Earth-abundant Mineral Research Articles

Modelling Ca2+ Mobility and Dynamics in Solvent-Free Molten Salt Electrolytes for Calcium Batteries

Multivalent elements based batteries using earth-abundant minerals is a route with promises, not only from a performance but also from a supply and cost point of view; this is not the last true for calcium (Ca) batteries since Ca is the fifth most abundant element in the Earth's crust [1,2,3]. There is, however, no functional electrolyte available yet for Ca batteries, calling for early modelling to be made to map the influence of different Ca-salts and salt concentrations on electrolyte physicochemical properties such as density, viscosity, ionic conductivity, charge carrier dynamics and diffusivity [3, 4]. One particular route little trodden is molten salt electrolytes (MSEs), materials that consist of ions with different valences in direct contact with each other due to the complete absence of any solvent. In practice, MSEs are multicomponent salt mixtures with reduced melting points with respect to the ingoing components and furthermore they also expand the operating temperature range upwards as compared to conventional liquid electrolytes. Moreover, MSEs have high ionic conductivities due to their intrinsically high ionic content and ionic mobility. Additionally, MSEs exhibit wide electrochemical stability windows, non-flammability, and non-toxicity [5, 6]. We have investigated MSEs composed of Ca(FSI)2, LiFSI, NaFSI, and KFSI, by molecular dynamics (MD) simulations. Apart from the basic properties, we focus on the relative dynamical properties of the different cations in the MSEs in order to obtain a fundamental understanding of the systems’ behaviour, both globally and locally, but for natural reasons with special emphasis on the Ca2+ ions.

Mechanism of pyrite photoconductance under an 808 nm-laser irradiation: a photo-thermal synergism

As an earth-abundant mineral semiconductor, pyrite absorbs and converts photons under solar radiation to produce electrons, which is considered one of the important basic energy forms newly discovered in nature, and the response mechanism of light radiation on semiconductor minerals remains to be further explained. Here in this study, we focus on the photoconductance mechanism of natural pyrite, that is, an optical and electrical phenomenon in which the conductivity of a semi-coke is enhanced by absorption of an 808 nm wavelength laser. On the one hand, the photon energy of the 808 nm laser is higher than the band gap of pyrite, thus it can excite photogenerated charge carriers. On the other hand, the thermal effect produced by pyrite after absorbing the light energy will also improve the electrical conductivity. By monitoring the relationship between photoconductance, temperature, and time under laser irradiation, a photo-thermal synergism can be observed and evaluated. We aim to provide a basis for the study of the basic physical properties of natural pyrite, which will help to describe its role in geological and biological evolution.

Interface regulation of Pt quantum dots doped nickel phosphide and cobalt hydroxide to promote electrocatalytic overall water splitting

The transition metal phosphates are earth-abundant minerals that have been shown to perform well in electrocatalytic water splitting, whereas these catalysts still tend to have excessively high overpotentials and slow kinetics in HER and OER processes. In the present work, hybrid catalysts consisting of Pt quantum dots doped NiP (NiP-Pt) nano-embroidery spheres and Co(OH)2 nanosheets were successfully prepared by two-step electrodeposition method. The excellent catalytic performance of the catalyst relies principally on the synergistic interaction between NiP and Pt quantum dots. Additionally, the NiP-Pt exhibits strong electronic interactions at the interface with Co(OH)2. Consequently, the catalyst has a strong catalytic performance in terms of HER and OER catalytic performance. In terms of HER, an overpotential of only 40 mV is required when the current density reaches 10 mA cm−2, corresponding to a Tafel slope of 49.85 mV·dec−1. At the same time, the catalyst also performs well at OER, with a current density of 10 mA cm−2 at an overpotential of 186 mV and a Tafel slope of 53.049 mV·dec−1 much less than most electrocatalysts. This study involving electrodeposition and doping of quantum dots provides a new idea for the efficient synthesis of fundamental HER and OER bifunctional catalysts.

