Layer-by-layer Process Research Articles

Manufacturing thick laminates using a layer by layer curing approach

The work presented in this paper puts forward a manufacturing strategy for the processing of thermosetting composites based on Layer by Layer (LbL) curing. The process operates additively with sublaminates placed in a heated press, partially cured while consolidating, followed by loading of the next sublaminate and repeating the cycle until part completion. Coupled consolidation-cure simulation was utilised to design the process and establish its capabilities showing that halving the cure time is possible for thick parts. Mechanical testing showed that for pre-cure of placed layers below the gelation degree of cure, interlaminar properties are equivalent to those of conventionally manufactured material. A trial was carried out demonstrating successfully the LbL process. On-line measurements of temperature and compaction matched the predictions of the simulation, whilst the quality of the material produced is equivalent to that of conventionally produced composites.

Photo-crosslinking and layer-by-layer processed organic photodetectors with remarkably suppressed dark current

The effective reduction of dark (or noise) current presents a significant hurdle in enhancing the detectivity of organic photodetectors (OPDs). To address this challenge, a photo-crosslinkable donor polymer, PM6-Br50, is synthesized by introducing bromoalkyl side-chains onto the PM6 structure. This modification enables the formation of a pseudo planar heterojunction (p-PHJ) structure of crosslinked donor/acceptor through a layer-by-layer (LbL) sequential process without the necessity for an semi-orthogonal solvent. This innovation effectively overcomes solvent-related limitations in the LbL process. Additionally, we replace the semi-metallic hole-transport layer (HTL), PEDOT:PSS, with a semiconducting conjugated polyelectrolyte (TPAFS-TMA) with a high conduction band. The p-PHJ configuration, featuring pure donor/anode and pure acceptor/cathode contacts, enhances the charge injection barrier for electrons (holes) from the anode (cathode) in the dark under reverse bias, effectively minimizing dark current. Furthermore, the TPAFS-TMA HTL serves to impede electron injection from the anode. Through the synergistic combination of these two strategies, a significantly reduced dark current density (4.03 × 10−10 A cm−2) is measured by four orders of magnitude, compared to the bulk heterojunction OPDs with PEDOT:PSS. Furthermore, we measure remarkably high shot noise-based and total noise current-based specific detectivities of 4.27 × 1013 and 6.97 × 1012 cm Hz1/2 W−1 (with linear dynamic range of 73.7 dB), respectively.

Light-Responsive Layer-By-Layer Film Containing Gold Nanorods for Sequential Drug Release.

Chemically and physically stable multidrug-loaded layer-by-layer (LbL) films are promising candidates for sequential and on-demand drug release at concentrations suitable for various applications. The synergistic effect of the sequential release of drugs may enhance their therapeutic efficacy in treating skin cancer and other complex medical conditions. In this study, we prepared LbL films by alternating the deposition of cationic linear polyethylenimine, camptothecin (CPT)-loaded gold nanorods (GNRs), anionic poly(styrenesulfonate), and doxorubicin (DOX) based on electrostatic interactions. The film exhibited loading of CPT and DOX, which could be tuned according to the requirements of the application by changing the parameters of the LbL process. Herein, CPT was encapsulated in GNRs and showed good stability and absorption in the near-infrared (NIR) range (650-900 nm). The prepared LbL film showed a pH-dependent DOX release. Subsequently, the functionalized GNRs showed excellent photothermal properties, which assisted the on-demand release of CPT upon NIR irradiation with further release of DOX. Our results suggest that the LbL approach for sequential drug release can be an effective drug delivery platform owing to its cytocompatibility, anticancer effects, and stimuli-responsive properties.

Advanced Functionalized Materials Based on Layer-by-Layer Assembled Natural Cellulose Nanofiber for Electrodes: A Review.

The depletion of fossil fuel resources and its impact on the environment provide a compelling motivation for the development of sustainable energy sources to meet the increasing demand for energy. Accordingly, research and development of energy storage devices have emerged as a critical area of focus. The electrode materials are critical in the electrochemical performance of energy storage devices, such as energy storage capacity and cycle life. Cellulose nanofiber (CNF) represents an important substrate with potentials in the applications of green electrode materials due to their environmental sustainability and excellent compatibility. By utilizing the layer-by layer (LbL) process, well-defined nanoscale multilayer structure is prepared on a variety of substrates. In recent years, increasing attention has focused on electrode materials produced from LbL process on CNFs to yield electrodes with exceptional properties, such as high specific surface area, outstanding electrical conductivity, superior electrochemical activity, and exceptional mechanical stability. This review provides a comprehensive overview on the development of functional CNF via the LbL approach as electrode materials.

