Three-Stage Battery Charging Using Volume Change Thresholds
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Solution Overview
Problem
Lithium ion secondary batteries face deterioration and reduced lifespan when charged with high currents, leading to decreased battery capacity and increased internal resistance, as high current values exacerbate volume changes in the active materials during charging.
Innovation Solution
A secondary battery system that includes a volume measurement part to monitor and control current flow based on measured volume changes, adjusting the current to prevent excessive volume changes and thereby reducing deterioration, using a charge controller that adjusts current flow according to threshold values set by a designation part.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If high current value is used for charging, then charging time is shortened, but battery deterioration is accelerated and lifetime is reduced
Solution Approach 1:
The patent applies dynamics by transitioning from static constant current charging to dynamic multi-stage current charging. The charging current is dynamically adjusted through three distinct stages: initial constant current charging, constant voltage charging, and final constant current charging with reduced amplitude. This dynamic adjustment optimizes charging speed while preventing battery deterioration, thereby resolving the contradiction between charging time and battery lifetime.
Solution Approach 2:
The patent implements periodic action by dividing the charging process into three sequential stages with different current characteristics. Each stage serves a specific purpose: the first stage provides high current for rapid charging, the second stage maintains voltage while reducing current, and the third stage uses reduced current to complete charging. This periodic structure enables efficient charging while protecting battery health, addressing the contradiction between charging speed and battery durability.
2Productivity
If high current value is used for charging, then charging speed is improved, but storage battery performance deteriorates due to excessive volume changes
Solution Approach 1:
The patent uses dynamics to adjust charging current based on battery state and charge level. By implementing three stages with varying current amplitudes, the system maintains high charging speed during early stages when the battery can accommodate rapid ion insertion, while reducing current in later stages to prevent excessive volume changes and capacity deterioration. This dynamic approach balances charging productivity with battery performance stability.
Solution Approach 2:
The patent applies preliminary action by performing constant voltage charging as an intermediate stage between the two constant current stages. This middle stage prepares the battery for the final low-current charging phase by gradually reducing voltage and current, preventing sudden stress on the battery structure. This preliminary action ensures that the battery is ready to receive the final charge without experiencing excessive volume changes that would harm capacity stability.
3Use of energy by moving object
If high current value is used for charging, then charging efficiency is increased, but internal resistance increases due to battery deterioration
Solution Approach 1:
The patent applies dynamics by implementing a three-stage charging protocol that adjusts current amplitude based on battery state. The initial high-current stage maximizes charging efficiency when the battery can accept rapid energy input, while the subsequent stages reduce current to prevent deterioration that would increase internal resistance. This dynamic current adjustment maintains high charging efficiency while minimizing the harmful effect of increasing internal resistance.
Solution Approach 2:
The patent uses preliminary action by inserting a constant voltage charging stage before the final constant current stage. This intermediate stage gradually reduces the charging rate and prepares the battery for the low-current final stage, preventing sudden electrical stress that would accelerate deterioration and increase internal resistance. This preliminary action preserves charging efficiency while controlling the rise in internal resistance.
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 reduced battery deterioration and shorter charging times while maintaining battery performance, as the system dynamically controls current flow to manage volume changes within safe thresholds, thereby extending battery life and efficiency.
Implementation Method 1
a first measurement part that measures a volume change of the secondary battery
Implementation Method 2
a controller that controls a current flowing through the secondary battery based on the volume change of the secondary battery measured by the first measurement part
Implementation Method 3
an active material used for a positive electrode and a negative electrode occludes and releases lithium ions to store and release electric energy
Data Source
AI summary
A secondary battery system includes a secondary battery and a controller. The secondary battery has a charging state including at least first to third sections. The controller controls a current flowing through the secondary battery so as to be smaller than a predetermined current in the first and third sections, and controls the current flowing through the secondary battery so as to be larger than the predetermined current in the second section.