Potential applications of sodium-ion batteries (SIBs) have motivated significant research interest in grid-scale energy storage. However, large radius of Na ions results in different electrochemical behaves. Therefore, synergistic understanding of the differences is greatly interested for future development of SIBs. Surface availability for ions with poor affinity to electrode materials is critical to rate performance in SIBs, but yet has rarely been reported. Here, to overcome the obstacles of material platform, amorphous TiO2 inverse opal is employed as a proof-of-concept prototype to illuminate the effects of surface ion availability and its relationship between solvent wettability and rate capability. Within expectation, superior rate capabilities are 2 achieved in return for enhanced solvent wettability, regardless of the type of electrolyte and the ion concentration in electrolyte. Even when the anode is cycled at a current density as high as 5000 mA g-1 , the reversible capacity could still retain a high value of ~113 mA h g-1. Our concept opens up a promising avenue to realize full potential of designing electrode materials for SIBs by adjusting the surface kinetics. This understanding shall extend the design principle to electrode materials for highly effective energy storage using other transport ions and other storage mechanisms.

The presence of two-dimensional (2D) layerstacking heterostructures that can efficiently tune the interface properties by stacking desirable materials provides a platform to investigate some physical phenomena, such as the proximity effect and magnetic exchange coupling. Here, we report the observation of antisymmetric magnetoresistance in a van der Waals (vdW) antiferromagnetic/ferromagnetic (AFM/FM) heterostructure of MnPS 3 /Fe 3 GeTe 2 when the temperature is below the Neel temperature of MnPS 3 . Distinguished from two resistance states in conventional giant magnetoresistance, the magnetoresistance in the MnPS 3 /Fe 3 GeTe 2 heterostructure exhibits three states, of high, intermediate, and low resistance. This antisymmetric magnetoresistance spike is determined by an unsynchronized magnetic switching between the AFM/FM interface layer and the bulk of Fe 3 GeTe 2 during magnetization reversal. Our work highlights that the artificial vdW stacking structure holds potential to explore some physical phenomena and spintronic device applications.

Topological Hall effect (THE) has been used as a powerful tool to unlock spin chirality in novel magnetic materials. Recent focus has been widely paid to THE and possible chiral spin textures in two-dimensional (2D) layered magnetic materials. However, the room-temperature THE has been barely reported in 2D materials, which hinders its practical applications in 2D spintronics. In this paper, we report a possible THE signal featuring antisymmetric peaks in a wide temperature window up to 320 K in Cr 1.2 Te 2 , a new quasi-2D ferromagnetic material. The temperature, thickness, and magnetic field dependences of the THE lead to potential spin chirality origin that is associated with the spin canting under external magnetic fields. Our work holds promise for practical applications in future chiral spin-based vdW spintronic devices.

inspiration from the similar rocking-chair mechanism with LIB, researchers has made rapid progress in identifying ideal electrodes, especially in the field of cathodes. [4] As for anodes, some state-of-the-art materials cannot accommodate the reversible intercalation of Na ions, [5] such as graphite. [6] The reasons mainly arise from the larger ionic radius of Na (1.02 Å) than Li (0.76 Å), [7] a higher ionization potential, [8] and preferable coordination in octahedral or prismatic site of Na ions. [9] More complex requirements for the intrinsic properties raise the difficulties in finding a suitable material, in particularly for electrodes with intercalation mechanism. A more open framework is favorable for acceptable mobility, otherwise, the (de-) sodiation processes could induce large distortions in the lattice that ultimately lead to pulverization of the electrode and the impending failure of batteries. [10] Concerning the discovery and design of ideal electrodes, the ordering of atomic arrangements is at the heart in SIBs, because the resulting changes on storage mechanism, [11] surface state, [12] and type/ volume of polyhedral sites [13] play a vital role on the important electrochemical processes, like electrical conductivity, ion absorption, ion insertion, ion diffusion, and so on. Disordered atomic arrangements with isotropic characteristics may form percolation pathways via some open active diffusion channels to facilitate ionic transport, while long-range ordered atomic arrangements have the primary electro-active species of choice, and narrow potential window required to achieve the capacities. [14,15] With regard to SIB field, the controversy about the ordering seems more obscure due to the large Na ions. Taking a typical electrode material, TiO 2 , as an example, Xiong et al. proposed that long-range ordered polymorphs (e.g., anatase, rutile) cannot support Na-ion intercalation at all because of higher sodium diffusion barrier. [12] But Su et al. found that anatase TiO 2 have superior capacities than disordered amorphous TiO 2 . [16] To reach a more accurate insight into the argument, a suitable platform is required for the systemic and scientific studies. Two factors of electrode design should be considered simultaneously.(1) The electrode should be tested without any conductive additive and polymeric binder, which will bring unclear changes on the electrical conductivity and surface state.(2) Morphological features of materials with different atomic In response to the increased demands of available energy storage, sodium ion batteries (SIBs) appear as promising alternatives to widely used lithium ion batteries. However, because of large radius of Na ions, more complex requirements for the intrinsic properties raise the difficulties in finding a suitable material, in particularly for electrodes with intercalation mechanism. Concerning the principle of designing effective electrodes, the ordering of atomic arrangements should be at the heart in SIBs due to its significant influences on various ele...

van der Waals crystals exhibit excellent material performance when exfoliated to few-atomic-layer thickness. In contrast, the van der Waals thin films more than 10 nm thick are believed to show bulk properties, in which outstanding material performance is rarely found. Here we report the largest anomalous Hall conductivity observed so far in a 170 nm van der Waals ferromagnetic 1T-CrTe2 flake, which reaches 67,000 Ω–1 cm–1. Such a colossal anomalous Hall conductivity in 1T-CrTe2 is dominated by the extrinsic skew scattering process rather than the intrinsic Berry phase effect, as evidenced by the linear relation between the anomalous Hall conductivity and the longitudinal conductivity. Defying the dilemma of mutually exclusive large anomalous Hall angle and high electric conductivity for most ferromagnets, 1T-CrTe2 achieves both in a thin film sample. Considering the shared physics of the anomalous Hall effect and the spin Hall effect, our finding offers a guideline for searching large spin Hall materials of high conductivity which may overcome the bottleneck of overheating in spintronics devices.

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Magnetic anisotropy is an important characteristic of magnetic materials. Particularly, perpendicular magnetic anisotropy (PMA) is superior for the design of spintronic devices, with the advantages of scalability, endurance, thermal stability, and low switching current density. Although a series of two-dimensional (2D) or quasi-2D layered ferromagnets have been demonstrated, the room temperature intrinsic ferromagnets with PMA is rarely found. Here, we report PMA in a room-temperature layered ferromagnet of Cr-intercalated CrTe2. By self-intercalation of the native Cr atoms, the in-plane anisotropy of CrTe2 can be switched to PMA. Meanwhile, the Cr-intercalated CrTe2 crystal can be easily exfoliated into thin flakes with thickness ∼10 nm. Besides the robust PMA at room temperature, Cr-intercalated CrTe2 also exhibits high saturation magnetization (208 emu cm−3 at 300 K), large anomalous Hall angle (2.23% at 300 K) and giant anomalous Hall factor (∼0.18 at 300 K). These excellent properties are highly desired for applications, and make Cr-intercalated CrTe2 a distinguished candidate among all existing magnetic materials. Our work reveals a promising platform for spintronic devices and offers a new route for controlling the magnetic anisotropy in layered materials.

A flexible three-dimensional WSe2/C nanofiber was reported and investigated by the in situ TEM, which finally exhibited high reversible cycling capability and ultra-long lifespan up to 10 000 cycles at ultrahigh rate.