Conductive composition for electrodes, and electrode and battery using same
Provided is a conductive composition for electrodes, the conductive composition having excellent electrical conductivity and dispersibility. Also provided are: a positive electrode for non-aqueous batteries, the positive electrode using the conductive composition and having low electrode plate resistance and excellent binding properties; and a non-aqueous battery having high energy density, high output characteristics, and high cycle characteristics. The conductive composition for electrodes contains a conductive material, an active material, a binder, and a dispersant, wherein the conductive material contains carbon black and a multi-walled carbon nanotube having a powder resistivity of 0.035 Ω·cm or less as measured under a load of 9.8 MPa, and a median volumetric diameter D50 value, which is as a measure of dispersibility, in the range of 0.3-8 μm The positive electrode which is for non-aqueous batteries and has low electrode plate resistance and excellent binding properties; and the non-aqueous battery having high output characteristics and high cycle characteristics are obtained by using the conductive composition in which the content of the multi-walled carbon nanotube in the conductive material is 3-50 mass %.
1. A conductive composition for electrodes, comprising: a conductive material containing carbon black and multi-walled carbon nanotubes; an active material; a binder; and a dispersant, wherein the multi-walled carbon nanotubes satisfy the following conditions (1) to (3):
(1) a powder resistivity of 0.035 Ω·cm or less, as measured under a load of 9.8 MPa;
(2) a volume-converted median diameter D50 value of from 0.3 to 8 μm, as measured in accordance with JIS Z 8825; and
(3) a content of from 3 to 50% by mass in the conductive material, and
wherein the conductive composition for electrodes has a binding property such that an electrode comprising the conductive composition on an aluminum foil current collector has a peel strength of 12 N/m or more as measured in accordance with JIS Z 0237.
2. The conductive composition for electrodes according to claim 1 , wherein the carbon black has a number-average primary particle diameter of from 20 to 40 nm and a DBP oil absorption amount of from 200 to 320 ml/100 g as measured in accordance with HS K 6217-4.
3. The conductive composition for electrodes according to claim 1 , wherein each of the multi-walled carbon nanotubes has a D/G value of from 0.8 to 1.3 according to Raman spectroscopic measurement.
4. The conductive composition for electrodes according to claim 1 , wherein the carbon black is acetylene black.
5. The conductive composition for electrodes according to claim 1 , wherein a content of the conductive material is from 0.1 to 2% by mass relative to the total amount of the conductive composition for electrodes.
6. The conductive composition for electrodes according to claim 1 , wherein the active material is at least one selected from LiCoO 2 , LiMn 2 O 4 , LiNiO 2 , LiMPO 4 , Li 2 MSiO 4 , LiNi X Mn (2-X) O 4 , Li(Mn X NiYCo Z )O 2 , Li(Al X Ni Y Co Z )O 2 and RLi 2 MnO 3 -(1-R)LiMO 2 , in which X in the LiNi X Mn (2-X) O 4 satisfies a relationship: 0<X<2; X, Y and Z in Li(Mn X NiYCo Z )O 2 or Li(Al X Ni Y Co Z )O 2 satisfy relationships: X+Y+Z=1, and 0<X<1, 0<Y<1, and 0<Z<1; and R in RLi 2 MnO 3 -(1-R)LiMO 2 satisfies a relationship: 0<R<1; and M in LiMPO 4 , Li 2 MSiO 4 or RLi 2 MnO 3 -(1-R)LiMO 2 is at least one element selected from Fe, Co, Ni and Mn.
7. The conductive composition for electrodes according to claim 1 , wherein the dispersant is at least one of polyvinyl pyrrolidone and copolymers comprising polyvinyl pyrrolidone.
8. A positive electrode for non-aqueous batteries comprising the conductive composition for electrodes according to claim 1 .
9. The positive electrode for non-aqueous batteries according to claim 8 , wherein each of the conductive composition for electrodes and an aluminum foil current collector has a peel strength of 12 N/m or more as measured in accordance with JIS Z 0237.
10. A non-aqueous battery comprising the positive electrode for non-aqueous batteries according to claim 8 .