Overcharge Protection Electrolyte Additive for Li-Ion Batteries
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Solution Overview
Problem
Lithium ion batteries face safety hazards due to thermal runaway and potential ignition when overcharged, as existing overcharge protection additives do not provide sufficient safety and electrochemical performance.
Innovation Solution
An electrolyte composition comprising specific compounds of general formulas (I) and (II), which act as overcharge protection additives, inhibiting hydrogen formation and limiting further overcharging by forming hydrogen gas when the battery is charged beyond its nominal voltage, thereby preventing heating and ignition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing overcharge protection additives are used, then some safety improvement is achieved, but the safety demand is not met and electrochemical performance is compromised
Solution Approach 1:
The patent combines two different additives with distinct functions: compound (I) that forms protective films on electrodes and compound (II) that generates hydrogen gas during overcharge. This composite approach allows simultaneous achievement of high overcharge protection efficiency and maintained electrochemical performance, as each compound contributes its specific mechanism without interfering with the other's function.
Solution Approach 2:
The overcharge protection function is segmented into two separate mechanisms performed by two different compounds: film formation on electrodes (compound I) and hydrogen gas generation (compound II). This segmentation allows each compound to optimize its specific function while working together to provide comprehensive protection, resolving the contradiction between safety efficiency and electrochemical performance.
2Use of energy by moving object
If lithium ion batteries are charged beyond nominal voltage, then energy storage is increased, but thermal runaway and ignition risk increases due to heat generation
Solution Approach 1:
The electrolyte additives perform preliminary protective actions before thermal runaway can occur: compound (I) forms protective films on electrode surfaces that prevent further harmful reactions, and compound (II) generates hydrogen gas that creates pressure to stop overcharging. These preliminary actions counteract the harmful thermal effects before they can lead to runaway conditions.
Solution Approach 2:
The patent converts the harmful effect of overcharging into a beneficial safety mechanism: the excessive charging voltage triggers hydrogen gas generation from compound (II), which creates internal pressure that automatically stops the overcharging process. The harmful overcharge condition is thus transformed into a beneficial self-protection mechanism.
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 electrolyte composition significantly enhances the safety of lithium ion batteries by preventing overheating and ignition during overcharging, as measured by hydrogen gas production, while maintaining high electrochemical performance.
Implementation Method 1
EP 1 335 445 discloses a combination of aromatic compounds as electrolyte additives which oxidatively polymerize in the electrolyte when the battery is overcharged
Implementation Method 2
forming hydrogen gas when the battery is charged beyond its nominal voltage
Data Source
AI summary
The present invention relates to an electrolyte composition for lithium ion batteries which improves overcharge protection. In particular the present invention relates to an electrolyte composition comprising (a) a compound of general formula (I) and (b) at least two compounds of general formula (II) which are different from each other formula (II) with the definitions given in the description.