Abstract: The present teaching provides a highly durable lithium ion secondary battery including a flat shape wound electrode body, with which a high capacity retention ratio and suppression of resistance rise are realized, and also provides a battery pack constructed by using the secondary battery as a unit battery. The lithium ion secondary battery (unit battery) provided in accordance with the present teaching has a flat-shaped wound electrode body 20, and in a state in which a constraint pressure is applied in the direction toward the flat surface of the wound electrode body under the same conditions as the conditions when the battery pack is constructed, the condition of a D/B ratio being 1.01 or more and 1.

Abstract: According to the present disclosure, there is provided a technique making it possible to improve suitably the performance of a nonaqueous electrolyte secondary cell in which a SEI film is formed on the surface of a negative electrode active material. The nonaqueous electrolyte secondary cell disclosed herein includes a positive electrode 10, a negative electrode 20, and a nonaqueous electrolytic solution, wherein a negative electrode SEI film 29 including at least a LiBOB skeleton and a fluorosulfonic acid skeleton is formed on the surface of a negative electrode active material 28, and a positive electrode SEI film 19 including at least a phosphoric acid skeleton is formed on the surface of a positive electrode active material 18.

Abstract: Provided is a lithium ion battery including a wound electrode body, in which a negative electrode active material layer 24 of the lithium ion battery is formed to be wider than a positive electrode active material layer 14 and has a facing portion 24c which faces the positive electrode active material layer 14 and a non-facing portions 24n which do not face the positive electrode active material layer 14. In a facing center region 24a of the facing portion 24c excluding regions 24b adjacent to the non-facing portion, plural straight measurement lines are set in a region ranging from one end portion to another end portion in the width direction. When the resistance of each measurement line is measured, in all the measurement lines, a highest resistance point is present in a length region of less than 15% from a center C0 of the facing center region 24a.

Abstract: According to the present disclosure, there is provided a technique making it possible to improve suitably the performance of a nonaqueous electrolyte secondary cell in which a SEI film is formed on the surface of a negative electrode active material. The nonaqueous electrolyte secondary cell disclosed herein includes a positive electrode 10, a negative electrode 20, and a nonaqueous electrolytic solution, wherein a negative electrode SEI film 29 including at least a LiBOB skeleton and a fluorosulfonic acid skeleton is formed on the surface of a negative electrode active material 28, and a positive electrode SEI film 19 including at least a phosphoric acid skeleton is formed on the surface of a positive electrode active material 18.

Abstract: A method of testing an electrode paste for producing an electrode for a secondary battery includes preparing an electrode paste obtained by kneading at least active material particles and water dispersible binder particles in an aqueous solvent; performing centrifugation on the electrode paste and collecting a supernatant containing the binder particles, and a free active material; and measuring an absorbance of the supernatant at an evaluation wavelength by using a spectrophotometer, wherein the evaluation wavelength is determined based on a relationship between an average particle size of the binder particles and the absorbance of the supernatant such that a proportion of an absorbance resulting from the binder particles in the absorbance of the supernatant becomes equal to or less than 30%, the relationship being determined in advance; and determining a quality of the electrode paste, based on the absorbance of the supernatant at the evaluation wavelength.

Abstract: The present teaching provides a highly durable lithium ion secondary battery including a flat shape wound electrode body, with which a high capacity retention ratio and suppression of resistance rise are realized, and also provides a battery pack constructed by using the secondary battery as a unit battery. The lithium ion secondary battery (unit battery) provided in accordance with the present teaching has a flat-shaped wound electrode body 20, and in a state in which a constraint pressure is applied in the direction toward the flat surface of the wound electrode body under the same conditions as the conditions when the battery pack is constructed, the condition of a D/B ratio being 1.01 or more and 1.

Abstract: Provided is a lithium ion battery including a wound electrode body, in which a negative electrode active material layer 24 of the lithium ion battery is formed to be wider than a positive electrode active material layer 14 and has a facing portion 24c which faces the positive electrode active material layer 14 and a non-facing portions 24n which do not face the positive electrode active material layer 14. In a facing center region 24a of the facing portion 24c excluding regions 24b adjacent to the non-facing portion, plural straight measurement lines are set in a region ranging from one end portion to another end portion in the width direction. When the resistance of each measurement line is measured, in all the measurement lines, a highest resistance point is present in a length region of less than 15% from a center C0 of the facing center region 24a.

Abstract: An easier method is provided for producing a battery comprising an oxalato complex-derived coating on the negative electrode. This invention provides a method for producing a non-aqueous secondary battery, the method comprising: preparing a negative electrode paste comprising a negative electrode active material, a binder, and a polycarboxylic acid-based gas formation inhibitor; fabricating a negative electrode by applying the negative electrode paste to a negative current collector surface; constructing an assembly with a positive electrode, the negative electrode, and a non-aqueous electrolyte solution comprising an oxalato complex; and subjecting the assembly to activation thereby to decompose the oxalato complex and forming a coating derived from the oxalato complex on the negative electrode surface while inhibiting gas formation with the gas formation inhibitor.

Abstract: An easier method is provided for producing a battery comprising an oxalato complex-derived coating on the negative electrode. This invention provides a method for producing a non-aqueous secondary battery, the method comprising: preparing a negative electrode paste comprising a negative electrode active material, a binder, and a polycarboxylic acid-based gas formation inhibitor; fabricating a negative electrode by applying the negative electrode paste to a negative current collector surface; constructing an assembly with a positive electrode, the negative electrode, and a non-aqueous electrolyte solution comprising an oxalato complex; and subjecting the assembly to activation thereby to decompose the oxalato complex and forming a coating derived from the oxalato complex on the negative electrode surface while inhibiting gas formation with the gas formation inhibitor.

