ionic conduction in lithium ion battery composite electrode governs cross-sectional reaction distribution - 3.7 volt rechargeable lithium ion battery
Composite Electrodes containing active materials, carbon and adhesives are widely used in lithium-ion batteries.
Since the electrode reaction occurs first in the area with lower resistance, the reaction distribution can occur in the composite electrode.
We investigate the relationship between the reaction distribution in the composite electrode and the depth direction and the electron/ion conductivity with the change of the electrode aperture.
2-dimensional X
The ray absorption spectrum shows that the reaction distribution occurs in the low-hole electrode.
We developed 6-
The probe method can measure the electronic/ionic conductivity in the composite electrode.
For low-hole electrodes, the ion conductivity is reduced, which controls the reaction distribution of the composite electrode and its properties.
Active material, carbon-
Use coated LiFePO powder with an average particle size of 200 nm.
Conductive additives, acetylene carbon black, with an average particle size of 40 nm (Japan). PolyVinylidene-DiFluoride (PVDF)
The binder is from Kureha (Japan).
For electrode preparation, 75% carbon-
Mix the coated lifpo powder, 10 u2009 % acetylene black, and 15 Poly-diammonium in 1-methyl-2-
Water (NMP, Wako)solvent.
Apply the slurry to the aluminum foil using the doctor blade.
Dry at 70 °c to remove the solvent and perform additional drying in a vacuum oven at 80 °c to evaporate the residual solvent.
These composite electrodes are dense 0 u2009 kgf, 300 u2009 kgf, 600 u2009 kgf, 900 u2009 kgf, and 1200 u2009 kgf pressure to control their porosity.
Assemble the lifpo electrode in lithium metal (
Benzhuang metal, Japan)
As an anti-electrode.
Two separators (Celgard 2500)
Between the electrodes.
LiPF with a volume ratio of 1 m (EC)
And the second radical (EMC)
Used as an electrolyte solution.
The Assembly of the battery was carried out in a dry glove box in an ar atmosphere.
After charging to 42u2009V at 0.
2 ℃, the measured discharge property is 2.
At a rate of 0 v at 10 °c at 25 °c.
Check the cross section of the composite electrode using a cross section Polish (CP, JEOL SM-09010)
Scanning electron microscope (Hitachi SU-SEM70).
To observe the cross section view of the composite electrode, polish the cross section of the composite electrode with CP and observe it with SEM.
The LiFePO electrode is discharged at a rate of 10 °c at 25 °c until the nominal composition of the LiFePO is close to u2009 = u2009 0. 45.
Once the electrodes are discharged, they are taken out of the battery and rinsed with a carbonated Suba (DMC)and dried.
To observe the cross-section view, dry electrodes were made with CP. 2D-
Imaging XAFS measurement on beam line BL-
SR center in the Life Hall (Japan).
Beam size is 3 (H)×u20094 (W)mm. Fe -
The edge XAS spectrum of the lifpo electrode is collected in transmission mode using a CMOS detector.
The spatial resolution is 10 μm.
Effective ion and electronic conductivity in composite electrodes were measured with 6-conductorprobe method.
Two aluminum plates were connected with polypropylene.
The measurement principle has been reported and the cell settings will be explained in the manuscript.