Single-Crystal Cathode Coating for Low-Gas Li-Ion Storage

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Solution Overview

Problem

Current positive active materials in lithium-ion batteries, such as high-nickel ternary materials, suffer from significant side reactions with electrolyte solutions, leading to gas production and deterioration of energy density, cycle performance, and storage performance, which hinders their commercialization.

Innovation Solution

A positive active material with a single crystal or quasi-single crystal particle morphology and a coating layer, composed of LixNiyCozMkMepOrAm, where 0.85≤x≤1.15, 0<y<1, 0<z<1, 0<k<1, 0≤p≤0.1, 1≤r≤2, 0≤m≤1, m+r≤2, and M and A are specific elements, is used to reduce side reactions and gas production, while maintaining energy density and performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If nickel content is increased to improve energy density, then energy density is improved, but side reactions with electrolyte solution increase causing severe gas production

Engineering Contradiction:

Improveenergy densityVSAvoidgas production

Core Design Contradiction:

Use of energy by moving objectVSObject-generated harmful factors

Solution Approach 1:

A coating layer comprising Li2SiO3 and Li4SiO4 is formed on the surface of the positive active material. This coating layer acts as an intermediary barrier between the high-nickel ternary material and the electrolyte solution, reducing direct contact and side reactions while maintaining the high energy density benefits of the nickel-rich material.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent uses a composite structure combining Li2SiO3 and Li4SiO4 in the coating layer. This composite material provides both protective functionality to reduce gas production and maintains electrochemical performance, allowing the battery to achieve high energy density without severe gas evolution.

Inventive Principle:

Principle #40Composite materials

2Object-generated harmful factors

If nickel content is reduced to decrease gas production, then gas production is decreased, but energy density deteriorates

Engineering Contradiction:

Improvegas productionVSAvoidenergy density

Core Design Contradiction:

Object-generated harmful factorsVSUse of energy by moving object

Solution Approach 1:

The Li2SiO3-Li4SiO4 coating layer serves as a protective intermediary that allows the use of high-nickel content materials without suffering from gas production issues. This enables maintaining high energy density while controlling gas evolution, reversing the traditional trade-off.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Object-generated harmful factors

If washing is performed to reduce residual lithium content, then gas production is reduced, but reversible capacity per gram decreases

Engineering Contradiction:

Improvegas productionVSAvoidreversible capacity

Core Design Contradiction:

Object-generated harmful factorsVSQuantity of substance

Solution Approach 1:

Instead of washing after material synthesis, the patent applies a coating layer treatment that prevents residual lithium from causing gas production in the first place. This preliminary protective action maintains the material's reversible capacity while controlling gas evolution during battery operation.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The coating layer acts as a barrier that prevents residual lithium on the material surface from reacting with the electrolyte to produce gas, eliminating the need for washing steps that would otherwise be required to remove residual lithium.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Speed

If particle size is reduced to improve reaction kinetics, then rate performance is improved, but specific surface area increases causing more side reactions and gas production

Engineering Contradiction:

Improverate performanceVSAvoidgas production

Core Design Contradiction:

SpeedVSObject-generated harmful factors

Solution Approach 1:

The Li2SiO3-Li4SiO4 coating layer provides a protective barrier that allows small particle sizes to be used for high rate performance without the penalty of increased gas production. The coating prevents side reactions on the high-surface-area particles while maintaining fast lithium ion transport kinetics.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS20250279426A1Positive active material, positive electrode plate, electrochemical energy storage apparatus, and apparatus

Publication Date: 2025.09.04 CONTEMPORARY AMPEREX TECHNOLOGY (HONG KONG) LIMITED

AI summary

This application provides a positive active material, a positive electrode plate, an electrochemical energy storage apparatus, and an apparatus. The positive active material is LixNiyCozMkMepOrAm, or LixNiyCozMkMepOrAm with a coating layer on its surface; and the positive active material is single crystal or quasi-single crystal particles, and a particle size Dn10 of the positive active material satisfies: 0.3 μm≤Dn10≤2 μm. In this application, particle morphology of the positive active material and an amount of micro powder in the positive active material are properly controlled, to effectively reduce side reactions between the positive active material and an electrolyte solution, decrease gas production of the electrochemical energy storage apparatus, and improve storage performance of the electrochemical energy storage apparatus without deteriorating an energy density, cycle performance, and rate performance of the electrochemical energy storage apparatus.