Anode Interlayer Research Articles

P-Doped Conducting Polyelectrolyte as an Anode Interlayer Enables High Efficiency for 1 cm2 Printed Organic Solar Cells.

Manufacturing large-area devices through a low-cost and large batch printing technique is the key to the commercialization of organic solar cells (OSCs). However, the lack of printable anode interlayer (AIL) materials severely impedes the development of high-efficiency printed OSCs. Herein, we synthesize three p-type self-doped conjugated polyelectrolytes (CPEs), namely, PCP-B, PCP-2B, and PCP-3B, as printable AIL materials for fabricating high-performance and large-area OSCs. By increasing the number of benzene units in the polymer backbone, the work function of the CPEs was enhanced from 4.57 to 5.01 eV, and the optical transparency was also improved because of the enlarged polymer band gap. The improved photoelectronic properties as well as a good film-forming capacity make the PCP-3B an ideal AIL material to be processed by the printing technique. By using PCP-3B, a 1 cm2 printed device was fabricated in which all the functional layers, including the AIL, active layer, and cathode interlayer were processed by blade-coating, achieving a power conversion efficiency (PCE) of 9.67%. The PCE belongs to the highest efficiency at present for printable large-area OSCs, showing a promising prospect for the OSC mass production.

Anode interlayer in organic photovoltaics: Narrow bandgap small molecular materials as exciton‐blocking layer

AbstractSix materials were used as an interlayer at the anode side (anode interlayer [AIL]) of an archetypical planar heterojunction organic solar cell (OSC). In addition to two conventional wide bandgap hole transport materials (HTMs), tris(4‐carbazol‐9‐ylphenyl)amine (TCTA) and trans‐4,4′‐bis[N‐(naphthalen‐1‐yl)‐N‐phenylamino]stilbene (NPAE), we explore four narrow bandgap materials, bis(biphenylaminospiro)‐fumaronitrile (PhSPFN), bis(N‐(naphthalen‐1‐yl)‐N‐phenylamino)anthraquinone (NPAAnQ), bis‐(di(2‐fluorophenyl)aminospiro)‐fumaronitrile (FPhSPFN), and bis[4‐(N‐(pyren‐1‐yl)‐N‐phenylamino)phenyl]fumaronitrile (PyPAFN), the energy levels of which essentially align with the ones of SubPc, the active light‐absorbing material of the OSC study herein. By using a narrow bandgap AIL, universally enhanced short‐circuit current density and power conversion efficiencies (PCEs) have been achieved. In addition, one of these materials, FPhSPFN, results in a PCE of 5.13%, which is the highest reported value for SubPc solar cells with a similar architecture. This is ascribed to the formation of an otherwise passive exciton‐blocking interface. Furthermore, this demonstrates that charge selectivity by way of a high‐lying lowest unoccupied molecular orbital (LUMO) energy level is not a prerequisite for successful AIL design. As such, in terms of energy level alignment and bandgap energies, we establish a viable alternative approach toward interface and interlayer material design.

Dual Interfacial Design for Efficient CsPbI2 Br Perovskite Solar Cells with Improved Photostability.

A synergic interface design is demonstrated for photostable inorganic mixed-halide perovskite solar cells (PVSCs) by applying an amino-functionalized polymer (PN4N) as cathode interlayer and a dopant-free hole-transporting polymer poly[5,5'-bis(2-butyloctyl)-(2,2'-bithiophene)-4,4'-dicarboxylate-alt-5,5'-2,2'-bithiophene] (PDCBT) as anode interlayer. First, the interfacial dipole formed at the cathode interface reduces the workfunction of SnO2 , while PDCBT with deeper-lying highest occupied molecular orbital (HOMO) level provides a better energy-level matching at the anode, leading to a significant enhancement in open-circuit voltage (Voc ) of the PVSCs. Second, the PN4N layer can also tune the surface wetting property to promote the growth of high-quality all-inorganic perovskite films with larger grain size and higher crystallinity. Most importantly, both theoretical and experimental results reveal that PN4N and PDCBT can interact strongly with the perovskite crystal, which effectively passivates the electronic surface trap states and suppresses the photoinduced halide segregation of CsPbI2 Br films. Therefore, the optimized CsPbI2 Br PVSCs exhibit reduced interfacial recombination with efficiency over 16%, which is one of the highest efficiencies reported for all-inorganic PVSCs. A high photostability with a less than 10% efficiency drop is demonstrated for the CsPbI2 Br PVSCs with dual interfacial modifications under continuous 1 sun equivalent illumination for 400 h.

