Composite Solid Electrolyte Membrane for All-Solid-State Battery

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Solution Overview

Problem

All-solid-state secondary batteries face issues with interfacial resistance and life characteristics due to dead spaces between electrodes and solid electrolyte membranes, which are exacerbated by non-uniform electrode surfaces and the use of liquid electrolytes that can soften the solid electrolyte.

Innovation Solution

A composite solid electrolyte membrane is introduced, comprising a phase transformation layer with a plasticizer and lithium salt that liquefies at increased temperatures, a porous polymer sheet layer, and a solid polymer electrolyte layer, reducing interfacial resistance and improving adhesion and ion conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a solid electrolyte membrane is used in an all-solid-state battery, then safety is improved and liquid electrolyte leakage is prevented, but dead spaces are generated at the electrode interface leading to increased resistance

Engineering Contradiction:

ImprovesafetyVSAvoidinterface contact uniformity

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The solid electrolyte membrane is divided into multiple layers: a porous layer (first solid electrolyte layer) that conforms to electrode surface irregularities, and a non-porous layer (second solid electrolyte layer) that provides bulk ionic conductivity. This segmentation allows the porous layer to fill dead spaces and improve interface contact while the non-porous layer maintains overall safety and ionic transport.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A porous layer is introduced as the first solid electrolyte layer in contact with the electrode. The porous structure allows the layer to adapt to surface irregularities of the electrode, fill dead spaces, and improve interfacial contact area, thereby reducing resistance while maintaining the solid electrolyte's safety advantages.

Inventive Principle:

Principle #31Porous materials

2Manufacturing precision

If liquid electrolyte is added to fill dead spaces, then interfacial resistance is reduced, but the solid electrolyte membrane softens and manufacturing complexity increases

Engineering Contradiction:

Improveinterface contact uniformityVSAvoidmanufacturing process complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The physical and chemical parameters of the solid electrolyte are modified by creating a composite structure with porous and non-porous layers. The porous layer has different density and structural parameters that enable it to fill dead spaces effectively, while the non-porous layer maintains the original safety properties. This parameter change allows achieving good interface contact without adding liquid electrolyte.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The solid electrolyte membrane is designed as a composite material system consisting of a porous layer and a non-porous layer. This composite structure combines the advantages of both porous structures (good interface contact) and dense structures (high ionic conductivity and safety), eliminating the need for liquid electrolyte addition and simplifying the manufacturing process.

Inventive Principle:

Principle #40Composite materials

3Quantity of substance

If the electrode surface is non-uniform due to active material shape, then capacity density is improved, but dead spaces increase and resistance increases

Engineering Contradiction:

Improvecapacity densityVSAvoidinterface contact uniformity

Core Design Contradiction:

Quantity of substanceVSManufacturing precision

Solution Approach 1:

The solid electrolyte membrane is designed with local quality variation through its layered structure. The porous first layer is specifically positioned at the electrode interface where non-uniformity exists, providing local adaptation to surface irregularities. The non-porous second layer provides uniform bulk properties. This local quality approach allows maintaining high capacity density from non-uniform electrode surfaces while improving interface contact.

Inventive Principle:

Principle #3Local quality

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 composite membrane reduces interfacial resistance, enhances ion conductivity, and improves the life and safety of the battery by filling dead spaces and forming a solid electrolyte interface film, while preventing softening of the solid polymer electrolyte layer.

Implementation Method 1

a phase transformation layer with a plasticizer and lithium salt that liquefies at increased temperatures

Methodology Applied

Scientific EffectPhase transformation: Phase Change

Data Source

PatentUS11476498B2Complex solid electrolyte membrane for all-solid-state battery and all-solid-state battery including same

Publication Date: 2022.10.18 LG ENERGY SOLUTION LTD

AI summary

Provided is a composite solid electrolyte membrane for an all-solid-state secondary battery, including: a phase transformation layer containing a plasticizer and a lithium salt; a porous polymer sheet layer; and a solid polymer electrolyte layer, wherein the phase transformation layer, the porous polymer sheet layer and the solid polymer electrolyte layer are stacked successively, and the phase transformation layer is disposed in such a manner that it faces a negative electrode when manufacturing an electrode assembly. An all-solid-state secondary battery including the composite solid electrolyte membrane is also provided. The composite solid electrolyte membrane for an all-solid-state secondary battery reduces the interfacial resistance with an electrode, increases ion conductivity, and improves the safety of a battery.