Li-Ion Battery Charging Method with Low Resistance Terminals
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing lithium ion secondary battery charging methods either prolong charging time or compromise cycle characteristics, as they struggle to balance high charge rates with the need for rapid charging and prolonged battery life.
Innovation Solution
A method involving multiple constant-current charging steps followed by constant-voltage charging, with specific current and voltage settings (1 to 5 C and 3.8 to 4.2 V) and a low internal terminal to external terminal resistance of 0.1 to 2 mΩ, to efficiently charge lithium ion secondary batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the charge current is raised to shorten charging time, then the charging speed is improved, but the acceptance of lithium ions deteriorates and the battery life is shortened
Solution Approach 1:
The charging process is divided into multiple stages with different charge rates. The patent applies a two-stage charging method: first stage uses a high charge rate (1-5C) to quickly charge the battery to a target voltage (3.8-4.2V), then switches to a lower charge rate (0.2-0.5C) to complete the charging. This segmentation allows rapid charging without subjecting the battery to prolonged high-current stress that would damage its lifespan.
Solution Approach 2:
The charge rate is dynamically adjusted based on the battery's charging state. The system transitions from a high current mode to a low current mode when the battery voltage reaches the target voltage. This dynamic adjustment optimizes the balance between charging speed and battery protection, allowing fast charging when the battery can accept it and protecting the battery when it approaches full charge.
2Reliability
If the charge current is lowered to improve cycle characteristics, then the battery life is extended, but the charging time is prolonged
Solution Approach 1:
The charging process is divided into multiple stages with different charge rates. The patent applies a two-stage charging method: first stage uses a high charge rate (1-5C) to quickly charge the battery to a target voltage (3.8-4.2V), then switches to a lower charge rate (0.2-0.5C) to complete the charging. This segmentation allows rapid charging without subjecting the battery to prolonged high-current stress that would damage its lifespan.
Solution Approach 2:
The patent changes the charge rate parameter based on the charging state. By switching from a high charge rate (1-5C) to a low charge rate (0.2-0.5C) when the battery voltage reaches the target voltage, the system optimizes both charging speed and battery protection. This parameter change allows the battery to accept fast charging when needed while protecting its cycle characteristics during the charging process.
3Reliability
If constant-voltage charging is performed at low current (0.2 to 0.5 C) to suppress deterioration, then the cycle characteristics are improved, but the charging time is extended
Solution Approach 1:
The charging process is divided into multiple stages with different charge rates. The patent applies a two-stage charging method: first stage uses a high charge rate (1-5C) to quickly charge the battery to a target voltage (3.8-4.2V), then switches to a lower charge rate (0.2-0.5C) to complete the charging. This segmentation allows rapid charging without subjecting the battery to prolonged high-current stress that would damage its lifespan.
Solution Approach 2:
The patent applies excessive action in the first charging stage by using a very high charge rate (1-5C, which exceeds the typical 0.2-0.5C used in conventional methods). This high-rate charging is applied partially, only until the battery reaches the target voltage (3.8-4.2V), after which the current is reduced. This partial excessive action enables significantly faster charging while the subsequent low-current stage protects the battery's cycle characteristics.
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 allows for significantly shorter charging times without sacrificing the battery's cycle life characteristics, effectively addressing the limitations of previous methods by optimizing charge rates and voltage settings.
Implementation Method 1
The internal terminal and the external terminal are connected to each other and have an electrical resistance therebetween of 0.1 to 2 mΩ
Implementation Method 2
lithium ion secondary batteries with high voltage and high energy density have been widely used as a power source
Data Source
AI summary
A lithium ion secondary battery which includes: a power generation element including a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and a non-aqueous electrolyte; a case accommodating the power generation element and having an opening; and a sealing plate sealing the opening of the case is charged. The sealing plate has an external terminal of the positive or negative electrode, and an internal terminal electrically connected to the positive or negative electrode. The external and internal terminals are connected to each other and have an electrical resistance therebetween of 0.1 to 2 mΩ. Two or more constant-current charging steps in each of which the secondary battery is charged at a constant charge current until a charge voltage reaches an end-of-charge voltage are performed. In the two or more constant-current charging steps, the secondary battery is subjected to constant-current charging at a current Ic(1) of 1 to 5 C until the charge voltage reaches a target voltage Ecs(1). After the charge voltage reached the target voltage Ecs(1), the secondary battery is subjected to constant-current charging at a current Ic(k) satisfying Ic(k)<Ic(1) until the charge voltage reaches a target voltage Ecs(k) higher than the target voltage Ecs(1).