Cathode For Lithium-air Batteries Research Articles

Influence of electrospun carbon nanofiber surface properties on lithium-air battery cathode behavior

Influence of electrospun carbon nanofiber surface properties on lithium-air battery cathode behavior

Influence of electrospun carbon nanofiber surface properties on lithium-air battery cathode behavior

The surface properties of carbons significantly influence their performance when they are used as lithium-air battery cathodes. This study used carbon nanofiber sheets derived from polyacrylonitrile (PAN) nanofiber sheets and prepared by electrospinning (ES-CNF) as a model cathode to investigate the influence of surface properties. The sheet structure enabled sufficient access of O2 to the carbon surface. For this investigation, five types of ES-CNF sheets having different surface properties were prepared by varying the heat-treatment temperature from 800 to 2200 °C. A portion of the heat-treated samples were further treated with nitric acid. The surface properties of the obtained samples were analyzed in detail by temperature programmed desorption analysis conducted under vacuum in the temperature range 100–1800 °C. The results indicated that discharge and charge voltages depend on the number of edge-H and the type and number of carbon functional groups. Oxygen-containing functional groups on the carbon promoted not only the surface-route deposition of Li2O2, which can be charged (decomposed) at voltages below 3.7 V, but also undesired side reactions, which can increase the charge voltage up to over 4.0 V. Furthermore, it was also found that carboxyl or phenol/ether groups effectively promote surface-route reactions much more efficiently than N-containing functional groups (NCFGs) and carbonyl groups. The knowledge obtained in this study can be utilized as a new guideline to design cathode carbon for lithium-air batteries.

Clarification of the Effects of Oxygen Containing Functional Groups on the Pore Filling Behavior of Discharge Deposits in Lithium–Air Battery Cathodes Using Surface-Modified Carbon Gels

In lithium–air batteries (LABs), controlling the characteristics of the Li2O2 deposited during discharging can lead to the reduction of the large overpotential required for charging. The large overpotential is one of the most significant problems that needs to be solved to improve the cycle performance of LABs. Here, we focused on the effects of functional groups in the cathode carbon on the characteristics of the Li2O2 deposited during discharging and the cathode performance of LABs. In this study, 4 types of carbon gels (CGs) were prepared using different treatment methods to modify their surface properties. The types and amounts of oxygen-containing functional groups (OCFGs) existing within the CGs were clarified along with the number of edge H’s by a high-sensitivity temperature-programmed desorption (TPD) technique. The results of N2 adsorption analysis of discharged CGs suggested that, by increasing the number of OCFGs from 0.40 to 1.80 mmol g–1 through acid treatment, the ratio of Li2O2 deposited within the mesopores of the porous carbon particles can be increased from 1% to 60%. This significant change in the manner of Li2O2 deposition led to the reduction of the charging overpotential. Side reactions that are thought to deteriorate cycle performance tended to proceed in CGs having a large number of OCFGs. This negative effect could be reduced by removing carboxyl groups in the CGs through simple heat treatment at 300 °C in an inert atmosphere. Our study clarified the critical roles of OCFGs in the cathode during the discharging and charging of LABs. The obtained knowledge can be utilized for the development of a high-performance cathode for LABs.

Co/Zn‐based bimetallic MOF ‐derived hierarchical porous Co/C composite as cathode material for high‐performance lithium‐air batteries

Structural optimization and electrocatalyst utilization in air cathodes have been identified as two major factors affecting the overall performance of a lithium-air battery. Herein, a cobalt@porous carbon composite, Co@C(700-1000) was obtained by facile annealing of a Co/Zn-bimetallic metal-organic framework (MOF). In the Co/Zn-MOF, cobalt cluster was used as a precursor of the catalyst and zinc cluster as a sacrificial template to generate meso- and macropores. The lithium-air battery with the assembled Co@C(700-1000) air cathode revealed a specific capacity as high as 4 mAh cm−2. Furthermore, the battery exhibited high cycling stability up to 67 cycles (limited capacity of 0.5 mAh cm−2). The high cell performance can be in relation to the catalytic activity of uniformly disseminated cobalt nanoparticles in the porous carbon matrix and the rapid diffusion and transport of Li+ and O2 owing to the optimized pore-distribution characteristics. Using a bimetallic MOF-derived material, this study sheds fresh light on the design of an air cathode for lithium-air batteries.