Tuning stimuli-responsive properties of alginate hydrogels through layer-by-layer functionalization for dual-responsive dual drug release

This study aimed to understand the effect of layer-by-layer (LbL) modification on the stimuli-responsive properties of physical alginate (ALG) hydrogels and examine the potential of LbL-coated hydrogels as dual responsive, dual drug releasing platforms for antibacterial applications. ALG hydrogels were functionalized through LbL self-assembly using temperature-responsive poly(2-isopropyl-2-oxazoline) (PiPOX) and pH-responsive tannic acid (TA). Ciprofloxacin (CIP) and Curcumin (CUR) were used as model hydrophilic and hydrophobic drugs, respectively. CIP was included in the hydrogel during LbL process, whereas CUR was incorporated into the hydrogel through gelation in the presence of CUR-loaded CaCO3 microparticles. The effect of LbL modification on the stimuli-responsive swelling, stability and drug release properties of hydrogels was examined in comparison with bare hydrogels. We have shown that LbL modification resulted in a partial loss of solid content from the hydrogel, leading to a greater swelling. In addition, LbL modification imparted temperature-responsiveness to ALG hydrogel and provided enhanced CIP release upon increasing the temperature at pH 7.4. On the other hand, LbL-coated hydrogels displayed minimal CIP release at pH 5.5 regardless of the temperature. The antibacterial activity of LbL-coated hydrogels was greater at pH 7.4 than pH 5.5 against both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) bacteria. The combination of CIP and CUR provided enhanced antibacterial effect on the inhibition of E.coli growth at both pH 7.4 and pH 5.5. This effect became more remarkable as the CIP concentration was decreased at a constant CUR concentration in the hydrogels. However, the combinatorial effect of CIP and CUR was not observed with S. aureus. Overall, these results may be promising for wound healing applications where drug release is triggered when the pH becomes alkaline in the presence of bacterial colonization.

Layer by layer self-assembly for coating a nanosuspension to modify drug release and stability for oral delivery

Layer-by-layer (LbL) modification is an effective way to tune the properties of particles. However, the traditional LbL process involves repeated washing steps which are not compatible with nanoparticles with a partial solubility. In this work, we demonstrate the use of a titration method for producing LbL coatings onto a nanosuspension of curcumin (a compound with a limited aqueous solubility). The aim of the work was to show how LbL can be used to enhance the release behaviour and stability of the curcumin in a nanosuspension form. Coated nanosuspension samples were produced using biocompatible and biodegradable polyelectrolytes, poly-l-arginine, and sodium alginate and was sizes approximately 500 nm. A stimuli-responsive nanosuspension was prepared by coating the nanosuspension with 5 layers of poly-l-arginine and alginate and Eudragit L100 as an outmost layer. The in vitro release of these nanosuspensions revealed that the use of a pH-responsive layer (Eudragit L100) as an outermost shell resulted in delay the release of curcumin (5%) in acidic pH and facilities its release in neutral pH (11%) over 72 h. Additionally, the bioaccessibility study showed that increasing the number of layers resulted in increasing the stability curcumin in nanosuspension when exposed to conditions that mimic the gastrointestinal tract from 20% for uncoated nanosuspension to 40% and 90% for 4-layered coated nanosuspension and stimuli-responsive (6-layered) coated nanosuspension, respectively. The cytotoxicity of LbL-coating of nanosuspension revealed a reduction in the toxicity of curcumin. This work shows how a titrated LbL modification approach could be used to tailor the stability and the release behaviour of nanosuspensions for oral drug delivery applications.

Organic Thermoelectric Nanocomposites Assembled via Spraying Layer-by-Layer Method

