Abstract: A nonaqueous electrolyte secondary battery includes a positive electrode, a negative electrode, and an electrolyte liquid. The negative electrode includes a negative electrode mixture layer containing a first negative electrode active material and a negative electrode collector to which the negative electrode mixture layer is adhered. The first negative electrode active material contains a first lithium silicate phase containing lithium, silicon, and oxygen and first silicon particles dispersed in the first lithium silicate phase. An atomic ratio A1:O/Si of the oxygen to the silicon in the first lithium silicate phase satisfies a relationship of 2<A1?3. At a surface side of the negative electrode, an existence ratio of the first negative electrode active material in the negative electrode mixture layer is high as compared to that at a negative electrode collector side of the negative electrode.

Abstract: A charging method for a non-aqueous electrolyte secondary battery according to one aspect of the present disclosure comprises a switching step for switching the control temperature of a non-aqueous electrolyte secondary battery from high temperature to low temperature, wherein the non-aqueous electrolyte secondary battery includes a positive electrode and a negative electrode which reversibly perform intercalation and deintercalation of lithium ions, and the negative electrode contains, as a negative electrode active material, a carbon material and a silicon compound. The timing of the switching step is determined by detecting that dQGr/dQ, that is, the ratio of the amount of change in a capacity QGr of the carbon material to the amount of change in a battery capacity Q, becomes larger than dQSi/dQ, that is, the ratio of the amount of change in a capacity QSi of the silicon compound to the amount of change in the battery capacity Q.

Abstract: A negative electrode for a non-aqueous electrolyte secondary battery includes a negative electrode current collector, and a negative electrode mixture layer supported on the negative electrode current collector. The negative electrode mixture layer includes a silicon material, a carbon material capable of electrochemically absorbing and releasing lithium ions, and electrically conductive fibers. The silicon material has a lithium-ion conductive phase, and silicon particles dispersed in the lithium-ion conductive phase. When the negative electrode mixture layer is divided into two layers, a first region and a second region, having the same thickness, the first region is nearer to the negative electrode current collector than the second region is, the silicon material is contained more in the second region than in the first region, and the conductive fibers are contained in the second region.

Abstract: A method for charging a nonaqueous electrolyte secondary battery includes a first charging step of charging a first capacity Q1st at a first constant current value I1st, the first capacity Q1st including a capacity range in which dQSi/dQ is more than or equal to a predetermined threshold value, a second charging step of charging a second capacity at a second constant current value more than the first constant current value, a detection step of acquiring at least one of dV/dQ and dQSi/dQ, and a changing step of changing at least one of the timing of switching between the first charging step and the second charging step and the first constant current value I1st on the basis of a change in time of dV/dQ or dQSi/dQ.

Abstract: A negative electrode for a non-aqueous electrolyte secondary battery includes a negative electrode material mixture including a negative electrode active material capable of electrochemically absorbing and desorbing lithium ions, a carbon nanotube; and an acrylic resin. The negative electrode active material includes a composite material including a silicate phase, and silicon particles dispersed in the silicate phase, and the silicate phase includes at least one selected from the group consisting of alkali metal elements and Group 2 elements.

Abstract: A method for charging a nonaqueous electrolyte secondary battery includes a first charging step of charging a first capacity Q1st at a first constant current value I1st, the first capacity Q1st including a capacity range in which dQSi/dQ is more than or equal to a predetermined threshold value, a second charging step of charging a second capacity at a second constant current value more than the first constant current value, a detection step of acquiring at least one of dV/dQ and dQSi/dQ, and a changing step of changing at least one of the timing of switching between the first charging step and the second charging step and the first constant current value I1st on the basis of a change in time of dV/dQ or dQSi/dQ.

Abstract: A nonaqueous electrolyte secondary battery includes a positive electrode, a negative electrode, and an electrolyte liquid. The negative electrode includes a negative electrode mixture layer containing a first negative electrode active material and a negative electrode collector to which the negative electrode mixture layer is adhered. The first negative electrode active material contains a first lithium silicate phase containing lithium, silicon, and oxygen and first silicon particles dispersed in the first lithium silicate phase. An atomic ratio A1:O/Si of the oxygen to the silicon in the first lithium silicate phase satisfies a relationship of 2<A1?3. At a surface side of the negative electrode, an existence ratio of the first negative electrode active material in the negative electrode mixture layer is high as compared to that at a negative electrode collector side of the negative electrode.

Abstract: A charge and discharge control device is provide. The charge and discharge control device includes a determination circuitry configured to determine an ion diffusion rate associated with electric conduction in a secondary battery, and determine a time integrated value of an overcharged amount of an active material based on the ion diffusion rate and a charge condition; an evaluation circuitry configured to evaluate the charge condition of the secondary battery based on a determination result obtained by the determination circuitry; and a charge and discharge controller configured to control state of current application and voltage application to the secondary battery at a time of charging or discharging the secondary battery based on an evaluation result obtained by the evaluation circuitry.

Abstract: In a secondary battery charging method, constant current charging is performed until a first predetermined voltage V0 is attained, constant voltage charging is then performed at the first predetermined voltage V0, the first constant voltage charging is completed when a charge current becomes (In??In) from In, and then n is incremented by one; and constant voltage charging is performed at a voltage Vn=Vn-1+?Vn, a step of completing the n-th constant voltage charging when the charge current becomes (In??In) from In is repeated by incrementing n by one, and the N-th constant voltage charging in which a value of the voltage Vn reaches a second predetermined voltage VN (>V0) is completed to terminate the constant voltage charging.

Abstract: Provided is a technology that can improve a cycle property without lowering a volume energy density. The present technology provides a method for evaluating a secondary battery, including conducting at least: a determination step of determining a degree of diffusion defect of an ion that performs electric conduction; an evaluation step of evaluating a state of the secondary battery on the basis the result of the determination in the determination step; and a control step of controlling states of current application and voltage application on the secondary battery during charging or during discharging of the secondary battery on the basis of the result of the evaluation in the evaluation step.

Abstract: A charge and discharge control device is provide. The charge and discharge control device includes a determination circuitry configured to determine an ion diffusion rate associated with electric conduction in a secondary battery, and determine a time integrated value of an overcharged amount of an active material based on the ion diffusion rate and a charge condition; an evaluation circuitry configured to evaluate the charge condition of the secondary battery based on a determination result obtained by the determination circuitry, and a charge and discharge controller configured to control state of current application and voltage application to the secondary battery at a time of charging or discharging the secondary battery based on an evaluation result obtained by the evaluation circuitry.

Abstract: Provided is a technology that can improve a cycle property without lowering a volume energy density. The present technology provides a method for evaluating a secondary battery, including conducting at least: a determination step of determining a degree of diffusion defect of an ion that performs electric conduction; an evaluation step of evaluating a state of the secondary battery on the basis the result of the determination in the determination step; and a control step of controlling states of current application and voltage application on the secondary battery during charging or during discharging of the secondary battery on the basis of the result of the evaluation in the evaluation step.