Reduction of Oxygen Transport Resistance of Lithium-Air Battery Cathode by using Ionomer

Reduction of Oxygen Transport Resistance of Lithium-Air Battery Cathode by using Ionomer

Porosity tailoring of the Zn-MOF-5 derived carbon materials and its effects on the performance as a cathode for lithium-air batteries

Metal-organic framework(MOF)-derived carbon material is a promising material for lithium-air battery cathode, but its pores are small (<5 nm) and narrow distribution, making it difficult to be applied as a charge-discharge active site. Herein, we introduce two types of pore-tailored Zn-MOF-5-derived carbon materials and investigate the effects of the porosity characteristics on the performance of a lithium-air battery: 1) Zn-MOF-5 carbonized at 1000 °C, where the pores are generated by the Zn metal evaporation.; and 2) Zn-MOF-5 carbonized at temperatures below the evaporation temperature of Zn, followed by etching out process of generated ZnO by hydrofluoric acid(HF). The ZnOs undergo a morphological change from nanoparticles to nanorods due to the reaction with gaseous Zn. Carbon materials obtained by etching the ZnOs with various shapes and sizes result in wider pore distribution and larger size pores compared to samples carbonized at 1000 °C. The initial discharge capacity of etched carbon with large pores and a wide pore distribution shows up to 5 times higher capacity than carbonized material (cycled at a current density of 0.2 mA cm −2 ). Furthermore, the detailed microscopic studies show that the porosity and morphology of the carbon materials derived from Zn-MOF-5 affect the performance of lithium-air battery. - Two types of pore-tailored Zn-MOF-5-derived carbon materials were synthesized by carbonization and etching process for lithium-air battery. - Carbon materials obtained by etching zinc oxides with various shapes and sizes result in wider pore distribution and larger size pores compared to samples carbonized at 1000 °C. - The initial discharge capacity of the Zn-MOF-5-derived carbon materials can be improved by tailoring the porosity.

Biologically synthesized TiO2 nanoparticles and their application as lithium-air battery cathodes

Electrocatalysts represent a sustainable solution for lithium-air batteries by eliminating side reactions. Herein, TiO2 nanoparticles were biosynthesized via the green method and investigated as air cathodes for lithium-air batteries. TiO2 nanoparticles were also synthesized via the facile sol-gel method to compare the efficiency of this green method. The flower extract of Matricaria chamomilla was utilized to biosynthesize the TiO2 nanoparticles. The particle size of the biosynthesized TiO2 nanoparticles was further controlled by manipulating the pH of the solution. In this way, the influence of pH on the nanoparticle’s properties could be evaluated. The phase structures, surface morphology, and elemental composition of the synthesized TiO2 nanoparticles were characterized as well. Additionally, the TiO2 cathodes were prepared on nickel foam, and their electrochemical performances were evaluated via an ECC-Air test cell using cyclic voltammetry, electrochemical impedance measurements, and galvanostatic charge-discharge tests. Consequently, the Bio-TiO2 air cathode showed a full discharge capacity of 2000 mAh g−1 and a specific capacity of 500 mAh g−1 for 30 stable cycles.

TiC MXene High Energy Density Cathode for Lithium–Air Battery

AbstractMXenes are reported to be great supercapacitor and lithium‐ion battery material recently. In this article, the density functional theory (DFT) calculations show that using TiC MXene TinCn − 1O2 (n = 2, 3, 4) as the cathode of lithium–air batteries (LABs) can potentially improve its efficiency by increasing the cathode conductivity and lowering the charging overpotential. In addition, the conservative predicted storage density is as high as ≈0.5 kWh kg−1. Compared with the bulk TiC{111}, the favorable structural agreement between the TiC MXenes and Li2O2, and better interfacial conduction help Li2O2 continuously grow on the TiC MXene; and the higher specific surface area (SSA) makes more Li2O2 deposition possible. The predicted reaction path calculations reveal that TiC MXenes have the charging overpotential of 0.13 V because they are excellent catalysts in the oxygen evolution reaction (OER). Thus, the lower charging overpotential can extremely suppress the side reactions and accelerate the OER rate. All the evidence supports that TiC MXene is a potential high energy density cathode for LABs.