Preparation of AZO:PDIN hybrid interlayer materials and application in high-gain polymer photodetectors with spectral response from 300 nm to 1700 nm

Abstract Inorganic-organic hybrid interlayer materials were prepared using aluminum doped ZnO nanoparticles (AZO) and amine-containing perylene diimide (PDIN). By employing this hybrid material as cathode interlayer and BCP as anode interlayer, high-gain polymer photodetectors have been realized. The low-bandgap polymer PB-D-T-TPT photodetector exhibited a significant increase in EQE as large as 25982% (−2.0 V, 360 nm), large responsivity of 77.2 A/W (−2.0 V, 830 nm) and high detectivity of >1012 Jones (All the specific detectivity in this paper were calculated from EQE and dark current.) over a broad spectral region (300–1700 nm). Using the same hybrid cathode interlayer, the devices based on P3HT and PTII-TT polymers also showed detectivity of >1015 Jones in 330–640 nm and >1012 Jones in 320–1600 nm, respectively, further demonstrating a unique ability of AZO:PDIN hybrid interlayer to improve the performance of polymer photodetectors.

Significant Effect of Fluorination on Simultaneously Improving Work Function and Transparency of Anode Interlayer for Organic Solar Cells

AbstractSince the highest occupied molecular orbital (HOMO) level of donors in organic solar cells (OSCs) is being constantly downshifted for achieving high open‐circuit voltage (Voc), a further enhancement of the anode work function (WF) is required. Herein, an effective approach of fluorination is demonstrated to simultaneously improve the WF and transparency for anode interlayer (AIL) material. By fluorination, in combination with the dialysis treatment in LiCl solution, the WF of PCP‐2F‐Li could be significantly enhanced from 4.86 to 5.0 eV, as compared to PCP‐Na. Meanwhile, the transparency of the polymer is also improved. As a result, PCP‐2F‐Li can be used to modify efficient active layers consisting of polymer donors with deep HOMO levels, such as PBDB‐T‐2F:IT‐4F, and an outstanding power conversion efficiency (PCE) of 12.7% is achieved in the corresponding device with a high Voc of 0.84 V. This result represents the highest efficiency for the OSCs using a solution‐processed pH‐neutral AIL, which is beneficial to the low‐cost fabrication of high‐performance OSCs with improved stability. More importantly, PCP‐2F‐Li could be processed by blade coating for making large‐area device of 1 cm2, and a PCE of 10.6% is achieved, bringing a promising prospect for the large‐area device fabrication.

Fine Tuning the Light Distribution within the Photoactive Layer by Both Solution‐Processed Anode and Cathode Interlayers for High Performance Polymer Solar Cells

Light management is important for improving light absorption within active layers in polymer solar cells (PSCs). Electrode buffer layers play an important role in modulating the distribution of optical electric filed within the photoactive layer. Herein, the authors employ solution‐processed WOx or ReOx to substitute the acidic poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as the anode buffer layer and ZrAcac or HfAcac to replace Mg as the cathode buffer layer. Optical transfer matrix formalism simulation is used to model the absorption spectra, exciton generation rate, and optical electric field distribution of devices. Simulated results shows that stronger absorption, quicker exciton generation rate, and more reasonable photoelectric field distribution can be achieved in the photoactive layer with solution‐processed buffer layer modification, which results in a higher short‐circuit current density (Jsc). Under the guidance of theoretical simulation, the device with architecture of ITO/WOx/PTB7‐Th:PC71BM/HfAcac/Al is optimized. Compared with the traditional PEDOT:PSS‐Mg based device, the Jsc is increased from 16.60 to 18.61 mA cm−2 and the best power conversion efficiency (PCE) is increased from 9.02% to 10.60% for the device with WOx‐HfAcac modification, which is among the best values reported for fullerene‐based PSCs. The good agreement between simulated and experimental results indicates that optical model is a useful tool for device design and optimization.

