The inversion (Li and Mn interchanging sites) of cathode material LiMn 2 O 4 (LMO) on the battery capacity is studied from the perspective of Jahn−Teller distortion (JTD) and manganese dissolution. The LMO spinel in the orthorhombic structure with anti-ferromagnetic ordering is studied using spinpolarized density functional theory calculations with anisotropic (U − J) corrections. The charge orderings and magnetic moments of the orthorhombic LMO spinel at normal, half-inverse, and fullinverse structures are connected with the battery's properties. It is found that the magnetic moments prefer high spin states in all the cases, and the JTD is mainly due to Mn 3+ . The existence of Mn 3+ at octahedral and tetrahedral sites in normal and full-inverse LMO spinel, respectively, induces strong JTD that will reduce the battery capacity. In half-inverse LMO spinel, the cubic-like phase with degraded JTD could retard the capacity decay of lithium-ion batteries, while the existence of Mn A 2+ at the tetrahedral sites would aggravate the manganese dissolution and exacerbate the capacity decay. In all, inversion in LMO does not always have a negative effect on battery capacity as JTD and Mn 2+ manganese dissolution compete with each other.

The indirect property of two-dimensional GaN bandgap hinders its application in optical field. Hydrogenation can convert the bandgap of GaN monolayer from an indirect to direct one and also tune...

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Two-dimensional (2D) a-plane gallium nitride, a non-layered 2D material, has promising applications in photoelectric nanodevices due to its direct band bandgap. Herein, employing molecular dynamics simulations, we studied the thermal transport properties of a-plane trilayer GaN, and the temperature, together with strain modulation on the thermal conductivity of the system. The a-plane trilayer GaN shows anisotropic thermal conductivity with 70.22 Wm-1K-1 and 41.81 Wm-1K-1 along zigzag- and armchair- directions respectively at room temperature when extrapolated to infinite size. In addition, the thermal conductivity of trilayer GaN exhibits decreasing trend in response to the increase of temperature. The thermal conductivity decreases monotonically with the increased compressive uniaxial and biaxial strain, while it shows an up-then-down trend under tensile strain. The tunability of thermal conductivity under biaxial strain is much larger than that of uniaxial strain. The phonon density of states is further investigated to understand the behavior of thermal conductivity. The tunability of the system thermal conductivity will expand its applications in thermal management and nanodevices.