Constrained Electrode Assembly for Battery Swelling Control

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Solution Overview

Problem

Rocking chair or insertion secondary batteries face challenges with electrode expansion and contraction during cycling, leading to reliability and cycle life issues, as well as misalignment causing shorts and failures.

Innovation Solution

Implementing constraint structures to mitigate macroscopic expansion of electrodes, improving energy density, reliability, and cycle life, while maintaining electrode alignment through a set of electrode constraints that include primary and secondary growth constraint systems.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If electrodes are allowed to expand and contract freely during battery cycling, then the battery can accommodate volume changes of active materials, but electrical shorts and battery failures occur due to electrode expansion

Engineering Contradiction:

Improveelectrode volume stabilityVSAvoidbattery reliability

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The patent employs flexible constraint structures including constraint layers and constraint elements that can accommodate electrode expansion and contraction while preventing electrical shorts. These flexible films and shells allow the electrode to change volume during cycling but maintain separation between electrodes, thus preventing shorts while managing expansion.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The constraint structure is divided into multiple segments including constraint layers, constraint elements, and spacers distributed throughout the electrode assembly. This segmentation allows different portions of the electrode to expand and contract independently while maintaining overall structural integrity and preventing shorts.

Inventive Principle:

Principle #1Segmentation

2Reliability

If constraint structures are added to control electrode expansion, then battery reliability and cycle life improve, but battery footprint increases

Engineering Contradiction:

Improvebattery reliabilityVSAvoidbattery footprint

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The constraint structures are nested within the existing battery architecture, with constraint layers positioned between electrodes and constraint elements integrated into the electrode assembly. This nesting approach allows the constraint structures to occupy space already allocated for electrode components, minimizing additional footprint while providing expansion control.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The use of thin film constraint structures allows for effective electrode constraint with minimal additional thickness. These thin films provide the necessary mechanical constraint while occupying minimal space, thus improving reliability without significantly increasing battery footprint.

Inventive Principle:

Principle #30Flexible shells and thin films

3Ease of manufacture

If electrode alignment is not controlled, then manufacturing is simpler, but mismatch in electrode alignment causes shorting and battery failure

Engineering Contradiction:

Improveelectrode assembly simplicityVSAvoidbattery reliability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The constraint structures including spacers and alignment features are pre-positioned during electrode assembly manufacturing to establish proper alignment before electrodes are stacked. This preliminary alignment action ensures correct electrode positioning is achieved during assembly, preventing misalignment-induced shorts while maintaining manufacturing simplicity.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Constraint elements and spacers act as intermediary components between electrodes, providing mechanical guidance and maintaining proper alignment during assembly and operation. These intermediary structures facilitate easy assembly while ensuring reliable electrode alignment, thus resolving the contradiction between manufacturing simplicity and reliability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS20250046879A1Constrained electrode assembly

Publication Date: 2025.02.06 ENOVIX CORP

AI summary

A secondary battery for cycling between a charged and a discharged state, wherein a 2D map of the median vertical position of the first opposing vertical end surface of the electrode active material in the X-Z plane, along the length LE of the electrode active material layer, traces a first vertical end surface plot, EVP1, a 2D map of the median vertical position of the first opposing vertical end surface of the counter-electrode active material layer in the X-Z plane, along the length LC of the counter-electrode active material layer, traces a first vertical end surface plot, CEVP1, wherein for at least 60% of the length Lc of the first counter-electrode active material layer (i) the absolute value of a separation distance, SZ1, between the plots EVP1 and CEVP1 measured in the vertical direction is 1000 μm≥|SZ1|≥5 μm.