One of the most critical issues in preparing high-performance transparent supercapacitors (TSCs) is to overcome the trade-off between areal capacitance and optical transmittance as well as that between areal capacitance and rate capability. Herein, we introduce a TSC with high areal capacitance, fast rate capability, and good optical transparency by minimizing the charge transfer resistance between pseudocapacitive nanoparticles (NPs) using molecular linker-and conductive NPmediated layer-by-layer (LbL) assembly. For this study, bulky ligand-stabilized manganese oxide (MnO) and indium tin oxide (ITO) NP multilayers are LbL-assembled through a ligand exchange reaction between native ligands and small multidentate linkers (tricarballylic acid). The introduced molecular linker substantially decreases the separation distance between neighboring NPs, thereby reducing the contact resistance of electrodes. Moreover, the periodic insertion of ITO NPs into the MnO NP-based electrodes can lower the charge transfer resistance without a meaningful loss of transmittance, which can significantly improve the areal capacitance. The areal capacitances of the ITO NP-free electrode and the ITO NP-incorporated electrode are 24.6 mF cm −2 (at 61.6% transmittance) and 40.5 mF cm −2 (at 60.8%), respectively, which outperforms state of the art TSCs. Furthermore, we demonstrate a flexible symmetric solid-state TSC that exhibits scalable areal capacitance and optical transmittance.

Achieving high energy storage performance and fast rate capability at the same time is one of the most critical challenges in battery technology. Here, a high‐performance textile cathode with notable specific/areal capacities and high rate capability through an interfacial interaction‐mediated assembly that can directly bridge all interfaces existing between textile and conductive materials and between conductive and active materials, minimizing unnecessary insulating organics is reported. First, amine (NH2)‐ and carboxylic acid (COOH)‐functionalized multiwalled carbon nanotubes (MWNTs) are alternately layer‐by‐layer (LbL)‐assembled onto cellulose textiles for the preparation of conductive textiles using hydrogen bonding interactions. Dioleamide‐stabilized LiFePO4 nanoparticles (DA‐LFP NPs) with high crystallinity and high dispersion stability in organic media are consecutively LbL‐assembled with MWNT‐NH2 onto conductive textiles through ligand replacement between native DA ligands bound to the surface of the LFP NPs and NH2 groups of MWNTs. In this case, 35 nm sized LFP NPs are densely and uniformly adsorbed onto all regions of the textile, and additionally, their areal capacities are increased according to the deposition number without a significant loss of charge transfer kinetics. The formed textile cathodes exhibit remarkable specific/areal capacities (196 mAh g−1/8.3 mAh cm−2 at 0.1 C) and high rate capability with highly flexible mechanical properties.

Electrical conductivity, mechanical flexibility, and large electroactive surface areas are the most important factors in determining the performance of various flexible electrodes in energy storage devices. Herein, a layer‐by‐layer (LbL) assembly‐induced metal electrodeposition approach is introduced to prepare a variety of highly porous 3D‐current collectors with high flexibility, metallic conductivity, and large surface area. In this study, a few metal nanoparticle (NP) layers are LbL‐assembled onto insulating paper for the preparation of conductive paper. Subsequent Ni electroplating of the metal NP‐coated substrates reduces the sheet resistance from ≈103 to <0.1 Ω sq−1 while maintaining the porous structure of the pristine paper. Particularly, this approach is completely compatible with commercial electroplating processes, and thus can be directly extended to electroplating applications using a variety of other metals in addition to Ni. After depositing high‐energy MnO NPs onto Ni‐electroplated papers, the areal capacitance increases from 68 to 811 mF cm−2 as the mass loading of MnO NPs increases from 0.16 to 4.31 mg cm−2. When metal NPs are periodically LbL‐assembled with the MnO NPs, the areal capacitance increases to 1710 mF cm−2.

Here, we report that metal nanoparticle (NP)-based paper/textile electrodes with bulk metallic conductivity can be prepared via organic linker-modulated ligand exchange reaction and in situ room-temperature metallic fusion without additional chemical or thermal treatments. For this study, amine-functionalized molecule linkers instead of bulky polymer linkers were layer-by-layer (LbL)-assembled with tetraoctylammonium bromide (TOABr)-stabilized Au NPs to form Au NP multilayered films. By conversion of the amine groups of the organic molecule linkers from −NH3 + to the −NH2 groups, as well as by a decrease in the size of the organic linkers, the LbL-assembled Au NPs became highly interconnected and fused during LbL deposition, resulting in Au NP multilayers with adjustable conductivity and transport behavior. These phenomena were also predicted by a density functional theory investigation for the model system. Particularly, LbL-assembled films composed of TOABr-Au NPs and diethylenetriamine (M w: ∼104) exhibited a remarkable electrical conductivity of 2.2 × 105 S·cm–1, which was higher than the electrical conductivity of the metal NP-based electrodes as well as the carbon material-based electrodes reported to date. Furthermore, based on our approach, a variety of insulating flexible papers and textiles were successfully converted into real metal-like paper and textile electrodes with high flexibility preserving their highly porous structure. This approach can provide a basis for further improving and controlling the electrical properties of flexible electrodes through the control of organic linkers.

No abstract