Composite Cathode Materials Research Articles

Experimental and computational insights into oxygen vacancy-rich MoO2-x/N-doped carbon nanowires as high-performance cathode for magnesium batteries and magnesium-lithium hybrid batteries

This work aims to develop efficient cathode materials for magnesium based batteries, which are considered promising next-generation energy storage and conversion devices. One major challenge in magnesium based batteries is the strong Coulomb interaction between magnesium ions and cathode materials, which hinders ion storage and diffusion. To overcome this, we designed and synthesized oxygen vacancy-rich MoO2-x/N-doped carbon nanowires (MoO2-x-NC-NWS). The materials were prepared through a controlled synthesis process, ensuring the incorporation of N-doped carbon and oxygen vacancies, which play crucial roles in improving magnesium ion diffusion and storage. The prepared MoO2-x-NC-NWS demonstrated superior energy storage performance, achieving a capacity of 64 mAh/g in magnesium batteries and 263 mAh/g in magnesium-lithium hybrid batteries at a current density of 50 mA/g. Theoretical calculations further confirmed that oxygen vacancies enhance the diffusion capabilities of magnesium and lithium ions, thereby improving the overall energy storage performance. Therefore, the controllable synthesis of defects such as oxygen vacancies and the development of composite cathode materials are clearly effective strategies for enhancing the performance of magnesium-based battery cathodes. Meanwhile, this rational design of MoO2-based nanostructures provides valuable insights into the development of high-performance cathode materials for magnesium-based energy storage systems.

Exploring the impact of structural modification of double perovskite composite cathode material on oxygen reduction reaction in intermediate temperature solid oxide fuel cell

Exploring the impact of structural modification of double perovskite composite cathode material on oxygen reduction reaction in intermediate temperature solid oxide fuel cell

Organic Heterophase Composites Induced Sulfur Vacancies and Internal Electric Field Enhancement for Advanced Magnesium Storage of Copper Sulfide Cathodes

AbstractRechargeable magnesium‐ion batteries (MIBs) hold significant promise for safe and efficient large‐scale energy storage, but the lack of high‐performance cathodes hinders their development for practical applications. In this work, a series of nanocomposites consisting of π‐conjugated perylene‐3,4,9,10‐tetracarboxylic dianhydride annealed at 450 °C and copper sulfide (CuSP) are synthesized solvothermally to explore their utility as a host for Mg2+ storage in MIBs. The carbonyl organics in the hybrid materials modify the predominant CuS phase, expanding interlayer spacing and enriching sulfur vacancies through modifications of the internal electric field. This synergistic interaction enhances magnesium storage performance and accelerates reaction kinetics. Using chlorine‐free Mg[B(hfip)4]2/DME electrolytes, the CuSP91 cathode containing an appropriate organic content displays a remarkably high reversible capacity of 285 mAh g−1 at 50 mA g−1, and demonstrates a stable capacity of 220 mAh g−1 at 100 mA g−1, surpassing pure CuS cathode in terms of shorter activation time. The CuSP91 cathode maintains a discharge capacity of 55 mAh g−1 over 1000 cycles at 500 mA g−1. A co‐redox mechanism is revealed through in/ex situ investigations and analyses. Overall, this research contributes valuable insights targeting the development of advanced organic–inorganic hybrid composite cathode materials in next‐generation energy storage systems.

Electrochemical-mechanical coupled interfacial degradation model of Ternary polymer composite cathodes in all-solid-state batteries

Despite significant attention focused on the composite cathode composed of active particles, which is considered to increase the interfacial areas and satisfy high areal load, suffers from interfacial issues. In this article, we formulate an electrochemical-mechanical model of LiNixMnyCozO2 (NMC) composite cathode coupling the relations between interfacial degradation, charge transformation, diffusion transport, and mechanical deformation under cyclic loads. Based on the transition state theory, we regard the interfacial degradation as an energy barrier dependent on the interfacial debonding state. Physical mismatch due to chemical expansion results in interfacial current distinction, anisotropic Li diffusion and excessive local stress. Compared to single-crystal NMC particles, the effect of interfacial separation and internal cracks triggers an extremely nonuniformity of Li distribution within random orientation polycrystalline-type particles. The external pressure in the range of operation can cause mechanical deformation to fill in the interface vacancies, which effectively alleviates the rapid growth of damage and provides a better cyclic performance. Moreover, soft polymer-based solid electrolytes take advantage of their flexible property to deal with solid-solid contact, providing considerable maintenance of interface stability. This present framework reveals the failure mechanism with electrochemical-mechanical coupled relations for composite cathode materials and broadens the design guidance toward improving interfacial integrity.

