Electrolyte Solution for High-Temperature Battery Stability

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Solution Overview

Problem

Non-aqueous electrolyte secondary batteries using fluoroethylene carbonate and chain carboxylate ester suffer from deterioration of output characteristics and charge/discharge cycle performance under high temperature environments due to the reductive decomposition of fluoroethylene carbonate, leading to increased viscosity and electrode interface resistance.

Innovation Solution

A non-aqueous electrolyte solution comprising lithium salts LiPO2F2 and LiSO3F at concentrations of 0.15 mol/L or more, combined with a solvent including fluoroethylene carbonate and a chain carboxylate ester with a dielectric constant of 6.0 or more, which suppresses the decomposition of fluoroethylene carbonate and generates a film that reduces viscosity and electrode resistance, thereby enhancing battery performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If fluoroethylene carbonate and chain carboxylate ester are used in the non-aqueous electrolyte solution, then output characteristics are improved, but charge/discharge cycle characteristics deteriorate under high temperature environment

Engineering Contradiction:

Improveoutput characteristicsVSAvoidcharge/discharge cycle characteristics

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The patent changes the chemical composition parameters of the electrolyte solution by introducing specific lithium salts (LiPO2F2 and LiSO3F) with defined concentration ratios (0.15 mol/L or more), which modifies the electrochemical behavior to suppress HF generation while maintaining output characteristics

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite electrolyte system combining fluoroethylene carbonate, chain carboxylate ester, and specific lithium salts in defined proportions, where the synergistic interaction between components suppresses decomposition reactions while maintaining conductivity and output performance

Inventive Principle:

Principle #40Composite materials

2Power

If fluoroethylene carbonate is used in the non-aqueous electrolyte solution, then output characteristics are improved, but decomposition occurs under high temperature environment to generate hydrofluoric acid

Engineering Contradiction:

Improveoutput characteristicsVSAvoidhydrofluoric acid generation

Core Design Contradiction:

PowerVSObject-generated harmful factors

Solution Approach 1:

The patent converts the potentially harmful decomposition of fluoroethylene carbonate into a beneficial process by controlling it to form protective films on electrodes that prevent further decomposition and HF generation, while the specific lithium salt composition suppresses excessive decomposition

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent introduces specific lithium salts (LiPO2F2 and LiSO3F) as intermediary substances that mediate between fluoroethylene carbonate and the electrode surfaces, suppressing direct decomposition reactions that generate HF while maintaining the beneficial output characteristics

Inventive Principle:

Principle #24Intermediary (Mediator)

3Power

If chain carboxylate ester is used in the non-aqueous electrolyte solution, then viscosity is reduced and output characteristics are improved, but decomposition occurs under high temperature environment

Engineering Contradiction:

Improveoutput characteristicsVSAvoidelectrolyte solution stability

Core Design Contradiction:

PowerVSStability of the object's composition

Solution Approach 1:

The patent optimizes the concentration parameters of chain carboxylate ester and specific lithium salts to achieve a balance where viscosity is sufficiently reduced for good output characteristics while the lithium salt concentration (0.15 mol/L or more) provides sufficient stability to suppress decomposition under high temperature conditions

Inventive Principle:

Principle #35Parameter changes

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 maintains good output characteristics and charge/discharge cycle performance under high temperature conditions by preventing excessive decomposition of fluoroethylene carbonate and suppressing hydrofluoric acid generation, thus improving the stability and efficiency of the non-aqueous electrolyte secondary battery.

Implementation Method 1

a non-aqueous electrolyte secondary battery comprising a positive electrode, a negative electrode, and a non-aqueous electrolyte solution wherein lithium ions are transferred between the positive electrode and the negative electrode

Methodology Applied

Scientific EffectIon transfer: Ion Repulsion/Attraction

Implementation Method 2

fluoroethylene carbonate is reductively decomposed on the negative electrode and the like by charge/discharge under a high temperature environment (for example, 45° C. or more) to generate hydrofluoric acid (HF)

Methodology Applied

Scientific EffectReductive decomposition: Reduction

Data Source

PatentUS11367903B2Nonaqueous electrolyte solution and nonaqueous electrolyte secondary battery

Publication Date: 2022.06.21 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

A nonaqueous electrolyte solution according to one embodiment of the present disclosure contains a lithium salt and a nonaqueous solvent; the nonaqueous solvent contains fluoroethylene carbonate and a chain carboxylic acid ester having a dielectric constant of 6.0 or more; the lithium salt contains LiPO2F2 and LiSO3F; and the respective concentrations of LiPO2F2 and LiSO3F in the non-aqueous solvent are 0.15 mol/L or more.