Nonaqueous Electrolyte Additive Coating for High-Temperature Li-Ion Stability
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Solution Overview
Problem
The oxidative decomposition of electrolytes in lithium secondary batteries leads to gas generation, metal ion precipitation, and a drop in open-circuit voltage (OCV), resulting in degraded performance and reduced lifespan, particularly at high temperatures.
Innovation Solution
A coating film is formed on the electrode surfaces using a compound represented by Formula 1, which includes a sulfonylimide group with a (meth)acrylate or acrylamide group, inhibiting direct contact between the positive electrode and electrolyte, thereby preventing gas generation and metal ion precipitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LiPF6 is used as the lithium salt in the electrolyte, then the battery shows good initial performance, but gas is generated and HF is produced under high temperature conditions, leading to degraded performance and reduced lifespan
Solution Approach 1:
The patent introduces a coating layer formed from a specific compound (Formula 1) as an intermediary between the positive electrode and the electrolyte containing LiPF6. This coating layer acts as a mediator that allows ionic conductivity while preventing direct contact between the electrolyte and electrode, thereby suppressing gas generation and HF production that would otherwise occur with LiPF6 decomposition
Solution Approach 2:
The patent applies a thin film coating layer on the positive electrode surface. This flexible thin film serves as a protective barrier that prevents harmful reactions between the electrolyte and electrode while maintaining ionic transport, thus resolving the contradiction between using LiPF6 for good performance and preventing gas/HF generation
2Power
If the battery operates at high temperature, then the power output is maintained, but oxidative decomposition of the electrolyte occurs, generating gas and causing metal ion precipitation
Solution Approach 1:
The patent applies preliminary anti-action by pre-forming a protective coating layer on the positive electrode before high-temperature operation occurs. This coating layer is specifically designed to resist oxidative decomposition of the electrolyte at high temperatures, preventing gas generation and metal ion precipitation while allowing the battery to maintain power output
3Reliability
If the positive electrode is directly contacted with the electrolyte, then ionic conductivity is maintained, but metal ions are eluted from the positive electrode, causing OCV drop and capacity retention degradation
Solution Approach 1:
The patent introduces a coating layer formed from the compound in Formula 1 as an intermediary between the positive electrode and electrolyte. This coating layer prevents direct contact that would cause metal ion elution, while maintaining ionic conductivity to preserve capacity retention rate and prevent OCV drop
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 coating film effectively prevents gas generation and OCV drop, improving capacity retention and high-temperature safety by stabilizing the electrolyte and reducing metal ion elution, enhancing battery durability and performance.
Implementation Method 1
forming a coating film on an electrode surface to prevent direct contact between a positive electrode and an electrolyte
Implementation Method 2
blocking direct contact between the positive electrode and HF or PF5
Data Source
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AI summary
An additive for a non-aqueous electrolyte, a non-aqueous electrolyte including the same, and a lithium secondary battery including the same are disclosed herein. The additive includes an ionic compound to form a coating film on an electrode surface, thereby preventing gas generation at high temperature, a cell open-circuit voltage (OCV) drop, and a decrease in capacity retention rate, which are caused by elution of metal ions from an electrode. The additive improves durability, performance, and high temperature safety of the battery.