Multilayer electrode for secondary battery, comprising binder having high crystallinity
A secondary battery and adhesive technology, applied in battery electrodes, non-aqueous electrolyte battery electrodes, positive electrodes, etc., can solve the problems of increasing the volume of the secondary battery and reducing the capacity per unit volume, etc., and achieves excellent process efficiency and material cost. excellent effect
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experiment example 1
[0085] The crystallinity of PVdF and the elongation and flexibility of the electrode of each of the first positive electrode composite material layers in the positive electrodes manufactured in Comparative Examples 1 and 2 and Inventive Examples 1 and 2 were measured and shown in Table 1 below. To this end, electrodes in which only the first positive electrode composite layer was formed in Comparative Examples 1 and 2 and Inventive Examples 1 and 2 were prepared, respectively.
[0086] Here, crystallinity, elongation and flexibility were measured as follows.
[0087] *Crystallinity: The electrode forming only the first positive electrode composite layer was vacuum-dried at 45° C., and a part of each electrode layer was scraped off with a spatula blade, followed by measurement of NMR of the powder. The analysis method is as follows. After the measurement, the areas of crystalline and non-crystalline peaks at the main peak of PVdF were obtained, and the percentage (%) of the cr...
experiment example 2
[0096] Manufacture of negative electrode
[0097] Artificial graphite was used as the negative electrode active material. A negative active material slurry prepared by adding 96.3 wt% of artificial graphite, 1.0 wt% of Super-P (conductive material), and 2.7 wt% of PVdF (binder) to NMP as a solvent was coated on On the copper foil, it was made to a thickness of 70 μm, and dried and rolled at a rate of 0.2 m / min (drying rate of about 5 minutes) in a drier at a temperature of 130° C. under an air atmosphere to produce a negative electrode.
[0098] Manufacturing of Secondary Batteries
[0099] Using the positive and negative electrodes produced in Inventive Examples 1 and 2 and Comparative Examples 1 to 3, a polyethylene film (Celgard, thickness: 20 μm) as a separator, and 1M LiPF therein 6 A secondary battery was manufactured with a liquid electrolyte dissolved in a solvent obtained by mixing ethylene carbonate, dimethyl carbonate, and diethyl carbonate at a ratio of 1:2:1.
...
experiment example 3
[0111] The positive electrode of Comparative Example 4 was again subjected to vacuum drying at 45° C., and a part of the electrode layer was scraped off with a spatula blade, and NMR of the powder was measured. The analysis method is as follows. After the measurement, the areas of crystalline and non-crystalline peaks at the main peak of PVDF were obtained, and the percentage (%) of the crystalline area to the sum of the areas was calculated to obtain the degree of crystallinity.
[0112] The device used was an Agilent 600MHz NMR / 1.6mm MAS probe.
[0113] According to the measurement results, the degree of crystallinity was 59.7. That is, it can be seen that the crystallinity of PVdF was 59.7 when it was dried again at 160° C. in a vacuum state.
[0114] Evaluation of output characteristics
[0115] A secondary battery fabricated according to Experimental Example 2 using the positive electrodes fabricated in Inventive Examples 1 and 2 and Comparative Examples 4 and 5 was ch...
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Abstract
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