Thermoelectric (TE) materials have been considered as a promising energy harvesting technology for sustainably providing power to electronic devices. In particular, organic-based TE materials that consist of conducting polymers and carbon nanofillers make a large variety of applications. In this work, we develop organic TE nanocomposites via successive spraying of intrinsically conductive polymers such as polyaniline (PANi) and poly(3,4-ethylenedioxy- thiophene):poly(styrenesulfonate) (PEDOT:PSS) and carbon nanofillers, and single-walled carbon nanotubes (SWNT). It is found that the growth rate of the layer-by-layer (LbL) thin films, which comprise a PANi/SWNT-PEDOT:PSS repeating sequence, made by the spraying method is greater than that of the same ones assembled by traditional dip coating. The surface structure of multilayer thin films constructed by the spraying approach show excellent coverage of highly networked individual and bundled SWNT, which is similarly to what is observed when carbon nanotubes-based LbL assemblies are formed by classic dipping. The multilayer thin films via the spray-assisted LbL process exhibit significantly improved TE performances. A 20-bilayer PANi/SWNT-PEDOT:PSS thin film (~90 nm thick) yields an electrical conductivity of 14.3 S/cm and Seebeck coefficient of 76 μV/K. These two values translate to a power factor of 8.2 μW/m·K2, which is 9 times as large as the same films fabricated by a classic immersion process. We believe that this LbL spraying method will open up many opportunities in developing multifunctional thin films for large-scaled industrial use due to rapid processing and the ease with which it is applied.

Multilayer self-assembled kappa carrageenan/ chitosan: Heparin coating on Mg alloys for improving blood compatibility

The study aims to develop a layer-by-layer (LbL) self-assembled coating of Kappa carrageenan (KC) and heparin-loaded chitosan nanoparticles on the AZ91 alloy modified using micro-arc oxidation (MAO) to control its high corrosion rate and improve the hemocompatibility. In this regard, after the MAO process, polyethylene imine (PEI) coating was initially coated on the AZ91 samples. Heparin was loaded on chitosan nanoparticles (chitosan: heparin) with an average size of 55–130 nm. Afterward LBL self-assembled process was performed to deposit subsequent Chitosan: heparin and KC layers on MAO modified AZ91 (KC/Chitosan: heparin). The LbL process was repeated for 10,20, and 30 layers to get a uniform coating with desired electrochemical and biological properties. The electrochemical performance of the samples in phosphate-buffered saline (PBS, pH= 7.4) showed a significant improvement in the corrosion resistance of AZ91 samples after a two-step MAO and 30-layer LbL coating. Moreover, the heparin release from the multilayered coated samples was enhanced by increasing the number of layers. Finally, the determination of blood cell count (red blood cells, white blood cells, and platelets) and platelet adhesion indicated that controlled release of heparin from the coating resulted in a significant improvement of hemocompatibility. Overall, this multilayer KC/Chitosan: heparin coating with significant corrosion resistivity and hemocompatibility could have the potential for cardiovascular stent applications.

Enhanced thermal performances of PCM heat sinks enabled by layer-by-layer-assembled carbon nanotube–polyethylenimine functional interfaces

Rationally designed hybrids of heat sinks (HSs) and phase change materials (PCMs) can mutually complement their fundamental limitations. However, integrating PCMs into HSs inevitably incurs additional thermal resistances and degradation during solid–liquid phase transitions owing to unstable contact interfaces. Herein, we report layer-by-layer (LbL)-assembled multiwalled carbon nanotube (MWCNT)–polyethyleneimine (PEI) functional interfaces between the PCM and HS surfaces to enhance thermal management capabilities. The LbL process used in this study involves direct fabrication of electrostatically adhered nanocoatings of multiple materials via a solution process, which resulted in facile formation of MWCNT-PEI percolation networks on an aluminum HS. The PCM-HS was completed by filling the HS channels with a PCM (n-eicosane). The functional interface increased the active surface areas for thermal transport and optimized the porous structures for the stabilization of the PCM–HS boundary under repetitive solid–liquid phase changes. Comparison of the fabricated specimens (bare and PCM-filled HSs without LbL interfaces) elucidated the enhanced thermal performances in transient-static operating conditions. This was confirmed by experimentally measuring the real-time temperature responses at various levels of heating power and the time delays to reach the set point temperatures, indicating a more than 10% improvement in effectiveness using the LbL interface. Furthermore, the LbL interfaces efficiently alleviated thermal shock or overload under intermittent thermal loads. The developed LbL interface offers a tunable–scalable method to fabricate PCM-filled HSs with advanced thermal properties that cannot be achieved using a conventional HS.

Robust and Highly Conductive PEDOT:PSS:Ag Nanowires/Polyethyleneimine Multilayers Based on Ionic Layer-by-Layer Assembly for E-Textiles and 3D Electronics

This study shows the production of robust and highly conductive multilayers through the layer-by-layer (LBL) assembly of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS):Ag nanowires and counterionic compounds, including monomeric tris(2-aminoethyl)amine and chitosan and polyethylenimine (PEI). These materials provide a strong electrostatic interaction with PEDOT:PSS and enable a reliable interface between the layers during the LBL process. Systematic chemical and electrical analyses of the multilayers reveal that the use of PEI results in the highest electrical conductivity (2034 S cm–1 at six LBL cycles) and interfacial adhesion (8.9 mN at the tearing stress). Furthermore, the use of PEI generates a powerful interconnection for electrical circuit patterns with low contact resistance (∼5 Ω) and robust mechanical durability during the water-assisted welding process. Finally, we successfully show the use of this material in electronic textile applications and 3D electronics based on water-assisted welding and transfer printing technology to confirm its feasibility for use in device applications.

