Flexible Battery Charge Control Circuit for Fast Overcharge Cutoff
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Solution Overview
Problem
Lithium-ion secondary batteries face challenges in detecting abnormalities such as overcharge and micro-short circuits during wireless charging, leading to potential safety issues and reduced battery life due to repeated charging cycles, while existing protection circuits are bulky and inefficient in minimizing size and power consumption.
Innovation Solution
A charge control circuit using an oxide semiconductor transistor is integrated over a flexible substrate, connected to the battery terminals, which detects abnormalities and controls charging by blocking power flow through switches, preventing overcharge and reducing power consumption, and is designed for miniaturization and high-temperature operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rigid substrate with IC chips is used for protection circuit, then safety function is ensured, but device size increases and flexibility is reduced
Solution Approach 1:
The patent applies this principle by replacing the traditional rigid substrate with a flexible substrate that can be conformally attached to the battery surface. The flexible substrate maintains the protection circuit's safety functions while significantly reducing device volume and enabling adaptive mounting on curved battery surfaces, thus resolving the contradiction between reliability and size.
Solution Approach 2:
The patent transitions from a planar rigid substrate layout to a three-dimensional conformal attachment on the battery surface. By wrapping the flexible substrate around the battery, the circuit board utilizes the curved surface area, effectively increasing the available mounting area without increasing the battery's linear dimensions, thus reducing overall device volume while maintaining safety functions.
2Adaptability or versatility
If multiple IC chips are mounted on rigid substrate, then protection and control functions are achieved, but device complexity and space requirement increase
Solution Approach 1:
The patent merges multiple separate IC chip functions onto a single flexible substrate, integrating the protection circuit and control circuit into one unified structure. This consolidation reduces device complexity by eliminating the need for multiple discrete components while maintaining all necessary protection and control functions through integrated circuit design on the flexible substrate.
3Reliability
If conventional protection circuit is used, then overcharge protection is provided, but response speed is insufficient for rapid abnormality detection
Solution Approach 1:
The patent replaces conventional protection circuits with an oxide semiconductor-based protection circuit that leverages the unique electrical characteristics of oxide semiconductors. These materials enable ultra-low off-state current and rapid response to voltage changes, allowing the circuit to detect abnormalities and respond within microseconds, thus dramatically improving response speed while maintaining overcharge protection reliability.
4Productivity
If repeated charging cycles are performed, then battery capacity is utilized, but battery life is reduced due to degradation
Solution Approach 1:
The patent implements a control circuit that continuously monitors battery parameters such as voltage, current, and temperature during charging cycles. Based on this real-time feedback, the control circuit dynamically adjusts charging parameters to optimize charging speed while preventing conditions that would accelerate battery degradation, thus extending battery life without compromising capacity utilization.
Solution Approach 2:
The protection circuit proactively detects early signs of battery stress and abnormal conditions before they lead to degradation or failure. By taking preliminary protective actions such as adjusting charging current or stopping charging when thresholds are approached, the system prevents cumulative damage from repeated aggressive charging cycles, thereby extending battery lifespan while maintaining productive usage.
Data Source
AI summary
A structure that includes a circuit for controlling the safe operation of a secondary battery but can overcome space limitations owing to miniaturization of the housing is provided. A charge control circuit is provided over a flexible substrate and bonded to an external surface of the secondary battery. The charge control circuit is electrically connected to at least one of two terminals of the secondary battery and controls charging. To prevent overcharge, both an output transistor of a charging circuit and a blocking switch are brought into off state substantially concurrently. Blocking two paths which connect to the battery can quickly stop charging when overcharge is detected and reduce damage to the battery owing to the overcharge.