Unconventional anode interlayer universally improving solar cell efficiency

Organic photovoltaic cells typically employ an interlayer sandwiched between the active donor or acceptor materials and the respective electrodes. Conventionally, the employed anode interlayer (AIL) adjacent to the anode has a wide optical band gap and a significantly higher lowest unoccupied molecular orbital (LUMO) energy level, compared to the adjunct electron donor material, such as boron subphthalocyanine chloride (SubPc) studied here. In this report, we synthesized three novel AIL materials, NP-β-PCN, NPAPMLI and NPAPMLI, having narrow optical band gaps but matching the LUMO energy levels of SubPc in a planar heterojunction solar cell of ITO/SubPc/C60/BCP/Al. Upon insertion of an ultrathin (2 nm) AIL, the device power conversion efficiency is increased from 3.98% to as high as 4.92%, mainly due to the significant increase of short-circuit current density (JSC) from 5.97 to 7.11–7.65 mA cm−2. From the detailed morphological and photophysical studies, we have demonstrated that the employed unconventional materials of AIL are effective in exciton (of SubPc) blocking, thereby enhancing exciton diffusion towards the charge-separating interface of SubPc/C60 and hence JSC. Since these AIL materials all have a LUMO energy level very close to that of SubPc, the study reported here clarifies that the electron blocking is not a necessary property of an AIL material.

Over 100‐nm‐Thick MoOx Films with Superior Hole Collection and Transport Properties for Organic Solar Cells

AbstractHerein, a novel and effective method to prepare n‐doped MoOx films with highly improved conductivity is reported. The MoOx films are readily prepared by spin‐coating an aqueous solution containing ammonium molybdate tetrahydrate and vitamin C (VC). As confirmed by UV–vis absorption, X‐ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy measurements, Mo(VI) is partially reduced to Mo(V) by VC, resulting in the n‐doping of MoOx. The conductivity of the n‐doped MoOx (H:V‐Mo) film can be enhanced by four orders of magnitude compared to pristine MoOx (H‐Mo), that is, from 1.2 × 10−7 to 1.1 × 10−3 S m−1. The device using a 10 nm H:V‐Mo anode interlayer (AIL) exhibits comparable photovoltaic performance to a poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate)‐modified device. More importantly, the hole transport and collection properties of the H:V‐Mo AILs show outstanding tolerance to thickness variation, that is, with increasing thickness of the H:V‐Mo AIL from 10 to 150 nm, the V oc and fill factor values of the devices remain unchanged. The device based on the blade‐coated H:V‐Mo AIL also has a high power conversion efficiency of 10.6%. To the best of the authors' knowledge, this work demonstrates the first example to prepare metal oxide AILs with outstanding tolerance to thickness, which is promising for the future large‐area manufacturing.

Graphene quantum dot derivatives as anode/cathode interlayers for polymer solar cells

The interlayers play critical roles in polymer solar cells (PSCs), and the development of novel interfacial materials is an efficient way to improve the device performance. We have developed graphene quantum dot (GQD) based interfacial materials, which is different from the conventional interfacial materials, such as semiconducting polymers, inorganic metal oxide, low work-function metals or salts, and polyelectrolytes. Compared with graphene oxide (GO), the edge-carboxylated graphene quantum dots (EC-GQDs) contain single oxygen species of carboxyl groups (COOH). EC-GQD based interfacial materials can improve the device performance of PSCs owing to their controllable chemical modification and tunable opto-electronic properties. EC-GQD itself can be used as anode interlayer to gain excellent device performance due to the high work-function and good film-forming property. Through chemical functionalization of EC-GQD from the COOH, the alkali metal cations, quaternary ammonium salts and other polar groups can be incorporated at the edge. The functionalized GQD can significantly decrease the work-function of electrodes, and thus can be used as the cathode interlayers for PSCs. In this review, we systemically introduced the unique structure of EC-GQDs, their chemical modification and the application of GQD-based interfacial materials in PSCs.

Electrospray-deposited vanadium oxide anode interlayers for high-efficiency organic solar cells

Abstract Spray coating, in competition with conventional spin coating, has attracted extensive attention among large-scale solution casting techniques for producing high-performance organic solar cell (OSC) devices. Solution-processed vanadium oxide (VOx) is used extensively as an anode interlayer (AIL) in OSCs because of its unique optical and electronic properties. In this study, we optimized VOx AILs prepared using electrospray deposition (ESD-VOx) and compared them with AILs prepared using spin coating (SC-VOx); various ESD-VOx properties were found to be optimized at a flow rate of 6.25 μL/min. The OSC active layer used was poly(4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl3- fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-bthiophenediyl): [6,6]phenyl-C71-butyric acid methyl ester (PTB7:PC71BM). The ESD-VOx devices had transmittance and surface morphology comparable to SC-VOx interlayers used in high-efficiency OSC devices. X-ray photoelectron spectroscopy indicated that the obtained ESD-VOx surfaces had a favorable chemical composition. Measurement of hole mobilities using the space charge limited current method showed values of 4.36 × 10−4 and 1.39 × 10−4 cm2 V−1 s−1 for ESD- and SC-VOx, respectively. The charge transport resistance, measured by impedance spectroscopy, was very low for ESD-VOx devices, indicating that there faster charge transportation occurs within these devices because of enhanced hole mobility. These data are consistent with the carrier lifetimes of 1.59 × 10−8 and 4.53 × 10−4 s for ESD- and SC-VOx, respectively. The enhanced charge transportation properties, which can reduce charge recombination, can be attributed to the advantageous surface and interfacial properties of ESD-VOx AILs. Results indicate that optimized ESD had unperturbed diode characteristics with an improved power conversion efficiency, compared to spin coated VOx, of 7.61%.

