Electric Storage Device Inorganic Filler Layer Gas Swelling

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Solution Overview

Problem

The challenge is to inhibit swelling in nonaqueous electrolyte cells due to gas generation during the initial charge and discharge, particularly when lithium difluorobis(oxalato)phosphate is added, as it can lead to reduced cycle performance and shortened cell life.

Innovation Solution

An electric storage device configuration with an inorganic filler layer between the electrodes, where the inorganic filler layer is disposed on the separator or active material layers, and the nonaqueous electrolyte solution contains lithium difluorobis(oxalato)phosphate, with specific porosity and thickness ranges to prevent gas generation and swelling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If lithium difluorobis(oxalato)phosphate is added to the nonaqueous electrolyte solution, then cycle performance and high-temperature storageability are improved, but gas generation during initial charge increases causing cell swelling

Engineering Contradiction:

Improvecycle performanceVSAvoidgas generation

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

An insulating layer is introduced as an intermediary between the electrode and the electrolyte solution containing lithium difluorobis(oxalato)phosphate. This layer prevents direct contact between the additive and the electrode during initial charge, thereby suppressing gas generation while allowing the additive to function during normal operation and storage.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The insulating layer is applied in advance to the electrode surface before the cell is filled with the electrolyte solution. This preliminary protective action prevents the harmful gas generation effect from occurring during initial charge, while not interfering with the beneficial effects of the additive during subsequent cycling and storage.

Inventive Principle:

Principle #9Preliminary anti-action

2Reliability

If a sufficient amount of lithium difluorobis(oxalato)phosphate is added to enhance performance, then cycle performance and storageability are improved, but cell swelling increases due to gas generation during initial charge

Engineering Contradiction:

ImprovestorageabilityVSAvoidcell swelling

Core Design Contradiction:

ReliabilityVSShape

Solution Approach 1:

The insulating layer serves as a mediator that allows full utilization of the lithium difluorobis(oxalato)phosphate additive for improving storageability without suffering from the detrimental gas generation effect. The layer blocks the harmful interaction during initial charge while permitting the additive to exert its beneficial effects during normal operation.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Object-generated harmful factors

If an insulating layer is provided on the separator to inhibit gas generation, then gas generation during cycle and storage is suppressed, but gas generation during initial charge is not adequately inhibited

Engineering Contradiction:

Improvegas generation during cycleVSAvoidgas generation during initial charge

Core Design Contradiction:

Object-generated harmful factorsVSReliability

Solution Approach 1:

Instead of relying on the separator's insulating layer which provides uniform protection, the invention applies an insulating layer directly to the electrode surface where the harmful reaction occurs. This localized approach targets the specific problem area during initial charge, providing effective protection where it is most needed.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The insulating layer on the electrode acts as a local intermediary that prevents direct contact between the lithium difluorobis(oxalato)phosphate in the electrolyte and the electrode surface during initial charge, thereby suppressing gas generation at the critical interface where the harmful reaction occurs.

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

This configuration effectively inhibits swelling and enhances cycle performance by allowing higher concentrations of lithium difluorobis(oxalato)phosphate, improving the energy and power density of the cells while maintaining lithium ion diffusion efficiency.

Implementation Method 1

an inorganic filler layer disposed between the positive electrode and the negative electrode... effectively inhibits swelling and enhances cycle performance

Methodology Applied

Scientific EffectGas absorption: Absorption (physical)

Implementation Method 2

ions are accepted and donated between the positive electrode and negative electrode in a nonaqueous electrolyte solution... maintaining lithium ion diffusion efficiency

Methodology Applied

Scientific EffectIon diffusion: Diffusion

Implementation Method 3

lithium difluorobis(oxalato)phosphate added to the nonaqueous electrolyte solution of a cell can be reductively decomposed to generate gas during initial charge

Methodology Applied

Scientific EffectReductive decomposition: Reduction

Data Source

PatentEP2978048B1Electric storage device

Publication Date: 2018.07.04 GS YUASA INT LTD

AI summary

Provided is an electric storage device including a positive electrode, a negative electrode, a separator disposed between the positive electrode and the negative electrode, a nonaqueous electrolyte solution in which an electrolyte is dissolved in a nonaqueous solvent, wherein an inorganic filler layer is disposed between the positive electrode and the negative electrode and the nonaqueous electrolyte solution contains lithium difluorobis(oxalato)phosphate.