Solid Electrolyte Separator with Graded Conductivity for Battery Safety

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Solution Overview

Problem

Solid electrolyte separators in secondary batteries face challenges with lithium ion conductivity variations, leading to uneven ion flow and accelerated deterioration at electrode corners, which affects cycle life and safety.

Innovation Solution

A solid electrolyte separator with a central region of higher lithium ion conductivity and a peripheral edge region of lower conductivity, designed to reduce ion flow concentration at electrode corners, is implemented to improve cycle life and safety.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a solid electrolyte separator with uniform high lithium ion conductivity is used, then the energy density and discharge capacity are improved, but the ion flow becomes uneven and deterioration at electrode corners accelerates

Engineering Contradiction:
Improvedischarge capacityVSAvoidcycle life
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The solid electrolyte separator is designed with spatially varying lithium ion conductivity: the central region has higher conductivity (first conductivity) to maintain high discharge capacity, while the peripheral edge region has lower conductivity (second conductivity) to reduce ion flow concentration at electrode corners. This local differentiation resolves the contradiction by optimizing performance in different spatial zones.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The separator is segmented into distinct conductivity regions - a central high-conductivity zone and a peripheral low-conductivity zone. This segmentation allows independent optimization of each region's function, enabling the separator to simultaneously achieve high overall capacity while protecting corner areas from excessive ion flow.

Inventive Principle:
Principle #1Segmentation

2Reliability

If the lithium ion conductivity in the peripheral edge region is reduced, then the ion flow concentration at electrode corners is reduced, but the overall lithium ion conductivity of the separator is lowered

Engineering Contradiction:
ImprovesafetyVSAvoidlithium ion conductivity
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

Different regions of the separator are assigned different conductivity qualities appropriate to their functional requirements. The peripheral region's lower conductivity is intentionally designed to improve safety by reducing corner deterioration, while the central region's higher conductivity maintains overall productivity.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The lithium ion conductivity parameter is changed spatially across the separator - higher in the central region and lower in the peripheral edge region. This parameter differentiation enables the separator to achieve both improved safety through reduced corner ion flow and maintained overall conductivity through the high-performance central zone.

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 reduces ion flow concentration at electrode corners, enhancing the cycle life and safety of secondary batteries by optimizing lithium ion conductivity distribution.

Implementation Method 1

a solid electrolyte separator in form of a sheet containing a solid electrolyte having a lithium ion conductivity

Methodology Applied
Scientific EffectIonic conduction: Conduction (electrical)

Data Source

PatentEP3460895B1Secondary battery with a solid electrolyte separator, battery pack and vehicle
Publication Date: 2021.03.24 KK TOSHIBA
  • EP3460895B1 patent drawingFigure 1~2
  • EP3460895B1 patent drawingFigure 3~4
  • EP3460895B1 patent drawingFigure 5~6

AI summary

According to one approach, a solid electrolyte separator (10) is provided. The solid electrolyte separator (10) is a sheet containing a solid electrolyte having a lithium ion conductivity. A first lithium ion conductivity in a peripheral edge region (12) along an in-plane direction of the sheet is lower than a second lithium ion conductivity in a central region (11) along the in-plane direction of the sheet.