Winding-Type Lithium Ion Battery Electrode Gap and Voltage Control
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Solution Overview
Problem
Conventional lithium ion secondary batteries experience deterioration in cycle characteristics and reduced discharge capacity when the charge cutoff voltage is increased above 4.41 V, leading to shorter battery life.
Innovation Solution
A lithium ion secondary battery with a winding-type electrode assembly, featuring a positive electrode, negative electrode, and separator, where the charge cutoff voltage is set between 4.41 V to 4.47 V, the area ratio of the negative electrode active material layer to the positive electrode active material layer is between 100.5% to 104.0%, and the gap between electrodes is 0.1 mm to 0.5 mm, ensuring improved cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the charge cutoff voltage is increased to 4.41 V or more, then the energy density is improved, but the cycle characteristics are deteriorated and battery life is shortened
Solution Approach 1:
The patent applies parameter changes by precisely controlling multiple parameters: charge cutoff voltage (4.41-4.47 V), area ratio of negative to positive electrode active material (100.5%-104.0%), gap between electrodes (0.1-0.5 mm), and discharge capacity per unit weight of positive electrode active material (169.0-178.0 mAh/g). This systematic parameter optimization resolves the contradiction by finding the optimal operating point that achieves high energy density while maintaining good cycle characteristics.
2Use of energy by moving object
If the charge cutoff voltage is increased to 4.41 V or more, then the energy density is improved, but the discharge capacity decreases due to repeated charge and discharge
Solution Approach 1:
The patent uses parameter changes to optimize the balance between energy density and discharge capacity. By setting the charge cutoff voltage within 4.41-4.47 V and controlling the area ratio of electrodes to be 100.5%-104.0%, the invention achieves high energy density while preventing excessive discharge capacity loss during cycling through controlled material utilization.
3Use of energy by moving object
If the charge cutoff voltage is increased to 4.41 V or more, then the energy density is improved, but the battery life is shortened
Solution Approach 1:
The patent resolves the contradiction between energy density and battery life through comprehensive parameter control. By optimizing the charge cutoff voltage (4.41-4.47 V), electrode area ratio (100.5%-104.0%), and gap (0.1-0.5 mm), the invention extends battery life while maintaining high energy density, preventing material deterioration that would otherwise occur at higher voltages.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The battery maintains better cycle characteristics and discharge capacity even at elevated charge cutoff voltages, resulting in extended battery life and improved energy density.
Implementation Method 1
lithium ions move between the positive electrode and the negative electrode through the electrolyte to charge and discharge the battery
Data Source
AI summary
A lithium ion secondary battery that includes a winding-type electrode assembly in which a positive electrode having a positive electrode active material layer, a negative electrode having a negative electrode active material layer, and a separator interposed therebetween are wound into a roll shape and have a charge cutoff voltage of 4.41 V to 4.47 V. In this lithium ion secondary battery, an area ratio of the entirety of the negative electrode active material layer to an area of a facing portion between the positive electrode active material layer and the negative electrode active material layer is 100.5% to 104.0%. A gap between the positive electrode and the negative electrode is 0.1 mm to 0.5 mm in an axial direction of the winding. A discharge capacity per unit weight of a positive electrode active material in the positive electrode active material layer is 169.0 mAh/g to 178.0 mAh/g.