Activation or passivation: Influence of halogen dopant (F, Cl, Br) on photothermal activity of Mn2O3 in degrading toluene

Mn2O3 is an exceptional earth-abundant mineral that has been extensively applied in catalytic oxidation because of the strong redox couples like Mn3+/Mn2+ and Mn4+/Mn3+ exposed on Mn2O3 surface. Herein, the catalytic activity of Mn2O3 in photothermal degradation of toluene was regulated by halogens including F-, Cl-, and Br-. As the electronegativity ordered in F (3.98) > O (3.44) > Cl (3.16) > Br (2.96), F- doped Mn2O3 overperforms Cl- doped and Br- doped Mn2O3 in decomposing toluene. DFT theoretical calculation illustrates that F- attracts the shared electrons from Mn to itself, the deviated charge center stretches the adjacent Mn-O bonds and boosts the generation of abundant oxygen vacancies, helping to strengthen the catalytic activity of Mn2O3. Conversely, Mn-O bonds are shortened by Cl- and Br- that have lower electronegativity than O. The multiple electrons circling Cl- and Br- push Mn towards O and squeeze Mn-O bonds, resulting in the formation of passivated Mn2O3. In conjunction with Mn redox couples and oxygen vacancies, 99% of 400 ppm toluene can be eliminated by F- doped Mn2O3, corresponding mineralization rate is high up to 95.8%.

Earth-abundant ZnS/ZnO/CuFeS2 films for air purification and solar fuels production

Heterogeneous photocatalysis is one of the most viable solutions for environmental remediation, and it helps to overcome energy crisis by solar fuel generation with an environmentally friendly approach. Hence, the search for efficient, stable, and inexpensive photocatalysts is one of the most significant challenges that scientists currently face for the implementation of this technology on a larger scale. One alternative is to use naturally occurring semiconductor materials as photocatalysts because they are obtained at low cost and have great potential in environmental remediation and solar fuel generation. Therefore, in this study, an earth-abundant chalcogenide mineral (ZnS), which is obtained directly from nature, was used as raw material to fabricate thick films over glass substrates by the doctor-blade technique. Both materials (pristine and thick films) were evaluated as photocatalysts to remove CH2O a commonly volatile organic compound (VOC) gas pollutant found in indoor spaces from the air, and for solar fuel generation (H2, CH3OH, and HCOOH) from CO2 reduction under simulated visible light. Pristine mineral contained ZnS and traces of CuFeS2 as crystal phases of micrometer-sized particles with visible-light response. When the earth-abundant mineral was immobilized on glass substrates as a thick film, it exhibited ZnS/ZnO/CuFeS2 as crystalline phases with a hierarchical morphology formed by stacking several plate-like particles. The thickness of the film was 2.5 μm and it was rough. These properties favored high efficiencies for air purification because more than 55% of gas pollutant was removed after 90 min. In addition, the films exhibited photocatalytic activity toward CO2 reduction to produce solar fuels such as H2 (615 μmol/g), CH3OH (150 μmol/g), and HCOOH (1693 μmol/g) at 25 °C. The good photocatalytic performance of earth-abundant films was related to an efficient charge transfer among the components (ZnS/ZnO/CuFeS2) and an enhanced light absorption owing to hierarchical morphology. The stability of samples was confirmed after three consecutive cycles.

