The formation of lithium dendrites induces the notorious safety issue and poor cycling life of energy storage devices, such as lithium–sulfur and lithium–air batteries. We propose a surface energy model to describe the complex interface between the lithium anode and electrolyte. A universal strategy of hindering formation of lithium dendrites via tuning surface energy of the relevant thin film growth is suggested. The merit of the novel motif lies not only fundamentally a perfect correlation between electrochemistry and thin film fields, but also significantly promotes larger‐scale application of lithium–sulfur and lithium–air batteries, as well as other metal batteries (e.g., Zn, Na, K, Cu, Ag, and Sn).

for supercapacitors. [1] However, toward this end the low conductivity nature and random orientation are two main obstacles for MOFs to overcome. Much efforts have been devoted into meeting challenges of the orientation and conductivity issues of MOFs, [2][3][4] the delicate addressing of which can lead to packaging performance enhancement in supercapacitors. [5] Using templates for epitaxial growth of MOF is an easy way to shape the orientation. [4] When it turns to electrochemical energy storage applications like supercapacitor, not only the conductivity of active materials, but the conductivity of the substrate as one part on the electrode can largely influence the overall performance. Sheberla and co-workers have successfully synthesized a conductive MOF for stable supercapacitors. [2] The rectangle cyclic voltammetry (CV) curve of this conductive MOF reveals that the inherent pseudocapacitive sites are not utilized. Recently, a Co-based MOF with conductive network frames was synthesized by Wei and co-workers, which showed promising properties. [6] Stimulated by these promising issues, it is the imperative direction to fabricate a hybrid supercapacitor that delivers a considerable energy density to battery and simultaneously maintain its high power density. To that end, oriented MOFs that can wield potential pseudocapacitance instead of being prepared in powder form on highly conductive substrate may be the best choice. To generate oriented MOF, templates are required, but the template removal procedure needs to be delicate, which may unavoidably trigger MOF deformation or even structural destruction.Affording the unrivalled flexibility to construct topologies and tune sizes or constituents, [7] MOFs have proved themselves versatile in electrochemical energy storage field. [8,9] So it is one common method with easy-manipulation and high efficiency to scarify MOFs as templates or precursors to synthesize target products like metal oxides, [8,10] metal hydroxides, [11] and carbon materials [12] with desired properties. The sacrifice process of MOFs is like DNA pairing, which assures those target products the conformal transformation and preserves pore structures and specific area from raw MOFs. It inspires us by the reverse thinking that: could it be possible to use target products as the Metal organic frameworks (MOFs) are considered as promising candidates for supercapacitors because of high specific area and potential redox sites. However, their shuffled orientations and low conductivity nature lead to severely-degraded performance. Designing an accessibly-manipulated and efficient method to address those issues is of outmost significance for MOF application in supercapacitors. It is the common way that MOFs scarify themselves as templates or precursors to prepare target products. But to reversely think it, using target products to prepare MOF could be the way to unlock the bottleneck of MOFs' performance in supercapacitors. Herein, a novel strategy using Co(OH) 2 as both the template and precursor to fab...

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Metal−organic frameworks (MOFs) and covalent−organic frameworks (COFs) are promising precursors for preparing high-performance carbonaceous materials for capacitive deionization (CDI). However, the simple pyrolysis of single MOFs or COFs usually leads to carbonaceous materials with disadvantages in salt adsorption capacity (SAC) and cycling stability, which are unfavorable to the further development of CDI. To address this issue, herein, we report the directed core−shell motif hybridization of COFs on MOFs to obtain selectively functionalized carbonaceous precursors, NH 2 -MIL-125(Ti) @TP-DQ COF, which then produce titanium dioxide nanoparticle-embedded nitrogenrich carbon architectures, called TiO 2 @COF, via pyrolysis. It is evidently expected that the resulting TiO 2 @COF possesses several advantageous features: (1) the inner core, which contains titanium dioxide nanoparticles, provides abundant faradic active sites for ion accommodation contributing additionally to the high SAC; (2) the outer capacitive shell, which is fibrous nitrogen-rich carbon, not only protects the inner core from the harsh environment of the solution and stabilizes the cycling performance but also affords plentiful nitrogen dopants for enhanced pseudocapacitive capacity and abundant pores for ion adsorption and electrolyte permeation; and (3) the outer COF-derived fibers interconnect with each other, giving rise to increasing electrical conductivity. As a result, TiO 2 @COF delivers a high SAC of 33.66 mg g −1 and favorable cycling stability over 40 cycles, significantly exceeding those of CDI electrodes derived from single MOFs or COFs. This work is expected to enrich the construction of selectively functionalized carbonaceous particles from MOFs and COFs and may also endow multiple promising applications of core−shell motif hybrids.

Using polymer electrolytes with relatively high mechanical strength, enhanced safety, and excellent flexibility to replace the conventional liquid electrolytes is an effective strategy to curb the Li-dendrite growth in Li-metal batteries (LMBs). However, low ionic conductivity, unsatisfactory thermal stability, and narrow electrochemical window still hinder their applications. Here, we fabricate Li0.35La0.55TiO3 (LLTO) nanofiber-enabled poly­(vinylidene fluoride) (PVDF)-based composite polymer electrolytes (CPEs) with enhanced mechanical property and wide electrochemical window. The results show that 15 wt % of LLTO nanofibers synergize with PVDF, giving a flexible electrolyte membrane with significantly improved performance, such as high ionic conductivity (5.3 × 10–4 S cm–1), wide electrochemical window (5.1 V), high mechanical strength (stress 9.5 MPa, strain 341%), and good thermal stability (thermal degradation 410 °C). In addition, an all-solid-state Li-metal battery of sandwich-type LiFePO4/PVDF–CPE (15 wt % of LLTO)/Li delivers satisfactory cycling stability and outstanding rate performance. A reversible capacity of 121 mA h g–1 is delivered at 1 C after 100 cycles. This work exemplifies that the introduction of LLTO nanofibers can improve the electrochemical performances of PVDF-based CPEs used as electrolytes for all-solid-state LMBs.