Li-Metal Battery Compression Assembly for Dendrite Suppression
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Solution Overview
Problem
Lithium metal anode batteries face challenges with dendrite formation and thickness changes during charging and discharging, which require elevated pressure to suppress dendrites and accommodate cell thickness variations, but existing materials like soft polymer foams cannot maintain the necessary pressure range without permanent compression and loss of pressure.
Innovation Solution
A compression assembly using rigid end plates and compressible polymeric foam layers that apply uniform mechanical pressure to lithium metal battery cells, maintaining pressure between 0.5 to 3.0 MPa while accommodating thickness changes, using materials with non-linear stress-strain behavior and porosity to prevent dendrite formation and maintain pressure consistency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If soft polymer foam materials are used to accommodate cell thickness changes, then the cell can expand and contract during charge/discharge, but the material cannot maintain the necessary pressure range (0.5 to 3.0 MPa) without permanent compression and loss of pressure
Solution Approach 1:
The patent applies parameter changes by transitioning from soft polymer foam to rigid compressible material, fundamentally changing the mechanical properties of the compression means. This enables the material to maintain pressure in the 0.5 to 3.0 MPa range while accommodating cell thickness changes during charge/discharge cycles without permanent compression set.
Solution Approach 2:
The patent employs composite materials by combining rigid end plates with compressible material layers. This composite structure provides both the rigidity needed to maintain overall pressure and the compressibility needed to accommodate thickness changes, resolving the contradiction between pressure maintenance and adaptability.
2Reliability
If elevated pressure (0.5 to 3.0 MPa) is applied to suppress dendrite formation, then lithium deposits in a smooth dense layer improving safety and operational life, but existing compression materials cannot maintain this pressure range without permanent compression
Solution Approach 1:
The patent changes the pressure parameter maintenance capability by using rigid compressible material instead of soft polymer foam. This enables sustained pressure in the 0.5 to 3.0 MPa range required for dendrite suppression without the material undergoing permanent compression that would cause pressure loss over time.
Solution Approach 2:
The patent avoids using short-living soft polymer foam materials that lose their compressive capability after permanent deformation. Instead, it employs durable rigid compressible material that can maintain pressure indefinitely, effectively replacing a short-living solution with a long-lasting one.
3Stress or pressure
If rigid compression means are used to maintain high pressure, then pressure consistency is improved, but the ability to accommodate thickness changes during charge/discharge is reduced
Solution Approach 1:
The patent uses composite materials combining rigid end plates with compressible material layers. The rigid plates provide structural support and pressure consistency, while the compressible layers accommodate thickness changes during charge/discharge, resolving the contradiction between rigidity and adaptability.
Solution Approach 2:
The patent segments the compression system into rigid end plates and compressible intermediate layers. This segmentation allows each component to perform its specialized function - the rigid plates maintain overall pressure structure while the compressible layers provide adaptability to thickness changes.
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 solution effectively suppresses dendrite formation and maintains consistent pressure across the cell surface, ensuring safe and long operational life by accommodating thickness changes and maintaining high energy density without excessive pressure rise during charge/discharge cycles.
Implementation Method 1
a compressible layer, or a plurality of compressible layers, wherein the compressible layer or the plurality of compressible layers comprises a polymeric foam selected for sufficient rigidity to operate at a high pressure in a range from 0.5 to 3.0 MPa
Implementation Method 2
using materials with non-linear stress-strain behavior and porosity to prevent dendrite formation and maintain pressure consistency
Implementation Method 3
using materials with non-linear stress-strain behavior and porosity to prevent dendrite formation and maintain pressure consistency
Data Source
AI summary
This disclosure relates to rechargeable battery packs and or rechargeable battery modules consisting of electrochemical cells in general and more specifically to lithium metal anode secondary electrochemical cells and the supporting mechanical structure of such packs or modules which apply and maintain a high and uniform normal compression pressure to the face of the interconnected cells of said battery packs, modules or individual cells, in order to suppress dendrite formation during charge and maintain a low cell impedance during charge and discharge. This is achieved with the use of a compression assembly having a compressible sheet with desired properties.