Lithium‐metal batteries (LMBs) with high energy densities are highly desirable for energy storage, but generally suffer from dendrite growth and side reactions in liquid electrolytes; thus the need for solid electrolytes with high mechanical strength, ionic conductivity, and compatible interface arises. Herein, a thiol‐branched solid polymer electrolyte (SPE) is introduced featuring high Li+ conductivity (2.26 × 10−4 S cm−1 at room temperature) and good mechanical strength (9.4 MPa)/toughness (≈500%), thus unblocking the tradeoff between ionic conductivity and mechanical robustness in polymer electrolytes. The SPE (denoted as M‐S‐PEGDA) is fabricated by covalently cross‐linking metal–organic frameworks (MOFs), tetrakis (3‐mercaptopropionic acid) pentaerythritol (PETMP), and poly(ethylene glycol) diacrylate (PEGDA) via multiple CSC bonds. The SPE also exhibits a high electrochemical window (>5.4 V), low interfacial impedance (<550 Ω), and impressive Li+ transference number (tLi+ = 0.44). As a result, Li||Li symmetrical cells with the thiol‐branched SPE displayed a high stability in a >1300 h cycling test. Moreover, a Li|M‐S‐PEGDA|LiFePO4 full cell demonstrates discharge capacity of 143.7 mAh g−1 and maintains 85.6% after 500 cycles at 0.5 C, displaying one of the most outstanding performances for SPEs to date.

Most Li+/Na+-conducting solid electrolytes are unstable in moisture, and the formed hydroxides and carbonates on their surfaces result in the increase of the interfacial resistance between solid electrolytes and alkali metal anodes. In this study, heat treatment was used to remove the byproduct coating on the surface of Na3Zr2Si2PO12 (NZSP) that also leads to the generation of Na-ion deficient surface simultaneously. This surface chemistry approach was used to reduce the interfacial resistance and suppress Na-dendrite growth during Na plating. A combination of the metallic Na wetting test, density functional theory, and electrochemical measurement was employed to investigate the origins of ultralow interfacial resistance and mechanism between the Na-ion deficient surface and the metallic Na anode. The analysis demonstrates that the Na-ion-deficient surface effectively improves the contact between NZSP and the metallic Na anode. Moreover, an ultrathin passivating layer involving Na2O was formed between NZSP with metallic Na that protected the NZSP electrolyte from the reduction by metallic Na. This study not only motivates the need for further understanding of the surface chemistry of NZSP but also provides guidelines for the future design of the Na-ion solid–electrolyte interface.

The sodium (Na) anode suffers severe interfacial resistance and dendrite issues in a classic NASICON-type Na3Zr2Si2PO12 (NZSP) electrolyte, resulting in poor electrochemical performance for solid-state Na metal batteries.

Although there are plenty of merits for lithium–sulfur (Li–S) batteries, their undesired shuttle effect and insulated nature are hindering the practical applications. Here, a conductive metal–organic framework (MOF)-modified separator has been designed and fabricated through a facile filtration method to address the issues. Specifically, its intrinsic microporous structure, hydrophilic polar property, and conductive feature could make it easy to contact with and trap polysulfides and boost the kinetics of electrochemical reactions. Both the physical and chemical properties of the as-prepared separator are beneficial to alleviating the shuttle effect and enhancing the rate capability. Accordingly, the electrochemical performance of the battery with a MOF-modified separator was significantly improved.

Nowadays, lithium-ion batteries (LIBs) have been widely used in portable electronics, electric vehicles, and grid energy storage systems. [1][2][3] However, the traditional LIBs based on graphite anode cannot satisfy the ever growing energy density demands. [4,5] In this background, next-generation Li-ion batteries based on Li metal anode with ultrahigh energy density have attracted worldwide attention in recent years, such as lithium-sulfur (2600 Wh kg −1 ), Li-O 2 batteries (3580 Wh kg −1 ). [6][7][8] Li metal anode with high theoretical specific capacity (3860 mAh g −1 ), low density (0.534 g cm −3 ), and the lowest potential (−3.040 V vs standard hydrogen electrode) demonstrated remarkable advantages in energy density as anode for Li metal batteries (LMBs). [9][10][11][12][13][14] However, the practical application of Li metal anode in LMBs is still suffering from low coulombic efficiency (CE), poor cycle life, and safety concerns because of serious Li dendrite growth during cycling. [15][16][17] The uncontrollable dendrite growth leads to the formation of "dead lithium" with low coulombic efficiency, and may even cause catastrophic failure of battery by internal short circuit. [18][19][20] During the past decade, there are majorly two kinds of strategies proposed to suppress dendrite growth and protect lithium metal anode. The first approach is based on a mechanical blocking strategy, such as, 1) optimization of the solid electrolyte interface (SEI) layer and improving its mechanical modulus and stability, for which LiF, [21][22][23] Li 3 N, [24] Li 2 S, [25][26][27] Li 3 PO 4 , [28] Li 2 O, [29] etc. have been introduced into the SEI layer and showed an improved cycling performance at 1.0-2.0 mA cm −2 ; 2) introducing an extra coating layer (poly(dimethylsiloxane), [30] hollow carbon spheres, [31] artificial solid electrolyte layer, [32] etc.) as a protecting layer on the surface of Li metal. The other approach is focused on designing various nanostructures to control the electric field distribution and accommodate volume expansion. In which, hierarchical frameworks such as 3D carbon fiber cloth, [33] Ni foam, [34] and 3D porous Cu foil [35,36] have been constructed to store Li metal and inhibit the growth of Li dendrites. However, these two strategies were both converged at inhibiting lithium deposition, which have not changed the fundamental, self-amplification behavior of the dendrite growth. Moreover, they failed to support the practical application of Li-S or Li-O 2 Uncontrollable Li dendrite growth and low Coulombic efficiency severely hinder the application of lithium metal batteries. Although a lot of approaches have been developed to control Li deposition, most of them are based on inhibiting lithium deposition on protrusions, which can suppress Li dendrite growth at low current density, but is inefficient for practical battery applications, with high current density and large area capacity. Here, a novel leveling mechanism based on accelerating Li growth in concave fashion is proposed, which ena...