Novel Architecture of Air Cathode for Rechargeable Lithium-Air Batteries

As the increased demand of eco-friendly rechargeable batteries in recent years, aqueous/non-aqueous lithium-air batteries have been attached more and more attention because of their high specific energy density, 3-5 times higher than that of lithium-ion batteries1-2. As the key component, the structure of the air cathode should been optimized to improve the cycle performance during discharge and charge process3-4. In this work, polyaniline-assisted polyvinylidene fluoride film was synthesized coated on graphene sponge as flexible cathode for lithium air batteries. With the 3D inter-connected structure of the graphene sponge for the guidance of oxygen flows, the assisted polyaniline for enhanced electron transfer, as well as the polyvinylidene fluoride film for the prevention of electrolyte flooding, the reaction zone can be reserved extremely during oxygen reduction reaction and oxygen evolution reaction, which can then promote charge transfer, and result to the lower overpotential for both discharge and charge process. The detailed electrochemical performance will be analyzed in the following presentation.

Towards real Li-air batteries: A binder-free cathode with high electrochemical performance in CO2 and O2

The current research on lithium-air batteries usually focuses on Li-O2 batteries without taking into account the essential involvement of CO2 in the operation of Li-air batteries. In this work a composite of N-doped worm-like carbon with embedded MoFeNi and MoC nanoparticles was prepared via a simple floating catalyst chemical vapour deposition (FCCVD) method. The composite shows high CO2 reduction and evolution activities. When used as a binder-free cathode for Li-CO2 batteries, low overpotential and long cycleability are achieved which are comparable with those of Li-O2 batteries. The composite produced in this work show promise as a binder-free cathode for lithium-air batteries operated in the presence of O2 and CO2.

Comment on “Out‐of‐Cell Oxygen Diffusivity Evaluation in Lithium–Air Batteries” by He et al.

AbstractIn a recent paper, He et al. (ChemElectroChem 2014, 1, 2052–2057) described a methodology for measuring out‐of‐cell oxygen diffusivity in lithium–air battery (LAB) cathodes, combining an electrochemical device with a classical gas‐transport model. We will demonstrate here that the authors erroneously assumed that the Knudsen diffusivity of gaseous oxygen in the porous cathode is smaller than the diffusivity in the electrolyte and, consequently, that the oxygen mass transport would limit the current output of the battery. Therefore, it is impossible to determine the oxygen diffusivity in LAB cathodes by using the electrochemical device proposed by the authors, comprising an oxygen pump, the LAB cathode, and an oxygen sensor.

Investigation of Self Supporting Paper-like Structures and Metallic Current Collector Backed Structures with Exfoliated Graphene Platelets As Cathodes for Lithium-Air Battery

Few-layer exfoliated graphene platelets are ultrathin particles of graphite that can also be thought of as short stacks of graphene sheets prepared through proprietary manufacturing processes. Several grades and sizes with thicknesses ranging from 1-20 nanometers and width ranging from 1-50µm are manufactured by XG Sciences, Lansing, MI, USA. Unique manufacturing processes for these platelet materials are non-oxidizing; thus, yielding a pristine graphitic surface of sp2 carbon molecules. This makes these platelet particles especially suitable for applications requiring high electrical and thermal conductivities. The surface areas of the resulting platelets predominantly consist of the open surface areas of the graphene basal planes. Open surface areas of the graphene basal planes as well the interlayer spaces between the graphene sheets coupled with high electrical conductivities are an important criteria for electrodes in many electrochemical energy storage technologies. Unique morphology of the platelets offer the potential to structure self-standing electrodes by doing away with inactive components such as current collectors and thus, enhance the energy density. Surface modification of the platelets through the deposition of transition metal oxides on the graphene basal planes has the potential to enhance the energy storage capacity due to the participation of two different components in the energy storage process. Few-layer exfoliated graphene platelets can be dispersed in various aqueous and non-aqueous solvents depending upon the nature of the interaction between their surfaces and the solvent molecules. Sometimes this nature of interaction can be altered by modifying the surfaces of the few-layer exfoliated graphene platelets with polymer surfactants that can control their hydrophobicity or hydrophilicity. Transition metal oxides can be deposited on few-layer exfoliated graphene platelet surface through the interaction with precursor materials in wet-chemical synthesis procedure. Presence of polymer surfactants in the synthesis procedure can bring in even further surface interaction phenomena and alter the structure of the deposited transition metal oxides. Dispersions of few-layer exfoliated graphene platelets and composites with transition metal oxides can be used to manufacture electrode structures either by coating directly onto metallic substrates with the help of a binder material or through the fabrication of self-standing structures without a binder material. Two types of few-layer exfoliated graphene platelets have been investigated in this research: Grade-M particles (15µ average diameter) have an average thickness of approximately 6-8 nanometers and a typical surface area of 120-150 m2/g; and Grade-C, generally consisting of aggregates of particles with diameter less than 2µm and a particle thickness of few nanometers with a surface area of 750 m2/g. In this research, platelets with different surface areas, particle sizes and structures combined with an organic electrolyte have been investigated as Lithium-air battery cathode materials. Grade-C was found to deliver higher discharge capacity with little overpotential compared to Grade-M. Binder free, self-standing electrodes have been investigated as higher energy density alternative to metal current collector cathodes. A new self-standing bilayer electrode composed of two types of platelets was found to counter the negative effect of higher electrode loading on discharge capacity by enhancing the net surface area of an electrode.

