Negative electrode for power storage device, power storage device, and electrical device

Abstract

A power storage device having high capacitance is provided. A power storage device with excellent cycle characteristics is provided. A power storage device with high charge and discharge efficiency is provided. A power storage device including a negative electrode with low resistance is provided. A negative electrode for the power storage device includes a current collector and an active material layer including a plurality of active material particles over the current collector. The active material particle is silicon, and the size of the silicon particle is greater than or equal to 0.001 μm and less than or equal to 7 μm.

What is claimed is: 
     
         1 . A negative electrode for a power storage device, comprising:
 a current collector; and   an active material layer including active material particles over the current collector,   wherein the active material particles include silicon, and   wherein a size of the silicon is greater than or equal to 0.001 μm and less than or equal to 7 μm.   
     
     
         2 . The negative electrode for a power storage device, according to  claim 1 ,
 wherein a resistivity of the silicon is higher than or equal to 10 −4  Ω·cm and lower than or equal to 50 Ω·cm.   
     
     
         3 . The negative electrode for a power storage device, according to  claim 1 ,
 wherein the active material layer includes an active material and a conductive additive, and   wherein a weight of the conductive additive is less than or equal to 30% of a weight of the active material.   
     
     
         4 . The negative electrode for a power storage device, according to  claim 3 ,
 wherein the conductive additive is graphene.   
     
     
         5 . The negative electrode for a power storage device, according to  claim 1 ,
 wherein the silicon contains phosphorus or boron.   
     
     
         6 . A power storage device comprising the negative electrode for a power storage device, according to  claim 1 . 
     
     
         7 . An electrical device comprising the power storage device according to  claim 6 . 
     
     
         8 . A negative electrode for a power storage device, comprising:
 a current collector; and   an active material layer including active material particles over the current collector,   wherein the active material particles include silicon, and   wherein a size of the silicon is greater than or equal to 0.3 μm and less than or equal to 3 μm.   
     
     
         9 . The negative electrode for a power storage device, according to  claim 8 ,
 wherein a resistivity of the silicon is higher than or equal to 10 −4  Ω·cm and lower than or equal to 50 Ω·cm.   
     
     
         10 . The negative electrode for a power storage device, according to  claim 8 ,
 wherein the active material layer includes an active material and a conductive additive, and   wherein a weight of the conductive additive is less than or equal to 30% of a weight of the active material.   
     
     
         11 . The negative electrode for a power storage device, according to  claim 10 ,
 wherein the conductive additive is graphene.   
     
     
         12 . The negative electrode for a power storage device, according to  claim 8 ,
 wherein the silicon contains phosphorus or boron.   
     
     
         13 . A power storage device comprising the negative electrode for a power storage device, according to  claim 8 . 
     
     
         14 . An electrical device comprising the power storage device according to  claim 13 .