Abstract: The present application discloses a positive electrode current collector, a positive electrode plate, an electrochemical device, and an electric equipment including the electrochemical device. The positive electrode current collector includes: a metal conductive layer; an overcharge blocking activation layer disposed on a surface of the metal conductive layer, the overcharge blocking activation layer including an overcharge blocking activation material, a binder material and a conductive material, wherein the overcharge blocking activation material includes an esterified saccharide.

Abstract: Methods of forming a composite material film can include providing a layer comprising a carbon precursor and silicon particles on a sacrificial substrate. The methods can also include pyrolysing the carbon precursor to convert the precursor into one or more types of carbon phases to form the composite material film, whereby the sacrificial substrate has a char yield of about 10% or less.

Abstract: According to one embodiment, a secondary battery is provided. The secondary battery includes a positive electrode, a negative electrode including titanium oxide particles, and an aqueous electrolyte. The surfaces of the titanium oxide particles are partially covered with an alkyl-based silane compound. The ratio IB/IA of the intensity IB of the second peak PB to the intensity IA of the first peak PA is within a range of 4 to 10. The first peak PA is a maximum peak present within a range of 3200 cm?1 to 3600 cm?1 in an infrared absorption spectrum of the titanium oxide particles. The second peak PB is a maximum peak present within a range of 565 cm?1 to 570 cm?1 in the infrared absorption spectrum of the titanium oxide particles.

Abstract: Erroneous identification of parts is prevented. A connection module disclosed in the present specification is a connection module that is to be attached to an electricity storage element group in which a plurality of electricity storage elements each including positive and negative electrode terminals are arranged. The connection module includes: a plurality of busbars configured to connect the electrode terminals of the adjacent electricity storage elements to each other; and an insulating protector configured to be fixed to the electricity storage element group in a state in which the insulating protector holds the plurality of busbars, wherein the insulating protector is formed by a first protector and a second protector that is separate from the first protector, the first protector is provided with a first identifier, and the second protector is provided with a second identifier that is different from the first identifier.

Abstract: An object is to provide a secondary-battery electrode that is capable of suppressing a short circuit between adjacent positive and negative electrodes when the secondary-battery electrode is applied to an electrode body of a secondary battery. A secondary-battery electrode (10) includes a thin-plate-shaped metal core body (11) and an active material layer (12a, 12b) containing an active material and formed on two surfaces of the core body (11). In a cut end portion (15) of the electrode, an end portion (16) of the core body (11) is positioned inward of an end portion (17a, 17b) of the active material layer (12a, 12b) in a surface direction Y of the electrode.

Abstract: A cathode includes a cathode collector layer, and a cathode active material layer on a surface of the cathode collector layer. The cathode active material layer includes a sintered polycrystalline material having a plurality of crystal grains of a lithium-based oxide, and each of the plurality of crystal grains includes a seed template, and a matrix crystal around the seed template, where the seed template is a single crystal and having a shape of a plate.

Abstract: A semiconductor structure is provided that contains a non-volatile battery which controls gate bias. The non-volatile battery has a stable voltage and thus the structure may be used in neuromorphic computing. The semiconductor structure may include a semiconductor substrate including at least one channel region that is positioned between source/drain regions. A gate dielectric material is located on the channel region of the semiconductor substrate. A battery stack is located on the gate dielectric material. In accordance with the present application, the battery stack includes, an anode current collector located on the gate dielectric material, an anode region located on the anode current collector, an ion diffusion barrier material located on the anode region, an electrolyte located on the ion diffusion barrier material, a cathode material located on the electrolyte, and a cathode current collector located on the cathode material.

Abstract: Provided is a bi-polar electrode for a battery, the electrode comprising: (a) a current collector comprising a conductive material foil (e.g. metal foil) having a thickness from 10 nm to 100 ?m and two opposed, parallel primary surfaces, wherein one or both of the primary surfaces is coated with a layer of exfoliated graphite or expanded graphite material having a thickness from 10 nm to 50 ?m; and (b) a negative electrode layer and a positive electrode layer respectively disposed on the two sides of the current collector, each in physical contact with the layer of exfoliated graphite or expanded graphite material or directly with a primary surface of the conductive material foil (if not coated with a exfoliated or expanded graphite layer). Also provided is a battery comprising multiple (e.g. 2-300) bipolar electrodes internally connected in series. There can be multiple bi-polar electrodes that are connected in parallel.

