Non-aqueous Electrolyte Battery Biphenyl Coating DME Decomposition

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Solution Overview

Problem

Non-aqueous electrolyte secondary batteries using 1,2-dimethoxyethane (DME) face oxidative decomposition issues at higher voltages, reducing cycle durability and limiting their energy density and low-temperature performance.

Innovation Solution

A method involving two electrolyte solutions is employed, where the first solution contains biphenyl (BP) but not DME, and the second solution contains DME, with the electrode group being charged to 4.3 V or more to form an oxide coating film from BP, which suppresses DME oxidative decomposition, and includes composite particles with amorphous carbon to enhance desolvation and prevent co-intercalation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If DME is used as electrolyte solvent to improve low-temperature properties and dissociation, then low-temperature performance and electrolyte dissociation are improved, but oxidative decomposition occurs at high voltage reducing cycle durability

Engineering Contradiction:

Improvelow-temperature performanceVSAvoidcycle durability

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The patent applies preliminary action by forming an oxide coating film on the positive electrode surface through initial charging to 4.3V or more before actual battery operation. This pre-formed coating acts as a protective barrier that prevents subsequent oxidative decomposition of DME during normal charging-discharging cycles, thereby resolving the contradiction between using DME for low-temperature performance and maintaining cycle durability at high voltage

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent changes the voltage parameter by charging to 4.3V or more during the initial formation process. This specific voltage threshold is critical as it enables complete oxidative decomposition of biphenyl to form a robust oxide coating film, which then protects DME from decomposition during subsequent operation at lower voltages, thus improving cycle durability while maintaining low-temperature performance

Inventive Principle:

Principle #35Parameter changes

2Reliability

If charging voltage is increased to 4.3 V or more to form oxide coating film, then oxidative decomposition of DME is suppressed, but higher voltage may cause other electrode degradation

Engineering Contradiction:

Improveoxidative decomposition suppressionVSAvoidelectrode degradation

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent segments the battery formation process into two distinct stages: (1) initial high-voltage charging to 4.3V or more to form the protective oxide coating film, and (2) subsequent normal operation at lower voltages. This segmentation allows the high voltage to be applied only temporarily during formation when the coating is needed, while avoiding prolonged high-voltage exposure that would cause electrode degradation during normal use

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies beforehand cushioning by forming the oxide coating film on the positive electrode surface before actual battery operation begins. This coating acts as a cushioning layer that absorbs and protects the electrode from the harmful effects of high voltage, preventing both DME decomposition and electrode degradation by providing a stable interface between the electrode and electrolyte

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 suppresses oxidative decomposition of DME, improving cycle durability and low-temperature properties while allowing for higher operating voltages and energy density in non-aqueous electrolyte secondary batteries.

Implementation Method 1

oxidative decomposition of biphenyl (BP) at a voltage of 4.3 V or more can suppress oxidative decomposition of DME

Methodology Applied

Scientific EffectOxidative decomposition: Oxidation

Implementation Method 2

a specific oxide coating film has a function of suppressing oxidative decomposition of 1,2-dimethoxyethane (DME)

Methodology Applied

Scientific EffectOxidative decomposition suppression: Oxidation

Implementation Method 3

DME has a high donor number. Accordingly, DME is advantageous for dissociation of a supporting electrolyte salt (lithium salt)

Methodology Applied

Scientific EffectDissociation:

Implementation Method 4

includes composite particles with amorphous carbon to enhance desolvation and prevent co-intercalation

Methodology Applied

Scientific EffectDesolvation:

Data Source

PatentUS10530013B2Method of manufacturing non-aqueous electrolyte secondary battery

Publication Date: 2020.01.07 TOYOTA JIDOSHA KK

AI summary

A method of manufacturing a non-aqueous electrolyte secondary battery includes: (A) constructing an electrode group including a positive electrode and a negative electrode; (B) impregnating the electrode group with a first electrolyte solution; (C) charging the electrode group impregnated with the first electrolyte solution to a voltage of 4.3 V or more; and (E) manufacturing the non-aqueous electrolyte secondary battery by impregnating the electrode group with a second electrolyte solution after the charging. The first electrolyte solution includes a first solvent, a first lithium salt, and biphenyl. The first solvent does not include 1,2-dimethoxyethane. The second electrolyte solution includes a second solvent and a second lithium salt. The second solvent includes 1,2-dimethoxyethane.