Secondary Battery Charging Method with Variable C-Rate
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Solution Overview
Problem
Conventional secondary battery charging methods, such as CC-CV, result in prolonged charging times and accelerated battery deterioration when high currents are used to increase charge speed, while reducing charge speed leads to reduced charge quantity.
Innovation Solution
A charging method involving a first step at a constant current rate (C-rate) from an initial charge voltage to a first charge voltage, followed by a second step where the C-rate is gradually decreased within the same range, allowing for reduced high voltage time and minimized battery deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If high charge current is used to increase charge speed, then charge time is reduced, but battery deterioration is accelerated
Solution Approach 1:
The patent applies dynamics by making the charge current variable rather than constant. The charging method dynamically adjusts the C-rate based on the battery's state of charge and voltage levels. During the constant current charge period, a high C-rate is used to minimize charge time, while during the constant voltage charge period, the C-rate is gradually reduced to prevent battery deterioration. This dynamic adjustment resolves the contradiction between fast charging and battery lifespan.
Solution Approach 2:
The patent implements periodic action by dividing the charging process into distinct periods or phases: a constant current charge period followed by a constant voltage charge period. Each period has different current characteristics - the first period uses high current for speed, while the second period uses gradually decreasing current to protect the battery. This periodic structure allows the system to achieve both fast charging and battery protection.
2Productivity
If high charge current is used, then charge speed is improved, but battery performance deterioration is accelerated
Solution Approach 1:
The patent uses dynamics to adjust charge current based on charging progress. During the constant current charge period, high current maintains high charge speed for improved productivity. During the constant voltage charge period, the current is dynamically reduced as the battery approaches full charge, preventing performance deterioration. This dynamic current adjustment allows the system to achieve high charge speed without compromising battery performance.
Solution Approach 2:
The patent segments the charging process into two distinct phases: constant current charge and constant voltage charge. The segmentation allows each phase to optimize for different objectives - the first phase maximizes charge speed through high current, while the second phase protects battery performance through gradually decreasing current. This segmentation resolves the contradiction between charge speed and battery performance.
3Reliability
If charge current is reduced to protect battery, then battery deterioration is reduced, but charge time increases
Solution Approach 1:
The patent applies periodic action by structuring the charging process into periods with different current levels. The constant current charge period uses high current to minimize charge time, while the constant voltage charge period uses gradually reduced current to protect the battery. This periodic structure ensures that the battery is protected during the most critical phases while maintaining fast charging during the initial high-capacity phase.
Solution Approach 2:
The patent maintains continuity of useful action by ensuring that charging continues throughout both periods without interruption. The constant current period provides continuous high-speed charging, and the constant voltage period continues charging at reduced current until the battery is fully charged. This continuous action ensures minimal charge time while still protecting the battery through current reduction in the second period.
Data Source
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AI summary
Disclosed herein is a charging method of a secondary battery including a first charging step of charging the secondary battery at a first C-rate from an initial charge voltage to a first charge voltage and a second charging step of charging the secondary battery to a target voltage while gradually decreasing a C-rate within a range not exceeding the first C-rate after the voltage of the secondary battery reached the first charge voltage. Consequently, it is possible to prevent deterioration of the battery, thereby improving lifespan characteristics of the battery.