Non-aqueous Electrolyte Battery Flame Retardant Gradient

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Solution Overview

Problem

Conventional non-aqueous electrolyte secondary batteries with flame retardants experience a decrease in flash point over time, leading to safety concerns and deterioration of battery characteristics such as cycle and floating charge characteristics.

Innovation Solution

A non-aqueous electrolyte secondary battery design where the flame retardant concentration in the electrolyte solution within the electrode body is lower than in the solution between the electrode body and the outer casing, preventing consumption of the flame retardant during charging and discharging and maintaining a higher flash point.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a flame retardant is mixed into the electrolyte solution to raise the flash point, then fire safety is improved, but the flash point may decrease over time and battery characteristics deteriorate

Engineering Contradiction:

Improvefire safetyVSAvoidbattery characteristics

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The electrolyte solution is divided into two regions with different flame retardant concentrations: a first electrolyte solution with lower concentration inside the electrode body and a second electrolyte solution with higher concentration outside the electrode body. This segmentation allows the flame retardant to be concentrated where it is needed for safety while minimizing its presence where it causes deterioration.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different parts of the battery have different electrolyte compositions tailored to their specific needs. The region near the electrodes (where electrochemical reactions occur) has lower flame retardant concentration to prevent characteristic deterioration, while the region away from electrodes has higher concentration to provide fire safety.

Inventive Principle:

Principle #3Local quality

2Temperature

If a flame retardant is added to the electrolyte solution, then the flash point is raised, but the flash point may drop after long-term use

Engineering Contradiction:

Improveflash pointVSAvoidlong-term stability

Core Design Contradiction:

TemperatureVSDuration of action of stationary object

Solution Approach 1:

The battery is pre-filled with a first electrolyte solution containing lower flame retardant concentration before electrochemical reactions begin. This preliminary configuration prevents excessive flame retardant consumption during reactions, ensuring the flash point remains stable over long-term use.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The flame retardant concentration parameter is optimized differently in two regions: lower concentration (0.01-5 wt%) in the first electrolyte solution near electrodes to minimize reaction interference, and higher concentration (5-20 wt%) in the second electrolyte solution away from electrodes to maintain flash point stability.

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

This configuration enhances safety by maintaining a stable flash point and reduces the deterioration of battery characteristics, such as cycle characteristics and capacity retention, even after repeated charging and discharging.

Implementation Method 1

a non-aqueous electrolyte solution containing a flame retardant; a positive electrode including a positive-electrode active material and a negative electrode including a negative-electrode active material are stacked with a separator interposed therebetween

Methodology Applied

Scientific EffectIon conduction: Conduction (electrical)

Implementation Method 2

mixing a flame retardant into an electrolyte solution has been studied as one of techniques of raising a flashpoint of an electrolyte solution

Methodology Applied

Scientific EffectFlame retardancy:

Data Source

PatentEP2933868B1Non-aqueous electrolytic solution secondary battery and method for producing non-aqueous electrolytic solution secondary battery

Publication Date: 2019.04.10 ELIIY POWER

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AI summary

The present invention provides a non-aqueous electrolyte secondary battery that can suppress a drop in a flash point of an electrolyte solution even if the non-aqueous electrolyte secondary battery is used for a long time. The non-aqueous electrolyte secondary battery includes: an electrode body having a structure in which a positive electrode including a positive-electrode active material and a negative electrode including a negative-electrode active material are stacked with a separator interposed therebetween; a non-aqueous electrolyte solution containing a flame retardant; and an outer casing accommodating the electrode body and the non-aqueous electrolyte solution. The non-aqueous electrolyte solution in the electrode body has a flame retardant concentration lower than a flame retardant concentration in the non-aqueous electrolyte solution between the electrode body and the outer casing.