Modeling of the lithium-air battery cathodes with broad pore size distribution

Achieving theoretical promises of 1000Wh/kg specific energy for lithium-air batteries is quite challenging due to limited transport in the cathode along with electrode passivation. Transport can be enhanced in the electrodes with complex hierarchical pore architecture. Here, using computer simulations we analyze the effects of cathode pore size distribution (PSD) on capacity and discharge curve shape. Calculations considering a broad PSD revealed that even small discharge product resistivity prevents larger pores from accumulating the discharge product and thus turning them into non-clogging oxygen supply channels. Thus optimization of cathode architecture by adding of large-scale cavities enables cell capacity enhancement.

RuO2 nanoparticles decorated MnOOH/C as effective bifunctional electrocatalysts for lithium-air battery cathodes with long-cycling stability

Manganite (MnOOH) is one of the most effective electrocatalysts for oxygen reduction reaction (ORR), and RuO2 nanoparticles exhibit high activity for oxygen evolution reaction (OER). We herein report a facile means of producing well dispersed RuO2/MnOOH on Ketjen black (RuO2/MnOOH/C) as a bifunctional catalyst for lithium-air (Li-air) batteries. RuO2/MnOOH/C was simply synthesized using a hydrothermal/precipitation based method, and was used as a cathode for a Li-air battery using a Swagelok-type cell. The importance of dispersing active catalysts on a carbon support was clearly demonstrated by textural, charge-discharge voltammetric, and electrochemical impedance spectroscopic (EIS) analyses, comparing results with a catalyst produced by physically mixing RuO2/MnOOH with carbon (RuO2/MnOOH + C). RuO2/MnOOH/C showed low overpotential and stable cycleability up to 170th cycles with 1000 mAh g−1 of charge–discharge capacity, which was attributed to its enhanced active surface area and low charge-transfer resistance. The results obtained suggest that this strategy can be widely applied to bifunctional electrocatalysis, such as secondary batteries and regenerative fuel cell (RFC).

New Evidence of LiO2 Dismutation in Lithium–Air Battery Cathodes

AbstractThe dismutation of electrochemically generated soluble lithium superoxide with the formation of a lithium peroxide deposit on Au has been studied by addition of lithium ions and following the mass uptake detected by the electrochemical quartz crystal microbalance at the open‐circuit potential and the surface morphology evolution by using atomic force microscopy.

Investigation of Few-Layer Exfoliated Graphene Platelets and Hierarchically Structured Paper-like Electrodes As Cathodes for Electrochemical Energy Storage: Lithium-Air Battery

