A battery (1), a battery module, a battery pack, and an electric vehicle are provided. The battery (1) includes a housing (10) and M battery core assemblies (20). The M battery core assemblies (20) are arranged in the housing (10), and M≥2. The M battery core assemblies (20) are stacked. The M battery core assemblies (20) are electrically connected. Each battery core (20) assembly includes multiple electrode core assemblies (21). The multiple electrode core assemblies (21) in each battery core assembly (20) are connected in series.

A test device for testing an oxidation potential of an electrolyte is provided. The test device comprises a cavity, a test unit, a detector, a processing unit, and a display. The test unit comprises a positive plate comprising a first through hole, a negative plate comprising a second through hole, a first infrared window covering the first through hole, a second infrared window covering the second through hole, and an electrolyte located between the positive electrode plate and the negative electrode plate. The first through hole and the second through hole penetrate each other. The first infrared window, the positive plate, the negative plate, and the second infrared window are stacked with each other. An infrared light beam passes through the first infrared window, the first through hole, the electrolyte, the second through hole, and the second infrared window in sequence and then is detected by the detector.

An electrode for batteries that does not include a metal-film-type current collector is disclosed herein. In some embodiments, the electrode comprises a composite having a core-shell structure including a core having an electrode active material, and a metal material coated on or doped in the surface of the core. A secondary battery having the electrode has increased capacity and energy density and exhibits improved lifespan characteristics.

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.

A cathode active material for a lithium secondary battery according to an embodiment of the present invention includes a plurality of a lithium-transition metal composite oxide particle having a shape of a secondary particle in which a plurality of primary particles are aggregated. The lithium-transition metal composite oxide particle includes a lithium-molybdenum-containing portion having a hexagonal close-packed structure formed between the primary particles.

Material compositions are provided that may comprise, for example, a vertically aligned carbon nanotube (VACNT) array, a conductive layer, and a carbon interlayer coupling the VACNT array to the conductive layer. Methods of manufacturing are provided. Such methods may comprise, for example, providing a VACNT array, providing a conductive layer, and bonding the VACNT array to the conductive layer via a carbon interlayer.

A positive-electrode material for a lithium secondary battery is provided. The material includes a lithium oxide compound or a complex oxide as reactive substance. The material also includes at least one type of carbon material, and optionally a binder. A first type of carbon material is provided as a coating on the reactive substance particles surface. A second type of carbon material is carbon black. And a third type of carbon material is a fibrous carbon material provided as a mixture of at least two types of fibrous carbon material different in fiber diameter and/or fiber length. Also, a method for preparing the material as well as lithium secondary batteries including the material is provided.

Alloy nanoparticles, and a method for forming the alloy nanoparticles, an alloy nanocatalyst comprising the alloy nanoparticles are provided. The alloy nanoparticles are formed by a method comprising mixing a first metal complex including a first metal and a second metal complex including a second metal to form a multimetal compound and heat-treating the multimetal compound to form an alloy compound. The first metal and the second metal comprise transition metal, the first metal complex comprises a pyridine-based ligand, and a carbon shell containing N is formed on the surface of the alloy compound by the heat treatment.

A binder for preparing a positive electrode of a lithium secondary battery, and a method for preparing a positive electrode using the same. The binder includes two or more different lithium-substituted polyacrylic acids with different molecular weights. The lithium-substituted polyacrylic acids include two different lithium-substituted polyacrylic acids differing in weight average molecular weight by 500,000 or more from each other.

A method of preparing an electrochemical electrode which is partially or totally covered with a film that is obtained by spreading an aqueous solution comprising a water-soluble binder over the electrode and subsequently drying same. The production cost of the electrodes thus obtained is reduced and the surface porosity thereof is associated with desirable resistance values.