Safety Electrode for Overcharge Protection in Lithium Batteries
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Solution Overview
Problem
Lithium secondary batteries face safety issues due to overcharging, which can lead to internal temperature and pressure increases, potentially causing fires or explosions, and existing solutions like protection circuits and thermal choking mechanisms are either restrictive or ineffective.
Innovation Solution
Incorporating an additional 'safety electrode' made of overcharge reaction material that undergoes an electrochemical reaction during overcharging, consuming excess current without affecting normal battery operation, thereby enhancing safety without compromising performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protection circuit is mounted to prevent overcharge, then battery safety is improved, but device complexity and manufacturing costs increase
Solution Approach 1:
The invention extracts the safety function from the external protection circuit and integrates it into the battery's internal electrode structure. The additional electrode layer is specifically designed to react only under overcharge conditions, providing intrinsic safety without requiring external electronic control systems.
Solution Approach 2:
The battery electrode assembly performs self-protection through the additional electrode layer that automatically activates during overcharge. The electrochemical reaction of this layer inherently limits excessive current without needing external sensing or control circuits.
2Reliability
If a protection circuit is mounted to prevent overcharge, then battery safety is improved, but manufacturing costs increase
Solution Approach 1:
The invention removes the need for separate protection circuit components and their associated assembly processes. The safety function is achieved through a single additional electrode layer that can be manufactured using standard electrode fabrication techniques.
Solution Approach 2:
The safety function is merged with the electrode structure itself rather than being a separate component. The additional electrode layer is integrated into the existing electrode assembly manufacturing process, eliminating the need for separate circuit board assembly and connection steps.
3Reliability
If thermal choking through separator is used to improve safety, then battery safety is improved, but the mechanism is ineffective when heat generation progresses rapidly
Solution Approach 1:
The additional electrode layer provides preliminary protection by electrochemically reacting to consume excess current before it can generate dangerous heat. This preventive action occurs at the electrochemical level, stopping the overcharge process before thermal runaway can initiate.
Solution Approach 2:
The invention converts the harmful excess electrical energy into a beneficial electrochemical reaction in the additional electrode layer. The overcharge current that would otherwise cause dangerous heating is instead used to drive a controlled electrochemical reaction that safely dissipates the excess energy.
4Reliability
If organic electrolyte additives are used to prevent overcharge, then battery safety is improved, but battery performance deteriorates during normal operation
Solution Approach 1:
The additional electrode layer is strategically positioned and designed to be electrochemically inactive during normal operating conditions. It only becomes active under specific overcharge conditions, providing safety functionality without interfering with the electrochemical reactions that generate power during normal use.
Solution Approach 2:
The electrode layer exhibits dynamic behavior, remaining electrochemically inert during normal operation and becoming active only when overcharge conditions are detected. This conditional activation ensures that the safety mechanism does not interfere with normal battery performance while providing protection when needed.
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
The safety electrode effectively delays and reduces the risk of thermal runaway during overcharging, improving battery safety without degrading normal operation or increasing costs, allowing for a larger amount of safety material to be used.
Implementation Method 1
an electrode (safety electrode) which is composed of a material capable of electrochemical reaction when the secondary battery is overcharged
Data Source
AI summary
Disclosed herein is a secondary battery including an electrode assembly that can be charged and discharged, wherein the electrode assembly includes an electrode (‘safety electrode’) composed of a material that effects an electrochemical reaction when the secondary battery is overcharged (Overcharge reaction material’). The safety electrode according to the present invention is not directly added to components related to the operation of the secondary battery. Consequently, the safety electrode does not deteriorate the performance of the battery during the normal operation of the battery, and the safety electrode consumes the overcharge current through the electrochemical reaction, when the battery is overcharged, whereby the safety of the battery is fundamentally secured.