Non-aqueous electrolyte battery with electron-withdrawing solvent

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Solution Overview

Problem

Lithium-containing transition metal oxide batteries experience degradation in rate characteristics due to metal atom elution during storage at high voltages and temperatures, leading to impedance increase and clogging of the separator, which existing non-aqueous electrolytes and separators cannot effectively prevent.

Innovation Solution

Incorporating a non-aqueous solvent with electron-withdrawing substituents, such as sulfonic, nitrile, fluorine-containing, or chlorine-containing solvents, and a separator material with electron-withdrawing substituents or unshared electron pairs, like polytetrafluoroethylene, to trap metal cations eluted from the positive electrode active material, thereby preventing deposition on the negative electrode.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional non-aqueous electrolyte and separator are used, then the battery can operate at high voltage and temperature, but metal atoms elute from the positive electrode and deposit on the negative electrode, causing impedance increase and rate characteristic degradation

Engineering Contradiction:

Improverate characteristics after storageVSAvoidmetal atom elution and deposition

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent introduces a fluorinated cyclic carbonic acid ester as an intermediary substance in the non-aqueous electrolyte. This compound acts as a mediator that preferentially reacts with eluted metal atoms to form stable complexes, preventing their deposition on the negative electrode. The fluorinated cyclic carboxylic acid ester serves as a chemical intermediary that captures harmful metal species before they can cause damage to the battery electrodes.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent modifies the chemical composition parameters of the non-aqueous electrolyte by incorporating fluorinated cyclic carbonic acid ester and fluorinated cyclic carboxylic acid ester at specific concentrations (0.01-5% and 0.01-5% respectively). These parameter changes alter the electrolyte's chemical properties to enhance its ability to complex with metal atoms, thereby preventing their harmful deposition while maintaining battery operation at high voltage and temperature.

Inventive Principle:

Principle #35Parameter changes

2Duration of action of moving object

If the battery is stored at high voltage and high temperature to maintain operational readiness, then the positive electrode active material undergoes intensive metal elution, but this leads to separator clogging and negative electrode impedance increase

Engineering Contradiction:

Improvestorage readinessVSAvoidmetal elution during storage

Core Design Contradiction:

Duration of action of moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary action by having the fluorinated cyclic carbonic acid ester and fluorinated cyclic carboxylic acid ester present in the electrolyte before metal elution occurs during storage. These compounds are pre-positioned to immediately complex with any metal atoms that elute from the positive electrode, preventing their migration and deposition. This preliminary presence of protective agents ensures that even during extended high-voltage storage, metal atoms are captured before they can cause separator clogging or negative electrode impedance increase.

Inventive Principle:

Principle #10Preliminary action

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

This approach effectively alleviates the degradation of rate characteristics by trapping metal cations, maintaining battery performance and capacity recovery even after storage at high voltages and temperatures.

Implementation Method 1

the non-aqueous solvent includes a solvent having an electron-withdrawing substituent. The solvent having an electron-withdrawing substituent includes at least one selected from the group consisting of a sulfonic solvent, a nitrile solvent, a ketonic solvent, a fluorine-containing solvent, a chlorine-containing solvent and a carboxylic acid ester solvent

Methodology Applied

Scientific EffectElectron-withdrawing substituent effect:

Implementation Method 2

a separator including a material containing an electron-withdrawing substituent or an atom having an unshared electron pair... to trap metal cations eluted from the positive electrode active material

Methodology Applied

Scientific EffectIon trapping:

Implementation Method 3

The separator includes a material containing an electron-withdrawing substituent or an atom having an unshared electron pair

Methodology Applied

Scientific EffectAdsorption: Adsorption

Data Source

PatentUS8067120B2Non-aqueous electrolyte secondary battery

Publication Date: 2011.11.29 PANASONIC HOLDINGS CORP

AI summary

The non-aqueous electrolyte secondary battery of the present invention includes a positive electrode containing a lithium-containing transition metal oxide as a positive electrode active material, a negative electrode, a separator interposed between the positive electrode and the negative electrode and a non-aqueous electrolyte. The non-aqueous electrolyte includes a non-aqueous solvent and a solute dissolved therein, and the non-aqueous solvent includes a solvent having an electron-withdrawing substituent. The solvent having an electron-withdrawing substituent includes at least one selected from the group consisting of a sulfonic solvent, a nitrile solvent, a ketonic solvent, a fluorine-containing solvent, a chlorine-containing solvent and a carboxylic acid ester solvent. The separator includes a material containing an electron-withdrawing substituent or an atom having an unshared electron pair.