Li8FePO4 Cathode Additive Encapsulation to Prevent Charging Gas

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Solution Overview

Problem

Existing lithium-supplementing materials for cathodes in batteries, such as Li5FeO4, produce gas during the charging process, affecting battery safety and stability.

Innovation Solution

A cathode lithium-supplementing additive with a Li8FePO4 core and an isolating conductive encapsulation layer is developed, which prevents gas production by oxidizing phosphorus ions instead of oxygen ions and encapsulating the core to protect it from moisture and oxygen, maintaining electrical conductivity and safety.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If Li5FeO4 is used as lithium supplementing material, then lithium supplementing capacity is improved, but gas production occurs during charging process

Engineering Contradiction:

Improvelithium supplementing capacityVSAvoidgas production

Core Design Contradiction:

Quantity of substanceVSObject-generated harmful factors

Solution Approach 1:

The patent changes the chemical composition parameters by replacing some Fe ions with P ions in the Li5FeO4 structure to create Li8FePO4. This compositional parameter change fundamentally alters the oxidation behavior during charging, causing phosphorus ions to be oxidized instead of oxygen ions, thereby eliminating gas production while maintaining high lithium supplementing capacity of 1036 mAh/g

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite material system by combining Li8FePO4 core particles with an isolating conductive encapsulation layer. This composite structure integrates the high capacity Li8FePO4 material with a protective coating that prevents direct contact with electrolyte, eliminating gas production while preserving the theoretical capacity of 1036 mAh/g

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If Li5FeO4 is used as lithium supplementing material, then lithium supplementing capacity is improved, but battery safety is worsened

Engineering Contradiction:

Improvelithium supplementing capacityVSAvoidbattery safety

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent modifies the chemical composition from Li5FeO4 to Li8FePO4, changing the oxidation mechanism during charging. This parameter change ensures that phosphorus ions are oxidized instead of oxygen ions, preventing oxygen gas release and improving battery safety while maintaining high lithium supplementing capacity

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent constructs a composite structure with Li8FePO4 core and isolating conductive encapsulation layer. This composite design provides both high lithium supplementing capacity and enhanced safety by isolating the reactive Li8FePO4 core from the electrolyte, preventing harmful reactions while allowing controlled lithium ion transport

Inventive Principle:

Principle #40Composite materials

3Quantity of substance

If Li8FePO4 core is exposed to atmosphere, then lithium supplementing capacity is maintained, but reaction with moisture and oxygen occurs

Engineering Contradiction:

Improvelithium supplementing capacityVSAvoidcomposition stability

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The patent creates a composite structure where the Li8FePO4 core is coated with an isolating conductive encapsulation layer. This composite design protects the compositionally sensitive Li8FePO4 from atmospheric moisture and oxygen while maintaining its high lithium supplementing capacity of 1036 mAh/g through controlled lithium ion transport

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent applies a thin film encapsulation layer around the Li8FePO4 core particles. This flexible protective shell isolates the core from atmospheric contaminants (moisture and oxygen) while allowing lithium ion diffusion, thereby preserving both composition stability and lithium supplementing capacity during storage and operation

Inventive Principle:

Principle #30Flexible shells and thin films

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 Li8FePO4 core with an isolating conductive encapsulation layer enhances lithium supplementing capacity, improves cycle stability and safety by preventing gas production during deintercalation, and maintains high energy density and capacity retention.

Implementation Method 1

During the charging and lithium deintercalation process, phosphorus ions are oxidized instead of oxygen ions

Methodology Applied

Scientific EffectOxidation: Oxidation

Implementation Method 2

avoiding moisture from reacting with Li8FePO4 to generate lithium hydroxide

Methodology Applied

Scientific EffectHydrolysis: Hydrolysis

Data Source

PatentUS20250015294A1Cathode lithium-supplementing additive and preparation method therefor, cathode sheet, and secondary battery

Publication Date: 2025.01.09 SHENZHEN INNOVAZONE TECH CO LTD

AI summary

Provided are a cathode lithium-supplementing additive and a preparation method therefor, a cathode sheet, and a secondary battery. The cathode lithium-supplementing additive comprises a Li8FePO4 core and an isolating conductive encapsulation layer coating the outer surface of the core. The cathode lithium-supplementing additive comprises the Li8FePO4 core and the isolating conductive encapsulation layer, so that the lithium supplement capacity is relatively good, and active lithium ions consumed due to formation of an SEI film during first charging of the battery are supplemented; moreover, lithium ions in Li8FePO4 can also serve as a cathode material to participate in lithium ion circulation in the battery. Moreover, no gas is generated during lithium deintercalation.