hybrid and electric vehicles. Here, we use molecular dynamics simulations with machine learning force field and climbing-image nudged elastic band calculations to show that Li-ion diffusivity in LFP increases when doped with the transition-metal dopant ruthenium. This increase is associated with a reduction in Li diffusion energy barrier, diffusion length, and Li-vacancy formation energy, and it is accompanied by changes in the electronic band structure, specifically the appearance of electronic states in the middle of the band gap and the vicinity of the conduction band. 

Few-layered HfS₃nanoribbons exhibit n-type conductivity and a large photoresponse to visible light. The photocurrent strongly depends on the polarization direction of the excitation laser due to the highly anisotropic quasi-1D crystal structure of HfS₃. 

Abstract Dielectrics have long been considered as unsuitable for pure electrical switches; under weak electric fields, they show extremely low conductivity, whereas under strong fields, they suffer from irreversible damage. Here, we show that flexoelectricity enables damage-free exposure of dielectrics to strong electric fields, leading to reversible switching between electrical states—insulating and conducting. Applying strain gradients with an atomic force microscope tip polarizes an ultrathin film of an archetypal dielectric SrTiO 3 via flexoelectricity, which in turn generates non-destructive, strong electrostatic fields. When the applied strain gradient exceeds a certain value, SrTiO 3 suddenly becomes highly conductive, yielding at least around a 10 8 -fold decrease in room-temperature resistivity. We explain this phenomenon, which we call the colossal flexoresistance, based on the abrupt increase in the tunneling conductance of ultrathin SrTiO 3 under strain gradients. Our work extends the scope of electrical control in solids, and inspires further exploration of dielectric responses to strong electromechanical fields.