Cover Feature: Hydrogen Bonding‐Based Layer‐by‐Layer Assembly of Nature‐Derived Eggshell Membrane Hydrolysates and Coffee Melanoidins in Single‐Cell Nanoencapsulation (ChemNanoMat 5/2022)

Layer-by-layer (LbL) assembly of food waste-derived materials, eggshell membrane hydrolysates and coffee melanoidins, is applied to the single-cell nanoencapsulation (SCNE) of Saccharomyces cerevisiae. The hydrogen bonding-based LbL process is extremely cytocompatible (viability > 99%), and the cell is protected from external assaults, such as heavy metals and UV-B, after the SCNE. The shell's durability is further augmented by ferric ion-mediated cross-linking. More information can be found in the Research Article by Insung S. Choi et al. Photo credit: E. K. Kang.

Precisely tuned photonic properties of crystalline nanocellulose biocomposite coatings by gradually tailored nanoarchitectures

Inspired by nature, we fabricated optically tuned bio-organic films of cellulose nanofibers (CNFs) and chitosan by precisely structuring layer-by-layer (LBL) assembly techniques. Directly extracted from tunicate, highly crystalline CNFs were deposited into gradual nanoporous structures, which dictates wave-like behaviors of optical transmittance and cyclic patterns of structural coloration. The optical transmittance of a glass substrate increased from 91% to 98.2% at a wavelength of 550 nm by reflectivity attenuation controls. The monochromic structural colors were discretely varied from orange to purple, seen only at a specific angle of the incident light, demonstrating visibly hidden security potential. Furthermore, we could modulate the coloration cycles by accelerating the LBL processes with polydopamine-coated CNFs. The 3D nanoporous structures of CNFs also provide synergies, including superhydophilic surface-driven antifogging properties. Our optically versatile biofilms made by all-natural CNFs and chitosan provide various potential applications, including solar cells, securities, and eco-friendly colors.

Insights into the Structural and Morphological Properties of Layer-by-Layer Processed Organic Photovoltaics.

Recently, with the development of figure-of-merit non-fullerene acceptor materials combined with a ternary strategy and layer-by-layer (LbL) processing, the efficiency of single-junction organic solar cells has exceeded 18%. However, the structural properties of LbL-processed films have not been sufficiently elucidated. Herein, we systematically investigate films fabricated via LbL processing of three different systems, including a ternary system. In particular, we focus on the structural and morphological transitions associated with the diffusion process controlled by thermal annealing and an additive solvent. Different diffusion and crystal formation mechanisms were clearly identified, which were observed to be dependent on the characteristics of the upper layer formed during the LbL process. Based on this insight, the photovoltaic properties associated with various LbL conditions are elucidated, and an ideal path toward a better device is suggested.

Synthesis of multilayered pH-responsive nanocapsules by using tolyltriazole as corrosion inhibitor and ZrO2 nanoparticles as core

Smart multilayered pH-sensitive nanocapsules were successfully fabricated using a Layer by Layer (LbL) process. The obtained products were characterized using FESEM, TEM, EDS and elemental mapping, zeta-potential, FTIR, TGA, SIMS and the Tafel polarization techniques. A 55% enhancement in ZrO2 particle size was detected in FESEM and TEM images with a corona view after the LbL process. EDS and elemental mapping analysis and measurements of zeta potential indicated the well-defined layered deposition. FTIR showed the electrostatic bonding between tolyltriazole (TTA) molecules and different overlapping layers. The thermal analysis and SIMS confirmed that 2.7% TTA loaded in nanocapsules. Tafel polarization results showed successful surface protection due to self-releasing of TTA from nanocapsules at high and low pH solutions.