Temperature-dependent electronic structure of bixbyite α-Mn2O3 and the importance of a subtle structural change on oxygen electrocatalysis

ABSTRACT Bixbyite -Mn2O3 is an inexpensive Earth-abundant mineral that can be used to drive both oxygen evolution (OER) and oxygen reduction reactions (ORR) in alkaline conditions. It possesses a subtle orthorhombic cubic phase change near room temperature that suppresses Jahn–Teller distortions and presents a unique opportunity to study how atomic structure affects the electronic structure and catalytic activity at a temperature range that is easily accessible in OER/ORR experiments. Previously, we observed that heat-treated -Mn2O3 had a better performance as a bifunctional catalyst in the oxygen evolution (OER) and oxygen reduction reactions (ORR) (Dalton Trans. 2016, 45, 18,494–18,501). We hypothesized that heat-treatment pinned the material into a more electrochemically active cubic phase. In this manuscript, we use high-resolution X-ray diffraction to collect the temperature-dependent structures of -Mn2O3, and then input them into ab initio calculations. The electronic structure calculations indicate that the orthorhombic cubic phase transition causes the Mn 3d and O 2p bands to overlap and mix covalently, transforming -Mn2O3 from a semiconductor to a semimetal. This subtle change in structure also modifies Mn-O-Mn bond distances, which may improve the activity of the material in oxygen electrochemistry. OER and ORR experiments were performed using the same electrode at various temperatures. They show a jump in the exchange current density near the phase change temperature, demonstrating the higher activity of the cubic phase.

Recyclable chalcopyrite sorbent for mercury removal from coal combustion flue gas

The development of cost-effective and high-efficient technologies for degrading Hg0 pollution from coal combustion flue gas remains a tremendous challenge. In this work, an earth-abundant mineral, i.e., chalcopyrite (CuFeS2), was adopted as an efficient trap for Hg0 sequestration. The CuFeS2 exhibited approximately excellent Hg0 removal performances in a wide temperature ranging from 40 to 100 °C. Typical flue gas components including oxygen (O2), sulfur dioxide (SO2), nitrogen monoxide (NO), and water vapor (H2O) negligibly interfered the Hg0 adsorption ability, which further solidify the application potential of CuFeS2 in coal-fired power plant. The Hg0 adsorption capacity and uptake rate was 37.24 mg·g−1 and 63.40 μg·g−1·min−1, respectively, significantly suppressing those of commercial activated carbons. The superior performance of CuFeS2 were primarily attributed that the disulfide ligands (S22−) could oxidize Hg0 into Hg2+ and subsequently immobilize Hg2+ into mercury sulfide (HgS). The spent CuFeS2 sorbent could be replenished and regenerated by a thermal decomposition method, which pronouncedly save the operation cost. Therefore, the CuFeS2 is a potential trap for cost-effective and efficient Hg0 remediation from coal combustion flue gas.

Interfacial and Activation Energies of Environmentally Abundant Heterogeneously Nucleated Iron(III) (Hydr)oxide on Quartz.

Poorly crystalline iron(III) (hydr)oxide nanoparticles are ubiquitous in environmental systems and play a crucial role in controlling the fate and transport of contaminants. Yet, the thermodynamic and kinetic parameters, e.g., the effective interfacial (α') and apparent activation (Ea) energies, of iron(III) (hydr)oxide nucleation on earth-abundant mineral surfaces have not been determined, which hinders an accurate prediction of iron(III) (hydr)oxide formation and its interactions with other toxic or reactive ions. Here, for the first time, we report experimentally obtained α' and Ea for iron(III) (hydr)oxide nucleation on quartz mineral surfaces by employing a flow-through, time-resolved grazing incidence small-angle X-ray scattering (GISAXS). GISAXS enabled the in situ detection of iron(III) (hydr)oxide nucleation rates under different supersaturations (σ, achieved by varying pH 3.3-3.6) and temperatures (12-35 °C). By quantitative analyses based on classical nucleation theory, α' was obtained to be 34.6 mJ/m2 and Ea was quantified as 32.8 kJ/mol. The fundamental thermodynamic and kinetic parameters obtained here will advance our fundamental understanding of the surface chemistry and nucleation behavior of iron(III) (hydr)oxides in subsurface and water treatment systems as well as their effects on the fate and transport of pollutants in natural and engineered water systems. The in situ flow-through GISAXS method can also be adapted to quantify thermodynamic and kinetic parameters at interfaces for many important solid-liquid environmental systems.

