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Planar optical elements have attracted widespread attentions because of their precise light modulation. Liquid crystals (LCs) are well known for their applications in the current displaying field, and show great potential in planar optical elements with the development and innovation of LC micro-operation technology. However, previous researches on LC elements mainly involved only one type of optical manipulation, which inevitably limited the functional diversity. In this work, we propose a multifunctional LC element which integrates the surface display into a binary-phase focusing lens by controlling the complex amplitude of the incident light. The light modulation of the anisotropic LC molecule satisfies a sinusoidal variation, which can be regarded as the combination of a continuous amplitude modulation and a binary phase modulation. The element with millimeter size is then fabricated, and the experimental measurements agree well with our design with a high-definition surface pattern and high-quality optical focusing/imaging performance. Furthermore, as the complex amplitude modulation changes from sine to cosine function after rotating the sample by 45°, a bifocal lens with two different focal lengths is also demonstrated. We expect the proposed multifunctional LC elements can find applications in information multiplexing, image displaying, etc.

The development of high‐energy‐density Li||LiCoO2 batteries is severely limited by the instability of cathode electrolyte interphase (CEI) at high voltage and high temperature. Here we propose a mechanically and thermally stable CEI by electrolyte designing for achieving the exceptional performance of Li||LiCoO2 batteries at 4.6 V and 70 °C. 2,4,6‐tris(3,4,5‐trifluorophenyl)boroxin (TTFPB) as the additive could preferentially enter into the first shell structure of PF6− solvation and be decomposed on LiCoO2 surface at low oxidation potential to generate a LiBxOy‐rich/LiF‐rich CEI. The LiBxOy surface layer effectively maintained the integrity of CEI and provided excellent mechanical and thermal stability while abundant LiF in CEI further improved the thermal stability and homogeneity of CEI. Such CEI drastically alleviated the crack and regeneration of CEI and irreversible phase transformation of the cathode. As expected, the Li||LiCoO2 batteries with the tailored CEI achieved 91.9 % and 74.0 % capacity retention after 200 and 150 cycles at 4.6 and 4.7 V, respectively. Moreover, such batteries also delivered an unprecedented high‐temperature performance with 73.6 % capacity retention after 100 cycles at 70 °C and 4.6 V. [ABSTRACT FROM AUTHOR]

The structure and components of solid electrolyte interphase (SEI) is crucial to direct the growth of lithium particles. However, it is hard to have control over them. Herein, an SEI that shares the properties of Li2CO3‐rich and LiF‐rich types is realized by using different fluorine phenylphospines, and constructing a Li2CO3/LiF‐rich heterostructured SEI by using tris(4‐fluorophenyl)phosphine (TFPP) as the electrolyte additive. The well‐balanced SEI formed in TFPP‐containing electrolyte has the fast Li+ transport kinetics of Li2CO3, good electron insulator capability of LiF, and strong affinity toward Li+. It can effectively guarantee fast, uniform Li+ flux through the SEI while preventing electrons from the Li anode entering into SEI, and thus realizes uniform and dense Li deposition at the SEI/Li interface. As expected, the Li anode with TFPP‐containing electrolyte achieves a stable Li plating/stripping over 400 h at 1mA cm−2 while the full cell with a high‐voltage LiNi0.6Co0.2Mn0.2O2 cathode also enables long‐term stability with a capacity retention (87.8% after 200 cycles) at 0.1 A g−1 and excellent rate performance. [ABSTRACT FROM AUTHOR]

Metasurfaces have an excellent ability to manipulate an incident electromagnetic wave through single-layer nano-structures, and thus, they have been successfully used to achieve the integration and miniaturization of optical devices. However, most reported metasurfaces achieve the phase/amplitude modulation through discrete antennas, which affect the performances of meta-devices. In this paper, a quasi-continuous metasurface composed of all-dielectric nanostrips with spatially continuous distribution is proposed. A meta-hologram based on quasi-continuous nanostrips is designed, and the broadband and high-efficiency properties of the designed sample are further demonstrated numerically. Compared to discrete structures, this demonstrated scheme can greatly increase the working bandwidth and energy efficiency of the meta-hologram. The quasi-continuous design can also be extended to some other applications that are associated with metasurfaces, such as meta-mirror, meta-lens, Bessel beam, orbital angular momentum generator and so on. [ABSTRACT FROM AUTHOR]

Liquid crystal (LC) planar optics have advanced wavefront engineering toward ultrathin designs, capturing widespread attention. However, most wavefront control in LC planar optics remains constrained to freespace due to limitations in the precision of freely controllable units. Here, LC on‐chip wavefront engineering is proposed and confirmed. By controlling the initial azimuth angle of the polarization grating, the initial phase can be engineered, as theoretically predicted by rigorous coupled‐wave analysis. Experimentally, the initial azimuth angle of a polarization volume hologram grating, used as a waveguide coupler, is ingeniously modulated using a holographic template. Consequently, several on‐chip optical elements, including lenses, vortex beam generators, and holograms, are demonstrated. Furthermore, exit pupil expansion and multiexposure technologies are adopted to enhance off‐chip functionality and enable multifunctional, highly integrated LC on‐chip photonic systems. The proposed LC on‐chip wavefront engineering may find applications in freeform optics, near‐eye displays, LIDAR, and integrated photonic systems. [ABSTRACT FROM AUTHOR]