Lithium Battery Negative Electrode with Concavo-Convex Current Collector

Solution Overview

Problem

Current lithium batteries face challenges in achieving high power and energy density while maintaining low self-discharge rates, with primary lithium batteries having lower output power and higher self-discharge rates compared to lithium-ion batteries, and existing methods to enhance metal lithium electrodes are either inefficient or costly and complex.

Innovation Solution

A lithium battery design featuring a negative electrode current collector with a planar or concavo-convex structure made from metal foil or mesh, coated with a thin metal lithium layer during charging, and an electrolyte system with high lithium salt concentration and flame-retardant solvents to facilitate even lithium deposition and enhance safety.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the thickness of metal lithium in the negative electrode is increased to improve mechanical strength, then the tension strength is improved, but the energy density is reduced and safety hazards increase

Engineering Contradiction:

Improvetension strengthVSAvoidenergy density

Core Design Contradiction:

StrengthVSQuantity of substance

Solution Approach 1:

The negative electrode is segmented into a thin metal lithium layer (5-50 nm) coated on a conductive support component (metal mesh or metal tape). This segmentation allows the thin lithium layer to provide sufficient tensile strength while the conductive support provides mechanical reinforcement, avoiding the need for thick lithium that would reduce energy density and create safety hazards.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The negative electrode uses a composite structure combining metal lithium with a conductive support component (metal mesh or metal tape). This composite material approach allows the thin lithium layer to maintain electrical conductivity and mechanical strength simultaneously, resolving the contradiction between strength and energy density.

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If the metal lithium negative electrode is made thinner to increase energy density, then the energy density is improved, but the electrode breaks during battery preparation due to low tension strength

Engineering Contradiction:

Improveenergy densityVSAvoidtension strength

Core Design Contradiction:

Quantity of substanceVSStrength

Solution Approach 1:

The negative electrode is segmented into a thin metal lithium layer (5-50 nm) coated on a conductive support component (metal mesh or metal tape). This segmentation allows the thin lithium layer to provide sufficient tensile strength while the conductive support provides mechanical reinforcement, avoiding the need for thick lithium that would reduce energy density and create safety hazards.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The negative electrode uses a composite structure combining metal lithium with a conductive support component (metal mesh or metal tape). This composite material approach allows the thin lithium layer to maintain electrical conductivity and mechanical strength simultaneously, resolving the contradiction between strength and energy density.

Inventive Principle:

Principle #40Composite materials

3Strength

If spraying or compression methods are used to add metal lithium to a thin conductive support, then the tension strength is improved, but the preparation cost increases and the process becomes complicated

Engineering Contradiction:

Improvetension strengthVSAvoidpreparation procedure

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical processes (spraying or compression in inert atmospheres) with a simple coating process that can be performed in conventional environments. The metal lithium is coated on the conductive support through a straightforward deposition method, eliminating the need for expensive inert atmosphere equipment and complex mechanical operations.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the thickness parameter of the metal lithium layer to an optimized range (5-50 nm) that provides sufficient mechanical strength without requiring complex preparation processes. This parameter optimization allows simple coating methods to achieve the desired performance, avoiding costly and complicated spraying or compression techniques.

Inventive Principle:

Principle #35Parameter changes

4Quantity of substance

If the lithium primary battery structure is used to increase energy density, then the energy density is improved, but the output power is reduced

Engineering Contradiction:

Improveenergy densityVSAvoidoutput power

Core Design Contradiction:

Quantity of substanceVSPower

Solution Approach 1:

The negative electrode uses a composite structure combining metal lithium with a conductive support component (metal mesh or metal tape). This composite material approach allows the thin lithium layer to maintain electrical conductivity and mechanical strength simultaneously, resolving the contradiction between strength and energy density.

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 design increases energy and power density, reduces self-discharge rates, and improves safety by allowing for even lithium deposition and preventing electrode breakage due to volume expansion, while maintaining the simplicity and cost-effectiveness of the manufacturing process.

Implementation Method 1

the negative current collector is coated with a thin metal lithium coating in the manner of plating during the charging

Methodology Applied

Scientific EffectElectrodeposition: Electrodeposition

Implementation Method 2

A high number of the migrated lithium ions will facilitate the quick migration of lithium ions, thereby facilitating the lithium deposition on the negative electrode surface

Methodology Applied

Scientific EffectIon migration: Ion Exchange

Data Source

PatentUS9742031B2Lithium battery and the preparation method thereof

Publication Date: 2017.08.22 EVE ENERGY CO LTD

AI summary

The present invention discloses a lithium battery, which comprises of a positive electrode plate, a negative electrode current collector substrate, a separator and electrolyte between the positive electrode plate and the negative electrode current collector substrate. The positive electrode plate comprises a positive electrode collector, a positive electrode active material-containing positive electrode layer attached to the positive electrode collector and positive electrode tab welded to the positive electrode collector. The negative electrode current collector substrate comprises a negative electrode current collector and negative electrode tab welded to the negative electrode current collector. The negative electrode current collector substrate is a current collector substrate with 6˜60 μm thickness having a planar or concavo-convex structure which is made from metal foil material or metal mesh with 6˜25 μm thickness. The electrolyte contains lithium salt and solvent, wherein the lithium salt is lithium hexafluorophosphate and its concentration in the electrolyte is between 1.5˜7 mol/L. The lithium battery of the present invention has characteristics of high power, high energy and low self-discharge rate. Meanwhile, the present invention also discloses a preparation method of the lithium battery and use thereof.