Gypsum: an environment-friendly, inexpensive and robust height calibration standard at nanometer-scale for atomic force microscopy

Gypsum is an Earth-abundant mineral with enormous applications in agriculture and civil engineering. Here, we show it is also an excellent height calibration standard alternative for atomic force microscopy (AFM). Using plain water as etchant, gypsum flakes readily review 0.75 nm tall terraces which are easy to image (lateral dimensions from tens to hundreds of nanometers) and robust against time in ambient conditions. Therefore, the present work demonstrates a new height standard alternative which is easily-available for all AFM microscopists around the world.

Native Void Space for Maximum Volumetric Capacity in Silicon-Based Anodes.

Volumetric energy density is considered a primary factor in developing high-energy batteries. Despite its significance, less efforts have been devoted to its improvement. Silicon-based materials have emerged as next-generation anodes for lithium-ion batteries due to their high specific capacity. However, their volumetric capacities are limited by the volume expansion rate of silicon, which restricts mass loading in the electrodes. To address this challenge, we introduce porous silicon templated from earth-abundant minerals with native internal voids, capable of alleviating volumetric expansion during repeated cycles. In situ transmission electron microscopy analysis allows the precise determination of the expansion rate of silicon, thus presenting an analytical model for finding the optimal content in silicon/graphite composites. The inner pores in silicon reduce problems associated with its expansion and allow higher silicon loading of 42% beyond the conventional limitations of 13-14%. Consequently, the anode designed in this work can deliver a volumetric capacity of 978 mAh cc-1. Thus, suppressing volume expansion with natural abundant template-assisted materials opens new avenues for cost-effective fabrication of high volumetric capacity batteries.

Room-temperature superionic-phase nanocrystals synthesized with a twinned lattice

The engineering of nanoscale features enables the properties of solid-state materials to be tuned. Here, we show the tunable preparation of cuprous sulfide nanocrystals ranging in internal structures from single-domain to multi-domain. The synthetic method utilizes in-situ oxidation to grow nanocrystals with a controlled degree of copper deficiency. Copper-deficient nanocrystals spontaneously undergo twinning to a multi-domain structure. Nanocrystals with twinned domains exhibit markedly altered crystallographic phase and phase transition characteristics as compared to single-domain nanocrystals. In the presence of twin boundaries, the temperature for transition from the ordered phase to the high-copper-mobility superionic phase is depressed. Whereas the superionic phase is stable in the bulk only above ca. 100 °C, cuprous sulfide nanocrystals of ca. 7 nm diameter and a twinned structure are stable in the superionic phase well below ambient temperature. These findings demonstrate twinning to be a structural handle for nanoscale materials design and enable applications for an earth-abundant mineral in solid electrolytes for Li-S batteries.

Three-dimensional atomic scale electron density reconstruction of octahedral tilt epitaxy in functional perovskites

Octahedral tilts are the most ubiquitous distortions in perovskite-related structures that can dramatically influence ferroelectric, magnetic, and electronic properties; yet the paradigm of tilt epitaxy in thin films is barely explored. Non-destructively characterizing such epitaxy in three-dimensions for low symmetry complex tilt systems composed of light anions is a formidable challenge. Here we demonstrate that the interfacial tilt epitaxy can transform ultrathin calcium titanate, a non-polar earth-abundant mineral, into high-temperature polar oxides that last above 900 K. The comprehensive picture of octahedral tilts and polar distortions is revealed by reconstructing the three-dimensional electron density maps across film-substrate interfaces with atomic resolution using coherent Bragg rod analysis. The results are complemented with aberration-corrected transmission electron microscopy, film superstructure reflections, and are in excellent agreement with density functional theory. The study could serve as a broader template for non-destructive, three-dimensional atomic resolution probing of complex low symmetry functional interfaces.

