Metal Sulfide Intermediate Layer for Uniform Lithium Deposition

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Solution Overview

Problem

Anode free all-solid-state batteries face challenges in improving the lifespan and energy density due to the lack of reactivity between conventional anode current collectors and lithium ions, leading to non-uniform lithium metal formation.

Innovation Solution

Incorporating a metal sulfide intermediate layer with specific compositions (e.g., In2S3, SnS) on the anode current collector, which reacts with lithium ions to form a lithium alloy, enhancing lithium distribution and stability, and including a lithium layer for electrochemical compatibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If an anode free all-solid-state battery is used to improve energy density, then energy density is improved, but lithium metal forms non-uniformly on the anode current collector

Engineering Contradiction:

Improveenergy densityVSAvoiduniformity of lithium metal formation

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

A lithium phosphate intermediate layer is introduced between the anode current collector and the solid electrolyte. This intermediate layer acts as a mediator that promotes uniform lithium metal formation during charging. The lithium phosphate layer has specific properties that facilitate uniform lithium deposition, solving the non-uniform formation problem while maintaining the high energy density benefits of anode-free batteries.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If conventional anode current collectors are used, then manufacturing is simple, but reactivity with lithium ions is low leading to poor lifespan

Engineering Contradiction:

Improvesimplicity of anode current collector fabricationVSAvoidbattery lifespan

Core Design Contradiction:

Ease of manufactureVSDuration of action of moving object

Solution Approach 1:

The anode current collector is transformed from a simple conventional material into a composite structure by adding a lithium phosphate intermediate layer. This composite structure combines the manufacturing simplicity of conventional current collectors with the enhanced lithium ion reactivity of lithium phosphate, thereby improving battery lifespan without significantly complicating the manufacturing process.

Inventive Principle:

Principle #40Composite materials

3Reliability

If lithium metal forms non-uniformly on the anode current collector, then capacity retention is poor, but adding intermediate layers increases device complexity

Engineering Contradiction:

Improvecapacity retention rateVSAvoidcomplexity of anode structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The thickness of the lithium phosphate intermediate layer is optimized to a specific range (1 nm to 100 nm). By controlling this parameter, the layer is thin enough to minimize added complexity and volume, while still sufficient to promote uniform lithium metal formation and improve capacity retention. This parameter optimization balances the trade-off between reliability improvement and device complexity.

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 enables uniform lithium metal formation on the anode current collector, improving the battery's lifespan, capacity retention, and energy density, allowing operation at room temperature with high lithium affinity and cycle stability.

Implementation Method 1

During charging, lithium ions move from the cathode to the anode and are converted into lithium metal through a reduction reaction with electrons on the surface of the anode current collector

Methodology Applied

Scientific EffectElectrochemical reduction: Redox Reactions