The low utilization of active sites and sluggish reaction kinetics of MoSe severely impede its commercial application as electrocatalyst for hydrogen evolution reaction (HER). To address these two issues, the first example of introducing 1T MoSe and N dopant into vertical 2H MoSe /graphene shell/core nanoflake arrays that remarkably boost their HER activity is herein described. By means of the improved conductivity, rich catalytic active sites and highly accessible surface area as a result of the introduction of 1T MoSe and N doping as well as the unique structural features, the N-doped 1T-2H MoSe /graphene (N-MoSe /VG) shell/core nanoflake arrays show substantially enhanced HER activity. Remarkably, the N-MoSe /VG nanoflakes exhibit a relatively low onset potential of 45 mV and overpotential of 98 mV (vs RHE) at 10 mA cm with excellent long-term stability (no decay after 20 000 cycles), outperforming most of the recently reported Mo-based electrocatalysts. The success of improving the electrochemical performance via the introduction of 1T phase and N dopant offers new opportunities in the development of high-performance MoSe -based electrodes for other energy-related applications.

power sources for electric vehicles and electronics. [4][5][6][7] In such a context, nextgeneration LIBs era with Li metal anode is spring up including Li-S, Li-O 2 , and solidstate Li batteries, which require high gravimetric capacity anodes and cathodes. [8][9][10][11][12][13] The maximum gravimetric capacity of cells would be significantly increased if Li is deposited on the anode directly as pure Li metal rather than stored in intercalation compounds such as graphite in LIBs during the charge/discharge processes. The theoretical capacity based on lithiated graphite is about 372 mA h g −1 , while pure Li metal theoretically delivers 3860 mA h g −1 . Therefore, Li metal anode is strongly considered recently. [14][15][16][17] In spite of the huge potential for highenergy-density device, the practical application of Li metal to a rechargeable anode is bumpy and has many challenges. [18,19] The most tough one is that Li metal problematically forms dendrites and related unstable structures during repeated plating/stripping. The fresh metallic deposit acts as an active site inducing reductive decomposition of electrolyte components. Part of the irregular deposition may become electrically isolated, and shedding may also occur. [20] Therefore, the disordered Li deposit gives rise to a poor Coulombic efficiency and a short cycle life. The metallic Li dendrites may easily penetrate into the separator and eventually induce internal short circuit, resulting in severe safety problem. [21,22] To circumvent these issues, great efforts are devoted to exploring dendrite-free Li metal anodes. Many emerging strategies have been investigated to enhance the electrochemical performance of Li metal anode: (1) Electrolyte additive is introduced into the electrolyte to form stable solid electrolyte interphase (SEI) film and reaction interface. [23][24][25][26][27][28] (2) Buffer layer or ion transfer layer is fabricated on the surface of Li metal by physical, chemical, or electrochemical methods and ensures homogeneous deposition of Li during cycling. [29][30][31][32] (3) Solidstate electrolyte is established on the surface of Li and proven to inhibit the dendrite growth. [33][34][35] (4) Highly porous conductive matrix is applied to guide the uniform deposition of Li metal in a working cell. [36][37][38][39][40] If the Li metal can be well protected by stable SEI, extra space is therefore required for the volume expansion/shrink of Li metal. Therefore, design/fabrication of novel porous conductive matrix is particularly important Construction of stable dendrite-free Li metal anode is crucial for the development of advanced Li-S and Li-air batteries. Herein, self-supported TiC/C core/shell nanowire arrays as skeletons and confined hosts of molten Li forming integrated trilayer TiC/C/Li anode are described. The TiC/C core/ shell nanowires with diameters of 400-500 nm exhibit merits of good lithiophilicity, high electrical conductivity, and abundant porosity. The as-prepared TiC/C/Li anode exhibits prominent electrochemical performance...

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In response to the growing energy demand, over the past decades, lithium takes the hold of world's attention because it possesses huge energy density due to light weight, low electrode potential (−3.04 V vs standard hydrogen electrode), and large theoretical-specific capacity (3860 mAh g −1 ). [1][2][3][4] Stuck with the stagnation of traditional lithium-ion batteries, the future Uncontrollable growth of Li dendrites and low utilization of active Li severely hinder its practical application. Construction of an artificial solid electrolyte interphase (SEI) onLi is demonstrated as one of the most effective ways to circumvent the above problems. Herein, a novel spray quenching method is developed in situ to fabricate an organic-inorganic composite SEI on Li metal. By spray quenching molten Li in a modified ether-based solution, a homogeneous and dense SEI consisting of organic matrix embedded with inorganic LiF and Li 3 N nanocrystallines (denoted as OIFN) is constructed on Li metal.Arising from high ionic conductivity and strong mechanical stability, the OIFN can not only effectively minimize the corrosion reaction of Li, but also greatly suppresses the dendrite growth. Accordingly, the OIFN-Li anode presents prominent electrochemical performance with an enhanced Coulombic efficiency of 98.15% for 200 cycles and a small hysteresis of <450 mV even at ultrahigh current density up to 10 mA cm −2 . More importantly, during the full cell test with limited Li source, a high utilization of Li up to 40.5% is achieved for the OIFN-Li anode. The work provides a brand-new route to fabricate advanced SEI on alkali metal for high-performance alkali-metal batteries.

Lithium-sulfur batteries (LSBs) are considered to be one of the most promising alternatives to the current lithium ion batteries (LIBs) to meet the increasing demand of energy storage due to their high energy density, natural abundance, low cost and environmental-friendliness. Despite great success, LSBs are still suffering from several problems including undermined capacity arising from low utilization of sulfur, unsatisfactory rate performance and poor cycling life due to shuttle effect of polysulfides and poor electrical conductivity of sulfur. Under such circumstances, design/fabrication of porous carbon-sulfur composite cathodes is regarded as an effective solution to overcome the above problems. In this review, we summarize different synthetic methods of porous carbon hosts and corresponding integration ways of carbon-sulfur cathodes. We also address the pore formation mechanism of porous carbon hosts. The pore size effect on electrochemical performance is highlighted and compared. The enhanced mechanism of porous carbon host on the sulfur cathode is systematically reviewed and revealed. Finally, we demonstrate the combination of porous carbon hosts and high-profile solid-state electrolytes nowadays, and discuss the challenges to realize large-scale commercial application of porous carbon-sulfur cathodes and propose their developing trend in the future.