Abstract: The present disclosure relates to an electrode for an electrochemical device and a method for manufacturing the same. More particularly, the present disclosure relates to an electrode having a small difference in porosity along the thickness direction of the electrode, and a method for manufacturing the same.

Abstract: A battery case including a container configured to house an electrode assembly, wherein the container includes a bottom wall and a plurality of side walls, the bottom wall and the side walls integrated to define a space for housing the electrode assembly and an open side opposed to the bottom wall, the container includes a composite including a polymer matrix, an inorganic moisture absorbent dispersed in the base polymer, and a compatibilizer to promote compatibility between the polymer matrix and the inorganic moisture absorbent, the compatibilizer is included in an amount of less than about 3 wt % based on a total weight of the composite, at least one of the bottom wall and the side walls at a thickness of 1 millimeter has a water vapor transmission rate of less than about 0.07 g/m2/day, when measured at 38° C. and a relative humidity of 100%.

Abstract: A rechargeable electrochemical cell includes a positive electrode having a recharged potential, a negative electrode, and a charge-carrying electrolyte. The rechargeable electrochemical cell further includes an active material having the following structure.

Abstract: A battery assembly disclosed herein is a battery assembly before being subjected to initial charge. In the battery assembly, a positive electrode has a positive electrode mixture layer that contains a positive electrode active material and NMP, and an oxalate complex compound and FSO3Li are contained in a nonaqueous electrolyte solution. In the battery assembly disclosed herein, a NMP content in the positive electrode mixture layer is 50 ppm to 1500 ppm, the DBP oil absorption of the positive electrode active material is 30 ml/100 g to 45 ml/100 g, and a FSO3Li content in the nonaqueous electrolyte solution is 0.1 wt % to 1.0 wt %. With this, it is possible to prevent a reduction in input-output characteristics caused by formation of a film derived from NMP on the surface of the positive electrode active material, and hence it is possible to prevent an increase in facility cost and a reduction in manufacturing efficiency caused by adjustment of the content of NMP.

Abstract: Embodiments of the present disclosure relate to a battery module. According to an embodiment of the present disclosure, there is provided a battery module including a plurality of battery cells each including at least one electrode tab, and a bus bar in contact with the electrode tabs to electrically connect the plurality of battery cells, wherein the bus bar includes a plate in which a plurality of holes are formed, and the electrode tabs are inserted into at least a portion of the plurality of holes to electrically connect the plurality of battery cells.

Abstract: Fabricating a layer including lithium lanthanum zirconate (Li7La3Zr2O12) layer includes forming a slurry including lanthanum zirconate (La2Zr2O7) nanocrystals, a lithium precursor, and a lanthanum precursor in stoichiometric amounts to yield a dispersion including lithium, lanthanum, and zirconium. In some cases, the dispersion includes lithium, lanthanum, and zirconium in a molar ratio of 7:3:2. In certain cases, the slurry includes excess lithium. The slurry is dispensed onto a substrate and dried. The dried slurry is calcined to yield the layer including lithium lanthanum zirconate.

Abstract: An electric storage device includes an electrode body including a plurality of first electrode plates and a plurality of second electrode plates, a first electrode output terminal, a second electrode output terminal, a first current collector, and a second current collector. The first electrode plates have first tabs that protrude from the electrode body and have conductivity and are connected to the first current collector. The first tabs are stacked to form a first tab stack, one surface of the first tab stack is in contact with the first current collector, and a first protective sheet is disposed on and in contact with the other surface on the side opposite to the one surface. On the periphery of the first protective sheet, there is a corner formed by two adjacent sides. At least the corner of the first protective sheet is joined to the first tab stack.

Abstract: An object of the present disclosure relates to an electrode active material that has excellent discharge capacity and is used in an all solid fluoride ion battery. The present disclosure achieves the object by providing an electrode active material to be used in an all solid fluoride ion battery, the electrode active material comprising: an active material region that contains an active material component including a layered structure; and a coating region positioned in a surface side of the active material region; and a fluorine concentration in the coating region is higher than a fluorine concentration in the active material region.

Abstract: The present invention pertains to an electrode-forming composition, to use of said electrode-forming composition in a process for the manufacture of a composite electrode, to said composite electrode and to a secondary battery comprising said composite electrode.

