Lithium Metal Anode Dual Protective Layer Design

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Solution Overview

Problem

Rechargeable lithium metal batteries face challenges due to lithium metal dendrite formation and reactions between lithium metal and electrolyte, leading to safety concerns, internal short circuits, and rapid capacity decay, which have hindered their commercialization for electric vehicles and electronic devices.

Innovation Solution

A lithium metal secondary battery design featuring a lithium anode with two protective layers: a thin lithium ion-conducting layer and an elastomer layer with high recoverable tensile strain, which prevents dendrite formation and maintains a stable lithium ion interface, reducing reactions with the electrolyte.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a lithium metal anode is used to achieve high capacity, then the energy density is significantly higher than lithium ion batteries, but lithium dendrites form during cycling leading to safety issues and internal short circuits

Engineering Contradiction:

Improveenergy densityVSAvoidsafety

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

A protective layer comprising a polymer matrix with lithium ion-conducting filler particles is introduced as an intermediary between the lithium metal anode and the electrolyte. This protective layer mediates the interaction by allowing lithium ion transport while preventing direct contact between lithium metal and electrolyte, thereby eliminating dendrite formation and safety issues while preserving high energy density

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The protective layer is constructed as a composite material system combining a polymer matrix (providing mechanical flexibility and ion conduction pathways) with lithium ion-conducting filler particles (providing high ionic conductivity). This composite structure enables simultaneous achievement of high energy density and safety by preventing dendrite formation while maintaining efficient lithium ion transport

Inventive Principle:

Principle #40Composite materials

2Reliability

If protective layers are added to prevent dendrite formation, then safety is improved, but the device complexity increases

Engineering Contradiction:

ImprovesafetyVSAvoidstructure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The protective layer is segmented into two functional components: a polymer matrix providing mechanical support and ion conduction pathways, and lithium ion-conducting filler particles providing high ionic conductivity. This segmentation allows each component to perform its specific function optimally while keeping the overall structure relatively simple and manufacturable

Inventive Principle:

Principle #1Segmentation

3Reliability

If a vacuum-evaporated thin film of Li ion-conducting polymer is used to stabilize the anode, then dendrite formation is prevented, but the manufacturing complexity and cost increase

Engineering Contradiction:

Improveanode stabilityVSAvoidmanufacturing simplicity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The protective layer uses a composite material system with tunable parameters including polymer matrix composition, filler particle type and concentration, and layer thickness. These parameters can be optimized to achieve the desired lithium ion conductivity and mechanical properties while using simpler, more cost-effective manufacturing methods such as solution casting or coating techniques instead of vacuum evaporation

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 prevents lithium dendrite formation, ensures stable lithium ion deposition, and enhances cycle life and safety, addressing the limitations of previous approaches by providing a simpler, cost-effective, and more efficient battery design.

Implementation Method 1

a first anode-protecting layer having a thickness from 1 nm to 100 μm and comprising a thin layer of a lithium ion-conducting material (having a lithium ion conductivity from 10−8 S/cm to 5×10−2 S/cm) in physical contact with and in protecting relation to the anode active material layer

Methodology Applied

Scientific EffectIon conduction: Conduction (electrical)

Implementation Method 2

a second anode-protecting layer, in contact with the first protecting layer, having a thickness from 1 nm to 100 μm and comprising an elastomer having a fully recoverable tensile elastic strain from 2% to 1,000%

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS10777810B2Lithium metal secondary battery containing a protected lithium anode

Publication Date: 2020.09.15 HONEYCOMB BATTERY CO

AI summary

Provided is a lithium secondary battery, comprising a cathode, an anode, and a porous separator or electrolyte, wherein the anode comprises: (a) an anode active layer containing a layer of lithium or lithium alloy, in a form of a foil, coating, or multiple particles aggregated together, as an anode active material; (b) a first anode-protecting layer having a thickness from 1 nm to 100 μm (preferably <1 μm and more preferably <100 nm) and comprising a lithium ion-conducting material having a lithium ion conductivity from 10−8 S/cm to 5×10−2 S/cm; and (c) a second anode-protecting layer having a thickness from 1 nm to 100 μm and comprising an elastomer having a fully recoverable tensile elastic strain from 2% to 1,000% and a lithium ion conductivity from 10−8 S/cm to 5×10−2 S/cm.