Class Of 2D Materials Research Articles

Electronic and optical characterization of 2D Ti2C and Nb2C (MXene) thin films

Two-dimensional (2D) transition metal carbides and/or nitrides (MXenes) are a new class of 2D materials, with extensive opportunities for property tailoring due to the numerous possibilities for varying chemistries and surface terminations. Here, Ti2AlC and Nb2AlC MAX phase epitaxial thin films were deposited on sapphire substrates by physical vapor deposition. The films were then etched in LiF/HCl solutions, yielding Li-intercalated, 2D Ti2CTz and Nb2CTz films, whose terminations, transport and optical properties were characterized. The former exhibits metallic conductivity, with weak localization below 50 K. In contrast, the Nb-based film exhibits an increase in resistivity with decreasing temperature from RT down to 40 K consistent with variable range hopping transport. The optical properties of both films were determined from spectroscopic ellipsometry in the 0.75 to 3.50 eV range. The results for Ti2CTz films confirm the metallic behavior. In contrast, no evidence of metallic behavior is observed for the Nb2CTz film. The present work therefore demonstrates that one fruitful approach to alter the electronic and optical properties of MXenes is to change the nature of the transition metal.

Ultrathin Ti3C2 nanosheets based “off-on” fluorescent nanoprobe for rapid and sensitive detection of HPV infection

MXenes as a new class of 2D materials have recently been widely applied in energy storage, electrocatalysis, sensors, adsorption, water purification, and so on, due to their tunable versatile properties. Herein, we demonstrate a simple, rapid and highly-sensitive sensing platform based on ultrathin two-dimensional MXene Ti3C2 nanosheets (Ti3C2 NSs) for selective analysis of Human papillomavirus (HPV), a major human pathogens and causative agents of cervical cancer. Ultrathin Ti3C2 NSs, obtained by exfoliating their layered HF-etched powder, exhibit high fluorescence quenching ability to dye-labeled single-stranded DNA (ssDNA) and different affinities for ssDNA and double-stranded DNA (dsDNA). Under the fluorescence quenching effect of Ti3C2 NSs, ssDNA probe (P) shows the minimal fluorescent emission. After the formation of duplex structure with its complementary target, ssDNA (T), the fluorescence intensity enhances evidently. Exonuclease III (Exo III) was used to improve the sensitivity by promoting more fluorescence enhancement. This magnified fluorescent sensor for HPV-18 detection shows a low detection limit of 100 pM and a high specificity. Furthermore, the developed DNA sensor can be employed to determine PCR amplified HPV-18 from cervical scrapes samples. It highlights ultrathin Ti3C2 NSs as a potential candidate for construction of fluorescence DNA biosensors with excellent performances.

MZI‐Based All‐Optical Modulator Using MXene Ti3C2Tx(T = F, O, or OH) Deposited Microfiber

AbstractAs a new class of 2D materials, MXenes have attracted a lot of interest because of their prominent performance in versatile applications, such as batteries, supercapacitors, catalysts, electronics, and optics. In this work, an all‐optical modulator using MXene Ti3C2Txdeposited on a microfiber is proposed. By inserting an MXene‐deposited phase shifter into one arm of a Mach–Zehnder interferometer, the MXene Ti3C2Txabsorbs the control light and generates heat, which induces significant refractive index changes through strong light–matter interactions and thermo‐optic effects. In this study, a maximum phase shift of 16π is obtained, and an efficient all‐optical switch with an extinction ratio of more than 18.53 dB and a rise time constant of 4.10 ms are demonstrated. The advantages of this modulator include its all‐fiber content, low cost, ease of integration, and compactness. All‐optical modulators based on thermo‐optical effects will play an active role in the future of optical communications and optical information processing.

Mn-doped SnS2 nanostructure as a potential efficiency CO catalyst: A first-principles study

The SnS2 is a new class of 2D materials with unique properties, which are still largely unexplored in the CO catalyst field. The modulation of electronic structures and chemical activities of the Mn atom substituted for S atom in SnS2 monolayer sheet is studied based on density functional theory. The electrons of doped Mn are introduced to the dangling bond of monovacancy SnS2 system, which can enhance the stability of Mn-Sn bond. The Mn-SnS2 monolayer sheet prefers good catalytic activity for the CO oxidation via the more favorable Langmuir-Hinshelwood mechanism with a two-step route to the Eley-Rideal or the latest report of termolecular Eley-Rideal mechanisms. In summary, we show first-principles evidence toward the realization of SnS2 based catalyst for CO catalytic oxidation which can facilitate the applications of SnS2 in the fields of catalysis and air pollution prevention.

