Sodium Oxide Cathode Surface Control for Stable Na-Ion Cycling

Solution Overview

Problem

Sodium-containing metal oxide cathode materials for sodium-ion batteries face issues with high soluble alkali content on their surface, leading to reduced safety performance, degraded specific discharge capacity, and rapid capacity attenuation due to irreversible structural changes and side reactions during cycling.

Innovation Solution

A sodium-containing oxide cathode material with a low surface alkali content is developed through a specific preparation method involving sintering in an oxygen-containing atmosphere with controlled conditions, including temperature, humidity, and flow rate, to reduce soluble alkali content and enhance structural stability, thereby improving cycle stability and rate performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If sodium-containing oxide cathode material is used in sodium-ion batteries, then high capacity and low cost are achieved, but high soluble alkali content on the surface causes safety performance degradation and capacity attenuation

Engineering Contradiction:

Improvesodium ion capacityVSAvoidcycle stability

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent applies local quality by creating a dual-layer surface structure where the inner layer contains high soluble alkali content for maintaining high sodium ion capacity, while the outer layer has low soluble alkali content for ensuring cycle stability and safety. This is achieved through controlled sintering in oxygen-containing atmosphere with specific humidity and flow rate parameters, which forms a stable surface phase that prevents excessive alkali dissolution during cycling.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent utilizes parameter changes by precisely controlling sintering conditions (temperature, oxygen concentration, humidity, and flow rate) to transform the surface properties of the cathode material. By adjusting these parameters during sintering, a surface layer with optimized soluble alkali content is formed, which resolves the contradiction between maintaining high capacity and achieving long cycle life.

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If high soluble alkali content is present on the surface, then sodium ion deintercalation/intercalation is facilitated, but side reactions occur during cycling causing capacity attenuation

Engineering Contradiction:

Improvesodium ion deintercalation/intercalationVSAvoidside reaction

Core Design Contradiction:

Ease of operationVSObject-generated harmful factors

Solution Approach 1:

The patent applies local quality by creating a dual-layer surface structure where the inner layer contains high soluble alkali content for maintaining high sodium ion capacity, while the outer layer has low soluble alkali content for ensuring cycle stability and safety. This is achieved through controlled sintering in oxygen-containing atmosphere with specific humidity and flow rate parameters, which forms a stable surface phase that prevents excessive alkali dissolution during cycling.

Inventive Principle:

Principle #3Local quality

3Ease of manufacture

If conventional sintering is used, then material synthesis is simple, but surface alkali content is too high causing safety performance reduction

Engineering Contradiction:

Improvesynthesis processVSAvoidsafety performance

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent utilizes parameter changes by precisely controlling sintering conditions (temperature, oxygen concentration, humidity, and flow rate) to transform the surface properties of the cathode material. By adjusting these parameters during sintering, a surface layer with optimized soluble alkali content is formed, which resolves the contradiction between maintaining high capacity and achieving long cycle life.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies strong oxidants by introducing oxygen-containing atmosphere during sintering. The oxygen environment promotes oxidation reactions on the material surface, forming a stable oxide layer with controlled soluble alkali content. This oxidation process, controlled through specific oxygen flow rates and humidity levels, creates a protective surface layer that enhances safety performance while maintaining electrochemical activity.

Inventive Principle:

Principle #38Strong oxidants (Accelerated oxidation)

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 method results in sodium-ion batteries with high capacity, long cycle life, and enhanced safety, allowing continuous sodium ion deintercalation/intercalation reactions without significant capacity reduction, and improves the overall performance and stability of the cathode material.

Implementation Method 1

an oxygen-containing atmosphere is introduced during the first sintering process

Methodology Applied

Scientific EffectOxidation: Oxidation

Implementation Method 2

subjecting a sodium-manganese-iron-containing cathode material precursor to first sintering

Methodology Applied

Scientific EffectSintering: Sintering

Data Source

PatentUS20240186500A1Sodium-containing oxide positive electrode material and preparation method therefor and use thereof, and positive electrode plate and use thereof

Publication Date: 2024.06.06 BEIJING EASPRING MATERIAL TECH CO LTD

AI summary

A sodium-containing oxide positive electrode material and a preparation method therefor and use thereof are disclosed. Also disclosed are a positive electrode plate and uses thereof.