Toyota Jidosha Kabushiki Kaisha

Yusuke Onoda

Koji Takahata

Masahiro Morita

Atsushi Watarai

Kenta Ishii

Takahiro Tsubouchi

Tomohiko Ishida

Ryo Hanasaki

Nobuaki Koiwa

Risa Sato

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, 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 1.07 or less is satisfied, where, in the lateral cross section of the wound electrode body, a thickness from an inner curve apex V to an outer curve apex P is taken as a center thickness D of a curved R portion, and a thickness from the inner curve apex V to an outer surface S of the wound electrode body along an R portion/F portion boundary line W is taken as a boundary thickness B of the curved R portion.

Lithium ion secondary battery and battery pack

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, a negative electrode, and a nonaqueous electrolytic solution, wherein a negative electrode SEI filmincluding at least a LiBOB skeleton and a fluorosulfonic acid skeleton is formed on the surface of a negative electrode active material, and a positive electrode SEI filmincluding at least a phosphoric acid skeleton is formed on the surface of a positive electrode active material. Where the component amount of the LiBOB skeleton in the negative electrode SEI filmis denoted by I, the component amount of the fluorosulfonic acid skeleton in the negative electrode SEI filmis denoted by I, and the component amount of the phosphoric acid skeleton in the positive electrode SEI filmis denoted by I, a formula of 4&#x2264;I/I&#x2264;10 and a formula of 5 &#x3bc;mol/m&#x2264;I&#x2264;15 &#x3bc;mol/mare satisfied.

Nonaqueous electrolyte secondary cell and method for manufacturing nonaqueous electrolyte secondary cell

Provided is a lithium ion battery including a wound electrode body, in which a negative electrode active material layerof the lithium ion battery is formed to be wider than a positive electrode active material layerand has a facing portionwhich faces the positive electrode active material layerand a non-facing portionswhich do not face the positive electrode active material layer. In a facing center regionof the facing portionexcluding regionsadjacent 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 Cof the facing center region

Wound electrode body lithium ion battery having active electrode material layers of different widths

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.

Method of testing electrode paste and method of manufacturing electrode

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.

Non-aqueous secondary battery and method for producing same

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&#xb0; to 90&#xb0;, the negative electrode plate is determined to be excellent.

Manufacturing method of negative electrode plate for non-aqueous secondary battery and manufacturing method of non-aqueous secondary battery

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.

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Toyota, Japan

Yusuke Onoda