Abstract: The bipolar secondary battery includes a power generation element including unit power generation elements stacked together and including bipolar electrodes stacked via separators, and current collecting plates arranged at both ends of the power generation element in the stacked direction of the unit power generation elements so as to be in contact with the power generation element, wherein the current collecting plates each include an electrically conductive layer and a resin film, the electrically conductive layer being formed on the resin film having a thermal shrinkage percentage of 2% or greater at a temperature of 150° C., and the separators have a higher thermal shrinkage start temperature than the resin films.

Abstract: Systems and methods for water soluble weak acidic resins as carbon precursors for silicon-dominant anodes may include an electrode coating layer on a current collector, where the electrode coating layer is formed from silicon and pyrolyzed water-soluble acidic polyamide imide as a primary resin carbon precursor. The electrode coating layer may include a pyrolyzed water-based acidic polymer solution additive. The polymer solution additive may include one or more of: polyacrylic acid (PAA) solution, poly (maleic acid, methyl methacrylate/methacrylic acid, butadiene/maleic acid) solutions, and water soluble polyacrylic acid. The electrode coating layer may include conductive additives. The current collector may include a metal foil, where the metal current collector includes one or more of a copper, tungsten, stainless steel, and nickel foil in electrical contact with the electrode coating layer. The electrode coating layer may be more than 70% silicon.

Abstract: A disclosed binder composition comprises a copolymer which comprises a nitrile group-containing monomer unit, an acidic group-containing monomer unit and a basic group-containing monomer unit, wherein the proportion of the nitrile group-containing monomer unit in the copolymer is 70.0 mol % or more and 99.0 mol % or less, and wherein the total proportion of the acidic group-containing monomer unit and the basic group-containing monomer unit in the copolymer is 0.8 mol % or more and 10.0 mol % or less.

Abstract: A battery incudes wound positive and negative electrodes, where the wound positive electrode includes a positive electrode current collector, a first positive electrode active material layer provided on an inner surface of the positive electrode current collector, and a second positive electrode active material layer provided on an outer surface of the positive electrode current collector. An inner circumference side end portion and an outer circumference side end portion of the positive electrode current collector are covered with the first active material layer, and the first positive electrode active material layer includes a low area density portion in a portion facing an inner circumference side end portion of the wound positive electrode.

Abstract: Provided are a silicon-based composite anode active material for a secondary battery and an anode including the same. The anode active material for a secondary battery may be a silicon-based composite anode active material, which may include a graphite and a silicon component including two or more selected from the group consisting of Si, Si-M, SiOx, and SiC. The Si-M may be a silicon alloy, and the M may include at least one selected from the group consisting of a transition metal, an alkaline earth metal, a group 13 element, a group 14 element, and a rare earth element.

Abstract: The present invention has an object to provide a positive electrode active material for a non-aqueous electrolyte secondary battery which not only suppresses gelation of a positive electrode mixed material paste upon producing the non-aqueous electrolyte secondary battery but also improves the stability thereof. Provided is the positive electrode active material represented by general formula LisNi1?x?y?zCoxMnyMzO2+? (0?x?0.35, 0?y?0.35, 0?z?0.10, 0.95<s<1.30, and 0???0.2, and M represents at least one element selected from V, Mg, Mo, Nb, Ti, W, and Al) and containing secondary particles formed by agglomeration of primary particles, wherein at least part of the surface of the primary particles thereof is covered with a lithium boron compound, and the amount of redundant lithium hydroxide of the positive electrode active material measured with a neutralization titration is at least 0.003% by mass and up to 0.5% by mass relative to the total of the positive electrode active material.

Abstract: A lithium secondary battery includes a positive electrode, a negative electrode, a separator, and a nonaqueous electrolyte having lithium-ion conductivity. The positive electrode contains a positive electrode active material containing lithium. The negative electrode faces the positive electrode. The separator is disposed between the positive and negative electrodes. The negative electrode includes a negative electrode current collector. The negative electrode current collector includes a layer and protrusions. The layer has a first surface on which lithium metal is deposited during charge. The protrusions protrude from the first surface. At least one of the protrusions includes a conductive material and an insulative material.