Metal-phenolic network as precursor for fabrication of metal-organic framework (MOF) nanofiltration membrane for efficient desalination

A continuous and ultra-thin metal-phenolic network top layer on a polyethersulfone substrate surface was used as metal precursor for a metal-organic framework (MOF) membrane synthesis. A plant polyphenol tannic acid (TA) and Zn2+ based network top layer prepared by a layer-by-layer (LBL) self-assembly process was immersed into a 2-methylimidazole aqueous solution, and then a ZIF-8 top layer was facilely formed due to the partial self-conversion of TA-Zn2+ network to ZIF-8. The LBL process provides sufficient controllability of preparing a continuous and ultra-thin ZIF-8 top layer, which are crucial factors for nanofiltration membrane separation performance. The optimized ZIF-8 membrane exhibited a pure water permeance (PWP) of 5.1 L m−2 h−1 bar−1, a 55.2% NaCl rejection and a 93.6% Na2SO4 rejection. This is one of the few MOF membranes that possesses a divalent inorganic salt rejection higher than 90%. The novel zinc source of ZIF-8 synthesis disclosed in this study can provide a new incentive to not only MOF membrane preparation but also engineering MOFs towards a wide energy and environmental applications.

Non-destructive determination of functionalized polyelectrolyte placement in layer-by-layer films by IR ellipsometry.

Layer-by-layer (LbL) assembly facilitates controlled coatings on a variety of surfaces with the ability to manipulate the composition through the thickness by selection of the complementary pairs. However, the characterization of these composition profiles tends to be destructive and requires significant compositional differences that can limit their utility. Here, we demonstrate the ability to non-destructively quantify the depth dependence of the allyl content associated with the selective incorporation of poly(sodium acrylate-co-allylacrylamide) (84 : 16 mol : mol) (allyl-PAA) in LbL films based on the assembly of poly(diallyldimethylammonium chloride) (PDAC)/poly(acrylic acid) (PAA) and PDAC/allyl-PAA. Although the atomic composition of the film is not dramatically influenced by the change between PAA and allyl-PAA, the absorption in the IR near 1645 cm-1 by the allyl group provides sufficient optical contrast to distinguish the LbL components with spectroscopic ellipsometry. The use of IR spectroscopic ellipsometry can determine the thickness of layers that contain allyl-PAA and also gradients that develop due to re-arrangements during the LbL process. With multiple films fabricated simultaneously, the location of the gradient between the 1st and 2nd series of multilayers (e.g., first PDAC/PAA bilayers and then PDAC/allyl-PAA bilayers) can be readily assessed. The results from a variety of different multilayer architectures indicate that the gradient is located within the thickness expected for the 1st deposited bilayer stack (PDAC/PAA or PDAC/allyl-PAA). These results are indicative of a dynamic dissolution-deposition process (in- and out- diffusion) during the fabrication of these LbL films. These results provide additional evidence into the mechanisms for exponential growth in LbL assemblies. The ability to quantify a gradient with the low contrast system examined indicates that spectroscopic IR ellipsometry should be able to non-destructively determine compositional gradients for most polymer films where such gradients exist.

Single‐Cell Nanoencapsulation of Saccharomyces cerevisiae by Cytocompatible Layer‐by‐Layer Assembly of Eggshell Membrane Hydrolysate and Tannic Acid

Single‐cell nanoencapsulation (SCNE) demands cytocompatible materials and processes to ensure the maintenance of cell viability and prefers the degradation‐on‐demand and postfunctionalization of the cytoprotective shells. Although the layer‐by‐layer (LbL) method has intensively been used for SCNE, there have been few reports on the cytocompatible LbL shells that are postfunctionalizable under mild conditions. Herein, the use of nature‐derived eggshell membrane hydrolysate (ESMH) as a counter component to tannic acid (TA) for hydrogen bonding‐based LbL shell formation on Saccharomyces cerevisiae is proposed. In addition to the great cytocompatibility of the LbL process and protective capability of the ESMH/TA shell (e.g., 18‐fold increase in survival against Cu2+), the shell is postfunctionalizable, benefitting from the presence of various functional groups in the ESMH, as demonstrated by reactions with N‐hydroxysuccinimide‐ or maleimide‐conjugated fluorescent probes and bioinspired silicification. This work suggests that ESMH would be an advanced biomaterial for chemically interfacing with living cells in a controlled fashion.

Highly Conductive PEDOT:PSS Thin Films with Two-Dimensional Lamellar Stacked Multi-Layers.