The Critical Role of Anode Work Function in Non-Fullerene Organic Solar Cells Unveiled by Counterion-Size-Controlled Self-Doping Conjugated Polymers

In this work, we demonstrated an effective method to modulate the p-type self-doping effect as well as the molecular energy level of an anionic conjugated polymer, namely PCP-x (x = H, Li, Na, K, Cs) by changing the counterions, and hence developed a series of anode interlayer materials for nonfullerene organic solar cells (NF-OSCs). With the decreasing cation radius, self-doping effect of PCP-x can be enhanced and hence the work function (WF) of the PCP-x-modified anodes can be tuned from 4.78 to 5.11 eV. The photovoltaic performance of NF-OSCs based on J52–2F:IT-4F active layer was significantly affected by the WF of the anodes, and a PCE of 12.8% could be achieved by using the PCP-H-modified ITO anodes. Furthermore, the PCP-x-modified anodes were used to fabricate NF-OSCs with different active layers, including PBDTTT-E-T:IEICO and PBDB-T-2F:IT-4F. It was found that the energetic offsets between WF of the anodes and ionization potential (IP) of the donors should be controlled below 0.1 eV to minimize t...

Cathode and Anode Interlayers Based on Polymer Carbon Dots via Work Function Regulation for Efficient Polymer Solar Cells

AbstractIn this work, the ability of tuning work function for polymer carbon dots (PCDs) is systematically studied for the first time. Their application of both cathode and anode interlayers in polymer solar cells (PSCs) is achieved. PCDs possess abundant surface functional groups, which can be modified under control. Through regulating surface groups with more electron‐donating amino (PCD‐NH2) or electron‐withdrawing carboxy (PCD‐COOH), PCDs can decrease or increase work function of electrode, respectively. Therefore, PCD‐NH2 can act as cathode interlayer while PCD‐COOH plays the role of anode interlayer in PSCs. The single material system to act as both interlayers is rarely reported previously. This can simplify the design of materials and the device fabrication process. In addition, PCDs are green, low‐cost, stable, and easily fabricated. Therefore, it is demonstrated that PCDs are promising for commercial interlayer materials in optoelectronic devices.

A PCPDTTPD-based narrow bandgap conjugated polyelectrolyte for organic solar cells

Extensive research on organic photovoltaics has granted impressive power conversion efficiencies, nowadays exceeding 13% for state-of-the-art photoactive material combinations. Nevertheless, different strategies can be adopted to further enhance the efficiency and the competitiveness with alternative photovoltaic technologies. Conjugated polyelectrolytes have been applied as anode or cathode interlayers to optimize ohmic contacts and lower the contact resistance, thereby improving the ultimate device efficiency. Here, we present an interlayer material belonging to the emerging class of narrow bandgap conjugated polyelectrolytes, based on an imidazolium functionalized 4H-cyclopenta[2,1-b:3,4-b']dithiophene (CPDT) as the electron-rich polymer building block and 4H-thieno[3,4-c]pyrrole-4,6(5H)-dione (TPD) as the electron-deficient subunit. The ionic polymer is applied as cathode interlayer for PBDTTPD:[70]PCBM (poly[bis(2′-ethylhexyloxy)benzo[1,2-b:4,5-b′]dithiophene-alt-N-octylthieno[3,4-c]pyrrole-4,6-dione]:[6,6]-phenyl-C71-butyric acid methyl ester) bulk heterojunction polymer solar cells, improving the overall device performance from 6.9 to 7.8%.

