Experimental purposes

In the manufacture of lithium secondary battery jelly roll type, and the slurry was kneaded cell reaction active material and a carbon material with a binder to create an electrode by applying an aluminum foil. Lithium cobalt oxide to be used as a battery reaction active material such as a mobile phone is likely to deteriorate in overcharging, polyvinylidene fluoride has been used for the binder. However, to use organic solvents such as N-methylpyrrolidone to the polyvinylidene fluoride is dissolved in a large batteries that use large quantities of electrode materials such as electric vehicles and smart grid, such as consideration of the processing cost increase and environmental challenges were. Therefore, change in the polyvinylidene fluoride polymer material such as styrene-butadiene rubber or acrylic attempts to use as a binder is dispersed in water have been made. However when using such a water-dispersed binder, it is necessary to control the rheology of when applying the slurry to an aluminum foil. Thus thickeners such as carboxymethyl cellulose is adapted to be added to the slurry in order to improve the coating properties by controlling the rheology. However can degrade the battery performance to improve the coating properties and is putting the cart before the horse. In this experiment, at the same time to evaluate the coating properties for the various carboxymethyl cellulose, is carried out electrochemical measurements, the carboxymethyl cellulose does not degrade the cell performance was intended to seek an ideal slurry designs that thickener.

Experimental methodology

CNT, SBR, the slurry that was created by mixing the CMC is applied to the aluminum foil, you have created a positive electrode.

Then, I went the CV measurement of two of the positive electrode. 

○Adjustment of slurry

Aluminum foil, I was cut to 1 × 4cm. Weighed WSCA-65 to 0.005g cup, I was stirring. Was added then 0.010g of VGCF, and stirred. The SBR dispersion was added 0.03g to put the cup to the electronic balance.

○ Creating a positive electrode

Coating amount of the WSCA-65 was 0.005 g.

The WSCA-65 that was coated on aluminum created a battery-powered cell below.

Al||WSCA-65,SBR,CNT|5wt%AAaq|SuS

○ experimental results

Nishina laboratory group conducted a CV measurement of CMC-Li and Jeruna QH300. · WSCA-65 WSCA-65 is to become a liquid that was a smooth adjustment of the slurry was Nukuka~tsu coating on aluminum. There is part that is not wet and dried. · CMCLi Nuriko-ryo of CMC-Li was 4.3mg. When led electrostatic induction from the calculation to determine the static induction per gram of carbon, the maximum value was 6.62V / s. Was confirmed a positive electrode state at the time of measurement, changes such as generation of air bubbles was observed. If you look at the cyclic voltammogram of CMC-Li, it can be said that the current is flowing in a stable from that deviation of the orbit is less. · Jeruna QH300 Nuriko-ryo of Jeruna QH300 was 3.08mg. When led electrostatic induction from the calculation to determine the static induction per gram of carbon, the maximum value was 10.6V / s. Looking at the cyclic voltammograms of Jeruna, it can be seen a large capacitance with a small amount of carbon state than CMC-Li. Was confirmed a positive electrode state at the time of measurement, and slight bubbles are generated, was made white spots on the applied active material.