Abstract: The present disclosure provides a secondary battery and an electrode plate thereof. The electrode plate comprises a current collector and an active material layer. The current collector comprises an insulating layer and a first conducting layer provided on a surface of the insulating layer; the first conducting layer has a main portion and a protruding portion connected with the main portion, the main portion is coated with the active material layer, the protruding portion is not coated with the active material layer. The electrode plate further comprises a second conducting layer, the second conducting layer comprises a first portion, the first portion is provided on a surface of the protruding portion away from the insulating layer. The secondary battery comprises an electrode assembly, the electrode assembly comprises the electrode plate.

Abstract: A sodium-ion battery includes an electrode and a passivation layer on the electrode material.

Abstract: A purpose of the present invention is to provide a binder composition for a secondary battery which improves the charge and discharge efficiency and the cycle characteristics of a battery. The binder composition for a secondary battery of the present invention is characterized by comprising a polyamide-imide comprising a repeating unit represented by chemical formula (1) or a precursor thereof, wherein A is a trivalent group obtained by removing carboxyl groups from a tricarboxylic acid, B is a divalent group obtained by removing amino groups from a diamine, and at least one of A and B is an aliphatic group.

Abstract: A purpose of the present invention is to provide a binder composition for a secondary battery which can impart excellent battery characteristics, even when the heat treatment temperature is low. The binder composition for a secondary battery according to the present invention is characterized by comprising a polyamic acid comprising a repeating unit represented by chemical formula (1) and an aromatic compound comprising an electron donating group and an organic acid group, wherein A is a tetravalent group obtained by removing acid anhydride groups from a tetracarboxylic dianhydride, B is a divalent group obtained by removing amino groups from a diamine, and at least one of A and B is an aliphatic group.

Abstract: A method for producing a positive electrode sheet is provided with a positive current collecting foil made of aluminum and a battery positive active material layer containing positive active material particles made of LiNiMn based spinel and applied and dried on the current collecting foil. The positive active material layer includes a first binder made of polyacrylic acid with a molecular weight of 50,000 or less and a second binder made of polyacrylic acid with a molecular weight of 300,000 or more. The first positive electrode paste forming the positive active material layer satisfies expressions (1) to (3): ??1.7??(1) ??0.9??(2) ?+??3.0??(3) where ? is an additive amount of the first binder in pts. wt. and ? is an additive amount of the second binder in pts. wt. when other solid content is 100 pts. wt.

Abstract: A method for producing an electrode tab according to an embodiment of the present invention may comprise: a step of preparing a thin plate of a strip shape having a first thickness; a step of forming an adhesion part by compressing the thin plate from one end thereof to a second thickness; and a step of forming, from the other end of the thin plate to the adhesion part, a lead tab part formed to have the first thickness, by releasing the compression applied to the adhesion part.

Abstract: The present application relates to a binder for a secondary battery. The binder includes a first copolymer unit including a carboxyl group-containing acrylic monomer and at least one of an acrylic acid derivative monomer and a substituted or unsubstituted styrene and a second copolymer unit including a residue of a polymer azo initiator. A mass ratio of the second copolymer unit relative to a total mass of the first copolymer unit and the second copolymer unit is 10 mass % to 40 mass %.

Abstract: An electrochemical cell including a positive electrode (e.g., a cathode) and a negative electrode (e.g., an anode), at least one of which includes an integrated ceramic separator. An integrated ceramic separator may include a plurality of ceramic particles. In some examples, an interlocking region may be disposed between the integrated ceramic separator layer and a corresponding electrode layer, the region including a non-planar boundary between the two layers. In some examples, the electrochemical cell includes a polyolefin separator disposed between the positive electrode and the negative electrode. In some examples, both the positive electrode and the negative electrode include an integrated ceramic separator. In these examples, the positive electrode and the negative electrode may be calendered together such that the integrated separator layers merge and become indistinguishable from each other.

Abstract: A method for manufacturing an electrode sheet including an electrode layer on both surfaces of a current collecting foil includes: feeding out an original electrode sheet including an unfinished electrode layer on each surface of the foil from a feeding part; causing a press roll pair to contact with the original sheet fed out to form the unfinished layers into electrode layers; receiving the sheet having passed through the roll pair by a sheet receiving part; and rotating rolls of the roll pair in a feeding direction. The feeding part, roll pair, and receiving part are placed such that the original sheet and the electrode sheet are to be wound on one of the rolls. The rolls are rotated such that a moving speed of cylindrical surface of one roll placed in a position where the sheets are wound thereon is higher than that of the other roll.

