Coated Lithium-Rich Cathode Additive for Air-Stable Capacity Retention
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Solution Overview
Problem
Graphite-based negative electrode materials for lithium secondary batteries have low theoretical capacity, and positive electrode additives containing excess lithium react with moisture and carbon dioxide to form impurities like Li2CO3 and LiOH, leading to irreversible capacity loss and deterioration of electrochemical properties.
Innovation Solution
A positive electrode additive for lithium secondary batteries is coated with a hydrophobic material (polydimethylsiloxane, PDMS) and an ion-conductive material (boron or aluminum oxide) to prevent impurity formation, using a lithium metal oxide core component with an orthorhombic crystal structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Li2NiO2 or Li2CuO2 positive electrode additive containing excess lithium is applied to overcome irreversible capacity loss of negative electrodes, then the electrochemical properties are improved, but impurities such as Li2CO3 and LiOH are formed on the surface when exposed to air
Solution Approach 1:
The patent applies preliminary anti-action by pre-coating the lithium metal oxide particles with a hydrophobic material and ion-conductive material before they can react with air. This protective coating is applied in advance to prevent the formation of impurities such as Li2CO3 and LiOH that would otherwise form when the excess lithium on the particle surfaces reacts with moisture and carbon dioxide in the air.
Solution Approach 2:
The patent uses an intermediary approach by introducing a coating layer comprising a hydrophobic material and an ion-conductive material as a mediator between the lithium metal oxide particles and the air environment. This intermediate layer allows lithium ions to pass through while blocking the direct contact between air (moisture and CO2) and the reactive lithium particle surfaces, thus preventing impurity formation.
2Quantity of substance
If Li2NiO2 or Li2CuO2 positive electrode additive is used to achieve high energy density, then capacity is improved, but gas is generated through side reactions with electrolytes leading to deterioration of electrochemical properties
Solution Approach 1:
The patent applies preliminary anti-action by pre-coating the lithium metal oxide particles with a protective layer before they can undergo side reactions with electrolytes. This coating is applied in advance to prevent the formation of gas and deterioration of electrochemical properties that would occur when exposed lithium reacts with the electrolyte.
Solution Approach 2:
The patent uses an intermediary approach by introducing a coating layer comprising a hydrophobic material and an ion-conductive material as a mediator between the lithium metal oxide particles and the electrolyte environment. This intermediate layer allows lithium ion transport while preventing direct contact between the reactive lithium particles and the electrolyte, thus preventing gas generation and maintaining electrochemical stability.
3Stability of the object's composition
If a coating layer with hydrophobic material and ion-conductive material is applied to prevent impurity formation, then atmospheric stability is improved, but device complexity increases
Solution Approach 1:
The patent applies composite materials by combining a hydrophobic material and an ion-conductive material in a coating layer. This composite structure provides both water repellency (from the hydrophobic component) and lithium ion conductivity (from the ion-conductive component), achieving atmospheric stability while maintaining electrochemical functionality through a single integrated coating system.
Solution Approach 2:
The patent uses universality by designing a coating layer that performs multiple functions simultaneously: the hydrophobic material provides water repellency and atmospheric protection, while the ion-conductive material enables lithium ion transport. This multi-functional coating reduces the need for separate layers for each function, thereby limiting the increase in device complexity.
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 coating layer reduces impurity formation, maintaining excellent electrochemical properties and capacity retention even when exposed to air, with improved atmospheric stability and reduced interfacial resistance.
Implementation Method 1
a coating layer containing a hydrophobic material and an ion-conductive material, the coating layer coating the surface of the core component
Implementation Method 2
an ion-conductive material, the coating layer coating the surface of the core component
Data Source
AI summary
Provided is a positive electrode additive containing an excess of lithium, the positive electrode additive being capable of demonstrating the inherent effect thereof when exposed to air through the coating of the surface of the positive electrode additive with a hydrophobic material and an ion-conductive material to achieve the effects of preventing the formation of impurities such as Li2CO3, LiOH, and the like generated on the surface of the positive electrode additive when left in air.