Positive electrode for secondary batteries, and secondary battery

Abstract

This positive electrode for secondary batteries is provided with: a positive electrode collector which has a plurality of recesses and projections in the surface; an intermediate layer provided on the surface of the positive electrode collector having the recesses and projections; and a positive electrode mixture layer provided on the intermediate layer and contains a positive electrode active material. This positive electrode being configured such that: the intermediate layer contains conductive material particles and inorganic material particles that have a higher resistance than the positive electrode active material: and both the ratio of the central particle diameter of the conductive material particles to the average depth of the recesses and projections of the positive electrode collector and the ratio of the central particle diameter of the inorganic material particles to the average depth of the recesses and projections of the positive electrode collector are 5:6 or less.

1 . A secondary battery positive electrode, comprising
 a positive electrode current collector having a plurality of irregularities on a surface thereof:   an intermediate layer provided on the irregularities of the positive electrode current collector; and   a positive electrode mixture layer including a positive electrode active material, herein   the intermediate layer includes conductive agent particles and inorganic material particles having higher resistance than the positive electrode active material, and   a ratio of a median particle diameter of the conductive agent particles to an average depth of the irregularities of the positive electrode current collector and a ratio of a median particle diameter of the inorganic material particles to the average depth of the irregularities of the positive electrode current collector are both 5:6 or less.   
     
     
         2 . The secondary battery positive electrode according to  claim 1 , wherein the average depth of the irregularities of the positive electrode current collector is 0.6 μm or more. 
     
     
         3 . The secondary battery positive electrode according to  claim 2 , wherein the average depth of the irregularities of the positive electrode current collector is 2.0 μm or less. 
     
     
         4 . The secondary battery positive electrode according to of  claim 1 , wherein the ratio of the median particle diameter of the inorganic material particles to the average depth of the irregularities of the positive electrode current collector is 5:20 or more. 
     
     
         5 . The secondary battery positive electrode according to  claim 1 , wherein the ratio of the median particle diameter of the inorganic material particles to the average depth of the irregularities of the positive electrode current collector is 5:8 or less. 
     
     
         6 . The secondary battery positive electrode according to  claim 1 , wherein the median particle diameter of the inorganic material particles is 0.2 μm or more and 1.0 μm or less. 
     
     
         7 . The secondary battery positive electrode according to  claim 1 , wherein
 the inorganic material particles have a resistivity of 10 12  Ωcm or more, and   the inorganic material particles are at least one of the group consisting of metal oxide particles, metal nitride particles, metal fluoride particles, and insulating magnetic particles.   
     
     
         8 . A secondary battery positive electrode, comprising:
 a positive electrode current collector having a plurality of irregularities on a surface thereof;   an intermediate layer provided on the irregularities of the positive electrode current collector, and   a positive electrode mixture layer provided on the intermediate layer and including a positive electrode active material, wherein   the intermediate layer includes inorganic material particles having higher resistance than the positive electrode active material, and   an average depth of the irregularities of the positive electrode current collector is 0.6 μm or more, and at least one of projections of the irregularities of the positive electrode current collector penetrates an interface between the intermediate layer and the positive electrode mixture layer and projects into the positive electrode mixture layer.   
     
     
         9 . The secondary battery positive electrode according to  claim 8 , wherein the average depth of the irregularities of the positive electrode current collector is 2.0 μm or less. 
     
     
         10 . The secondary battery positive electrode according to  claim 8 , wherein a ratio of a median particle diameter of the inorganic material particles to the average depth of the irregularities of the positive electrode current collector is 5:20 or more and 5:6 or less. 
     
     
         11 . The secondary battery positive electrode according to  claim 8 , wherein the intermediate layer consists only of the inorganic material particles and a binder. 
     
     
         12 . The secondary battery positive electrode according to  claim 8 , wherein in a cross section of the positive electrode current collector, a length of recesses of the positive electrode current collector which are in contact with the intermediate layer is 0.8 or more times and 1.8 or less times a length of projections of the positive electrode current collector which are in contact with the positive electrode mixture layer. 
     
     
         13 . The secondary battery positive electrode according to  claim 8 , wherein the median particle diameter of the inorganic material particles is 0.2 μm or more and 1.0 μm or less. 
     
     
         14 . The secondary battery positive electrode according to  claim 8 , wherein
 the inorganic material particles have a resistivity of 10 12  Ωcm or more, and   the inorganic material particles are at least one of the group consisting of metal oxide particles, metal nitride particles, metal fluoride particles, and insulating magnetic particles.   
     
     
         15 . A secondary battery, comprising:
 the positive electrode according to  claim 1 ;   a negative electrode; and   an electrolyte.   
     
     
         16 . A secondary battery, comprising:
 the positive electrode according to  claim 8 ;   a negative electrode; and   an electrolyte.