Winding Electrode Assembly Layout for Lithium Plating Prevention

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Solution Overview

Problem

Lithium plating occurs in lithium ion batteries due to the mismatch in size between the negative active material layer and the positive active material layer in the winding axial direction, leading to potential safety issues such as short circuits and reduced cycle performance.

Innovation Solution

The design of a winding type electrode assembly with specific width differences between the negative and positive active material layers at different sections, ensuring that the maximum width difference between the negative active material layer and the positive active material layer at the winding end portions is greater than the width difference at the middle section, thereby reducing the risk of lithium plating.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the negative active material layer width is uniformly larger than the positive active material layer width throughout the winding structure, then lithium plating is reduced, but the winding end portions may cause short circuits due to excessive protrusion

Engineering Contradiction:

Improvelithium plating preventionVSAvoidshort circuit risk at winding ends

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by creating different width relationships between negative and positive active material layers at different locations: at the winding middle section, the negative layer protrudes beyond the positive layer to prevent lithium plating, while at the winding end portions, the positive layer protrudes beyond the negative layer to prevent short circuits. This spatially varying design optimizes both lithium plating prevention and short circuit avoidance.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent segments the winding structure into distinct regions: a winding middle section and winding end portions. By dividing the structure into these segments with different dimensional characteristics, the patent can apply different width relationships in each segment to address the conflicting requirements of lithium plating prevention and short circuit prevention.

Inventive Principle:

Principle #1Segmentation

2Reliability

If the negative active material layer exceeds the positive active material layer at winding end portions, then lithium plating is prevented, but the structural integrity and safety are compromised

Engineering Contradiction:

Improvelithium plating preventionVSAvoidsafety issues

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent implements local quality by making the width relationship location-dependent: the negative active material layer exceeds the positive layer only at the winding middle section where lithium plating occurs, while the positive layer exceeds the negative layer at the winding end portions where safety concerns arise. This localized approach prevents lithium plating without compromising safety.

Inventive Principle:

Principle #3Local quality

3Object-affected harmful factors

If the positive active material layer is uniformly larger than the negative active material layer, then short circuit risk is reduced, but lithium plating occurs due to insufficient coverage

Engineering Contradiction:

Improveshort circuit preventionVSAvoidlithium plating prevention

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent applies local quality by reversing the width relationship based on location: at the winding end portions, the positive layer exceeds the negative layer to prevent short circuits, while at the winding middle section, the negative layer exceeds the positive layer to prevent lithium plating. This spatially varying design simultaneously addresses both safety and reliability concerns.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent segments the winding structure into winding end portions and winding middle section, allowing different width relationships in each segment. This segmentation enables the positive layer to provide adequate coverage at ends while the negative layer provides sufficient coverage at the middle section, preventing both short circuits and lithium plating.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS12407029B2Winding type electrode assembly, battery cell, battery and power consumption device

Publication Date: 2025.09.02 CONTEMPORARY AMPEREX TECHNOLOGY (HONG KONG) LIMITED

AI summary

The embodiments of the present application provide a winding type electrode assembly including a positive electrode plate and a negative electrode plate; the positive electrode plate includes a first positive winding end portion and a positive winding middle section; the negative electrode plate includes a first portion and a second portion; and an active material layer of the negative electrode plate exceeds an active material layer of the positive electrode plate, and a difference between a maximum width of a negative active material layer of the first portion and a minimum width of a positive active material layer of the first positive winding end portion is larger than a difference between a maximum width of a negative active material layer of the second portion and a minimum width of a positive active material layer of the positive winding middle section.