Conjugated polymers are desired as organic electrode materials because of their functional properties such as solution process, low cost, and transparency. Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), in particular, shows the highest applicability, but its heterogeneous structure presents limitations in terms of electrical conductivity. In this study, a facile method to fabricate multi-layered thin films with higher ordered structures was developed. Through the etching process with H2SO4 and dimethyl sulfoxide(DMSO), the insulated rich-PSS was removed from the upper layer to improve its electrical properties and rearrange the PEDOT molecular structures. The thickness of PEDOT:PSS thin films was experimentally optimized to maximize the enhancement of carrier mobility via a layer-by-layer (LBL) process. The combined method, consisted of etching and the LBL process, showed the improvement of the charge carrier mobility from 0.62 to 2.80 cm2 V−1 s−1. The morphology and crystallinity of the ordered PEDOT:PSS structure were investigated by X-ray photoemission spectroscopy (XPS), Raman, and X-ray diffraction (XRD). As a result, two-dimensional lamellar-stacked PEDOT:PSS thin films were fabricated through the repetitive etching and LBL process. The optimized PEDOT:PSS thin film showed an excellent electrical conductivity of 3026 S cm−1, which is 3.8 times higher than that of the pristine film (801 S cm−1).

Layer‐by‐layer self‐assembly of collagen and chitosan biomolecules on polyurethane films

AbstractPolyurethane (PU) films used in wound dressing applications often have appropriate properties. Still, surface modification is necessary to increase the biocompatibility. In this research, the surface of the PU films was modified with collagen and chitosan biomolecules through layer by layer (LbL) self‐assembly process. The PU films were synthesized from castor oil and hexamethylene diisocyanate. Then, they were treated with low‐pressure nitrogen plasma to graft with poly(acrylic acid). Before performing the LbL process, the surfaces of the PU films were modified using three different reagents, including (A) NaOH solution, (B) EDC/NHS solution, or (C) hexamethylene diamine. Then, the collagen and chitosan deposited in three and five layers on the surface. The images of FESEM, confocal microscopy, and AFM showed that the best performance of the LbL deposition process was after the surface modification with hexamethylenediamine (HMDA). The MTT assay showed that the presence of these biomolecules had boosted the proliferation of fibroblast cells. Increasing the number of the deposited layer from three to five, decreased the cell viability and antibacterial activity of the films. The obtained results propose the modification with HMDA and the deposition of three layers of collagen and chitosan on the PU films to improve its biocompatibility.

High-Energy Density Li-O2 Battery with a Polymer Electrolyte-Coated CNT Electrode via the Layer-by-Layer Method.

Li-O2 batteries have attracted considerable attention for several decades due to their high theoretical energy density (>3400 Wh/kg). However, it has not been clearly demonstrated that their actual volumetric and gravimetric energy densities are higher than those of Li-ion batteries. In previous studies, a considerable quantity of electrolyte was usually employed in preparing Li-O2 cells. In general, the electrolyte was considerably heavier than the carbon materials in the cathode, rendering the practical energy density of the Li-O2 battery lower than that of the Li-ion battery. Therefore, air cathodes with significantly smaller electrolyte quantities need to be developed to achieve a high specific energy density in Li-O2 batteries. In this study, we propose a core-shell-structured cathode material with a gel-polymer electrolyte layer covering the carbon nanotubes (CNTs). The CNTs are synthesized using the floating catalyst chemical vapor deposition method. The polymeric layer corresponding to the shell is prepared by the layer-by-layer (LbL) coating method, utilizing Li-Nafion along with PDDA-Cl [poly(diallyldimethylammonium chloride)]. Several bilayers of Li-Nafion and PDDA, on the CNT surface, are successfully prepared and characterized via X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The porous structure of the CNTs is retained after the LbL process, as confirmed by the nitrogen adsorption-desorption profile and BJH pore-size distribution analysis. This porous structure can function as an oxygen channel for facilitating the transport of oxygen molecules for reacting with the Li ions on the cathode surface. These polymeric bilayers can provide an Li-ion pathway, after absorbing a small quantity of an ionic liquid electrolyte, 0.5 M LiTFSI EMI-TFSI [1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide]. Compared to a typical cathode, where only liquid electrolytes are employed, the total quantity of electrolyte in the cathode can be significantly reduced; thereby, the overall cell energy density can be increased. A Li-O2 battery with this core-shell-structured cathode exhibited a high energy density of approximately 390 Wh/kg, which was assessed by directly weighing all of the cell components together, including the gas diffusion layer, the interlayer [a separator containing a mixture of LiTFSI, 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (PYR-14), and PDDA-TFSI], the lithium anode, and the LbL-CNT cathode. The cycle life of the LbL-CNT-based cathode was found to be 31 cycles at a limited capacity of 500 mAh/gcarbon. Although this is not an excellent performance, it is almost 2 times better than that of a CNT cathode without a polymer coating.