Non-aqueous Electrolyte Battery Current Interruption Mechanism
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Solution Overview
Problem
Nonaqueous electrolyte secondary batteries face safety issues due to the potential for the current interruption mechanism to conduct again after activation, potentially igniting flammable gases generated by overcharging inhibitors, especially when the battery is subjected to extraordinarily high voltages.
Innovation Solution
The battery design includes a positive electrode plate, negative electrode plate, and a wound electrode assembly with a nonaqueous electrolyte solution, where excess electrolyte solution is present outside the assembly, ensuring it does not contact the current interruption mechanism when the battery is horizontal, thus preventing re-conduction and enhancing safety by using lithium carbonate to generate carbon dioxide for early activation of the current interruption mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If overcharging inhibitors are added to the electrolyte solution, then overcharging is inhibited, but flammable gas may be generated that can be ignited by sparks from re-conduction
Solution Approach 1:
The patent applies preliminary anti-action by preventing the condition that would lead to harmful effects. By positioning the current interruption mechanism above the electrolyte level, the patent preemptively prevents re-conduction and potential sparks before they can occur, thereby eliminating the ignition risk for flammable gases generated by overcharging inhibitors.
Solution Approach 2:
The patent converts the potential harm of flammable gas generation into a benefit by using overcharging inhibitors that generate identifiable gas signatures. The current interruption mechanism responds to this gas generation (through pressure changes) to interrupt charging, while the mechanism's elevated position ensures no sparks are present to ignite the gas, thus converting a hazardous byproduct into a useful activation signal.
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 design effectively prevents the current interruption mechanism from re-conducting after activation, even under high voltage conditions, thereby enhancing the safety of nonaqueous electrolyte secondary batteries by minimizing the risk of ignition from flammable gases.
Implementation Method 1
If lithium carbonate is added to a positive electrode mixture for a nonaqueous electrolyte secondary battery, carbon dioxide gas is generated from the positive electrode plate when a high voltage is applied to the battery
Implementation Method 2
The pressure-responsive current interruption mechanism is activated by gas rapidly generated inside the battery in the event of an abnormal condition
Data Source
AI summary
A nonaqueous electrolyte secondary battery includes a positive electrode plate including a positive electrode core and a positive electrode mixture layer formed thereon; a negative electrode plate including a negative electrode core and a negative electrode mixture layer formed thereon; a wound electrode assembly in which the positive electrode plate and the negative electrode plate are wound with a separator therebetween so as to be insulated from each other; a nonaqueous electrolyte solution; a pressure-responsive current interruption mechanism electrically connected to at least one of the positive electrode plate and the negative electrode plate; and an outer casing. Excess electrolyte solution is present outside the electrode assembly in the outer casing. The liquid level of the excess electrolyte solution is at such a height that the excess electrolyte solution does not come into contact with a component of the current interruption mechanism when the outer casing is placed horizontally.