Lithium-Sulfur Battery Negative Electrode Using Lithium-Calcium Alloy

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Solution Overview

Problem

Lithium-sulfur accumulators face challenges with the handling and manufacturing of thin negative electrodes made from metallic lithium, which can lead to lithium dendrite formation and high costs, limiting power density and scalability.

Innovation Solution

A lithium-sulfur accumulator with a negative electrode composed of a lithium and calcium alloy, where calcium is present in the range of 2% to 34% atomic, allowing for easier production of thin electrodes with improved mechanical properties and reduced manufacturing costs, eliminating the need for a current collector.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If metallic lithium is used as the negative electrode material, then high energy density is achieved, but handling and manufacturing difficulty increases due to dendrite formation and cost

Engineering Contradiction:

Improveenergy densityVSAvoidhandling and manufacturing difficulty

Core Design Contradiction:

Use of energy by moving objectVSEase of manufacture

Solution Approach 1:

The patent uses a lithium-aluminum alloy as the negative electrode material, combining lithium (providing high energy density) with aluminum (providing mechanical strength and ease of handling). This composite material approach resolves the contradiction by integrating the beneficial properties of both materials: the alloy maintains the high energy density of lithium while gaining the manufacturability and dendrite resistance of aluminum.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent changes the physical and chemical parameters of the negative electrode material by creating a lithium-aluminum alloy with specific composition ratios. This parameter change transforms pure lithium into an alloy form that retains electrochemical activity while improving mechanical properties, handling characteristics, and manufacturing feasibility.

Inventive Principle:

Principle #35Parameter changes

2Power

If thin negative electrodes are produced to increase power density, then power density improves, but mechanical strength decreases leading to handling difficulties

Engineering Contradiction:

Improvepower densityVSAvoidmechanical strength

Core Design Contradiction:

PowerVSStrength

Solution Approach 1:

The lithium-aluminum alloy serves as a composite material where aluminum provides the mechanical strength necessary to maintain thin electrode structures. The alloyed structure allows the negative electrode to be produced at reduced thickness for high power density while the aluminum component prevents structural failure and handling issues.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The alloying creates local structural variations at the material level, where the lithium and aluminum atoms form a distributed composite structure. This local quality enhancement provides mechanical reinforcement throughout the thin electrode, enabling it to maintain strength despite reduced overall thickness.

Inventive Principle:

Principle #3Local quality

3Ease of manufacture

If thin negative electrodes are produced to reduce manufacturing costs, then cost decreases, but manufacturing precision requirements increase

Engineering Contradiction:

Improvemanufacturing costVSAvoidelectrode thickness control

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The lithium-aluminum alloy material inherently provides better processability and formability during manufacturing. The alloy's mechanical properties allow for more tolerant processing conditions, reducing the stringency of thickness control requirements while still achieving thin electrode structures that lower material costs.

Inventive Principle:

Principle #40Composite materials

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 lithium and calcium alloy enables the production of thin, self-supporting negative electrodes with enhanced tensile strength, facilitating higher power density and reducing manufacturing costs, while maintaining high energy storage capacity.

Implementation Method 1

the oxidation reaction of the lithium at the negative electrode that produces electrons, which will supply the external circuit

Methodology Applied

Scientific EffectOxidation reaction: Oxidation

Implementation Method 2

the reduction reaction of the sulfur at the positive electrode

Methodology Applied

Scientific EffectReduction reaction: Reduction

Implementation Method 3

production of ions that will circulate from one electrode to the other by means of an electrolyte

Methodology Applied

Scientific EffectIon transport: Ion Exchange

Data Source

PatentUS11289732B2Lithium electrochemical accumulator of the lithium-sulfur type comprising a specific negative-electrode material

Publication Date: 2022.03.29 COMMISSARIAT A LENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES

AI summary

A lithium-sulfur accumulator comprising at least one electrochemical cell comprising a positive electrode comprising, as active material, at least one sulfur-containing material, a negative electrode and an electrolyte conducting lithium ions disposed between the negative electrode and the positive electrode, wherein the negative electrode comprises, as active material, a lithium and calcium alloy, wherein the calcium is present in the alloy to the extent of 2% to 34% atomic.