Positive Electrode Plate Thickness Tuning for Sodium Dendrite Control

Solution Overview

Problem

The issue of sodium dendrite generation due to uneven metal deposition on surfaces in sodium-based batteries, leading to structural instability and reduced lifespan, is not adequately addressed by current positive electrode plates and preparation methods.

Innovation Solution

A positive electrode plate with a sodium-containing active material layer and a specific thickness ratio (Dmax/Dmin of 104.5% to 300%) and porosity (25% to 50%) is designed to mitigate stress changes caused by the volume change of the negative electrode, using layered oxides or polyanionic compounds with sodium supplement additives to enhance energy density and cycling performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a sodium metal negative electrode is used to achieve high energy density, then the energy density is improved, but sodium dendrite generation occurs due to uneven metal deposition

Engineering Contradiction:

Improveenergy densityVSAvoidstructural stability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent applies local quality by creating a non-uniform thickness distribution in the positive electrode plate, with different thickness regions (first thickness in a first region, second thickness in a second region) to match the local volume changes of the negative electrode during charge-discharge cycles. This localized adaptation prevents uneven stress distribution that would otherwise cause sodium dendrite formation.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the thickness parameter of the positive electrode plate across different regions to optimize performance. By controlling the thickness ratio between different regions and adjusting the overall thickness, the patent accommodates volume changes during operation, preventing dendrite formation while maintaining high energy density with sodium metal negative electrodes.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the positive electrode plate thickness is increased to accommodate negative electrode volume expansion, then structural stability is improved, but the thickness change during charge/discharge becomes excessive

Engineering Contradiction:

Improvestructural stabilityVSAvoidthickness stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent applies local quality by creating a non-uniform thickness distribution in the positive electrode plate, with different thickness regions (first thickness in a first region, second thickness in a second region) to match the local volume changes of the negative electrode during charge-discharge cycles. This localized adaptation prevents uneven stress distribution that would otherwise cause sodium dendrite formation.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent uses partial action by having the positive electrode plate thickness change only in specific regions and by controlled amounts. The thickness ratio is designed to be within a specific range (1.05-1.5 times), providing just enough accommodation for negative electrode expansion without excessive thickness variation that would compromise overall stability.

Inventive Principle:

Principle #16Partial or excessive action

3Ease of manufacture

If a uniform thickness positive electrode plate is used, then manufacturing is simplified, but it cannot accommodate the volume change of the negative electrode during charge/discharge

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidstress accommodation

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies local quality by creating a non-uniform thickness distribution in the positive electrode plate, with different thickness regions (first thickness in a first region, second thickness in a second region) to match the local volume changes of the negative electrode during charge-discharge cycles. This localized adaptation prevents uneven stress distribution that would otherwise cause sodium dendrite formation.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent introduces dynamics by designing the positive electrode plate with variable thickness that can adapt to changing conditions during operation. The different thickness regions allow the electrode to dynamically respond to volume changes in the negative electrode, providing stress accommodation while maintaining manufacturing feasibility through controlled thickness variations.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS20250279418A1Positive electrode plate and preparation method thereof, battery, and electric apparatus

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

AI summary

A positive electrode plate includes: a positive electrode current collector and a positive electrode active material layer disposed on a surface of at least one side of the positive electrode current collector and including a positive electrode active material. The positive electrode active material includes a sodium-containing positive electrode active material. A thickness of the positive active plate satisfies that Dmax/Dmin is 104.5% to 300%, where for a battery assembled from the positive electrode plate and a negative electrode plate, Dmax is a thickness of the positive electrode plate of the battery at 0% SOC, and Dmin is a thickness of the positive electrode plate of the battery at 100% SOC. The negative electrode plate includes a negative electrode current collector, and when the battery is at 100% SOC, a surface of at least one side of the negative electrode current collector has a sodium metal layer.