Cytotoxicity of layered metal phosphorus chalcogenides (MPXY) nanoflakes; FePS3, CoPS3, NiPS3

Metal phosphorus chalcogenides is a new class of 2D materials that have shown interesting semiconducting, electronic, anisotropic, magnetic, dielectric, structural and optical properties. Recently, NiPS3, FePS3 and CoPS3 in particular have been highlighted for promising potential in important energy applications such as electrocatalysts for water splitting and hydrogen storage. However, little is known about the toxicological hazards that they may pose on humans. Here, we investigated the cytotoxicity of NiPS3, FePS3 and CoPS3 on human lung carcinoma cells (A549) and normal human bronchial cells (BEAS-2B) to address this concern. Upon treatment of these cells with different MPXY materials, we determined the remaining cell viability using water soluble tetrazolium salt (WST-8) assay. We found that CoPS3 was most toxic followed by FePS3 with intermediate toxicity while NiPS3 showed the lowest toxicity among the three materials tested for both cell lines. When viewed with other layered materials, these MPXY samples present comparable toxicities with transition metal dichalcogenides and black phosphorus at low concentrations.

Borocarbonitrides as Metal‐Free Catalysts for the Hydrogen Evolution Reaction

Hydrogen generation by water splitting is clearly a predominant and essential strategy to tackle the problems related to renewable energy. In this context, the discovery of proper catalysts for electrochemical and photochemical water splitting assumes great importance. There is also a serious intent to eliminate platinum and other noble metal catalysts. To replace Pt by a non-metallic catalyst with desirable characteristics is a challenge. Borocarbonitrides, (Bx Cy Nz ) which constitutes a new class of 2D material, offer great promise as non-metallic catalysts because of the easy tunability of bandgap, surface area, and other electronic properties with variation in composition. Recently, Bx Cy Nz composites with excellent electrochemical and photochemical hydrogen generation activities have been found, especially noteworthy being the observation that Bx Cy Nz with a carbon-rich composition or its nanocomposites with MoS2 come close to Pt in electrocatalytic properties, showing equally good photochemical activity.

Saddle‐Point Excitons and Their Extraordinary Light Absorption in 2D β‐Phase Group‐IV Monochalcogenides

AbstractIn 2D materials, saddle‐points in the electronic structure give rise to diverging density of states, which leads to intriguing physical phenomena useful for applications, including magnetism, superconductivity, charge density wave, as well as enhanced optical absorption. Using first‐principles calculations, monolayer β‐phase group‐IV monochalcogenides (MX, M = Ge or Sn; X = S or Se) are shown to be a new class of 2D materials that possess saddle‐points in both the lowest conduction band and the highest valence band as well as in the joint density of states. Due to the existence of saddle‐points, a remarkable absorption peak within the fundamental gap is found in these materials when the light polarization is along the armchair (y) direction. The properties of saddle‐point excitons can be effectively tuned by both the strain and thickness of these materials. Importantly, the strong optical absorbance induced by saddle‐point exciton absorptions and the appropriate bandgap give ideal power conversion efficiencies as large as 1.11% for monolayer β‐SnSe, significantly higher than reported high‐performance ultrathin solar cells using transition metal dichalcogenides. These results not only open new avenues for exploring novel many‐body physics, but also suggest β‐phase MXs could be promising candidates for future optoelectronic devices.

Two-dimensional ferromagnetism in few-layer van der Waals crystals: Renormalized spin-wave theory and calculations

Dimensionality shapes the behavior of magnetism. Recent experiments on quasi two-dimensional (2D) van der Waals crystals have demonstrated unusual ferromagnetic orders and phase transitions distinct from their bulk counterparts. In this work, we present a method using renormalized spin-wave theory to study the ferromagnetic behavior in Heisenberg-type 2D ferromagnets, and apply our method to few-layer Cr2Ge2Te6 crystals. We present the details of the method, which includes a self-consistent updating scheme of the spin-wave spectra at the Hartree-Fock level. The theoretical results obtained quantitatively explain the experimental measurements, showing strong dimensionality effects and sensitive external magnetic-field dependence which leads to easily tunable magnetism in this class of 2D materials. This method can be generalized to study various magnetic phenomena in other systems.