Abstract: A method of testing an electrode paste for producing an electrode for a secondary battery includes preparing an electrode paste obtained by kneading at least active material particles and water dispersible binder particles in an aqueous solvent; performing centrifugation on the electrode paste and collecting a supernatant containing the binder particles, and a free active material; and measuring an absorbance of the supernatant at an evaluation wavelength by using a spectrophotometer, wherein the evaluation wavelength is determined based on a relationship between an average particle size of the binder particles and the absorbance of the supernatant such that a proportion of an absorbance resulting from the binder particles in the absorbance of the supernatant becomes equal to or less than 30%, the relationship being determined in advance; and determining a quality of the electrode paste, based on the absorbance of the supernatant at the evaluation wavelength.

Abstract: A method of manufacturing a negative electrode plate for a non-aqueous secondary battery is disclosed, in which it is possible to assess whether or not a binder is localized in an electrode surface without lowering the productivity of the negative electrode plate. The method includes coating an electrode mixture containing at least a negative electrode active material and a binder to a current collector and drying the coated electrode mixture. The method includes an inspection step of measuring a reflectance of a coating surface of the negative electrode plate to thereby determine the quality of the negative electrode plate. If the reflectance of the coating surface of the negative electrode plate falls within a range of 15 to 35% when an incident angle and a light receiving angle each fall within the range of 80° to 90°, the negative electrode plate is determined to be excellent.

Abstract: A battery production method according to the invention includes a winding step of winding an electrode assembly around a winding core and a flattening step of pressing the electrode assembly wound in the winding step, in a direction orthogonal to an axial direction thereof to form a flattened shape in which the wound electrode assembly is flattened in a direction that is orthogonal to the pressing direction and the axial direction, wherein a rod-shaped spacer is inserted, in parallel to the axial direction, into the electrode assembly wound during the course of winding the electrode assembly around the winding core in the winding step, and wherein the spacer is pulled out between the winding step and the flattening step.

Abstract: A battery production method according to the invention includes a winding step of winding an electrode assembly around a winding core and a flattening step of pressing the electrode assembly wound in the winding step, in a direction orthogonal to an axial direction thereof to form a flattened shape in which the wound electrode assembly is flattened in a direction that is orthogonal to the pressing direction and the axial direction, wherein a rod-shaped spacer is inserted, in parallel to the axial direction, into the electrode assembly wound during the course of winding the electrode assembly around the winding core in the winding step, and wherein the spacer is pulled out between the winding step and the flattening step.

Abstract: A nonaqueous electrolyte solution is prepared in a divided form as a first solution having a lower solute content rate than the nonaqueous electrolyte solution, and a second solution formed of ingredients of the nonaqueous electrolyte solution excluding ingredients of the first solution. Next, the first solution is injected into a battery case housing an electrode assembly. Then, the first solution is impregnated into the electrode assembly. Subsequently, the second solution is injected into the battery case. Then, the second solution is impregnated into the electrode assembly.

Abstract: Disclosed is a method of manufacturing a negative electrode plate for a non-aqueous secondary battery in which it is possible to assess whether or not a binder is localized in an electrode surface without lowering the productivity of the negative electrode plate for a non-aqueous secondary battery.

Abstract: A metal photoetching product comprising at least one large cavity of minor axis W1S, major axis W1L and depth D1 in a surface of the product, wherein one or more cavities are included inside at least one of the at least one large cavity, and a smallest hole among the cavities has minor axis of W2S, major axis W2L, and depth D2; and the product satisfies the following dimensions, D1+D2=plate thickness D, 0.02 mm?D?2 mm, 0.4×D<W1S<D, and 0.2×D<W2S<0.8×D.

Abstract: A metal photoetching product comprising at least one large cavity of minor axis W1S, major axis W1L and depth D1 in a surface of the product, wherein one or more cavities are included inside at least one of the at least one large cavity, and a smallest hole among the cavities has minor axis of W2S, major axis W2L, and depth D2; and the product satisfies the following dimensions, D1+D2=plate thickness D, 0.02 mm?D?2 mm, 0.4×D<W1S<D, and 0.2×D<W2S<0.8×D.

Abstract: A metal photoetching product comprising at least one large cavity of minor axis W1S, major axis W1L and depth D1 in a surface of the product, wherein one or more cavities are included inside at least one of the at least one large cavity, and a smallest hole among the cavities has minor axis of W2S, major axis W2L, and depth D2; and the product satisfies the following dimensions, D1+D2=plate thickness D, 0.02 mm?D?2 mm, 0.4×D<W1S<D, and 0.2×D<W2S<0.8×D.

Abstract: A metal photoetching product comprising at least one large cavity of minor axis W1S, major axis W1L and depth D1 in a surface of the product, wherein one or more cavities are included inside at least one of the at least one large cavity, and a smallest hole among the cavities has minor axis of W2S, major axis W2L, and depth D2; and the product satisfies the following dimensions, D1+D2=plate thickness D, 0.02 mm?D?2 mm, 0.4×D<W1S<D, and 0.2×D<W2S<0.8×D.