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The design of supercapacitor materials with both high mass loading and high areal capacity is a major strategy to overcome relatively low energy density of supercapacitors. Herein, NiCo‐layered double hydroxide (NiCo‐LDH)/NiCoOOH composite films with both ultrahigh mass loading and high areal capacity are prepared by a two‐step cyclic voltammetry method. The films consist of NiCo‐LDH/NiCoOOH microspheres assembled with ultrafine nanosheets with highly ordered pore distribution from macropores to micropores and abundant defect active sites, which are conducive to the transport of electrolyte ions, increasing the reaction kinetics, and greatly improving the utilization of active material. The optimal film with hierarchical microstructure featuring an ultrahigh mass loading of 80 mg cm−2 not only exhibits a state‐of‐the‐art high areal capacity of 14.7 mAh cm−2, but also shows a record‐high energy density of 10.7 mWh cm−2 , as well as presents remarkable mechanical stabilityand superior capacity retention of 99% after 20000 galvanostatic charge‐discharge cycles. Moreover, by combining the experimental analysis and theoretical calculations, the mechanism of preferential conversion of the NiCo‐LDH in the subtle defect region to NiCoOOH by electrochemistry and the synergistic effect in electrochemical energy storage of the NiCo‐LDH and NiCoOOH phases is proposed. [ABSTRACT FROM AUTHOR]

A facile method to prepare flexible n‐type Ag2Se/Se/polypyrrole (PPy) composite films is developed. First, Ag2Se nanostructures (NSs) are wet chemically synthesized; PPy is then in situ polymerized at the surface of the Ag2Se NSs; and finally, the Ag2Se/Se/PPy composite film on a porous nylon membrane is fabricated by a vacuum‐assisted filtration process followed by hot pressing. An optimal composite film shows an exceptionally high power factor of ≈2240 µW m−1 K−2 at 300 K, mainly because of the synergistic effect between well‐developed crystalline Ag2Se grains and a small amount of Se and PPy. The film also possesses outstanding flexibility (only about 6.5% decrease in electrical conductivity after 1000 times bending along a rod with a radius of 4 mm). Moreover, a flexible thermoelectric generator composed of six legs of the film outputs a voltage of 21.2 mV and a maximum power of 4.04 µW (corresponding power density of 37.6 W m−2) at a temperature difference of 34.1 K, verifying exceptionally high thermoelectric properties. This work shows the promise of the as‐prepared composite film for practical applications in wearable devices and will surely promote the research and development of flexible TE generators. [ABSTRACT FROM AUTHOR]

High-performance, breathable, conductive, and flexible polypyrrole (PPy) coated paper electrodes are prepared by an interfacial polymerization method using air-laid paper as a substrate. Owing to the synergistic effect of superior electrical conductivity, high wettability, and the porous architecture, the prepared electrode not only shows an outstanding specific capacitance and rate abilities (3100 and 2579 mF cm−2 at 1 and 20 mA cm−2 for a PPy coated paper electrode), but also exhibits excellent flexibility, wearability, and breathability. Based on these superior features, an all-solid-state supercapacitor assembled with the PPy coated paper electrodes shows an outstanding energy density of 62.4 µW h cm−2, remarkable air permeability and excellent flexibility to sustain various deformations. Furthermore, large-scale fabrication of conductive flexible paper electrode can be easily achieved through this method. Therefore, this work offers a new vision for flexible energy storage. [ABSTRACT FROM AUTHOR]

Thermoelectric (TE) fibers are more suitable than films for portable or wearable devices. Herein, 2–3 nm thick poly (3,4‐ethylenedioxythiophene): poly (styrenesulfonate) (PEDOT:PSS) layer‐coated tellurium nanowires (PC‐Te NWs) are in situ prepared by a hydrothermal method. Then a series of PEDOT: PSS/PC‐Te NWs composite fibers are prepared by wet spinning and post‐treatment. The nanolayer prevents the agglomeration of the Te NWs and makes the NWs and PEDOT:PSS matrix have good compatibility, which results in the PC‐Te NWs content to a high value of 70 wt% and the fibers still with flexibility. The high aspect ratio of the PC‐Te NWs and the stress from the inner wall of the needle during spinning make the NWs ordered align along the composite fiber. Due to the large content and orientational arrangement of the PC‐Te NWs, as well as effective post‐treatment, an optimized composite fiber shows a power factor of 385.4 µW m−1 K−2 at 300 K, which is ≈4.9 times as high as the highest value of previously reported PEDOT:PSS/Te NWs‐based composite fibers. In addition, the composite fiber has good flexibility. The flexible TE generators assembled have excellent output performance. This work provides an effective strategy for the preparation of high‐performance flexible TE composite fibers. [ABSTRACT FROM AUTHOR]

In recent years, poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)‐based nanocomposite thermoelectric (TE) materials are extensively investigated since they can take the advantages of both PEDOT:PSS (e.g., low thermal conductivity, high electrical conductivity, solution processability, and flexibility) and inorganic nanocrystals (e.g., high Seebeck Coefficient) to yield TE performance comparable to that of traditional inorganic TE materials. Besides, various preparation processes allow the mass fabrication of PEDOT:PSS‐based TE materials using some time‐saving and cost‐effective technologies, such as roll‐to‐roll and screen printing methods. This review focuses on the recent progress of PEDOT:PSS/inorganic nanocrystal composites for TE application. The relevant preparation strategies and TE properties are discussed intensively. In addition, the fabrication method, synergistic effect, and energy filtering effect involved in the composites, and flexible devices assembled from the composites are also discussed. Finally, challenges and prospects for future studies are summarized. [ABSTRACT FROM AUTHOR]

Solid‐state Li metal batteries (SSLMBs) are attractive due to their capability to simultaneously offer high energy density and high‐level safety when combining Li metal anodes, solid‐state electrolytes (SSEs), and high‐voltage cathodes together. However, SSLMBs may well incur short circuits caused by Li dendrites penetrations, which mainly originate from the instability and poor contact between Li metal and SSEs. Herein, by taking full advantage of the reaction products of Li and Li1.3Al0.3Ti1.7(PO4)3 (LATP), a lithium‐LATP composite anode (Li‐LATP) is obtained, in which a stable matrix is formed to enhance the contact between Li and the garnet‐type SSEs, alleviating the volume change and preserving an intact interface during the charge/discharge process. Consequently, the Li‐LATP/garnet/Li‐LATP symmetric cell displays a fairly low interfacial resistance of 6 Ω cm2 and stable cycling performance for over 2500 h with a low overpotential. Furthermore, the LiCoO2/garnet/Li‐LATP full cell also shows a high discharge capacity of 159 mAh g−1 and great cycling performance. [ABSTRACT FROM AUTHOR]