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Commercialized lithium cobalt oxide (LCO) only shows a relatively low capacity of ≈175 mAh g

Low-cost Mn- and Li-rich layered oxides suffer from rapid voltage decay, which can be improved by increasing the nickel content to derive high nickel Li-rich layered oxides (HNLO) but is normally accompanied by reduced capacity and inferior cycling stability. Herein, Na or K ions are successfully doped into the lattice of high nickel Li-rich Li

Nonvolatile memories have attracted a lot of interest because they retain the data when the power is interrupted. Smaller size and improved performance of nonvolatile memories are pursued both for basic research and applications. In this work, a molecular wire made of seamless junctions between semiconducting single-walled carbon nanotubes (SWNT) and partially unzipped segments of the SWNTs are reported. This novel nanostructure is demonstrated to be a nonvolatile memory, which works at room temperature under atmospheric conditions. The characteristics of the device are measured with a four-terminal configuration and a non-local voltage (Vnon-local) is used as the storage signal. An electrical hysteresis of Vnon-local is observed, wherein two states with different Vnon-local can be switched by the application of an electric field through an insulating gate device structure, exhibiting nonvolatile characteristics. Vnon-local can be modulated with external magnetic fields and the mechanism of the electrical hysteresis is attributed to the magnetic moments at the partially unzipped SWNT. The smaller size of SWNT and high working temperature may lead to the development of molecular nanomagnets as nonvolatile memory devices for practical applications. Supported by Major Nanoprojects of Ministry of Science and Technology of China (Grant Nos.2018YFA0208403, 2017YFA0207104), National Natural Science Foundation of China (21973021, 11874129), the GBA National Institute for Nanotechnology Innovation, Guangdong, China (2020B0101020003), CAS Project for Young Scientists in Basic Research (YSBR-030), Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDB36000000, NBSDC-DB-18).

Optical superoscillation, a phenomenon that the local optical field can oscillate much faster than that allowed by its highest harmonic, can significantly overcome the Abbe diffraction limit. However, as the spot size is compressed below the superoscillation criteria of 0.38λ/NA, huge sidebands will inevitably appear around the central lobe with intensity hundreds of times higher than that of the central lobe. Here, we propose an approach to realize superoscillation by using destructive interference. The central lobe size can be compressed beyond the superoscillation criteria without formation of strong sidebands by destructive interference between focused fields. Such a super-resolution metalens can find its application in label-free far-field super-resolution microscopy.

Superoscillation metalenses have demonstrated promising prospects in breaking the theoretical diffraction limitations on the resolution of optical devices and systems. However, most reported superoscillation metalenses have a very small field of view of several tenths of a degree, which greatly limits their applications in imaging and microscopy. Therefore, it is of critical importance to achieve absolute high resolution by increasing the numerical apertures (NAs) of optical devices and systems. Unfortunately, similar to the case in traditional optics, it is challenging to realize a large field of view at high NA, especially in the superoscillation regime. To date, no attempt has been made to achieve flat-field focusing in the superoscillation regime, to our knowledge. Here, we demonstrate a high-NA superoscillation metalens with an entrance aperture stop, which is optimized for superoscillation performance with a comparatively large field of view. The proposed flat-field superoscillation metalens has an effective NA as large as 0.89 and achieves superoscillation focusing within a field of view of 9°. Such a superoscillation metalens may offer a promising way toward superoscillation imaging and fast-scanning label-free far-field superoscillation microscopy.

In this work, octahedral LiMn2O4 (O-LMO) with exposed {111} crystal facets was prepared using MnCO3 as a precursor via solid phase reactions. O-LMO was revealed to have the superior rate performance and good cycling stability in both a three-electrode system and full aqueous batteries with Li2SO4 solution.The capacity retentions of 87% for 200 cycles at 0.1 A g-1 and 87% for 500 cycles at 1 A g-1 were achieved, in sharp contrast with 56% and 70% for the commercial LMO (C-LMO). Also, O-LMO showed the excellent performance in organic systems as well. The superior performance for both aqueous and organic systems may be related to the maintaining of octahedral structures and surface morphologies for O-LMO cycled 200 times at 0.1 A g-1 in aqueous system and the suppression of Mn dissolution and side reactions in both aqueous and organic systems, which originates from the stable {111} facets.

Metalenses are expected to play an increasingly important role in miniaturized and integrated optical imaging components/systems. However, devising broadband achromatic metalenses with high focusing efficiencies is still quite challenging. In this work, we proposed an aperture-shared partition phase cooperative manipulation approach for designing a high-efficiency broadband achromatic metalens composed of two concentric sub-metalenses. As a proof-of-concept, an achromatic polarization-independent metalens is successfully designed for the visible and near-infrared range from 450 nm to 1400 nm with the focusing efficiency over 70% for the wavelength range of 600 nm to 1400 nm. The approach reported here provides a possibility for designing a high-performance metalens, which has great potential applications in integrated optics.