Garnet Ceramic Solid Electrolyte for Lithium Battery Safety

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Solution Overview

Problem

The development of a solid electrolyte for all-solid-state lithium secondary batteries has been hindered by the lack of a ceramic material with sufficient compactness and conductivity, particularly due to the challenges posed by lithium metal dendrite crystallization and the reactivity of lithium metal, which has limited the use of lithium metal in batteries.

Innovation Solution

A ceramic material with a garnet-type or garnet-like crystal structure containing lithium, lanthanum, zirconium, oxygen, and aluminum is developed, which is produced through a process involving multiple firing steps and the inclusion of aluminum to enhance sintering density and lithium conductivity, thereby stabilizing the material for use as a solid electrolyte.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If lithium metal is used in the battery to improve specific capacity and energy density, then battery performance is improved, but lithium metal dendrite crystallization occurs causing safety problems

Engineering Contradiction:

Improvespecific capacityVSAvoidsafety

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

A solid electrolyte layer is introduced as an intermediary between the lithium metal anode and cathode. This solid electrolyte prevents direct contact and dendrite penetration while allowing lithium ion transport, thus maintaining high capacity benefits while eliminating safety hazards associated with liquid electrolytes and dendrite formation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The electrolyte state is changed from liquid to solid phase. This phase change fundamentally alters the interaction between lithium metal and electrolyte, preventing dendrite crystallization and penetration while maintaining ionic conductivity necessary for battery operation.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If a solid electrolyte is used to prevent lithium dendrite penetration, then safety is improved, but lithium metal reactivity and lack of suitable solid electrolyte materials remain problems

Engineering Contradiction:

ImprovesafetyVSAvoidmaterial availability

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The solid electrolyte is formulated as a composite material containing multiple components including lithium phosphate, lanthanum phosphate, and various dopants. This composite structure combines the benefits of high ionic conductivity, chemical stability with lithium metal, and manufacturability, overcoming the limitations of single-component solid electrolytes.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The chemical composition and stoichiometric ratios of the solid electrolyte components are optimized to achieve the desired balance between ionic conductivity, stability, and manufacturability. By adjusting dopant concentrations and phase compositions, the material properties are tuned to satisfy both safety requirements and manufacturing feasibility.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If LLZ ceramic material is used as solid electrolyte, then lithium resistance is improved, but insufficient compactness and conductivity prevent practical application

Engineering Contradiction:

Improvelithium resistanceVSAvoidcompactness

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The solid electrolyte combines LLZ (Li7La3Zr2O12) ceramic material with lithium phosphate and lanthanum phosphate components. This composite formulation enhances the compactness and density of the sintered electrolyte while maintaining the excellent lithium resistance properties of LLZ, making it suitable for practical battery applications.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The sintering temperature, time, and atmospheric conditions are optimized to achieve maximum compactness and density of the solid electrolyte. By controlling these processing parameters, the material achieves both high lithium resistance and sufficient compactness for practical use.

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 resulting ceramic material exhibits improved lithium conductivity and stability, enabling the safe and efficient operation of all-solid-state lithium secondary batteries by preventing lithium metal dendrite formation and enhancing battery performance.

Implementation Method 1

exhibits excellent lithium conductivity

Methodology Applied

Scientific EffectIon conduction: Conduction (electrical)

Implementation Method 2

a first firing step of firing a starting material containing a lithium (Li) component, lanthanum (La) component, and zirconium (Zr) component to obtain a primary firing powder for ceramic synthesis

Methodology Applied

Scientific EffectSintering: Sintering

Data Source

PatentUS9350047B2Ceramic material and process for producing the same

Publication Date: 2016.05.24 SCHOTT AG

AI summary

A ceramic material that can exhibit sufficient compactness and lithium (Li) conductivity to enable the use thereof as a solid electrolyte material for a lithium secondary battery and the like is provided. The ceramic material contains aluminum (Al) and has a garnet-type crystal structure or a garnet-like crystal structure containing lithium (Li), lanthanum (La), zirconium (Zr) and oxygen (O).