Defect engineering of sulfur vacancies in vanadium disulfide integrated with graphene as advanced potassium-ion battery cathode

Potassium-ion batteries (PIBs) have economic and environmental potential, but slow potassium ion diffusion and electrode material degradation hinder the development of effective cathode materials. This research designs a composite cathode material that vanadium disulfide with sulfur vacancies integrated with reduced graphene oxide (VS2-x@rGO). The introduction of sulfur vacancies increases active sites for ion storage, while rGO ensures a stable electronic conductivity and structural integrity. VS2-x@rGO shows a great rate performance of 116.2 mAh g−1 at 20 mA g−1, 77.5 mAh g−1 at 500 mA g−1, and high cycling stability with 94.5 % retention of capacity after 100 cycles at 100 mA g−1. Moreover, the full cell assembled with hard carbon achieves a specific capacity close to 120 mAh g−1. Energy density up to 220 Wh kg−1 in 38.4 W kg−1 and 72 Wh kg−1 in 960 W kg−1. Through in-situ XRD and other ex-situ analyses, the crystal structure rapidly transformed into K0.6VS2 and slight displacement of the crystal plane occurred during K+ insertion until KxVS2 formed in the discharge process. The charging process is reversible and forms VS2. This study provides a novel approach for advancing PIBs cathode materials, contributing valuable insights into the optimization of energy storage solutions.

In-situ Ti4+-doped modification of layer-structured Ni-rich LiNi0.83Co0.11Mn0.06O2 cathode materials for high-energy lithium-ion batteries

The further commercialization of layer-structured Ni-rich LiNi0.83Co0.11Mn0.06O2 (NCM83) cathode for high-energy lithium-ion batteries (LIBs) has been challenged by severe capacity decay and thermal instability owing to the microcracks and harmful phase transitions. Herein, Ti4+-doped NCM83 cathode materials are rationally designed via a simple and low-cost in-situ modification method to improve the crystal structure and electrode–electrolyte interface stability by inhibiting irreversible polarizations and harmful phase transitions of the NCM83 cathode materials due to Ti4+-doped forms stronger metal-O bonds and a stable bulk structural. In addition, the optimal doping amount of the composite cathode material is also determined through the results of physical characterization and electrochemical performance testing. The optimized Ti4+-doped NCM83 cathode material presents wider Li+ ions diffusion channels (c = 14.1687 Å), lower Li+/Ni2+ mixing degree (2.68 %), and compact bulk structure. The cell assembled with the optimized Ti4+-doped NCM83 cathode material exhibits remarkable capacity retention ratio of 95.4 % after 100cycles at 2.0C and room temperature, and outstanding reversible discharge specific capacity of 148.2 mAh g−1 at 5.0C. Even under elevated temperature of 60 °C, it delivers excellent capacity retention ratio of 92.2 % after 100cycles at 2.0C, which is significantly superior to the 47.9 % of the unmodified cathode material. Thus, the in-situ Ti4+-doped strategy presents superior advantages in enhancing the structural stability of Ni-rich cathode materials for LIBs.

A nanoflower structure rare-earth La3+ doping Sn3O4 with highly catalytic active interfaces as a sulfur host facilitates the conversion kinetics of polysulfides in high-performance lithium-sulfur batteries

Lithium-sulfur batteries are considered a favourable contender for next-generation energy storage systems owing to their high energy density (2600 Wh·kg−1). However, the severe "shuttle effect" of polysulfides and the slow redox kinetics involving phase transitions have seriously limited the commercialization of lithium-sulfur batteries. On this basis, in this paper, a type of nanoflower structure rare-earth lanthanum ion (La3+) doping Sn3O4 with a large number of catalytic active interfaces is designed via a facile one-step hydrothermal method. When serves as a capture centre to immobilize polysulfides, it exhibits a strong chemical adsorption capacity. Moreover, due to the unique 4 f electron configuration of the rare-earth elements, nanoflower structure La3+ doping Sn3O4 (La@Sn3O4) as sulfur-wrapped matrix has a strong catalytic activity, which can effectively accelerate the conversion process of polysulfides. At the same time, the catalytic mechanism of La@Sn3O4/S composite cathode material targeting the solid to liquid phase transformation of polysulfides is effectively revealed via in-situ Raman spectroscopy test and the initial discharge capacity can reach 1429.6 mAh·g−1 at a current density of 0.1 C, and the capacity retention rate is 76.5 % after 130 cycles.