Conversion of Copper Carbonate into a Metal–Organic Framework

The preparation of porous metal–organic frameworks (MOFs) at industrial scales requires careful selection of the metal precursor to ensure the sustainability of the synthetic process, in terms of both the environmental impact and cost. The use of earth abundant minerals is attractive for this purpose, provided that they are sufficiently reactive under the conditions of MOF formation. In this work, we investigate the use of copper carbonate and its naturally occurring counterparts, malachite and azurite, as precursors for the synthesis of Cu3(BTC)2 (HKUST-1; BTC3– = 1,3,5-benzenetricarboxylate). Using a water/ethanol solution of copper carbonate and H3BTC, HKUST-1 was obtained at room temperature within 3 h, as confirmed by a suite of characterization techniques. The identity of the products was determined by the reaction conditions, highlighting the importance of optimizing the synthetic parameters. When prepared under optimized conditions, HKUST-1 synthesized here showed analogous performance characteris...

Proton transfer ferroelectricity/multiferroicity in rutile oxyhydroxides.

Oxyhydroxide minerals such as FeOOH have been a research focus in geology for studying the Earth's interior, and also in chemistry for studying their oxygen electrocatalysis activity. In this paper the first-principle evidence of a new class of ferroelectrics/multiferroics is given. In this class are: β-CrOOH (guyanaite), ε-FeOOH, β-GaOOH, and InOOH, which are earth-abundant minerals which have been experimentally verified to possess distorted rutile structures, are ferroelectric with considerable polarizations (up to 24 μC cm-2) and piezoelectric coefficients. Their atomic-thick layer may possess vertical polarization will not be diminished by depolarizing field because of the formation of O-HO bonds that can be hardly symmetrized. Furthermore, β-CrOOH is revealed to be a combination of a high Curie temperature (TC) in-plane type-I multiferroics and vertical type-II multiferroics, which is strain tunable and may give a desirable coupling between magnetism and ferroelectricity. Supported by experimental evidence on reversible conversion between metal oxyhydroxides and dioxides and their good lattice match that gives convenient epitaxial growth, a heterostructure composed of oxyhydroxides and common metal dioxides (e.g., TiO2, SnO2 and CrO2) may be constructed for various applications such as ferroelectric field-effect transistors and multiferroic tunneling junctions.

Pyrite-Type Nanomaterials for Advanced Electrocatalysis.

Since being proposed by John Bockris in 1970, hydrogen economy has emerged as a very promising alternative to the current hydrocarbon economy. Access to reliable and affordable hydrogen economy, however, requires cost-effective and highly efficient electrocatalytic materials that replace noble metals (e.g., Pt, Ir, Ru) to negotiate electrode processes such as oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and oxygen reduction reaction (ORR). Although substantial advances in the development of inexpensive catalysts, successful deployment of these materials in fuel cells and electrolyzers will depend on their improved activity and robustness. Recent research has demonstrated that the nanostructuring of Earth-abundant minerals provides access to newly advanced energy materials, particularly for nanostructured pyrites, which are attracting great interest. Crystalline pyrites commonly contain the characteristic dianion units and have cations occurring in octahedral coordination-whose generalized formula is MX2, where M can be transition metal of groups 8-12 and X is a chalcogen. The diversity of pyrites that are accessible and their versatile and tunable properties make them attractive for a wide range of applications from photovoltaics to energy storage and electrocatalysis. Pyrite-type structures can be further extended to their ternary analogues, for example, CoAsS (cobaltite), NiAsS (gersdorffite), NiSbS (ullmannite), CoPS, and many others. Moreover, improved properties of pyrites can be realized through grafting them with promoter objects (e.g., metal oxides, metal chalcogenides, noble metals, and carbons), which bring favorable interfaces and structural and electronic modulations, thus leading to performance gains. In recent years, research on the synthesis of pyrite nanomaterials and on related structure understanding has dramatically advanced their applications, which offers new perspectives in the search for efficient and robust electrocatalysts, yet a focused review that concentrates the critical developments is still missing. In this Account, we describe our recent progress on the discoveries and applications of nanostructured pyrite-type materials in the area of electrocatalysis. We first briefly highlight some interesting properties of pyrite-type materials and why they are attractive for modern electrocatalysis. Some recent advances on their synthesis that allows access to highly nanostructured pyrite-type materials are reviewed, along with the grafting of resultant pyrites with foreign materials (e.g., metal oxides, metal chalcogenides, noble metals, and carbons) to enable improved catalytic performances. We finally spotlight the exciting examples where pyrite nanostructures were used as efficient electrocatalysts to drive the OER, HER, and methanol-tolerant ORR. It is reasonable to assume that, with significant efforts and focus, the next few years will bring new advances on the pyrites and other minerals for electrocatalysis.