Self-Assembly of Transition Metal Oxide Nanostructures on MXene Nanosheets for Fast and Stable Lithium Storage.

Recently, a new class of 2D materials, i.e., transition metal carbides, nitrides, and carbonitrides known as MXenes, is unveiled with more than 20 types reported one after another. Since they are flexible and conductive, MXenes are expected to compete with graphene and other 2D materials in many applications. Here, a general route is reported to simple self-assembly of transition metal oxide (TMO) nanostructures, including TiO2 nanorods and SnO2 nanowires, on MXene (Ti3 C2 ) nanosheets through van der Waals interactions. The MXene nanosheets, acting as the underlying substrate, not only enable reversible electron and ion transport at the interface but also prevent the TMO nanostructures from aggregation during lithiation/delithiation. The TMO nanostructures, in turn, serve as the spacer to prevent the MXene nanosheets from restacking, thus preserving the active areas from being lost. More importantly, they can contribute extraordinary electrochemical properties, offering short lithium diffusion pathways and additional active sites. The resulting TiO2 /MXene and SnO2 /MXene heterostructures exhibit superior high-rate performance, making them promising high-power and high-energy anode materials for lithium-ion batteries.

Bismuth Oxychloride/MXene symmetric supercapacitor with high volumetric energy density

Since the discovery of two-dimensional (2D) graphene, a new class of 2D materials with excellent electrical conductivity has recently been attracting attention in studying promising electrode materials in energy storage applications. Herein, bismuth oxychloride nanosheets-immobilised Ti3C2Tx MXene material (TCBOC) is synthesised by a facile and cost-effective chemical bath deposition (CBD) route. The bismuth oxychloride (BiOCl) nanosheets are grown and immobilised on surfaces of Ti3C2Tx-MXene flakes. An electrode based on the TCBOC nanocomposite exhibited a remarkably volumetric specific capacitance of 396.5 F cm-3 at 1 A g−1 and 228.0 F cm-3 at 15 A g−1. Furthermore, a symmetric supercapacitor (SSC) assembled using TCBOC material proves to have a high energy density of 15.2 Wh kg−1 at a power density of 567.4 W kg−1 compared to SSCs using previously reported Ti3C2Tx MXene materials. The SSC shows cycle life retention of 85.0% after 5000 cycles (at 5 A g−1). The enhanced capacitive performance is attributed to the increased surface area due to BiOCl nanosheets anchored on a 2D MXene surface, the activities of BiOCl sheets, and the excellent conductivity of a Ti3C2Tx MXene material.

2D Photovoltaic Devices: Progress and Prospects

AbstractThe discovery of the new class of 2D materials has stimulated extensive research interest for fundamental studies and applied technologies. Owing to their unique electronic and optical properties, which differ from their bulk counterparts and conventional optoelectronic materials, 2D materials at the atomic scale are very attractive for future photovoltaic devices. Over the past years, their great potential for photovoltaic applications has been widely investigated by creating a variety of specific device structures. Here, the recent progress made toward the exploitation of 2D materials for high‐performance photovoltaic applications is reviewed. By addressing both lateral and vertical configurations, the prospects offered by 2D materials for future generations of photovoltaic devices are elucidated. In addition, the challenges facing this rapidly progressing research field are discussed, and routes to commercially viable 2D‐material‐based photovoltaic devices are proposed.

Large optical gain from the 2D-transition metal dichalcogenides of MoS2/WSe2 quantum wells

In this work, the optical gain in the new class of 2D-materials is calculated for MoS2/WSe2 single quantum well (QW). For this purpose, numerical solution of the k.p equation at (K+, K−) points of the Brillouin zone is done in order to obtain the energy levels and their corresponding wave functions of electrons and holes in QW. Then, we discussed the band gap dependence on temperature of MoS2 and WSe2 materials. Further, we examined the temperature and the QW width effects on the optical and the maximum of gain. We found that MoS2/WSe2 QW can satisfy the lasing requirements and can give interesting results about the performance of laser emitting devices. The results are compared to the available data reported in the literature.

Phonons and thermal conducting properties of borocarbonitride (BCN) nanosheets.

