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Li-rich layered oxides have been in focus because of their high specific capacity. However, they usually suffer from poor kinetics, severe voltage decay, and capacity fading. Herein, a long-neglected Li-deficient method is demonstrated to address these problems by simply reducing the lithium content. Appropriate lithium vacancies can improve dynamics features and induce in situ surface spinel coating and nickel doping in the bulk. Therefore, the elaborately designed Li 1.098 Mn 0.533 Ni 0.113 Co 0.138 O 2 cathode possesses improved initial Coulombic efficiency, excellent rate capability, largely suppressed voltage decay, and outstanding long-term cycling stability. Specifically, it shows a superior capacity retention of 93.1% after 500 cycles at 1 C (250 mA g −1 ) with respect to the initial discharge capacity (193.9 mA h g −1 ), and the average voltage still exceeds 3.1 V. In addition, the discharge capacity at 10 C can be as high as 132.9 mA h g −1 . More importantly, a Li-deficient cathode can also serve as a prototype for further performance enhancement, as there are plenty of vacancies.

Herein, we introduce a facile electrostatic attraction approach to produce zinc-silver citrate hollow microspheres, followed by thermal heating treatment in argon to ingeniously synthesize sandwich-like Ag-C@ZnO-C@Ag-C hybrid hollow microspheres. The 3D carbon conductive framework in the hybrids derives from the in situ carbonation of carboxylate acid groups in zinc-silver citrate hollow microspheres during heating treatment, and the continuous and homogeneous Ag nanoparticles on the outer and inner surfaces of hybrid hollow microspheres endow the shells with the sandwiched configuration (Ag-C@ZnO-C@Ag-C). When applied as the anode materials for lithium ion batteries, the fabricated hybrid hollow microspheres with sandwich-like shells reveal a very large reversible capacity of 1670 mAh g(-1) after 200 cycles at a current density of 0.2 A g(-1). Even at the very large current densities of 1.6 and 10.0 A g(-1), the high specific capacities of about 1063 and 526 mAh g(-1) can be retained, respectively. The greatly enhanced electrochemical properties of Ag-C@ZnO-C@Ag-C hybrid microspheres are attributed to their special structural features such as the hollow structures, the sandwich-like shells, and the nanometer-sized building blocks.

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Development of microwave absorption materials with tunable thickness and bandwidth is particularly urgent for practical applications but remains a great challenge. Here, two-dimensional nanocomposites consisting of perovskite oxides (LaFeO) and amorphous carbon were successfully obtained through a one pot with heating treatment using sodium chloride as a hard template. The tunable absorption properties were realized by introducing A-site cation deficiency in LaFeO perovskite. Among the A-site cation-deficient perovskites, LaFeO/C (LFOC) has the best microwave absorption properties in which the maximum absorption is -26.6 dB at 9.8 GHz with a thickness of 2.94 mm and the bandwidth range almost covers all X-band. The main reason affecting the microwave absorption performance was derived from the A-site cation deficiency which induced more dipoles polarization loss. This work proposes a promising method to tune the microwave absorption performance via introducing deficiency in a crystal lattice.

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"Welcome-mat"-like porous Si/Cu composite amorphous films are fabricated by applying the predeposited Cu-nanoparticle-assembled film as the growth direction template for the subsequent deposition of a Si active layer with the cluster beam deposition technique. When used as the binder-free anodes for lithium ion batteries, the acquired single-layer porous Si/Cu composite film exhibits a large reversible capacity of 3124 mA h g after 1000 cycles at 1 A g. Even when cycled at 20 A g for 450 cycles, the porous Si/Cu composite film still delivers a decent reversible capacity of 2086 mA h g. Also, multilayer porous Si/Cu composite films are synthesized through layer-by-layer sputtering and exhibit outstanding cyclability and relatively high specific capacity and initial Coulombic efficiency irrespective of increasing the layer number from two to four layers. The reasons for the excellent electrochemical properties of single-layer and multilayer porous Si/Cu composite films are discussed in detail.

The valleys of two-dimensional transition metal dichalcogenides (TMDCs) offer a new degree of freedom for information processing. To take advantage of this valley degree of freedom, on the one hand, it is feasible to control valleys by utilizing different external stimuli, such as optical and electric fields. On the other hand, nanostructures are also used to separate the valleys by near-field coupling. However, for both of the above methods, either the required low-temperature environment or low degree of coherence properties limit their further applications. Here, we demonstrate that all-dielectric photonic crystal (PhC) slabs without in-plane inversion symmetry (C 2 symmetry) can separate and route valley exciton emission of a WS 2 monolayer at room temperature. Coupling with circularly polarized photonic Bloch modes of such PhC slabs, valley photons emitted by a WS 2 monolayer are routed directionally and are efficiently separated in the far field. In addition, far-field emissions are directionally enhanced and have long-distance spatial coherence properties.