A computational assessment of the electronic, thermoelectric, and defect properties of bournonite (CuPbSbS3) and related substitutions.

Bournonite (CuPbSbS3) is an earth-abundant mineral with potential thermoelectric applications. This material has a complex crystal structure (space group Pmn21 #31) and has previously been measured to exhibit a very low thermal conductivity (κ < 1 W m-1 K-1 at T ≥ 300 K). In this study, we employ high-throughput density functional theory calculations to investigate how the properties of the bournonite crystal structure change with elemental substitutions. Specifically, we compute the stability and electronic properties of 320 structures generated via substitutions {Na-K-Cu-Ag}{Si-Ge-Sn-Pb}{N-P-As-Sb-Bi}{O-S-Se-Te} in the ABCD3 formula. We perform two types of transport calculations: the BoltzTraP model, which has been extensively tested, and a newer AMSET model that we have developed and which incorporates scattering effects. We discuss the differences in the model results, finding qualitative agreement except in the case of degenerate bands. Based on our calculations, we identify p-type CuPbSbSe3, CuSnSbSe3 and CuPbAsSe3 as potentially promising materials for further investigation. We additionally calculate the defect properties, finding that n-type behavior in bournonite and the selected materials is highly unlikely, and p-type behavior might be enhanced by employing Sb-poor synthesis conditions to prevent the formation of SbPb defects. Finally, we discuss the origins of various trends with chemical substitution, including the possible role of stereochemically active lone pair effects in stabilizing the bournonite structure and the effect of cation and anion selection on the calculated band gap.

First principles study of the Mn-doping effect on the physical and chemical properties of mullite-family Al2SiO5.

Transition metal (TM) modification is a common strategy for converting an earth-abundant mineral into a cost-effective catalyst for industrial applications. Among a variety of minerals, Al2SiO5, which has three phases, andalusite, sillimanite and kyanite, is emerging as a promising candidate for new catalyst development. In this paper, we use Mn to demonstrate the rationale of 3d TM doping at the Al sites in each of these three phases through first-principles calculations and the cluster expansion method. The results of cluster expansion show that Mn has a strong site preference for the six-coordinated Al octahedral chains in the andalusite and sillimanite phases, while distributing randomly in the kyanite phase. Moreover, Mn can only replace Al in sillimanite and kyanite in low concentrations; however, higher concentrations of Mn can replace Al in andalusite. We found that the concentration sensitivity is due to the Jahn-Teller distortion and 3d orbital splitting. This finding can also explain the low doping concentrations of other 3d TMs (Fe, Cr and V) in Al2SiO5 compounds. Based on the calculated Helmholtz free energy, we constructed a (MnxAl1-x)AlSiO5 temperature-composite phase diagram, which explains the physical mechanisms behind the results for 3d transition metal doping and phase transitions in Al2SiO5. This work could shed light on the related physics, chemistry, and geoscience of (MnxAl1-x)AlSiO5, and more importantly, a design rationale for the engineering of cheap catalysts.

