K-Gradient Layered Cathode Material for Stable Sodium-Ion Cycling

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Solution Overview

Problem

Lithium-ion batteries face challenges due to the scarcity of lithium resources, and sodium-ion batteries suffer from poor interfacial stability and crystal structure instability caused by high amounts of free alkaline substances on the surface of positive electrode active materials, affecting their performance.

Innovation Solution

A potassium-ion-doped layered transition metal oxide positive electrode active material with a decreasing K element concentration from the surface to the interior, stabilized by a specific preparation method involving alkaline washing and sintering, reduces stress and microcracks, enhancing cycling and rate performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional preparation processes are used for positive electrode active material, then the material can be produced, but a high amount of free alkaline substance is present on the surface which adversely affects battery performance

Engineering Contradiction:

Improvepreparation process simplicityVSAvoidbattery performance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies parameter changes by controlling the pH of the washing solution within a specific range (11-13) and controlling the washing temperature (20-40°C) to optimize the removal of free alkaline substances while preventing structural damage to the positive electrode active material, thereby improving battery performance without complicating the preparation process

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite washing solution containing both NaOH and KOH in specific concentration ratios to effectively remove free alkaline substances from the surface of the positive electrode active material. This composite approach enhances the cleaning efficiency while maintaining the structural integrity of the material

Inventive Principle:

Principle #40Composite materials

2Reliability

If the positive electrode active material is washed to remove free alkaline substances, then battery performance improves, but the crystal structure may become unstable and undergo irreversible transformation

Engineering Contradiction:

Improvebattery performanceVSAvoidcrystal structure stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent carefully controls washing parameters including pH (11-13) and temperature (20-40°C) to remove free alkaline substances while maintaining crystal structure stability. The controlled parameters prevent excessive washing that could cause structural collapse or irreversible transformation

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs a two-step washing process where the first washing step removes bulk free alkaline substances, and the second washing step with adjusted pH parameters provides a cushioning effect to prevent structural damage during the removal process, thereby protecting the crystal structure from irreversible transformation

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Stability of the object's composition

If the K element is uniformly distributed throughout the positive electrode active material, then the crystal structure is stabilized, but the pillar effect is reduced and microcracks still occur

Engineering Contradiction:

Improvecrystal structure stabilityVSAvoidresistance to microcracks

Core Design Contradiction:

Stability of the object's compositionVSStrength

Solution Approach 1:

The patent applies local quality by creating a non-uniform distribution of K element where the concentration is higher at the surface and gradually decreases toward the interior. This gradient distribution optimizes the pillar effect at the surface to prevent microcrack initiation while maintaining overall crystal structure stability

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent introduces asymmetry in the K element distribution pattern, where the surface region contains a higher concentration of K elements compared to the interior. This asymmetric distribution enhances the pillar effect where it is most needed (at the surface) while avoiding the weakening effect of uniform distribution throughout the material

Inventive Principle:

Principle #4Asymmetry

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 stabilizes the crystal structure, improves interfacial stability, and enhances cycling and rate performance of sodium-ion batteries by reducing the probability of irreversible transformations during sodium deintercalation.

Implementation Method 1

washing the initial positive electrode active material with an alkaline washing solution

Methodology Applied

Scientific EffectWashing:

Implementation Method 2

sintering the washed initial positive electrode active material

Methodology Applied

Scientific EffectSintering: Sintering

Data Source

PatentUS20260015252A1Positive electrode active material, preparation method thereof, and positive electrode plate, battery, and electric apparatus including same

Publication Date: 2026.01.15 CONTEMPORARY AMPEREX TECHNOLOGY CO LTD

AI summary

This application provides a positive electrode active material, a preparation method thereof, and a positive electrode plate, a battery, and an electric apparatus including the same. The positive electrode active material includes a layered transition metal oxide represented by Formula (I), with parameters as defined herein. The positive electrode active material includes a K element, and an amount of the K element decreases from a particle surface to a particle interior of the positive electrode active material.