Few-layer exfoliated graphene platelets are ultrathin particles of graphite that can also be thought of as short stacks of graphene sheets prepared through proprietary manufacturing processes. Several grades and sizes with thicknesses ranging from 1-20 nanometers and width ranging from 1-50µm are manufactured by XG Sciences, Lansing, MI, USA. Unique manufacturing processes for these platelet materials are non-oxidizing; thus, yielding a pristine graphitic surface of sp2 carbon molecules. This makes these platelet particles especially suitable for applications requiring high electrical and thermal conductivities. The surface areas of the resulting platelets predominantly consist of the open surface areas of the graphene basal planes. Open surface areas of the graphene basal planes as well the interlayer spaces between the graphene sheets coupled with high electrical conductivities are an important criteria for electrodes in many electrochemical energy storage technologies. Unique morphology of the platelets offer the potential to structure self-standing electrodes by doing away with inactive components such as current collectors and thus, enhance the energy density. Surface modification of the platelets through the deposition of transition metal oxides on the graphene basal planes has the potential to enhance the energy storage capacity due to the participation of two different components in the energy storage process. Few-layer exfoliated graphene platelets can be dispersed in various aqueous and non-aqueous solvents depending upon the nature of the interaction between their surfaces and the solvent molecules. Sometimes this nature of interaction can be altered by modifying the surfaces of the few-layer exfoliated graphene platelets with polymer surfactants that can control their hydrophobicity or hydrophilicity. Transition metal oxides can be deposited on few-layer exfoliated graphene platelet surface through the interaction with precursor materials in wet-chemical synthesis procedure. Presence of polymer surfactants in the synthesis procedure can bring in even further surface interaction phenomena and alter the structure of the deposited transition metal oxides. Dispersions of few-layer exfoliated graphene platelets and composites with transition metal oxides can be used to manufacture electrode structures either by coating directly onto metallic substrates with the help of a binder material or through the fabrication of self-standing structures without a binder material. Two types of few-layer exfoliated graphene platelets have been investigated in this research: Grade-M particles (15µm average diameter) have an average thickness of approximately 6-8 nanometers and a typical surface area of 120-150 m2/g; and Grade-C, generally consisting of aggregates of particles with diameter less than 2µm and a particle thickness of few nanometers with a surface area of 750 m2/g. In this research, platelets with different surface areas, particle sizes and structures combined with an organic electrolyte have been investigated as Lithium-air battery cathode materials. Grade-C was found to deliver higher discharge capacity with little overpotential compared to Grade-M. Binder free, self-standing electrodes have been investigated as higher energy density alternative to metal current collector cathodes. A new self-standing bilayer electrode composed of two types of platelets was found to counter the negative effect of higher electrode loading on discharge capacity by enhancing the net surface area of an electrode.

Synthesis of flexible pure graphene papers and utilization as free standing cathodes for lithium-air batteries

In Lithium-air cathode, graphene containing materials have been reported as ideal cathode materials due to their large theoretical specific surface area, chemical stability, high electrical conductivity and charge capacity. In this study; three free-standing flexible graphene cathodes were produced with different thickness by vacuum filtration technique. For preparation of the graphene electrodes, graphene oxide (GO) papers were chemically reduced. Surface morphology of the produced graphene cathodes were characterized using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) was conducted to understand elemental composition of the GO paper. X-ray diffraction (XRD) technique and Raman spectroscopy were carried out to investigate the structure of the GO paper electrode. Moreover, specific surface area and porosity distribution of the GO paper was performed using Brunauer–Emmett–Teller (BET) method from N2 adsorption and desorption isotherms and the pore size were calculated using the Barrett–Joyner–Halenda (BJH) algorithm on the desorption branch. Electrochemical performance of the free-standing graphene electrodes were assessed in ECC-Air test cell from 1.5 V to 4.5 V at a constant current density.

Synthesis, Characterization and Performance Evaluation of an Advanced Solid Electrolyte and Air Cathode for Rechargeable Lithium-Air Batteries

Synthesis and characterization of a tri-layered solid electrolyte and oxygen permeable solid air cathode for lithium-air battery cells were carried out in this investigation. Detailed fabrication procedures for solid electrolyte, air cathode and real-world lithium-air battery cell are described. Materials characterizations were performed through FTIR and TGA measurement. Based on the experimental four-probe conductivity measurement, it was found that the tri-layered solid electrolyte has a very high conductivity at room temperature, 23。C, and it can be reached up to 6 times higher at 100。C. Fabrication of real-world lithium-air button cells was performed using the synthesized tri-layered solid electrolyte, an oxygen permeable air cathode, and a metallic lithium anode. The lithium-air button cells were tested under dry air with 0.1 mA - 0.2 mA discharge/ charge current at elevated temperatures. Experimental results showed that the lithium-air cell performance is very sensitive to the oxygen concentration in the air cathode. The experimental results also revealed that the cell resistance was very large at room temperature but decreased rapidly with increasing temperatures. It was found that the cell resistance was the prime cause to show any significant discharge capacity at room temperature. Experimental results suggested that the lack of robust interfacial contact among solid electrolyte, air cathode and lithium metal anode were the primary factors for the cell’s high internal resistances. It was also found that once the cell internal resistance issues were resolved, the discharge curve of the battery cell was much smoother and the cell was able to discharge at above 2.0 V for up to 40 hours. It indicated that in order to have better performing lithium-air battery cell, interfacial contact resistances issue must have to be resolved very efficiently.

