Nonaqueous Electrolyte Additives Suppress Battery Swelling

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Solution Overview

Problem

Nonaqueous electrolyte secondary batteries experience swelling and efficiency degradation when continuously charged at high temperatures due to decomposition of organic solvents at the electrode surface, particularly when vinylene carbonate is used as a solution.

Innovation Solution

Incorporating a compound represented by the general formula (1) along with vinylene carbonate in the nonaqueous electrolyte, which forms a stable composite film on the negative electrode, reducing decomposition and gas generation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If vinylene carbonate is added to a nonaqueous electrolyte to suppress decomposition at the electrode surface, then charge-discharge efficiency is improved, but gas generation increases during continuous high-temperature charging causing battery swelling

Engineering Contradiction:

Improvecharge-discharge efficiencyVSAvoidbattery swelling

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent combines vinylene carbonate (VC) with a fluorinated cyclic carbonate compound (Formula 1) to create a composite electrolyte system. This composite approach allows VC to form the initial protective film on the electrode surface while the fluorinated compound suppresses gas generation during high-temperature charging, resolving the contradiction between efficiency improvement and swelling prevention

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent specifies precise compositional parameters: VC at 0.01-5 mass% and the fluorinated cyclic carbonate compound at 0.01-5 mass% in the nonaqueous electrolyte. By controlling these concentration parameters, the electrolyte achieves optimal balance between forming protective films (improving efficiency) and suppressing gas generation (preventing swelling) during continuous high-temperature charging

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If organic solvent is used in nonaqueous electrolyte to enable charge-discharge reactions, then battery operation is enabled, but decomposition occurs at the electrode surface resulting in gas generation and efficiency degradation

Engineering Contradiction:

Improvebattery operationVSAvoidcharge-discharge efficiency

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent employs VC and the fluorinated cyclic carbonate compound to perform preliminary action by forming protective films on the electrode surface before actual charge-discharge operations begin. This preliminary film formation prevents subsequent decomposition of the organic solvent during battery operation, enabling reliable and efficient charging and discharging

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The VC and fluorinated cyclic carbonate compound act as intermediary substances between the electrode and the bulk electrolyte. They form interfacial layers that mediate the interaction, allowing ionic conduction while preventing direct contact and decomposition reactions between the organic solvent and electrode surface

Inventive Principle:

Principle #24Intermediary (Mediator)

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 solution effectively suppresses swelling, maintains high initial charge-discharge efficiency, and enhances capacity retention and recovery ratios even under continuous high-temperature charging.

Implementation Method 1

an organic solvent or the like contained in a nonaqueous electrolyte is decomposed by reduction at a surface of an electrode

Methodology Applied

Scientific EffectReduction: Reduction

Implementation Method 2

a lithium salt, vinylene carbonate, and a compound represented by general formula (1) below

Methodology Applied

Scientific EffectIon conduction: Conduction (electrical)

Data Source

PatentUS9240615B2Nonaqueous electrolyte and nonaqueous electrolyte secondary battery

Publication Date: 2016.01.19 PANASONIC ENERGY CO LTD

AI summary

There is provided a nonaqueous electrolyte that can suppress swelling of a nonaqueous electrolyte secondary battery. A nonaqueous electrolyte for a nonaqueous electrolyte secondary battery 1 contains a lithium salt, vinylene carbonate, and a compound represented by general formula (1) below. In the general formula (1), X is an alkylene group with 2 to 4 carbon atoms that may have a substituent. Rf is a fluorine-containing linear or branched alkyl group with 1 to 6 carbon atoms. R is a linear, branched, or cyclic alkyl group with 1 to 6 carbon atoms that may have a substituent.