Hexagonal borocarbonitrides (BCN) are a class of 2D materials, which display excellent catalytic activity for water splitting. Here, we report the analysis of thermal stability, phonons and thermal conductivity of BCN monolayers over a wide range of temperatures using classical molecular dynamics simulations. Our results show that in contrast to the case of graphene and boron nitride monolayers, the out-of-plane phonons in BCN monolayers induce an asymmetry in the phonon density of states at all temperatures. Despite possessing lower thermal conducting properties compared to graphene and BN monolayers, the BCN nanosheets do not lose thermal conductivity as much as graphene and BN in the studied temperature range of 200-1000 K, and thus, BCN nanosheets are suitable for thermal interface device applications over a wide range of temperatures. Besides their promising role in water splitting, the above-mentioned results highlight the possibility of expanding the use of BCN 2D materials in thermal management applications and thermoelectrics.

A Red‐Phosphorous‐Assisted Ball‐Milling Synthesis of Few‐Layered Ti3C2Tx (MXene) Nanodot Composite

AbstractLayered two‐dimensional (2D) early transition metal carbides (MXenes) are a new class of 2D materials with established activity for electrochemical energy conversion and storage. The use of MXenes is expected to increase by reducing their lateral size to the nanoscale. Herein, using Ti3C2Tx (T=O, OH, F) MXenes as an example, we show that μm‐sized MXenes can be reduced in size to ≈6 nm nanodots by ball‐milling with red phosphorous (P). It is remarkable almost all starting MXenes were converted to nanodots with this method. The Ti3C2Tx surface O groups interacted with P strongly and chemically to drive the nanodots formation. Ti3C2Tx nanodots (TNDs) with different sizes could also be obtained by ball‐milling Ti3C2Tx with other solid‐state elements such as carbon, sulfur and silicon. The as‐prepared TNDs and P composite was evaluated as a sodium‐ion battery anode material. A good sodiation capacity (≈600 mA h g−1) at 260 mA g−1 and good cycle stability for 150 cycles were shown.

3D Anisotropic Thermal Conductivity of Exfoliated Rhenium Disulfide.

ReS2 represents a different class of 2D materials, which is characterized by low symmetry having 1D metallic chains within the planes and extremely weak interlayer bonding. Here, the thermal conductivity of single-crystalline ReS2 in a distorted 1T phase is determined at room temperature for the in-plane directions parallel and perpendicular to the Re-chains, and the through-plane direction using time-domain thermoreflectance. ReS2 is prepared in the form of flakes having thicknesses of 60-450 nm by micromechanical exfoliation, and their crystalline orientations are identified by polarized Raman spectroscopy. The in-plane thermal conductivity is higher along the Re-chains, (70 ± 18) W m-1 K-1 , as compared to transverse to the chains, (50 ± 13) W m-1 K-1 . As expected from the weak interlayer bonding, the through-plane thermal conductivity is the lowest observed to date for 2D materials, (0.55 ± 0.07) W m-1 K-1 , resulting in a remarkably high anisotropy of (130 ± 40) and (90 ± 30) for the two in-plane directions. The thermal conductivity and interface thermal conductance of ReS2 are discussed relative to the other 2D materials.

Antimonene Oxides: Emerging Tunable Direct Bandgap Semiconductor and Novel Topological Insulator.

Highly stable antimonene, as the cousin of phosphorene from group-VA, has opened up exciting realms in the two-dimensional (2D) materials family. However, pristine antimonene is an indirect band gap semiconductor, which greatly restricts its applications for optoelectronics devices. Identifying suitable materials, both responsive to incident photons and efficient for carrier transfer, is urgently needed for ultrathin devices. Herein, by means of first-principles computations we found that it is rather feasible to realize a new class of 2D materials with a direct bandgap and high carrier mobility, namely antimonene oxides with different content of oxygen. Moreover, these tunable direct bandgaps cover a wide range from 0 to 2.28 eV, which are crucial for solar cell and photodetector applications. Especially, the antimonene oxide (18Sb-18O) is a 2D topological insulator with a sizable global bandgap of 177 meV, which has a nontrivial Z2 topological invariant in the bulk and the topological states on the edge. Our findings not only introduce new vitality into 2D group-VA materials family and enrich available candidate materials in this field but also highlight the potential of these 2D semiconductors as appealing ultrathin materials for future flexible electronics and optoelectronics devices.

