Lithium Ion Battery Additive Mixture for Overcharge Protection

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Solution Overview

Problem

Conventional additives for lithium ion secondary battery electrolytes degrade cycle performance and low temperature performance while improving safety performance, leading to potential explosions and fires during overcharge.

Innovation Solution

An additive mixture comprising biphenyl based compounds, cyclohexylbenzene, vinylene carbonate, t-alkyl benzene, and phenyl vinyl sulfone is used in the electrolyte, enhancing safety, cycle, and low temperature performance by improving overcharge protection and reducing swelling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional additives (aromatic compounds and cyclohexyl benzene) are added to improve safety performance, then overcharge protection is enhanced, but cycle performance and low temperature performance deteriorate

Engineering Contradiction:

Improvesafety performanceVSAvoidcycle performance

Core Design Contradiction:

ReliabilityVSDuration of action of moving object

Solution Approach 1:

The patent combines multiple additives (aromatic compound, cyclohexyl benzene, and high-activity monomer of polymer) into a composite additive system. This composite approach allows the synergistic effects of different components to improve safety performance while mitigating the negative impact on cycle performance that occurs with single additives.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent optimizes the concentration ratios of different additives in the mixture. By adjusting the parameters (concentrations) of aromatic compounds, cyclohexyl benzene, and polymer monomers within specific ranges, the system achieves improved safety performance while maintaining acceptable cycle performance characteristics.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If conventional additives are added to improve safety performance, then overcharge protection is enhanced, but low temperature performance deteriorates

Engineering Contradiction:

Improvesafety performanceVSAvoidlow temperature performance

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The composite additive system incorporates high-activity monomer of polymer alongside aromatic compounds and cyclohexyl benzene. This composite formulation provides overcharge protection while the polymer component helps maintain low temperature performance by forming stable SEI layers that facilitate ion transport at low temperatures.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The different additives in the mixture provide localized functions: aromatic compounds and cyclohexyl benzene primarily provide overcharge protection, while the high-activity monomer of polymer specifically addresses low temperature performance by modifying the electrode surface properties to enable better ion transport in cold conditions.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS7790322B2Additive mixture for electrolyte of lithium ion secondary battery and electrolyte of lithium ion secondary battery comprising the same

Publication Date: 2010.09.07 BYD CO LTD

AI summary

Disclosed herewith are an additive mixture for the electrolyte of lithium ion secondary batteries and electrolyte of lithium ion secondary batteries comprising the said additive mixture. The additive mixture comprises biphenyl based compound 0.5-95.4 wt %, cyclohexyl benzene based compound 0.1-93.8 wt %, vinylene carbonate 0.4-93.2 wt %, t-alkyl benzene based compound 0.5-96.5 wt %, and phenyl vinyl sulfone 0.5-95.8% based on total weight of the additive mixture.