Title:
ELECTRODE AND POWER STORAGE ELEMENT
Document Type and Number:
WIPO Patent Application WO/2023/090325
Kind Code:
A1
Abstract:
The present invention relates to an electrode which comprises at least graphite, a binder and a non-graphite carbonaceous material. If a half cell is produced using this electrode as a working electrode, an Li foil as a reference electrode, and a solution obtained by dissolving lithium hexafluorophosphate at a concentration of 1 mol/L into a mixed solution of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate as an electrolyte solution, the mixed solution having an (ethylene carbonate)/(dimethyl carbonate)/(ethyl methyl carbonate) volume ratio of 1/1/1, (A) with respect to a cyclic voltammogram obtained by doping the electrode with lithium until the cell voltage reaches 0.01 V, subsequently sweeping a potential at a sweep rate of 0.01 mV/s toward the reduction side until the cell voltage falls to -0.05 V from +0.01 V and further sweeping a potential toward the oxidation side until the cell voltage reaches +0.5 V by cyclic voltammetry, the ratio (A/B) of the area of the region A described below to the area of the region B described below is 4.0% or more, the areas being calculated on the basis of reference points E1, E2, E3 and E4 described below; and (B) the electrode mixture density at a depth of charge of 50% is 1.30 g/cm3 or more if the capacity at the time when the electrode is doped with lithium until the cell voltage reaches 0.05 V is taken as a depth of charge of 100%.
Reference point E1: the point at which the absolute value of the current is minimum within the range of -0.05 V ≤ E1 ≤ 0.01 V on the current-voltage curve on the reduction side
Reference point E2: the intersection point of the coordinate axis of the voltage (current is 0 mA) and a tangent line with the maximum slope within the range of -0.05 V ≤ E2 ≤ 0.01 V on the current-voltage curve on the reduction side
Reference point E3: the point at which the absolute value of the current is minimum within the range of 0.05 V ≤ E3 ≤ 0.1 V on the current-voltage curve on the oxidation side
Reference point E4: the point at which the voltage is 0.3 V on the current-voltage curve on the oxidation side
Region A: the region surrounded by the current-voltage curve on the reduction side, a straight line that passes through the reference point E1 and is perpendicular to the coordinate axis of the voltage (current is 0 mA), a straight line that passes through the reference point E2 and is perpendicular to the coordinate axis of the voltage (current is 0 mA), and the coordinate axis of the voltage (current is 0 mA)
Region B: the region surrounded by the current-voltage curve on the oxidation side, a straight line that passes through the reference point E3 and is perpendicular to the coordinate axis of the voltage (current is 0 mA), a straight line that passes through the reference point E4 and is perpendicular to the coordinate axis of the voltage (current is 0 mA), and the coordinate axis of the voltage (current is 0 mA)
Inventors:
HASENAKA YUKI (JP)
TACHIKAWA KENGO (JP)
TACHIKAWA KENGO (JP)
Application Number:
PCT/JP2022/042427
Publication Date:
May 25, 2023
Filing Date:
November 15, 2022
Export Citation:
Assignee:
KURARAY CO (JP)
International Classes:
H01M4/133; H01M4/36; H01M4/587
Foreign References:
| JP2010245017A | 2010-10-28 | |||
| JPH1173990A | 1999-03-16 | |||
| JP2012089267A | 2012-05-10 | |||
| CN111370650A | 2020-07-03 | |||
| US20200395599A1 | 2020-12-17 |
Attorney, Agent or Firm:
YAMAO, Norihito et al. (JP)
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