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In a system of C2 symmetry, symmetry-protected bound states in the continuum (SP-BICs) exist with a continuous spectrum of radiating waves that can carry energy away and enable an infinite radiative quality (Q) factor and zero linewidth. However, the SP-BICs transform into quasi-BICs by breaking the C2 symmetry of the system, where the resonance lifetime and linewidth become finite and measurable. As such, the quasi-BICs are very sensitive to the polarization of incident radiation. Owing to the application of a biosensor or a lasing device, it is unavoidable to work with an unpolarized radiative beam. Herein, we propose a metasurface in a C4 symmetric layout, which exhibits polarization-insensitive terahertz symmetry-protected quasi-BICs. The orientations of adjacent two meta-molecules (MMs) are designed to be orthogonal to each other. By tuning the degree of asymmetry along the orientation of MMs, the quasi-BICs exhibit insensitivity to the polarization of the incident terahertz wave. A large degree of asymmetry results in a deformation of an electric quadrupole, which forms an energy leaky channel to the free space. Due to the translational symmetry, the wave-vector of the lattice in C4 symmetry is conserved so that the electric components of transmitted radiation along the x axis is identical to that along the y axis, Txx = Tyy. As such, the leaky channel of electromagnetic scattering becomes insensitive to the incident polarization. Our results present an approach to achieve polarization-insensitive quasi-BICs in a topologically symmetric metasurface, which is helpful for the innovation of terahertz biosensor. [ABSTRACT FROM AUTHOR]

Garnet‐based solid‐state Li‐metal batteries (GSSBs) have the merits of high energy density and high safety. However, the realization of a stable and well‐matched Li|garnet interface for GSSBs remains challenging due to electron leakage and lithiophobic Li2CO3 impurity. To address these issues, herein, new surface chemistry is reported that converts the undesired Li2CO3 contaminant into an ultra‐thin lithium polyphosphate (Li‐PPA) layer through anhydrous polyphosphoric acid ‐induced in situ substitution reaction without damaging the water‐sensitive garnet electrolyte. In particular, the Li‐PPA interlayer not only facilitates the homogenous spreading of molten Li but also creates a robust electron‐blocking shield to suppress Li dendrite formation. As a result, the assembled Li symmetric cell exhibits a low interfacial impedance (4 Ω cm2) and high critical current density (1.8 mA cm−2) at 25 °C, which enables the cell to continuously cycle over 2500 h at 0.2 mA cm−2. Furthermore, the GSSBs paired with LiFePO4 deliver a high capacity of 149.3 mAh g−1 at 1 C and maintain 92.3% of the initial capacity after 500 cycles and can be used for solar energy storage, suggesting the feasibility of this interfacial engineering strategy for GSSBs. [ABSTRACT FROM AUTHOR]

Rapid development of electronic and grid storage technologies based on lithium-ion batteries are leading to tight supply of lithium resources in the future. Extracting lithium from seawater can completely solve the problem of lithium resource shortage. An electro-deposition method based on a lithium superionic conductive solid-state electrolyte, Li1.5Al0.5Ge1.5(PO4)3 (LAGP), has been reported to obtain metallic lithium from seawater. However, expensive LAGP increases the cost of lithium extraction, while Li1.3Al0.3Ti1.7(PO4)3 (LATP) with relatively lower prices cannot meet the stable requirements. Herein, a low-cost, stable glass–ceramics, Li1.5Al0.3Ti1.7Si0.2P2.8O12 (LATSP), has been prepared for lithium extraction from seawater. The LATSP glass–ceramics show good selectivity towards Li+ and exhibit a high ionic conductivity of 3.98 × 10−4 S cm−1 at 22 °C. After soaking in simulated seawater, LATSP showed much better stability than LATP, comparable to LAGP. The resultant LATSP glass–ceramics was successfully employed in a seawater lithium extraction device, with a high lithium extraction Coulombic efficiency of 94.0%. Moreover, the LATSP exhibits an ionic conductivity of 2.80 × 10−4 S cm−1 and maintains a complete structure after 45 h of lithium extraction. This work presents an effective and practical Li-ion conducting membrane for lithium extraction from seawater.Graphical Abstract: Rapid development of electronic and grid storage technologies based on lithium-ion batteries are leading to tight supply of lithium resources in the future. Extracting lithium from seawater can completely solve the problem of lithium resource shortage. An electro-deposition method based on a lithium superionic conductive solid-state electrolyte, Li1.5Al0.5Ge1.5(PO4)3 (LAGP), has been reported to obtain metallic lithium from seawater. However, expensive LAGP increases the cost of lithium extraction, while Li1.3Al0.3Ti1.7(PO4)3 (LATP) with relatively lower prices cannot meet the stable requirements. Herein, a low-cost, stable glass–ceramics, Li1.5Al0.3Ti1.7Si0.2P2.8O12 (LATSP), has been prepared for lithium extraction from seawater. The LATSP glass–ceramics show good selectivity towards Li+ and exhibit a high ionic conductivity of 3.98 × 10−4 S cm−1 at 22 °C. After soaking in simulated seawater, LATSP showed much better stability than LATP, comparable to LAGP. The resultant LATSP glass–ceramics was successfully employed in a seawater lithium extraction device, with a high lithium extraction Coulombic efficiency of 94.0%. Moreover, the LATSP exhibits an ionic conductivity of 2.80 × 10−4 S cm−1 and maintains a complete structure after 45 h of lithium extraction. This work presents an effective and practical Li-ion conducting membrane for lithium extraction from seawater. [ABSTRACT FROM AUTHOR]