Empowering Low-Temperature Lithium-Sulfur Batteries: Unlocking the Potential of Transition Metal Alloy-Based Cathode Materials.

At low temperatures, lithium-sulfur (Li-S) batteries have poor kinetics, resulting in extreme polarization and decreased capacity. In this study, we investigated the electrochemical performance of Li-S batteries utilizing transition metal alloy-based cathode materials. Specifically, binary transition metal alloys (FeNi, FeCo, and NiCo) are integrated into a porous carbon nanofiber (CNF) matrix as composite cathode material. Our findings reveal that alloying metallic Ni with Fe in the FeNi@CNFs composite enhances the catalytic conversion of sulfur species, mitigating the shuttle effect and improving battery performance even under low temperatures. Li-S batteries employing a Li2S6/FeNi@CNFs cathode exhibited a significantly high initial discharge capacity of 1655 mAh g-1 at 0.1 C. Even at the higher current density of 10 C, the Li2S6/FeNi@CNFs composite can still reach an ultrahigh specific capacity of 828 mAh g-1. In addition, Li2S6/FeNi@CNFs demonstrated exceptional initial discharge capacities of 890.5 and 382.7 mAh g-1 at 0.1 C under -20 and -40 °C, respectively. With an initial capacity of 392.02 mAh g-1 and a capacity retention rate of 88.86% (after 60 cycles) at 0.2 C, the conversion of LiPSs in Li2S6/FeNi@CNFs is significantly enhanced even at ultralow temperatures of -40 °C. The findings of this study hold significant implications for the advancement of extremely low-temperature Li-S batteries.

Effect of graphite concentration on the electrochemical performance of a novel α-MnO2-expanded graphite-PVDF composite cathode material based on FTO substrate

A facile chemical reduction method is employed for the synthesis of α-MnO2 followed by ultrasonication with synthetic graphite and poly (vinylidene pyrrolidone) PVDF for the development of α-MnO2-expanded graphite-PVDF (MGP) composite. Known masses of MGP composite are drop-casted on a fluorine-doped tin oxide (FTO) conducting glass substrate for the fabrication of composite electrodes to use as the cathode. The compositional effects of various weight percentages of graphite on the electrochemical performance of the MGP composite are studied. The increase in graphite’s weight percentage is always accompanied by an equal reduction in the weight of MnO2 by maintaining a constant amount of PVDF. We demonstrate a maximum electrochemical performance for the composite containing 80% MnO2, 10% expanded graphite, and 10% PVDF, further increases in graphite concentration (reduction in that of MnO2) have detrimental effects on the performance. The basis characterisation of the composite is carried out using XRD, FTIR, UV–vis, AFM, and SEM and the electrochemical studies are done using CV, GCD and EIS. We observe both faradaic and non-faradaic charge storage mechanisms in the composite samples with a 35% capacitive contribution and a 65% diffusive contribution to the total capacitance. Moreover, the composite electrode demonstrates a maximum specific capacitance of 358 F g−1 at 10 mV s−1 with an outstanding power density of 2.8 KW Kg−1.

Cathode performance of novel γ-LixV2O5/carbon composite in organic and aqueous electrolyte

