Use of aluminum in a lithium rich cathode material of the general formula (I) for suppressing gas evolution from the cathode material during a charge cycle and for increasing the charge capacity of the cathode material.

A lithium cobalt-based positive electrode active material is provided. The lithium cobalt-based positive electrode active material includes a core portion including a lithium cobalt-based oxide represented by Formula 1 and a shell portion including a lithium cobalt-based oxide represented by Formula 2, wherein the lithium cobalt-based positive electrode active material includes 2500 ppm or more, preferably 3000 ppm or more of a doping element M based on the total weight of the positive electrode active material. An inflection point does not appear in a voltage profile measured during charging/discharging a secondary battery including the lithium cobalt-based positive electrode active material.

The present invention discloses a selenium-doped MXene composite nano-material and a preparation method thereof, comprising the following steps: (1) adding MXene and an organic selenium source into a dispersant, and stirring to prepare a dispersion with a concentration of 1 mg/ml to 100 mg/ml; (2) transferring the dispersion into a reaction kettle, then heating, reacting, and then naturally cooling to a room temperature; (3) washing the product obtained in the step (2) with a cleaning agent, then centrifuging to collect a precipitate, and drying the precipitate under vacuum; and (4) placing the sample obtained in the step (3) into a tubular furnace for calcination, introducing protective gas, heating, and then cooling to a room temperature to obtain the selenium-doped MXene composite nano-material. The material prepared by the present invention has high specific surface area, good electrical conductivity, cycle stability performance, rate performance and high theoretical specific capacity.

Proposed are a layered Group III-V arsenic compound, a Group III-V nanosheet that may be prepared using the same, and an electrical device including the materials. There is proposed a layered compound having a composition represented by [Formula 1] Mx-mAyAsz (Where M is at least one of Group I elements, A is at least one of Group III elements, x, y, and z are positive numbers which are determined according to stoichiometric ratios to ensure charge balance when m is 0, and 0<m<x).

The present invention relates to a lithium metal complex oxide and a preparation method thereof, and more particularly, to a lithium metal complex oxide mixed with a metal compound for a lithium reaction, stirred and heat-treated to allow residual lithium and a metal compound for reducing lithium (or a metal compound for lithium reduction) to react with each other on a surface to form a product, which is included in the lithium metal complex oxide, in which the content of Ni.sup.3+ is higher than the content of Ni.sup.2+ and a ratio of Ni.sup.3+/Ni.sup.2+ is 1.5 or greater so that life characteristics and capacity characteristics are improved, while residual lithium is reduced, and a preparation method thereof.

A hydrogel comprising a colloidal suspension of M.sup.I.sub.XM.sup.II.sub.YP.sub.Z two-dimensional nanocrystals in water, wherein M.sup.I is Na.sup.+ and/or Li.sup.+, M.sup.II is Mg.sup.2+ or a mixture of Mg.sup.2+ with one or more Ni.sup.2+, Zn.sup.2+, Cu.sup.2+, Fe.sup.2+ and/or Mn.sup.2+, P is a mixture of dibasic phosphate ions (HPO.sub.4.sup.2−) and tribasic phosphate ions (PO.sub.4.sup.3−). X ranges from about 0.43 to about 0.63, Y ranges from about 0.10 to about 0.18, Z ranges from about 0.29 to about 0.48, X, Y, Z being mole fractions, is provided.

Exemplary embodiments of positive electrode active materials in the form of single particles, and a method of preparing each of them, are provided. The single particles of the exemplary embodiments include single particles of a nickel-based lithium composite metal oxide, having a plurality of crystal grains, each having a size of 180 nm to 300 nm, as analyzed by a Cu Kα X-ray (X-rα). The single particles include a metal doped in the crystal lattice thereof. One embodiment includes a surface coating. The total content of the metal doped in the crystal lattice thereof and the metal of the metal oxide coated on the surface thereof is controlled in the range of 2500 ppm to 6000 ppm.

Use of nickel in a cathode material of the general formula Li (4/3-2x/3-y/3-z/3)Ni.sub.xCo.sub.yAl.sub.zMn(2/3-x/3-2y/3-2z/3)0.sub.2 wherein x is greater than 0.06 and equal to or less than 0.4; y is equal to or greater than 0 and equal to or less than 0.4; and z is equal to or greater than 0 and equal to or less than 0.05 for suppressing gas evolution during a charge cycle and/or increasing the charge capacity of the material.

The present disclosure generally relates to compositions comprising substrate-free crystalline 2D bismuthene, and the method of making and using the substrate-free crystalline 2D bismuthene.

A stabilized lithium metal oxide cathode material comprises microparticles of lithium metal oxide in which individual particles thereof a core of lithium metal oxide and a coating of a different lithium metal oxide surrounding the core. There is an interface layer between the cores and the coatings in which there are gradients of metal ions in the direction of coating to core. The materials are made by a three stage process involving coprecipitating precursor metal hydroxide core particles at a controlled pH; coprecipitating a different metal hydroxide coating on the particles without controlling the pH; and then calcining the resulting coated precursor particles with lithium hydroxide to form the stabilized lithium metal oxide material.