Lithium-Ion Conductive Protective Layers for Cell Cycle Life

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Solution Overview

Problem

Lithium-ion electrochemical cells face performance inhibition due to adverse interactions between battery components, such as electrodes and electrolyte, leading to loss of active lithium, electrolyte decomposition, and increased cell impedance, which reduces cycle life and efficiency.

Innovation Solution

A lithium-ion-conductive layer, typically an inorganic material like lithium oxide or lithium oxysulfide, is integrated between the anode and cathode to inhibit the transport of deleterious species and byproducts, acting as a physical barrier and acid trap to maintain electrode structure and reduce electrolyte loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a lithium-ion electrochemical cell uses conventional electrodes and electrolyte without protective layers, then the cell structure is simple, but adverse interactions occur between components leading to loss of active lithium, electrolyte decomposition, and increased cell impedance

Engineering Contradiction:

Improvecell performance and cycle lifeVSAvoidelectrode structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

An inorganic protective layer is introduced as an intermediary between the electrode and electrolyte. This layer acts as a mediator that prevents direct adverse interactions while allowing lithium-ion transport, thereby improving cell reliability and cycle life without fundamentally changing the electrode structure

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The electrode is modified by integrating an inorganic protective layer with the electroactive material, creating a composite structure. This composite material combines the electrochemical activity of the original electrode with the protective properties of the inorganic layer, reducing electrolyte decomposition and active lithium loss

Inventive Principle:

Principle #40Composite materials

2Object-affected harmful factors

If no protective layer is used, then manufacturing process is simple, but harmful species are transported between electrodes causing performance degradation

Engineering Contradiction:

Improvetransport of harmful speciesVSAvoidfabrication process complexity

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The inorganic protective layer serves as a physical barrier and intermediary that blocks the transport of harmful species between electrodes. It allows lithium-ion conduction while preventing the migration of decomposition products and other harmful factors, thus protecting electrode integrity

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

A thin inorganic protective film is applied to the electrode surface. This film is sufficiently thin to allow lithium-ion transport but thick enough to provide effective barrier protection against harmful species transport, maintaining ease of manufacture through established thin-film deposition techniques

Inventive Principle:

Principle #30Flexible shells and thin films

3Use of energy by moving object

If electrodes are in direct contact with electrolyte, then ion transport is efficient, but electrolyte decomposition occurs and active lithium is lost

Engineering Contradiction:

Improvelithium-ion transport efficiencyVSAvoidelectrolyte loss and active lithium loss

Core Design Contradiction:

Use of energy by moving objectVSLoss of substance

Solution Approach 1:

The protective layer is applied locally at the electrode-electrolyte interface where the harmful interactions occur. This localized protection allows efficient lithium-ion transport through the layer while preventing electrolyte decomposition and active lithium loss at the critical interface region

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The electrode structure is transformed into a composite material system where the inorganic protective layer is integrated with the electroactive material. This composite structure enables simultaneous lithium-ion conduction and protection against electrolyte decomposition, reducing substance loss while maintaining transport efficiency

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-ion-conductive layer effectively reduces the transport of harmful species, enhancing cell performance by maintaining electrode integrity, reducing electrolyte decomposition, and increasing cycle life and efficiency.

Implementation Method 1

an inorganic lithium-ion-conductive layer integrated with the layer comprising the electroactive material

Methodology Applied

Scientific EffectIon conduction: Conduction (electrical)

Implementation Method 2

acting as a physical barrier and acid trap to maintain electrode structure and reduce electrolyte loss

Methodology Applied

Scientific EffectPhysical barrier effect: Filter (physical)

Implementation Method 3

acting as a physical barrier and acid trap to maintain electrode structure

Methodology Applied

Scientific EffectAcid trap: Absorption (physical)

Data Source

PatentUS11038178B2Protective layers in lithium-ion electrochemical cells and associated electrodes and methods

Publication Date: 2021.06.15 SION POWER CORP

AI summary

Protective layers in lithium-ion electrochemical cells, and associated electrodes and methods, are generally described. The protective layers may comprise lithium-ion-conductive inorganic ceramic materials, such as lithium oxide, lithium nitride, and/or lithium oxysulfide. The resulting lithium-ion electrochemical cells may exhibit enhanced performance, including reduced capacity fade rates and reduced self-discharge rates.