Controllably Designed “Vice-Electrode” Interlayers Harvesting High Performance Lithium Sulfur Batteries

An interlayer has been regarded as a promising mediator to prolong the life span of lithium sulfur batteries because its excellent absorbability to soluble polysulfide efficiently hinders the shuttle effect. Herein, we designed various interlayers and understand the working mechanism of an interlayer for lithium sulfur batteries in detail. It was found that the electrochemical performance of a S electrode for an interlayer located in cathode side is superior to the pristine one without interlayers. Surprisingly, the performance of the S electrode for an interlayer located in anode side is poorer than that of pristine one. For comparison, glass fibers were also studied as a nonconductive interlayer for lithium sulfur batteries. Unlike the two interlayers above, these nonconductive interlayer did displays significant capacity fading because polysulfides were adsorbed onto insulated interlayer. Thus, the nonconductive interlayer function as a "dead zone" upon cycling. Based on our findings, it was for the first time proposed that a controllably optimized interlayer, with electrical conductivity as well as the absorbability of polysulfides, may function as a "vice-electrode" of the anode or cathode upon cycling. Therefore, the cathodic conductive interlayer can enhance lithium sulfur battery performance, and the anodic conductive interlayer may be helpful for the rational design of 3D networks for the protection of lithium metal.

Capillarity Composited Recycled Paper/Graphene Scaffold for Lithium–Sulfur Batteries with Enhanced Capacity and Extended Lifespan

An effective strategy to tackle the twin crises of global deforestation and fossil fuel depletion is to recycle biomass materials for energy storage devices. This study reports a unique and innovative solution to capitalize on a currently overlooked resource to produce high-performance lithium-sulfur (Li-S) batteries from recycled paper. The recycled paper fibers are creatively composited with graphene oxide sheets via a capillary adsorption method. The recycled paper/graphene oxide hybrid is then converted to activated paper carbon/reduced graphene oxide (APC/graphene) scaffold for sulfur infiltration. The assembled Li-APC/graphene/S battery exhibits a superior lifespan of 620 cycles with an excellent capacity retention rate of 60.5%. An APC interlayer is sandwiched between the Li anode and the separator to suppress the degradation of Li anode by preventing the nonhomogeneous growth of mossy Li whiskers, stretching the battery lifespan up to 1000 cycles with a capacitance retention rate of 52.3%. The capillary adsorption method coupled with the porous carbonaceous anode interlayer configuration creates a new opportunity for the development of batteries derived from porous biomass materials.

Orienting the Microstructure Evolution of Copper Phthalocyanine as an Anode Interlayer in Inverted Polymer Solar Cells for High Performance.

Recent advances in the interfacial modification of inverted-type polymer solar cells (PSCs) have resulted from controlling the surface energy of the cathode-modified layer (TiO2 or ZnO) to enhance the short-circuit current (Jsc) or optimizing the contact morphology of the cathode (indium tin oxide or fluorine-doped tin oxide) and active layer to increase the fill factor. Herein, we report that the performance enhancement of PSCs is achieved by incorporating a donor macromolecule copper phthalocyanine (CuPc) as an anode modification layer. Using the approach based on orienting the microstructure evolution, uniformly dispersed island-shaped CuPc spot accumulations are built on the top of PTB7:PC71BM blend film, leading to an efficient spectral absorption and photogenerated exciton splitting. The best power conversion efficiency of PSCs is increased up to 9.726%. In addition to the enhanced light absorption, the tailored anode energy level alignment and optimized boundary morphology by incorporating the CuPc interlayer boost charge extraction efficiency and suppress the interfacial molecular recombination. These results demonstrate that surface morphology induction through molecular deposition is an effective method to improve the performance of PSCs, which reveals the potential implications of the interlayer between the organic active layer and the electrode buffer layer.

Recycled Paper Derived Graphene Lithium-Sulfur Batteries with Enhanced Capacity and Extended Lifespan

