Sectioned Electrode Assembly for Lithium-Ion Batteries

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Solution Overview

Problem

The existing electrode assemblies in polymer lithium-ion batteries face challenges in increasing energy density due to the large innermost blank substrate area, which reduces the specific gravity of active substances, and the risk of lithium deposition at the starting end of the electrode sheet, leading to decreased capacity and safety hazards.

Innovation Solution

The electrode assembly design includes a first and second electrode sheet with active substance layers on both surfaces of specific sections, with a bending section to reduce lithium deposition risk, and a separator arrangement to prevent short circuits, while maintaining energy density through strategic placement of active substance layers and empty foil regions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the area of the innermost blank substrate region is reduced to increase energy density, then the specific gravity of active substance improves, but the risk of lithium deposition at the starting end increases

Engineering Contradiction:

Improvespecific gravity of active substanceVSAvoidrisk of lithium deposition

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The electrode sheet is divided into a first section with active substance on both surfaces and a second section with active substance on only one surface. The second section includes a bending section where the electrode sheet is bent for the first time. This segmentation allows the blank substrate area to be reduced while avoiding lithium deposition at the bending portion by providing active substance coverage on the bending section.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different sections of the electrode sheet have different active substance layer configurations. The first section has double-sided active substance coverage while the second section has single-sided coverage. This local quality variation optimizes energy density in different regions while specifically protecting the bending section from lithium deposition.

Inventive Principle:

Principle #3Local quality

2Quantity of substance

If thinner current collectors and separators are used to increase energy density, then the battery energy density improves, but the risk of short circuit increases

Engineering Contradiction:

Improveenergy densityVSAvoidrisk of short circuit

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The electrode sheet design incorporates a bending section with active substance coverage that serves as a protective measure before short circuits can occur. By ensuring proper active substance distribution and electrode structure at the bending portion, the design preemptively reduces the risk of short circuits that could result from using thinner separators and current collectors.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Quantity of substance

If double-sided insertion structure is used to improve energy density, then the specific gravity of active substance increases, but lithium deposition occurs at the starting end

Engineering Contradiction:

Improvespecific gravity of active substanceVSAvoidlithium deposition

Core Design Contradiction:

Quantity of substanceVSObject-generated harmful factors

Solution Approach 1:

The electrode sheet is segmented into sections with different active substance configurations. The second section, which includes the bending section, has active substance on only one surface, creating a asymmetric structure that prevents lithium deposition while maintaining overall high energy density through the double-sided insertion structure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The electrode sheet employs asymmetric active substance distribution where the first section has double-sided coverage and the second section has single-sided coverage. This asymmetry, particularly at the bending section, prevents lithium deposition that would otherwise occur with symmetric double-sided insertion structures.

Inventive Principle:

Principle #4Asymmetry

Data Source

PatentUS11127982B2Electrode assembly and battery with sectioned active layers

Publication Date: 2021.09.21 NINGDE AMPEREX TECHNOLOGY LTD

AI summary

The present application provides an electrode assembly including a first electrode sheet including a first current collector and a first active substance layer arranged on the surface of the first current collector; the first electrode sheet includes a first section and a second section; both surfaces of the first section is applied with the first active substance layer while one surface of the second section is applied with the first active substance layer; the second section is electrically connected to the first section, and the first section is closer to a starting end of the first electrode sheet than the second section is; wherein the second section includes a first bending section, and the first bending section is a region where the first electrode sheet is bent for the first time. Thereby, the risk of lithium decomposition of the battery is reduced, and the life is prolonged.