Electronic Properties of Acetaminophen Adsorbed on 2D Clusters: A First Principles Density Functional Study

AbstractThe interaction of acetaminophen (N‐acetyl‐para‐aminophenol), a prominent analgesic and antipyretic, with 2D clusters was investigated using density functional theory with inclusion of van der Waals dispersion correction. The implicit solvation model with three different solvents; water, ethanol and carbon tetrachloride were utilized to observe the trends in binding energy as a function of solvent polarity. The calculated results demonstrate that interactions are not solely dependent on solvent polarity, but inherent properties of the 2D clusters drive the nature of the interaction; i. e. physisorbed states were favored for graphene, boron nitride (BN), and phosphorene, whereas a chemisorbed state is preferred for silicene. Analysis of the frontier orbitals and density of states (DOS) show that the acetaminophen functionalization induces mid‐gap energy states in BN. Chemisorbed acetaminophen on silicene induces a 2p core level shift in silicon. The calculated results provide atomistic insights on the nature of interactions of acetaminophen with the new class of 2D materials beyond graphene for potential sensing applications.

Template-free 3D titanium carbide (Ti3C2Tx) MXene particles crumpled by capillary forces.

Ti3C2Tx and other types of MXene nanosheets are an exciting new class of 2D materials. However, little has been reported on manipulating the shape of MXene nanosheets. Here, we demonstrate that flat Ti3C2Tx nanosheets encapsulated within spray-dried droplets can be scrolled, bent, and folded into 3D crumpled structures. This morphological change was observed to be reversible upon rehydration.

(Invited) Silicene: Silicon at the Two Dimensional Limit and Its Applications to Nanoelectronics

The evolution of semiconductor nanoelectronics demands for a progressive miniaturization of the device feature size. Downscaling the silicon channel down to the ultra-thin film regime is a current trend in the semiconductor technology roadmap for digital devices such as ultra-thin body silicon-on-insulator field (UTB-SOI) or Fin field effect transistors. Future technology nodes are to require a turning point in the choice of alternative semiconductors replacing silicon. One approach is to make use of mobility boosters such as germanium or III-V’s in order to overcome the physical limits of silicon in the CMOS technology. However, new emerging materials are yet to come which imply a reduced dimensionality of the silicon channels (see the Figure below for a silicon roadmap).[1] This route inspired the concept of silicene as a silicon at the extreme two-dimensional (2D) limit. Silicene can be thought of as a structural analogue of graphene as well as a graphene follower in the periodic table. Silicene has recently attracted a tremendous attraction for its potential to bring the current silicon technology down to an ultimate thickness limit. Apart from the technology drivers, the existence of a silicene monolayer paves the way to the exploration of new exotic physical effecs such as the quantum spin Hall effect in an elementary crystal and to a new class of 2D materials, the so-called Xenes (X denoting other group IV semiconductors such as Ge and Sn). Despite the natural tendency of silicon to hybridize sp3 instead of sp2as carbon in graphene, the concept of silicene was previously proposed in its theoretical terms as a pseudo planar free-standing lattice. However, unlike graphene, silicene is not free-standing in nature. Silicene can be artificially forced to grow upon epitaxy on substrates with a commensurate surface lattice. The details of the silicene epitaxy are reported from the monolayer to the multilayer regime taking the growth onto Ag(111) substrates as paradigmatic example.[2] According to the ideal case of free-standing silicene, the epitaxial silicene is buckled in nature and can be grown in number of differently buckled phase depending on the growth temperature and the deposition rate. A full exploitation of silicene for device applications is hurdled by stability issues at its top and bottom interfaces. At its top interface, silicene is highly reactive under environmental condition thereby suffering from fast structural degradation and oxidation. Encapsulation with an Al2O3 ultra-thin capping films is shown to prevent silicene from degradation thus allowing for ex situ characterization and further processing steps. At the bottom interface of silicene is the hosting substrate. Previously studied hosting substrates are metallic in character, serve as stabilizers for the silicene lattice and strongly interact with it thereby suppressing the formation of Dirac cones in the silicene band structure and ultimately causing a metallization of the silicene itself. The latter fact is a detrimental obstacle for silicene handling. Two approaches are outlined to bypass this drawback. A) On one hand, a methodology for the silicene encapsulation, delamination, and isolation is presented as enabling technology for device integration. The key-point is this procedure relies on the use of epi-Ag(111) film on mica as cleavable substrates for the silicene epitaxy. A silicene-based transistor can be then fabricated by patterning the native Ag as source/drain contacts of a pure silicene channel.[3] Room temperature operation of field effect transistor incorporating silicene monolayer and multilayer as active channel materials is demonstrated. The observation of an ambipolar behavior in the transistor transfer curves turns out to be the electrical hallmark of silicene. B) On the other hand, template engineering is also explored as alternative approach to create a metal-free platform for the technological implementation of silicene. As a representative case, the epitaxy of silicene on MoS2 templates is reported and the electronic band alignment between the two terms described. [4] Silicene-on-MoS2 is then integrated into a heterosheet junction transistor making evidence of an effective electrical transport at the Si/MoS2interface. Possible advances in the functionalization of silicene are discussed which pave the way to a multifunctional applications based on the same silicene platform. Finally, an outlook of silicene contemporaries, germanene, stanene, etc., is proposed aiming at the exploitation of their non-trivial topological properties in nanoelectronics. [1] “2D Materials for Nanoelectronics”, Eds. M. Houssa, A. Dimoulas, A. Molle, CRC Press, Taylor&Francis Group, 2016 Boca Raton, FL [2] C. Grazianetti, E. Cinquanta, and A. Molle, 2D Materials 3, 012001 (2016) (Topical Review). [3] L. Tao, et al., Nature Nanotech. 10, 227 (2015). [4] A. Molle, et al., Adv. Mater. Interf. (2016), DOI: 10.1002/admi.201500619. Figure 1

