Electrode material for capacitor

Abstract

Provided are a boron-doped nanodiamond having a large specific surface area and high electrical conductivity, an electrode containing the boron-doped nanodiamond, and a sensor or an electricity storage device provided with the electrode. The boron-doped nanodiamond of the present invention has a specific surface area of 110 m2/g or greater and electrical conductivity at 20° C. of 5.0×10−3 S/cm or greater. The boron-doped nanodiamond preferably has a median diameter of 200 nm or smaller. Additionally, the electrode of the present invention contains the boron-doped nanodiamond.

1 . A boron-doped nanodiamond having a specific surface area of 110 m 2 /g or greater, and electrical conductivity at 20° C. of 5.0×10 −3  S/cm or greater. 
     
     
         2 . The boron-doped nanodiamond according to  claim 1 , wherein a median diameter is 200 nm or smaller. 
     
     
         3 . The boron-doped nanodiamond according to  claim 1 , having bands at from 1370 to 1420 cm −1  and from 1580 to 1620 cm −1  in a Raman spectrum with a light source wavelength of 325 nm. 
     
     
         4 . An electrode comprising the boron-doped nanodiamond described in  claim 1 . 
     
     
         5 . The electrode according to  claim 4 , wherein an electrical double-layer capacitance per mass is 3 F/g or greater. 
     
     
         6 . A sensor comprising the electrode described in  claim 4 . 
     
     
         7 . An electricity storage device comprising the electrode described in  claim 4 . 
     
     
         8 . The boron-doped nanodiamond according to  claim 1 , wherein a content of boron is from 0.1 to 100 mg/g. 
     
     
         9 . The boron-doped nanodiamond according to  claim 1 , comprising a boron-containing diamond layer and/or a boron-containing carbon layer on a surface of nanodiamond particles. 
     
     
         10 . A method for manufacturing a boron-doped nanodiamond, the method including depositing a boron-containing diamond layer and/or carbon layer onto the surface of nanodiamond particles using a microwave plasma CVD method to produce a boron-doped diamond having a specific surface area of 110 m 2 /g or greater, and electrical conductivity at 20° C. of 5.0×10 −3  S/cm or greater. 
     
     
         11 . A lithium ion capacitor comprising an electrode including a boron-doped nanodiamond having a specific surface area of 110 m 2 /g or greater, and electrical conductivity at 20° C. of 5.0×10 −3  S/cm or greater.