Balanced stepped electrode assembly, and battery cell and device comprising the same

An electrode assembly comprising a combination of two or more types of electrode units having different areas, the two or more types of electrode units being stacked so as to form a stepped portion therebetween,

• wherein a positive electrode and a negative electrode are formed to face each other at an interface between the electrode units, and
• when 500 charge and discharge cycles have been performed at 25° C. under a charging conditions (A) and discharging conditions (B), an electrical capacitance is 60% or more of an electrical capacitance after a single charge and discharge cycle, and a total thickness variation ratio of the electrode assembly is 15% or less:
• charging conditions (A):
• after a battery is charged to 4.2V or 4.35V in a constant current mode of 1 C, the constant current mode is converted to a constant voltage mode, and the charging is completed after current flows until the amount of charged current becomes 1/20 of a minimum capacitance of the battery;
• and
• discharging conditions (B):
• a discharge current of 1 C flows in the constant current mode, and the discharge is completed when the voltage reaches at 3V,
• wherein Equation 1 is satisfied:
• Nn/Pn≦Nn/Pn+1, Equation 1:
• where n is an integer not less than 1,
• Nn is reversible capacitance per unit area of the negative electrode of the electrode unit that is the n-th largest in area,
• Pn is reversible capacitance per unit area of the positive electrode of the electrode unit that is the n-th largest in area, and
• Pn+1 is reversible capacitance per unit area of the positive electrode of the electrode unit that is the (n+1)-th largest in area, and
• wherein Equation 4-1 is satisfied:
• 1.0≦dNn/dPn≦dNn/dPn+1≦1.5 Equation 4-1:
• where n is an integer not less than 1,
• dNn is a thickness of the negative electrode of the electrode unit that is the n-th largest in area,
• dPn is a thickness of the positive electrode of the electrode unit that is the n-th largest in area, and
• dPn+1 is a thickness of the positive electrode of the electrode unit that is the (n+1)-th largest in area.