Electrode for secondary battery and secondary battery
An electrode using a carbon nanotube as a conductive material and having a small resistance is provided. An electrode for a secondary battery disclosed herein has a collector, and an active material layer formed on the collector. The active material layer includes an active material and carbon nanotubes. Each of the carbon nanotube has a coating of a material including an element with a higher electronegativity than that of carbon on at least a part of the surface thereof.
1. An electrode for a secondary battery, comprising:
a collector; and
an active material layer formed on the collector,
wherein the active material layer includes an active material and carbon nanotubes,
each of the carbon nanotubes has a coating of a material including an element with a higher electronegativity than that of carbon on at least a part of the surface thereof,
an average length of the carbon nanotubes is 1 μm or more and 50 μm or less;
an average diameter of the carbon nanotubes is 0.1 nm or more and 30 nm or less;
a content of the carbon nanotubes is 0.1 mass % or more and 15 mass % or lower in the active material layer; and
a coating ratio of the surface of the carbon nanotubes by coating with the material including the element with a higher electronegativity than that of carbon is 20% or more and 90% or lower.
2. The electrode for a secondary battery according to claim 1 ,
wherein the element with a higher electronegativity than that of carbon is at least one selected from the group consisting of F, N, and Cl.
3. The electrode for a secondary battery according to claim 1 ,
wherein the electrode for a secondary battery is a positive electrode, and the active material is a positive electrode active material.
4. The electrode for a secondary battery according to claim 1 ,
wherein the coating ratio of the surface of the carbon nanotubes by coating with the material including the element with a higher electronegativity than that of carbon is 40% or more and 70% or lower.
5. The electrode for a secondary battery according to claim 1 ,
wherein each of the carbon nanotubes further has a coating of a material including an element with a lower electronegativity than that of carbon.
6. The electrode for a secondary battery according to claim 5 ,
wherein the element with a lower electronegativity than that of carbon is at least one selected from the group consisting of Ti, P, B, Si, Al, Zn, and W.
7. The electrode for a secondary battery according to claim 5 ,
wherein the coating ratio of the surface of the carbon nanotubes by coating with the material including the element with a higher electronegativity than that of carbon is smaller than the coating ratio of the surface of the carbon nanotube by coating with the material including the element with a lower electronegativity than that of carbon.
8. A secondary battery comprising the electrode for a secondary battery according to claim 1 .