Active material layer for negative electrode, method for producing same, electrode mixture paste for power storage device negative electrode, negative electrode for power storage device, and power storage device

1 . A negative electrode active material layer comprising:

carbon particles,

silicon-based particles comprising silicon as a component and capable of absorbing and releasing lithium ions, and

a polyimide-based binder which is an organic polymer having an imide bond in a main chain;

wherein the negative electrode active material layer has a porosity of more than 40%,

wherein the negative electrode active material layer is obtained by forming a paste of the carbon particles, silicon-based particles and the polyimide-based binder and heating the paste at 80° C. to 350° C.,

wherein a precursor for forming the polyimide-based binder is a polyamic acid comprising a repeating unit represented by following chemical formula (I);

wherein A is one or more groups selected from the group consisting of a tetravalent group obtained by removing carboxyl groups from an aromatic tetracarboxylic acid, a tetravalent group obtained by removing carboxyl groups from an aliphatic tetracarboxylic acid, and a tetravalent group obtained by removing carboxyl groups from an alicyclic tetracarboxylic acid, and

wherein B comprises a divalent group obtained by removing amino groups from an aliphatic diamine.

2 . The negative electrode active material layer according to claim 1 , wherein the silicon-based particles have an average particle diameter of less than 10 μm.

3 . The negative electrode active material layer according to claim 1 , wherein the carbon particles are graphite particles.

4 . The negative electrode active material layer according to claim 1 , further comprising a polymer-based binder other than the polyimide-based binder.

5 . An electrode mixture paste for a negative electrode of a power storage device, wherein the electrode mixture paste is used to form the negative electrode active material layer according to claim 1 .

6 . A method for producing the negative electrode active material layer of claim 1 , comprising casting or applying the electrode mixture paste for a negative electrode of a power storage device on a current collector, and heat-treating the paste.

7 . A negative electrode for a power storage device, comprising the negative electrode active material layer according to claim 1 .

8 . A power storage device comprising the negative electrode for the power storage device according to claim 7 .

9 . The negative electrode active material layer according to claim 1 , wherein heating the paste occurs at 150° C. to 350° C.