Li-Ion Battery Charging by Cycle Count to Limit Anode Plating
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Solution Overview
Problem
Lithium-ion batteries experience increased impedance with age, leading to longer charging times due to increased charging polarization, and the lithium precipitation phenomenon can occur in the anode, affecting battery cycle life.
Innovation Solution
A charging method that calculates a first charging current based on the battery's anode impedance and potential differences across charge-discharge cycles to optimize charging stages, thereby shortening the constant current and constant voltage charging times and preventing lithium precipitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If constant current charging is performed with a preset current to a certain voltage, then the battery can be charged to full charge state, but the charging time becomes much longer due to increased battery impedance with age
Solution Approach 1:
The patent implements dynamic charging current adjustment based on battery cycle count. The charging current is divided into multiple stages (first charging current for initial cycles, second charging current for later cycles) with different magnitudes. This dynamic adjustment optimizes charging speed while preventing lithium precipitation as the battery ages, resolving the contradiction between charging completeness and charging time.
Solution Approach 2:
The patent changes the charging current parameter based on the number of charge-discharge cycles. By adjusting the charging current magnitude according to battery age (cycle count), the system achieves faster charging for newer batteries while maintaining safety for older batteries, thus reducing overall charging time without compromising reliability.
2Productivity
If charging current is increased to shorten charging time, then charging speed improves, but lithium precipitation phenomenon occurs in the anode
Solution Approach 1:
The patent uses dynamic current adjustment where the charging current magnitude depends on the battery's cycle count. This ensures that high charging currents are only applied when safe (fewer cycles), while older batteries receive lower currents to prevent lithium precipitation, thus maintaining both charging speed and battery reliability.
Solution Approach 2:
The patent performs preliminary assessment of battery age through cycle counting before determining the appropriate charging current. This preliminary action allows the system to pre-determine safe charging parameters that prevent lithium precipitation while maximizing charging speed appropriate for the battery's current state.
3Device complexity
If constant current charging is performed with fixed parameters, then the charging process is simple, but the charging time extends due to increased polarization in aged batteries
Solution Approach 1:
The patent introduces dynamic charging parameters that adjust based on battery cycle count. The charging current is determined by comparing the current cycle count to a threshold, automatically selecting appropriate current magnitudes. This maintains relative simplicity while significantly reducing charging time for aged batteries compared to fixed-parameter charging.
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
This method reduces the overall charging time of lithium-ion batteries and prevents lithium precipitation, improving battery cycle life by dynamically adjusting charging currents and voltages based on the battery's state and impedance.
Implementation Method 1
a charging method for a battery... charging the battery with a first charging current at a constant current in an mth charge-discharge cycle of the battery
Implementation Method 2
the battery's impedance will increase. The increase of the battery's impedance will lead to increased charging polarization
Implementation Method 3
The increase of the battery's impedance will lead to increased charging polarization, causing the constant current charging stage of a cut-off point to occur more quickly
Data Source
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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.