Self-Assembled Mace-Like Fe3O4 Nanostructures as a Lithium–Air Battery Cathode Material

Mace-like Fe3O4 nanostructures with a length of 200–300 nm and a diameter of 10–30 nm were successfully synthesized via a microemulsion-mediated solvothermal method and used as an electrode catalyst for lithium–air batteries. The results showed that the mace-like Fe3O4 nanostructures were obtained by adjusting the NaOH concentration and reaction temperature, and by adding polyethylene glycol-1000. The growth and assembly mechanism of the mace-like Fe3O4 nanostructures was also discussed. Polyethylene glycol-1000 not only acted as a soft template to form Fe3O4 nanorods, but also assisted in the assembly of the Triton X-100-decorated Fe3O4 nanoparticles onto the nanorods. The results of charge–discharge tests showed that the lithium–air battery based on mace-like Fe3O4 nanostructures exhibited a high discharge capacity of 1427 mA h g−1 in ambient air. The unique one-dimensional mace-like Fe3O4 nanostructures could effectively enhance the catalytic activity for the oxygen evolution reduction process, which is effective for decreasing the charging potential plateau.

Multi-Wall Carbon Nanotubes As Cathodes for Lithium-Air Batteries: Effect of Catalysts and Additives

Batteries with high specific energy densities have attracted a lot of attention due to their demand in electric vehicles (EVs). Due to the increase in demand for energy storage devices for applications such as load-levelling of electrical energy supply and demand [1], propulsion for electric vehicles, and microelectro-mechanical devices, the research for new classes of electrode materials that provide high energy, high power and cycle life longer than lithium-ion batteries is being motivated [2,3]. Lithium air batteries have high specific energy density and they can achieve four times higher energy density than the current lithium ion batteries [2, 3]. Lithium air batteries also have higher theoretical energy density than lithium ion batteries [4]. Catalysts have been shown to improve both the battery capacity and the recyclability of these batteries when used in cathodes. Several catalysts have been discovered for lithium air batteries. Debart et al. used several catalysts for lithium oxygen batteries with non-aqueous electrolyte. The electro-catalysts used by them included Pt, La0.8Sr0.2MnO3, Fe2O3, NiO, CuO, CoFe2O4. Co3O4 exhibited highest discharge capacity and best cycling performance. Later Debart et al. examined manganese oxides as catalysts for lithium oxygen batteries. Mn3O4, bulk Mn2O3, bulk α, β, λ, γ-MnO2, α-MnO2 nanowires and β-MnO2 nanowires were used as catalysts [6]. The air cathode with α-MnO2 as the catalyst showed the highest capacity of about 3000 mAh/g (carbon) Lu et al. reported ORR studies on polycrystalline metal catalysts of palladium, platinum, ruthenium, gold and glassy carbon surfaces in non-aqueous electrolyte [5]. In this study, we investigate various modes of loading palladium-based catalysts and their effect on the capacity and round-trip efficiency of lithium-air batteries. The aim of our study is to increase the first discharge capacity, improve the recyclability, increase capacity retention and improve the recyclability of the battery. The loading and morphology the catalyst-CNT cathodes were studied using transmission electron microscopy. Electrochemical testing using electrochemical impedance spectroscopy and charge-discharge cycling were also investigated. The cathode consisted of conductive carbon cloth coated with MWCNT or palladium inside MWCNT. Celgard 2040 was used as a separator. LiTFSi (Bis Trifluoromethane sulfonamide Lithium salt) in TEGDME (Tetraethyl glycol di-methyl ether) was used as electrolyte. The battery was assembled in the Swagelok cell. Figure 1 shows the assembly of the battery. Figure 2 shows the TEM images of palladium nanoparticles inside MWCNT. Figure 3 shows Pristine CNT with first cycle at a current rate of 200 mA/g showing a discharge capacity of 9300 mAh/g and a charge capacity of 8250 mAh/g. Figure 4 shows catalyst-loaded CNT with first cycle at a current rate of 200 mA/g showing a discharge capacity of 13800 mAh/g and a charge capacity of 3000 mAh/g.