Cycle-Adaptive Battery Charging to Shorten Constant-Voltage Time
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Solution Overview
Problem
Lithium-ion batteries experience increased impedance with usage, leading to longer charging times due to earlier cut-off points in constant current charging, which extends the constant voltage charging stage and reduces battery cycle life.
Innovation Solution
A charging method that adjusts the first charge current and cut-off voltage based on the number of charge-discharge cycles, using formulas to calculate Im=In+k×In and V1=V2+b, where 0<k≤1 and 0≤b≤0.5, to optimize charging times and prevent overcharging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If constant current charging is used with a preset charging limit voltage, then the battery can be charged efficiently, but the battery impedance increases with usage causing the constant current charging stage to end earlier, which extends the constant voltage charging time and increases total charging time
Solution Approach 1:
The patent applies dynamics by making the charging current adaptive rather than fixed. The charging current is dynamically adjusted based on the battery's cycle number and impedance characteristics. Specifically, the system calculates a first charging current for early cycles and a second charging current for later cycles, allowing the charging process to adapt to the battery's aging and impedance changes, thereby optimizing the balance between charging speed and total charging time
Solution Approach 2:
The patent changes the charging current parameter based on the battery's cycle number. By dividing the charging process into different stages (early cycles vs. later cycles) and applying different current values, the system optimizes charging efficiency at each stage. This parameter change approach allows the constant current charging stage to be extended in early cycles while managing the extended constant voltage stage in later cycles, reducing overall charging time
2Ease of operation
If the constant current charging stage is cut off at a fixed voltage, then the charging process is simple to control, but the extended constant voltage charging time reduces battery cycle life
Solution Approach 1:
The patent makes the charging control dynamic by adjusting the charging current based on cycle number rather than using a fixed approach throughout the battery's life. The system calculates different charging currents for early cycles (first charging current) and later cycles (second charging current), allowing the control strategy to adapt to battery aging while maintaining simplicity in implementation through formula-based calculations
Solution Approach 2:
The patent changes the charging current parameter based on the battery's cycle number to optimize both simplicity and reliability. By implementing different current values for different cycle stages, the system maintains simple voltage-based cut-off control while extending battery cycle life through optimized current parameters that reduce stress on the cathode during high potential stages
Data Source
AI summary
A method for charging a battery, and electronic device using the method, includes charging the battery with a first charge current Im at constant current in a mth charge-discharge cycle of the battery, wherein the battery has a first cut-off voltage V1 when the constant current charging stage of the battery is cut off in the mth charge-discharge cycle. The first charge current Im is calculated according to a formula Im=In+k×In, where, 0<k≤1, In is the charging current of the constant current charging stage of the battery or another battery identical to the battery in the nth charge-discharge cycle, or In can be a preset value, n is an integer and is greater than or equal to 0, and m is an integer greater than n, the value of k is not the same in at least two charge-discharge cycles of the battery.