Preparation of in-situ composites with carbon by pyrolysis of an organic precursor is an effective strategy to improve performances of insulating and semiconducting cathode materials. However, due to the property of organic precursor to act as a strong reductive agent during carbonization process, the in-situ synthesis of LiV2O5/C composite cathode material is delicate and presents a challenge for researchers, since vanadium in LiV2O5 coexists in two oxidation states, V4+ and V5+. In our research, we utilized an adopted conventional solid state method for the in-situ preparation of LixV2O5/C composite (x ≈ 0.86). By using methylcellulose polymer as a carbon source, LixV2O5/C was synthesized via two-step solid state reaction at elevated temperatures. LixV2O5 crystallized as gamma polymorph phase, and the amount of in-situ formed carbon does not exceed 3wt%. The electrochemical characteristics of the as-prepared LixV2O5/C were investigated in aqueous and non-aqueous electrolyte via cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) tests and electrochemical impedance spectroscopy (EIS). On lithium insertion/removal, the LixV2O5/C composite exhibits stable cycling performance and achieves significant storage capacity enhancement when compared to pristine LixV2O5 obtained under similar conditions. Under current densities of 0.1, 0.2, 0.3 and 1 A/g, the specific capacity enhancement is around 112, 91, 80 and 62 %, respectively. Replacing the organic electrolyte with the aqueous one has a negligible effect on the mechanism and efficiency of lithium intercalation within the LixV2O5/C, which opens up the possibility of using this material in aqueous as well as in organic-electrolyte batteries. The decay of cathode's activity evidenced during electrochemical exchange of lithium with sodium in aqueous environment comes as a result of the formation of electrochemically inactive β-NaxV2O5.

An olivine LiFe0.5Mn0.5PO4/rGO composite cathode material prepared from manganese ore tailings with excellent lithium storage performance

An olivine LiFe0.5Mn0.5PO4/rGO composite cathode material prepared from manganese ore tailings with excellent lithium storage performance

Molten salt synthesis of MnO2/Mn2O3 composite as a high-performance cathode material for rechargeable button zinc‑manganese ultra-high temperature battery

Herein, a novel rechargeable button zinc‑manganese ultra-high temperature battery is first reported for the efficient utilization and conversion of thermal and electrical energy. The battery system uses zinc anode, Zn-K-Cl molten salt electrolyte and MnO2/Mn2O3 composite cathode to work at 300 °C. In this study, MnO2/Mn2O3 composites were synthesized by molten salt method, and the crystal structure of the materials was adjusted by adding reduced graphene oxide (rGO). The results showed that the spherical nanoparticles and nanobelts of MnO2/Mn2O3 composite cathode materials increased the active sites and ion transport channels of the electrochemical reaction, thus providing high coulombic efficiency. By modifying with rGO, the MnO2/Mn2O3 (Mn-O-2) composite cathode material exhibits excellent electrochemical performance in the button zinc‑manganese ultra-high temperature battery. The as-prepared button ultra-high temperature battery exhibits a relatively high specific capacity (300 and 175 mAh g−1 at 1 mA cm−2 and 30 mA cm−2) and competent cyclability (> 95 % coulombic efficiency after 50 cycles). This work firstly and systematically reveals the role of the Mn cathode materials and shows that the application in button molten salt batteries.

Preparation of Expanded Graphite-VO2 Composite Cathode Material and Performance in Aqueous Zinc-Ion Batteries.

Due to safety problems caused by the use of organic electrolytes in lithium-ion batteries and the high production cost brought by the limited lithium resources, water-based zinc-ion batteries have become a new research focus in the field of energy storage due to their low production cost, safety, efficiency, and environmental friendliness. This paper focused on vanadium dioxide and expanded graphite (EG) composite cathode materials. Given the cycling problem caused by the structural fragility of vanadium dioxide in zinc-ion batteries, the feasibility of preparing a new composite material is explored. The EG/VO2 composites were prepared by a simple hydrothermal method, and compared with the aqueous zinc-ion batteries assembled with a single type of VO2 under the same conditions, the electrode materials composited with high-purity sulfur-free expanded graphite showed more excellent capacity, cycling performance, and multiplicity performance, and the EG/VO2 composites possessed a high discharge ratio of 345 mAh g-1 at 0.1 A g-1, and the Coulombic efficiency was close to 100%. The EG/VO2 composite has a high specific discharge capacity of 345 mAh g-1 at 0.1 A g-1 with a Coulombic efficiency close to 100%, a capacity retention of 77% after 100 cycles, and 277.8 mAh g-1 with a capacity retention of 78% at a 20-fold increase in current density. The long cycle test data demonstrated that the composite with expanded graphite effectively improved the cycling performance of vanadium-based materials, and the composite maintained a stable Coulombic efficiency of 100% at a high current density of 2 A/g and still maintained a specific capacity of 108.9 mAh/g after 2000 cycles.

