Li-Ion Battery Charging Method Temperature Control
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Solution Overview
Problem
Lithium ion secondary batteries experience deterioration and reduced battery characteristics when charged at high temperatures, particularly due to the degradation of the passivating film on the electrodes, leading to a decrease in discharge capacity and electrode instability.
Innovation Solution
A method for charging lithium ion secondary batteries that involves temperature-dependent switching between constant current and constant voltage charging modes, where at temperatures below a certain threshold, constant current charge is performed until a given voltage is reached, followed by constant voltage charge, and at higher temperatures, only constant current charge is performed to prevent electrode damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If constant current/constant voltage charge is performed at high temperature, then charging capacity is improved, but electrode deterioration occurs and battery characteristics degrade
Solution Approach 1:
The charging method dynamically adjusts the charging mode based on temperature conditions. At temperatures below the threshold, the system transitions from constant current charging to constant voltage charging to maximize capacity. At temperatures at or above the threshold, the system maintains constant current charging only to prevent electrode deterioration. This dynamic adaptation resolves the contradiction between achieving high charging capacity and maintaining electrode stability under varying temperature conditions.
Solution Approach 2:
The invention changes the charging parameters (current and voltage) based on temperature. By setting a temperature threshold and adjusting the charging mode accordingly, the system optimizes charging capacity when cool while preventing thermal degradation when hot. This parameter adjustment strategy resolves the contradiction by adapting charging conditions to temperature-dependent electrode stability requirements.
2Productivity
If constant voltage charge is performed after reaching given voltage, then charging efficiency is improved, but passivating film degradation occurs at high temperature
Solution Approach 1:
The invention changes the charging parameter regime based on temperature. When temperature is below the threshold, the system performs constant voltage charging after reaching given voltage to improve charging efficiency. When temperature is at or above the threshold, the system performs only constant current charging to prevent passivating film degradation. This conditional parameter change resolves the contradiction between charging efficiency and passivating film stability.
Solution Approach 2:
The charging process dynamically adjusts between constant current and constant voltage modes based on real-time temperature monitoring. This dynamic control allows the system to maximize charging efficiency under favorable temperature conditions while protecting the passivating film under harsh temperature conditions, thereby resolving the contradiction between productivity and harmful effects.
3Speed
If charging is performed without temperature control, then charging speed is maintained, but electrode deterioration and reduced discharge capacity occur
Solution Approach 1:
The invention implements temperature feedback control in the charging process. The system monitors temperature during charging and uses this feedback to adjust the charging mode in real-time. When temperature exceeds the threshold, the system modifies charging parameters to prevent electrode deterioration. This feedback mechanism resolves the contradiction by maintaining charging speed through constant current charging while preventing discharge capacity loss through temperature-dependent mode switching.
Solution Approach 2:
The charging system dynamically responds to temperature conditions, adjusting charging speed and mode accordingly. By making the charging process adaptive rather than static, the system maintains high charging speed when safe while preventing electrode deterioration that would reduce discharge capacity. This dynamic approach resolves the contradiction between charging speed and long-term battery reliability.
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 approach prevents the deterioration of electrodes and battery characteristics by optimizing charging conditions based on temperature, ensuring stable capacity and performance.
Implementation Method 1
the solvent is reduced and decomposed and a passivating film (also referred to as a solid electrolyte interface (SEI)) is formed on a surface of the negative electrode active material layer
Implementation Method 2
the solvent is reduced and decomposed and a passivating film (also referred to as a solid electrolyte interface (SEI)) is formed on a surface of the negative electrode active material layer
Implementation Method 3
The passivating film prevents the electrolyte from being further decomposed, and lithium ions can be inserted
Implementation Method 4
lithium ions can be inserted. In the case where graphite is used for a negative electrode active material layer... a material which can occlude and release lithium ions is used for the active materials
Implementation Method 5
a lithium ion secondary battery itself might have high temperature due to heat generation in charge and discharge of the lithium ion secondary battery
Data Source
AI summary
A lithium ion secondary battery includes a positive electrode including a positive electrode active material layer containing lithium iron phosphate, a negative electrode including a negative electrode active material layer containing graphite, and an electrolyte including a lithium salt and a solvent including ethylene carbonate and diethyl carbonate between the positive electrode and the negative electrode. When the battery temperature of the lithium ion secondary battery or the temperature of an environment in which the lithium ion secondary battery is used is T and given temperatures are T1 and T2 (T1<T2), in the case where T<T1, constant current charge is performed until voltage reaches a given value and then constant voltage charge is performed; in the case where T1≤T<T2, only constant current charge is performed; and in the case where T2≤T, charge is not performed.