Electrical storage device and electrical storage module
An advantage of the present invention is to suppress an increase in resistance during high-rate charge and discharge and a reduction in capacity during a charge and discharge cycle. An electrical storage module of the present embodiment includes: an electrical storage device, and an elastic body that is placed with the electrical storage device and receives a load from the electrical storage device in a placement direction. The electrical storage device includes a positive electrode, a negative electrode, and a separator. The negative electrode includes a negative-electrode active material layer. The negative-electrode active material layer includes a first layer formed on the negative-electrode current collector, and a second layer that is formed on the first layer and has a higher compression modulus than the first layer. The separator has a lower compression modulus than the first layer, and the elastic body has a lower compression modulus than the separator.
1. An electrical storage module comprising: at least one electrical storage device, and an elastic body that is placed with the electrical storage device and receives a load from the electrical storage device in a placement direction of the elastic body,
wherein the electrical storage device includes an electrode body in which a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode are stacked, and a housing accommodating the electrode body,
the negative electrode includes a negative-electrode current collector, and a negative-electrode active material layer that is formed on the negative-electrode current collector and contains negative-electrode active material particles, the negative-electrode active material layer including a first layer formed on the negative-electrode current collector, and a second layer that is formed on the first layer and has a higher compression modulus than the first layer,
the separator has a lower compression modulus than the first layer, and
the elastic body has a lower compression modulus than the separator.
2. The electrical storage module according to claim 1 , wherein the negative-electrode active material particles contained in the second layer have a smaller BET specific surface area than the negative-electrode active material particles contained in the first layer.
3. The electrical storage module according to claim 1 , wherein the negative-electrode active material particles contained in the second layer contain a surface-modified carbon material with a surface of a carbon material coated with an amorphous carbon film, and a content of the amorphous carbon film is at least 1.5 mass % relative to the surface-modified carbon material.
4. The electrical storage module according to claim 1 , wherein the negative-electrode active material particles contained in the first layer contain a carbon material, and the carbon material has a particle-internal porosity rate of at least 10%.
5. The electrical storage module according to claim 1 , wherein the second layer has a higher porosity rate than the first layer.
6. The electrical storage module according to claim 1 , wherein the elastic body has a compression modulus of at most 120 MPa.
7. The electrical storage module according to claim 1 , wherein the elastic body is a stack of a plurality of elastic sheets.
8. The electrical storage module according to claim 1 , wherein the elastic body has a soft portion, and a hard portion placed on an outer edge of the elastic body with respect to the soft portion, the soft portion being more deformable than the hard portion.
9. The electrical storage module according to claim 1 , wherein the elastic body has a hard portion, and a soft portion more deformable than the hard portion,
the hard portion is deformed by the load not smaller than a predetermined load, and
the elastic body shifts, in response to deformation of the hard portion, from a first state in which the load is received by the hard portion to a second state in which the load is received by the sail portion.
10. An electrical storage device comprising: an electrode body in which a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode are stacked, an elastic body configured to receive a load from the electrode body in an stacking direction of the electrode body, and a housing accommodating the electrode body and the elastic body,
wherein the negative electrode includes a negative-electrode current collector, and a negative-electrode active material layer that is formed on the negative-electrode current collector and contains negative-electrode active material particles, the negative-electrode active material layer including a first layer formed on the negative-electrode current collector, and a second layer that is formed on the first layer and has a higher compression modulus than the first layer,
the separator has a lower compression modulus than the first layer, and
the elastic body has a lower compression modulus than the separator.