Synthesis of MnO-LiF composite cathode material using NH4F as a fluorine source

Synthesis of MnO-LiF composite cathode material using NH4F as a fluorine source

Enhanced zinc ions storage performance of Mn2O3/Mn3O4/NiMn2O4 composite cathode material synthesized by a thermal decomposition method

Constructing multi-phase composite (heterostructure) materials has proved to be an effective method to improve the electrochemical performance of electrode materials. Herein, a novel ternary Mn2O3/Mn3O4/NiMn2O4 composite is synthesized by a facile thermal decomposition method. Benefiting from the synergistic effect and rich oxygen defects, this composite shows high specific capacity of 646 mA h g−1 at 0.2 A g−1 and maintains a specific capacity of 185 mA h g−1 after 1000 cycles at 1.0 A g−1, much better than that of binary Mn2O3/Mn3O4. This work reports a promising cathode material for aqueous zinc-ion batteries.

Co-extruded triple-layer micro-tubular solid oxide fuel cell: The influence of cathode extrusion rate on the fuel cell properties and performance

Micro-tubular solid oxide fuel cells (MT-SPFC) have emerged as a potential alternative for efficient energy generation. This study investigates the impact of cathode extrusion rates (ranging from 3 to 6 mL min−1) on the triple layer anode/electrolyte/cathode MT-SOFC fabricated via a simplified phase inversion-based co-extrusion/co-sintering technique. Higher cathode extrusion rates (6 mL min−1) indirectly thin the electrolyte layer, improving ion hopping efficiency between the cathode and anode. Moreover, increasing the extrusion rate enhances anode thickness, providing ample electrode reaction sites and thereby enhancing the gas diffusion process. The C6 sample attains a peak power density of 1.46 W cm−2 with 1.08 V OCV at an optimum 800 °C operating temperature, which is high for MT-SOFCs in high-temperature applications. There was a 71.8 % increase in power density for C6 when the temperature changed from 750 °C to 800 °C. The composite cathode material fulfilled both the electronic and ionic conductivity requirements. The optimal cathode extrusion rate for this simplified MT-SOFC fabrication was found to be 6 mL min−1.

Understanding the Correlation between Electrochemical Performance and Operating Mechanism of a Co-free Layered-Spinel Composite Cathode for Na-Ion Batteries.

Compositing different crystal structures of layered transition metal oxides (LTMOs) is an emerging strategy to improve the electrochemical performance of LTMOs in sodium-ion batteries. Herein, a cobalt-free P2/P3-layered spinel composite, P2/P3-LS-Na1/2Mn2/3Ni1/6Fe1/6O2 (LS-NMNF), is synthesized, and the synergistic effects from the P2/P3 and spinel phases were investigated. The material delivers an initial discharge capacity of 143 mAh g-1 in the voltage range of 1.5-4.0 V and displays a capacity retention of 73% at the 50th cycle. The material shows a discharge capacity of 72 mAh g-1 at 5C. This superior rate performance by the material could be by virtue of the increased electronic conductivity contribution of the incorporated spinel phase. The charge compensation mechanism of the material is investigated by in operando X-ray absorption spectroscopy (in a voltage range of 1.5-4.5 V vs Na+/Na), which revealed the contribution of all transition metals toward the generated capacity. The crystal structure evolution of each phase during electrochemical cycling was analyzed by in operando X-ray diffraction. Unlike in the case of many reported P2/P3 composite cathode materials and spinel-incorporated cobalt-containing P2/P3 composites, the formation of a P'2 phase at the end of discharge is absent here.

Novel Cu(II)-based metal–organic framework STAM-1 as a sulfur host for Li–S batteries