Investigation of the Charge Storage Mechanism of Mxenes As Anode Materials for Na-Ion Batteries

Two dimensional (2D) materials such as graphene have attracted tremendous interest and have shown promising potential in various applications due to their unique physical structure and properties. Another new class of 2D materials, a group of early transition metal carbides and/or carbonitrides, called MXene, have been studied and reported recently. MXenes are chemically derived from layered Mn+1AXn or MAX phases, where M is early transition metal, A is an A-group element (mainly groups 13 and 14), X is C and/or N, and n=1,2, and 3. Since discovery of the first MXene (Ti3C2) in 2011, more than 10 new MXenes have been synthesized and demonstrated its interesting and unique properties in many applications. It has been shown that MXenes have promising potential in electrochemical energy storage applications such as lithium ion batteries (LIBs) and electrochemical capacitors (ECs), due to their high electrical conductivity, good structural/chemical stability, and large surface areas. Recently, MXene application studies are expanding to other battery systems such as Na-ion batteries (NIBs). The growing concerns on the cost and resource limit of lithium for large scale applications have triggered the development of NIBs as an alternative battery system to LIBs for large scale energy storage applications due to their potentially low-cost and natural abundance. Moreover, the accumulated knowledge and technology of LIBs enables fast-advancements of NIBs research since the operating principles of the NIBs are similar to that of “rocking-chair” mechanism in LIBs. Although many concepts can be adopted from LIB in NIB research, the electrochemistry of NIBs turns out to be different in many aspects requiring new design of electrode materials and electrolyte for improving and/or optimizing performance of NIBs. In particular, Na+ has a larger radius than Li+, which directly affects the mass transport and storage in the electrochemical reaction. This makes many of current LIB anode materials, such as graphite, unsuitable for NIBs. In this regards, the laminar nature of MXenes bonded by weak van der walls forces and its inherent interlayer spacing are very attractive as anode materials for NIBs. However, most of studies on the electrochemical behavior of MXenes as anode materials for NIBs are just at the theoretical estimation only without much experimental support. In this study, we present a systematic study on the electrochemical properties and their charge storage mechanisms of V2C and Nb2C MXenes as anode materials for NIBs. X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) were used in both ex situ and in situ way to look at the structural changes during electrochemical cycling. By utilizing such combined X-ray techniques, we are able to get better understanding of structural/electronic structure changes of MXenes and their related charge storage behavior during sodiation/desodiation process. A systematic comparison of electrochemical properties and charge storage mechanism for MXenes between NIBs and LIBs as well as the approaches to improve them will also be discussed. Acknowledgement The work done at Brookhaven National Lab was supported by the U.S. Department of Energy, the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies, under Contract Number DE-SC0012704. The work performed at Drexel University was supported by the Office of Electricity Delivery and Energy Reliability, Energy Storage Systems Program, through Sandia National Laboratories. The Advanced Light Source is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.