Abstract: A lithium ion secondary battery including a plurality of electrode laminates, each electrode laminate including a positive electrode, a separator, and a negative electrode being alternatively laminated, each positive electrode and negative electrode having respective positive and negative electrode tabs protruding from a respective line segment, the positive electrode tabs of adjacent electrode laminates face each other and are connected to each other to provide a positive electrode tab bundle and the negative electrode tabs of the adjacent electrode laminates face each other and are connected to each other to provide a negative electrode tab bundle.

Abstract: A secondary battery of sealed structure disclosed herein is provided with a stacked electrode body inside a battery case. At a region closer to a lid body of the battery case when a rectangular positive electrode sheet and rectangular negative electrode sheet that make up the electrode body is bisected with respect to a direction from the lid body to a bottom surface of a case body, a positive electrode collector exposed portion and a negative electrode collector exposed portion, which do not have a positive or negative electrode active material layer, are formed, in the rectangular positive electrode sheet and negative electrode sheet, on the inward side of the rectangular positive and negative electrode sheets, in such a manner that one side of each exposed portion makes up part of an edge, of the positive and negative electrode sheets, neighboring and opposing the lid body.

Abstract: Surface-treated copper foils including a copper foil having a first side and an opposite-facing second side and two treatment layers disposed on the first side and the second side respectively are described. Each treatment layer provides a treated surface which exhibit a ten-point average roughness Rz in a range of 1.2 ?m to 4.6 ?m and a peak density (Spd) in a range of 490,000 to 1,080,000 mm?2. Additionally, the Cr content in each of the treatment layers is a range of 25 to 70 ?g/dm2. The surface-treated copper foils have excellent electrode active material coating properties, such as good adhesion and uniformity.

Abstract: A battery includes a first positive electrode collector, a first negative electrode collector, a first power generating element, a second power generating element, and a first insulating part. The first and second power generating elements each include a positive electrode active material-containing layer, a negative electrode active material-containing layer, and an inorganic solid electrolyte-containing layer. In each of the first and second power generating elements, the inorganic solid electrolyte layer is in contact with the positive electrode active material-containing layer and the negative electrode active material-containing layer. The positive electrode active material layers of the first and second power generating elements are in contact with the first positive electrode collector. The negative electrode active material layers of the first and second power generating elements are in indirect contact with the first negative electrode collector.

Abstract: Provided is a slurry composition for a non-aqueous secondary battery positive electrode that has excellent stability and enables formation of a positive electrode mixed material layer that causes a non-aqueous secondary battery to display excellent output characteristics. The slurry composition contains a positive electrode active material and a copolymer. The proportion constituted by nickel among transition metal in the positive electrode active material is at least 30.0 mol % and not more than 100.0 mol %. The copolymer includes a nitrile group-containing monomer unit in a proportion of at least 70.0 mass % and not more than 96.0 mass % and a basic group-containing monomer unit in a proportion of at least 0.1 mass % and not more than 5.0 mass %.

Abstract: Provided are electrochemical cells that include as a cathode active material within the cathode of the cell secondary particles that provide excellent capacity and improved cycle life. The particles are characterized by grain boundaries between adjacent crystallites of the plurality of crystallites and comprising a second composition having a layered ?-NaFeO2-type structure, a cubic structure, a spinel structure, or a combination thereof, wherein the electrochemically active cathode active material has an initial discharge capacity of 180 mAh/g or greater; and wherein the electrochemical cell has an impedance growth at 4.2V less than 50% for greater than 100 cycles at 45° C.

Abstract: The present invention relates to a magnetic cesium adsorbent, a preparation method therefor, and a cesium removal method using the same, the preparation method comprising the steps of: (a) preparing a metal hexacyanoferrate; and (b) hydrothermally reacting the metal hexacyanoferrate so as to prepare a metal hexacyanoferrate having a rhombohedral crystal structure.

Abstract: A negative electrode for a rechargeable lithium battery may include a negative electrode active mass layer including a negative active material having a Young's modulus of about 10 GPa to about 35 GPa and having an active mass density of greater than or equal to about 1.65 g/cc and a current density of greater than or equal to about 3.2 mAh/cm2.

Abstract: Disclosed is a secondary battery which can improve safety by forming a carbon coating layer and an electrode active material layer on an electrode plate such that ends of the carbon coating layer and the electrode active material layer are in different positions.