Nano-iron pyrite seed dressing: a sustainable intervention to reduce fertilizer consumption in vegetable (beetroot, carrot), spice (fenugreek), fodder (alfalfa), and oilseed (mustard, sesamum) crops

Continuous agricultural innovations are required to feed the exploding human population through natural or artificial resources. Though light is ample on earth, two-third of unavailable ocean and one-third of available soil are major limiting factors to free growth. Excessive fertilizer usage is irreversibly altering the chemical ecology of soil, further reducing the available area. Seed metabolism might be a potential answer to this resource crunch. Without genetic modification and thus maintaining the existing biodiversity, manipulation of seed metabolism at the very onset of germination is a sustainable alternative. The current work presents seed priming with iron pyrite (FeS2) prior to sowing as one such sustainable and innovative intervention to reduce fertilizer consumption in vegetable (beetroot, carrot), spice (fenugreek), fodder (alfalfa), and oilseed (mustard, sesamum) crops. A 12-h seed pretreatment in an aqueous suspension of nano-iron disulfide/pyrite (FeS2) resulted in significant yield increase in the above crops. While agriculturists aim to restore the natural genomic diversity of different domesticated crops, environmental engineers require technologies to reduce fertilizer consumption without compromising agricultural yields, thereby making the planet more sustainable. This nanoscale seed pretreatment approach using FeS2, otherwise a benign earth abundant mineral, suggests the sustainable opportunity to translate this technology to other crops thereby enhancing the global agricultural production.

Pyrite nanoparticles: an Earth-abundant mineral catalyst for activation of molecular hydrogen and hydrogenation of nitroaromatics

Pyrite (FeS2) nanoparticles, a kind of Earth-abundant mineral, can efficiently activate molecular hydrogen under mild conditions.

Investigation of Na2/3Ni1/3Ti2/3O2 as Novel Bi-Functional Electrode Material for Non-Aqueous, Room Temperature Na-Ion Batteries

Developing long life, low-cost energy storage solutions based on earth abundant minerals is crucial for renewable energy sources, smart electric grid networks, portable electronics and automotive sector. Na-ion batteries, engineered to operate under ambient conditions with non-aqueous electrolytes, offer much promise in that they do not have resource constraints1and by selecting appropriate materials they can be fabricated into high voltage electrochemical cells, similar to Li-ion chemistry. The objective of the current work is to study the electrochemical properties of a new oxide material with the composition Na2/3Ni1/3Ti2/3O2 (SNTL)2 as a “bi-functional” intercalation-type electrode for Na-ion battery applications. The presence of two transition metals in this layered oxide enables us to activate two redox couples (Ni2+/3+ and Ti4+/3+) of different species in the same material and thereby provides the opportunity to use it as anode or cathode depending on the potential window. This approach of making both electrodes (anode and cathode) using the same material can simplify electrode design and potentially reduce manufacturing costs for commercial applications. The solid state synthesis conditions of SNTL have been optimized to make phase-pure oxide with minimal particle size as shown in Figure 1a and Figure 1b. Galvanostatic cycling shows that up to 50% of sodium ions can be removed reversibly by oxidizing nickel from 2+ to higher oxidation state without any significant capacity loss. This contributes to a sloping voltage profile in the range of 3-4.2 V (Figure 1c) with solid solution-type mechanism involving no phase transitions. Sodium insertion into pristine SNTL, due to its sodium deficient nature, activates the Ti4+/3+ redox couple. This leads to again a sloping voltage profile with an average voltage of 0.7 V vs. Na/Na+ as shown in Figure 1d. The reaction has been confirmed to be of solid solution-type using ex-situ XRD measurements. Thus, SNTL can be used to fabricate 3V intercalation-based Na-ion batteries. Wet chemistry-based synthetic routes (sol gel) are being currently explored to reduce the particle size, decrease the diffusion length scale of electrons and thereby improve the electrochemical performance under higher currents. Fabrication and testing of solid state batteries using SNTL material as active electrodes (anode and cathode) and Na3Zr2P1Si2O12 material (NASICON)3as fast sodium conducting solid electrolyte is also currently under progress.