Magnetic skyrmions are topologically protected vortex-like nanometric spin textures that have recently received growingly attention for their potential applications in future highperformance spintronic devices. Such unique mangetic naondomains have been recently discovered in bulk chiral magnetic materials, such as MnSi [1][2][3][4] , FeGe [5,6] , FeCoSi [7] , Cu 2 OSeO 3 [8][9][10] , -Mn-type Co-Zn-Mn [11] , and also GaV 4 S 8[12] a polar magnet. The crystal structure of these materials is cubic and lack of centrosymmetry, leading to the existence of Dzyaloshinskii-Moriya (DM) interactions. Unlike the conventional spin configurations, such as helical or conical, that are usually found in chiral magnets, a magnetic skyrmion has a particle-like swirling-spin configuration characterized by a topological index called the skyrmion number [13,14] . The nontrivial topology of magnetic skyrmions results in a number of

Li2MnO3 is the parent compound of the well‐studied Li‐rich Mn‐based cathode materials xLi2MnO3·(1‐x)LiMO2 for high‐energy‐density Li‐ion batteries. Li2MnO3 has a very high theoretical capacity of 458 mA h g−1 for extracting 2 Li. However, the delithiation and lithiation behaviors and the corresponding structure evolution mechanism in both Li2MnO3 and Li‐rich Mn‐based cathode materials are still not very clear. In this research, the atomic structures of Li2MnO3 before and after partial delithiation and re‐lithiation are observed with spherical aberration‐corrected scanning transmission electron microscopy (STEM). All atoms in Li2MnO3 can be visualized directly in annular bright‐field images. It is confirmed accordingly that the lithium can be extracted from the LiMn2 planes and some manganese atoms can migrate into the Li layer after electrochemical delithiation. In addition, the manganese atoms can move reversibly in the (001) plane when ca. 18.6% lithium is extracted and 12.4% lithium is re‐inserted. LiMnO2 domains are also observed in some areas in Li1.63MnO3 at the first cycle. As for the position and occupancy of oxygen, no significant difference is found between Li1.63MnO3 and Li2MnO3.

Plasmon induced water splitting is a promising research area with the potential for efficient conversion of solar to chemical energy, yet its atomic mechanism is not well understood. Here, ultrafast electron-nuclear dynamics of water splitting on gold nanoparticles upon exposure to femtosecond laser pulses was directly simulated using real time time-dependent density functional theory (TDDFT). Strong correlation between laser intensity, hot electron transfer, and reaction rates has been identified. The rate of water splitting is dependent not only on respective optical absorption strength, but also on the quantum oscillation mode of plasmonic excitation. Odd modes are more efficient than even modes, owing to faster decaying into hot electrons whose energy matches well the antibonding orbital of water. This finding suggests photocatalytic activity can be manipulated by adjusting the energy level of plasmon-induced hot carriers, through altering the cluster size and laser parameter, to better overlap adsorbate unoccupied level in plasmon-assisted photochemistry.

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Stable lattice oxygen redox (l-OR) is the key enabler for achieving attainable high energy density in Li-rich layered oxide cathode materials for Li-ion batteries. However, the unique local structure response to oxygen redox in these materials, resulting in energy inefficiency and hysteresis, still remains elusive, preventing their potential applications. By combining the state-of-the-art neutron pair distribution function with crystal orbital overlap analysis, we directly observe the distinct local structure adaption originated from the potential O-O chemical bonds. The structure adaptability is optimized based on the nature of multi transition metals in our model compound Li 1.2 Ni 0.13 Mn 0.54 Co 0.13 O 2 , which accommodates the oxygen redox and at the same time preserves the global layered structure. These findings not only advance the understanding of l-OR, but also provide new perspectives in the rational design of high-energy-density cathode materials with reversible and stable l-OR.

Lattice‐oxygen redox (l‐OR) has become an essential companion to the traditional transition‐metal (TM) redox charge compensation to achieve high capacity in Li‐rich cathode oxides. However, the understanding of l‐OR chemistry remains elusive, and a critical question is the structural effect on the stability of l‐OR reactions. Herein, the coupling between l‐OR and structure dimensionality is studied. We reveal that the evolution of the oxygen‐lattice structure upon l‐OR in Li‐rich TM oxides which have a three‐dimensional (3D)‐disordered cation framework is relatively stable, which is in direct contrast to the clearly distorted oxygen‐lattice framework in Li‐rich oxides which have a two‐dimensional (2D)/3D‐ordered cation structure. Our results highlight the role of structure dimensionality in stabilizing the oxygen lattice in reversible l‐OR, which broadens the horizon for designing high‐energy‐density Li‐rich cathode oxides with stable l‐OR chemistry.

Crystallographic and magnetic structures of the cubic NaZn 13 -type intermetallic compound LaFe 11.4 Si 1.6 have been studied by means of powder neutron diffraction. Rietveld analysis indicates that Si atoms substitute for Fe atoms randomly on two different Fe sites. All spins in the unit cell are aligned ferromagnetically with the Fe I (8b) moment smaller than the Fe II (96i) one. The long-range ferromagnetic ordering induces a drastic expansion of the lattice and the coexistence of the large and small volume phases near the Curie temperature. Even in the ferromagnetic state, the lattice expansion still correlates strongly with the spontaneous magnetic moment, marked by a large positive magnetovolume coupling constant kC = 1.14 × 10 −8 cm 6 emu −2 . From the temperature dependence of Fe-Fe bond lengths, we suggest that the Fe-Fe exchange interaction between the clusters (each formed by a central Fe I atom and 12 surrounding Fe II atoms) plays an important role in the magnetic properties of La(Fe 1−x Al/Si x ) 13 , as does that within the clusters.

Combining the first-principles density functional method and crystal structure prediction techniques, we report a series of hexagonal two-dimensional transition metal borides including Sc2B2, Ti2B2, V2B2, Cr2B2, Y2B2, Zr2B2, and Mo2B2. Their dynamic and thermal stabilities are testified by phonon and molecular dynamics simulations. We investigate the potential of the two-dimensional Ti2B2 monolayer as an anode material for Li-ion and Na-ion batteries. The Ti2B2 monolayer possesses high theoretical specific capacities of 456 and 342 mA h g-1 for Li and Na, respectively. The very high Li/Na diffusivity with an ultralow energy barrier of 0.017/0.008 eV indicates an excellent charge-discharge capability. In addition, good electronic conductivity during the whole lithiation process is found by electronic structure calculations. The very small change in volume after the adsorption of one, two, and three layers of Li and Na ions indicates that the Ti2B2 monolayer is robust. These results highlight the suitability of Ti2B2 monolayer as well as the other two-dimensional transition metal borides as excellent anode materials for both Li-ion and Na-ion batteries.