Abstract: According to an embodiment, a nonaqueous electrolyte battery is provided. The nonaqueous electrolyte includes a negative electrode, a positive electrode and a nonaqueous electrolyte. The negative electrode includes negative electrode active material particles. The negative electrode active material particles include a spinel-type lithium titanate. The negative electrode has such a surface state that a ratio ALi/ATi of an Li atom abundance ratio ALi to a Ti atom abundance ratio ATi, according to a photoelectron spectroscopic measurement for a surface, is increased at a rate of 0.002 to 0.02 per cycle in a charge-and-discharge cycle test under the predetermined condition.

Abstract: A state detecting device which can be applied even in a severe environment. The state detecting device includes a chargeable all-solid-state battery, a piezoelectric element which supplies charging power to the all-solid-state battery, and an integrated circuit including various sensors which operate with electric power supplied from the all-solid-state battery. The all-solid-state battery, the piezoelectric element, and the integrated circuit are mounted on one surface of a flexible substrate. The flexible substrate is attached to a flexible object which is either an object to be measured or constitutes at least part of an inner surface of a space to be measured.

Abstract: The present disclosure provides an electrode tab coupling member and an electrode tab coupling assembly including the same that can solve the limitations of existing arts and the technical issues demanded from the past.

Abstract: The present invention relates to a method of producing a sodium iron(II)-hexacyanoferrate(II) (Na2-xFe[Fe(CN)6].mH2O), where x is <0.4) material commonly referred to as Prussian White. The method comprises the steps of acid decomposition of Na4Fe(CN)6.10H2O to a powder of Na2-xFe[Fe(CN)6].mH2O, drying and enriching the sodium content in the Na2-xFe[Fe(CN)6].mH2O powder by mixing the powder with a saturated or supersaturated solution of a reducing agent containing sodium in dry solvent under an inert gas. The steps of acid decomposition and enriching the sodium content are performed under non-hydrothermal conditions.

Abstract: An electrode assembly and rechargeable battery, the electrode assembly including a first electrode including a first sub-electrode in which an active material is on both surfaces of a base substrate, a second sub-electrode in which the active material is on one surface of the base substrate, and a first electrode uncoated region extending from the first sub-electrode; a second electrode including a third sub-electrode in which an active material is on both surfaces of a base substrate, a fourth sub-electrode in which the active material is on one surface of the base substrate, and a second electrode uncoated region extending from the third sub-electrode; and a separator between the electrodes, wherein the active material at the third sub-electrode includes a protruding portion protruding therefrom, and a distance from the end of the active material at sides based on the third sub-electrode to the protruding portion is 0 to 3 mm.

Abstract: A negative electrode active material including a negative electrode active material particle; the negative electrode active material particle including a silicon compound shown by SiOx (0.5?x?1.6), wherein at least part of the Si4+ contained in the negative electrode active material particle is to be changed to at least one state selected from valence states of Siy+ (y is any of 0, 1, 2, and 3) in occlusion of Li in the negative electrode active material. This provides a negative electrode active material that is capable of increasing battery capacity and improving cycle performance when it is used as a negative electrode active material for a secondary battery.

Abstract: The present invention relates to a cathode active material for a secondary battery and a preparation method thereof, and more particularly, to a lithium composite oxide including a secondary particle formed as primary particles cohere, in which a manganese (Mn) oxide is present in the periphery of the primary particles, a concentration of an Mn oxide in the primary particle has a concentration gradient from the center of the primary particle to a surface of the particle, a concentration of an Mn oxide in the secondary particle has a concentration gradient from a surface of the secondary particle to the center thereof, and a lithium ion migration path is formed in the primary particle, and a preparation method thereof. A secondary battery including the cathode active material for a secondary battery may have high safety, while exhibiting high capacity and high output.

Abstract: A negative electrode active material for a non-aqueous electrolyte secondary battery, wherein the negative electrode active material includes negative electrode active material particles, the negative electrode active material particles include a silicon compound particle which includes a silicon compound including oxygen, the silicon compound particle includes a Li compound, and the silicon compound particle is adhered with a phosphate salt in an outermost surface layer thereof. With this, the negative electrode active material which is high in the capacity and the stability to aqueous slurry as well as excellent in the cycle characteristic and the first efficiency can be provided.