Due to the increasing demand for energy storage devices, the development of high-energy density batteries is very necessary. Lithium–sulfur (Li–S) batteries have gained wide interest due to their particularly high-energy density. However, even this type of battery still needs to be improved. Novel Cu(II)-based metal–organic framework STAM-1 was synthesized and applied as a composite cathode material as a sulfur host in the lithium–sulfur battery with the aim of regulating the redox kinetics of sulfur cathodes. Prepared STAM-1 was characterized by infrared spectroscopy at ambient temperature and after in-situ heating, elemental analysis, X-ray photoelectron spectroscopy and textural properties by nitrogen and carbon dioxide adsorption at − 196 and 0 °C, respectively. Results of the SEM showed that crystals of STAM-1 created a flake-like structure, the surface was uniform and porous enough for electrolyte and sulfur infiltration. Subsequently, STAM-1 was used as a sulfur carrier in the cathode construction of a Li–S battery. The charge/discharge measurements of the novel S/STAM-1/Super P/PVDF cathode demonstrated the initial discharge capacity of 452 mAh g−1 at 0.5 C and after 100 cycles of 430 mAh g−1, with Coulombic efficiency of 97% during the whole cycling procedure at 0.5 C. It was confirmed that novel Cu-based STAM-1 flakes could accelerate the conversion of sulfur species in the cathode material.

Application metal oxide cathode materials for lithium ion batteries

The popularity of portable electronic devices has boosted the speedy advancement of devices for storing electrical energy. At the same time, the development of electric vehicles urgently requires lithium batteries to have higher power density and performance. The strong points of lithium ion battery are environmental friendliness, also specific capacity of high level. Lithium cathode material is one of the key factors affecting battery performance. The requirements for positive electrode materials are good safety, good service life, and less self-discharge. Among all cathode materials, metal oxide cathode material is the most potential types, which comes from a wide range of sources and has rich production experience. In this paper, four kinds of lithium metal oxide cathode materials including lithium cobaltate, lithium nickelate, lithium manganate and ternary composite oxide cathode material were analyzed, and discussed the performance of lithium metal oxide cathode materials in practical applications, where further pointed out the existing problems of metal oxide cathode materials and put forward several directions for future improvement to improve the performance of lithium ion battery cathode materials in the future development and production process.

Dual-modified LiNi0.8Co0.1Mn0.1O2 cathode materials with lithium conducting hybrid oligomer and single-walled carbon nanotube for improving electrochemical performance and thermal stability of lithium-ion batteries: A novel approach for high-power and high-safety applications

In this study, we investigated the synergetic effect of a novel lithium-ion conducting hybrid oligomer [N, N′-bismaleimide-4, 4′-diphenylmethane (BMI), lithiated trithiocyanuric acid (Li-TCA) and Jeffamine®-M1000 (JA®); Li-BTJ] coating layer on a nickel-rich LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode material wrapped with highly electron-conductive single-walled carbon nanotubes (SWCNTs) to enhance electrochemical performance and thermal stability for high-power and high-safety lithium-ion batteries (LIBs). Morphological analyses using scanning electron microscopy/energy dispersive spectroscopy and transmission electron microscopy showed that the NCM811 active material surface was uniformly coated with a hybrid oligomer to form NCM811@Li-BTJ, which was subsequently wrapped with SWCNTs (NCM@Li-BTJ/SWCNT composite cathode). CR2032 coin-type cells with optimized NCM811@1 wt% Li-BTJ/0.2 wt% SWCNT composite electrodes delivered a significantly enhanced capacity retention (CR) of 90.1 % relative to that of bare NCM811 electrodes (CR: 82.1 %) at 1C for 200 cycles from 2.8 to 4.3 V (vs. Li/Li+). Electrochemical impedance spectroscopy and cyclic voltammetry revealed that this superior cycling performance resulted from a lower charge transfer resistance (Rct: 96.2 vs. 324.3 Ω) and a lower polarization voltage (∆V: 0.243 vs. 0.411 V vs. Li/Li+). The in-situ micro-calorimetric results presented the total heat generation (Qt) values of the coin cells with the delithiated NCM811@Li-BTJ and NCM@Li-BTJ/SWCNT electrodes at 5C and 35 °C were substantially lower by ~9.3 % and ~ 14.6 %, respectively, compared to the bare NCM811 counterpart, indicating that the surface modifications on the NCM811 active materials could prevent the LIBs' thermal instability. Furthermore, X-ray photoelectron spectroscopy studies revealed that the Li-BTJ hybrid oligomer coating layer effectively suppressed the formation of residual Li side products such as Li2CO3 evidently on the surface of the NCM811 active material particles, thereby inhibiting undesirable side reactions. Post-mortem analyses of the dual-modified NCM811 electrode after cycling revealed that the microstructure and particle morphology of the NCM composite cathode material were extensively maintained through the synergistic effects of the Li-BTJ ion-conductive and SWCNTs electron-conductive agents.