An effective strategy to tackle the twin crises of global deforestation and fossil fuel depletion is to recycle bio-mass materials for energy storage devices. Batteries have been proven to be the most effective electrochemical energy conversion and storage devices. As the most widely used battery system, lithium-ion (Li-ion) batteries have served our daily life and changed the world extensively in the past two decades. However, the potential of Li-ion battery system is approaching its limit and unable to fulfill diverse requirements. Among all possible candidates, lithium sulfur (Li-S) battery chemistry is considered to be one of the most promising next-generation, high energy density battery chemistries. The theoretical gravimetric capacity of this reaction is 1675 mAh g-1, and with the expected average voltage during discharge, the maximum energy density can be 2600 mWh g-1. However, how to build high-capacity and long-life span Li-S batteries via accessible and scalable methods is still questionable. Here we report a unique and innovative solution to capitalize on a currently overlooked resource to produce high-performance lithium-sulfur (Li-S) batteries from recycled paper. Common paper hardboard was peeled into long stripes and integrated with graphene oxide (GO) sheets by a capillary absorption method. The paper/GO hybrid was then activated at high temperature, forming activated paper carbon (APC)/graphene scaffold. The capillary absorbed GO sheets were homogeneously coated on the APC fibers and shrined geometrically during heating, forming nano sized bulges and pores, which remarkably improved sulfur loading and cathode conductivity. The recycled paper derived graphene Li-S battery exhibited superior life span of 620 cycles with an excellent capacity retention rate of 60.5%. More importantly, the APC/graphene/S stayed integral without pulverization even after such long cycling, indicating excellent mechanical robustness of cathode material. Since the malfunction of the battery can be ascribed to the anode, an activated paper carbon (APC) interlayer was sandwiched between the Li anode and the separator to suppress the degradation of Li anode by protecting the Li from unfavorable reactions, stretching the battery lifespan up to 980 cycles with a capacitance retention rate of 52.3% and improved rate ability. The capillary adsorption method and the porous anode interlayer configuration should find more applications in other porous bio-mass materials for energy storage devices. Figure 1

Enhanced efficiency and stability in low band-gap polymer solar cells by introducing nickel acetate as anode interlayer

Abstract Nickel acetate (Ni(Ac)2) was successfully introduced to the low band-gap system for the first time and incorporated as the anode interlayer in conventional polymer solar cells (PSCs). For PBDT-TS1/PC71BM system, the device based on as-prepared Ni(Ac)2 performs a lower power conversion efficiency (PCE) of 6.26% in comparison to that of PEDOT:PSS-based device (6.56%). After appropriate pre-bias treatment, the device efficiency rapidly increases to 7.27%, which is 11% and 16% higher than that of PEDOT:PSS- and as-prepared Ni(Ac)2-based device, respectively, due to the suppressed charge recombination and enhanced hole transport at anode interface. More importantly, device with pre-bias treated Ni(Ac)2 as anode interlayer exhibits significantly improved lifetime in N2 atmosphere. The Ni(Ac)2-based PSCs could maintain almost 85% of its original PCE after 200 h, while PEDOT:PSS-based PSCs only retains 60% of its original efficiency. This work demonstrates that the low-cost Ni(Ac)2 is an ideal anode interlayer material, which could simultaneously improve the device efficiency and stability, to replace the widely used and high-cost PEDOT:PSS.

The effects of anodic interlayer on the morphology and mechanical performances of electroless Ni–P coating on Al alloy

We fabricate anodic film on Al alloy and deposit Ni–P coatings on the porous surface by electroless plating (EP) technique in comparison with those deposited directly on Al alloy. When Ni–P particles are directly deposited on the surface of Al alloy, a thicker film made by particles with bigger grain sizes is observed by SEM images, and the atom diffusions between their contacting interfaces may lead to the formation of loosely packed interlayer with thickness of around 4 μ as determined by EDS results. The porous anodic surface refines the size of Ni–P particles to form more compact Ni–P coating with smaller grain size and narrower size distributions; it also promotes particles embedding in the pores to form ‘interlock’ transient layer with depth of around 1 μ. Thus, the rougher surface and the interlocking function provided by the porous anodic surface enhance the compactness and stability of the composite coating, which in turn result in the great improvements in its microhardness and adhesion performances.

Effects of Electrospun Carbon Nanofibers' Interlayers on High-Performance Lithium-Sulfur Batteries.

Two different interlayers were introduced in lithium–sulfur batteries to improve the cycling stability with sulfur loading as high as 80% of total mass of cathode. Melamine was recommended as a nitrogen-rich (N-rich) amine component to synthesize a modified polyacrylic acid (MPAA). The electrospun MPAA was carbonized into N-rich carbon nanofibers, which were used as cathode interlayers, while carbon nanofibers from PAA without melamine was used as an anode interlayer. At the rate of 0.1 C, the initial discharge capacity with two interlayers was 983 mAh g−1, and faded down to 651 mAh g−1 after 100 cycles with the coulombic efficiency of 95.4%. At the rate of 1 C, the discharge capacity was kept to 380 mAh g−1 after 600 cycles with a coulombic efficiency of 98.8%. It apparently demonstrated that the cathode interlayer is extremely effective at shutting down the migration of polysulfide ions. The anode interlayer induced the lithium ions to form uniform lithium metal deposits confined on the fiber surface and in the bulk to strengthen the cycling stability of the lithium metal anode.