Secondary Battery Cycling Pressure with Isotropic Fluid Pressing
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Solution Overview
Problem
Existing battery cell pressing devices fail to apply uniform pressure consistently, leading to degraded battery performance and reduced lifespan, especially when using anodes with substantial volume fluctuations like silicon and lithium metal.
Innovation Solution
A battery cell pressing device that uses a case filled with fluid to isotropically press the battery cell during charging and discharging, ensuring uniform pressure application and preventing non-uniform pressing issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional pressing device is used to apply pressure to the battery cell, then the battery cell can be pressed during activation, but the pressure is non-uniform which degrades battery performance and reduces lifespan
Solution Approach 1:
The patent employs a fluid (gas or liquid) contained in a chamber to apply isostatic pressure to the battery cell. The fluid transmits pressure uniformly in all directions through Pascal's principle, ensuring consistent pressure distribution across the battery cell surface during activation and cycling, thereby preventing performance degradation and extending lifespan.
Solution Approach 2:
The patent changes the physical state and properties of the pressing medium by using a compressible fluid instead of rigid mechanical components. The fluid's ability to transmit pressure isotropically and its compressibility allow for uniform pressure application that adapts to the battery cell's volume changes during charging and discharging cycles.
2Productivity
If non-uniform pressure is applied during battery cell pressing, then the activation process can be completed, but battery performance deteriorates and lifetime is reduced
Solution Approach 1:
The fluid-based pressing system ensures uniform pressure distribution throughout the battery cell during activation and cycling. The fluid transmits pressure isotropically, eliminating non-uniform stress concentrations that would otherwise degrade battery performance and reduce lifetime while still completing the activation process effectively.
Solution Approach 2:
The patent creates an equipotential pressure field around the battery cell by using a fluid medium that transmits pressure uniformly in all directions. This eliminates pressure gradients and non-uniform stress distribution, ensuring that every part of the battery cell experiences the same pressure level during activation and cycling operations.
3Quantity of substance
If anodes with substantial volume fluctuations (silicon, lithium metal) are used, then higher energy density is achieved, but non-uniform pressing causes performance degradation
Solution Approach 1:
The fluid pressing system is particularly suited for anodes with substantial volume fluctuations because the fluid can accommodate changes in battery cell volume while maintaining uniform pressure distribution. As the anode expands or contracts during cycling, the fluid pressure remains isotropic and uniform, preventing performance degradation associated with non-uniform pressing.
Solution Approach 2:
The patent employs a dynamic pressing system using compressible fluid that can adapt to real-time volume changes of the battery cell during charging and discharging cycles. The fluid pressure adjusts dynamically to maintain uniform distribution despite the substantial volume fluctuations of silicon or lithium metal anodes, enabling high energy density without performance degradation.
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 device effectively prevents deterioration in battery performance and lifetime by ensuring consistent, uniform pressure, thereby optimizing energy density and extending the battery's operational life.
Implementation Method 1
a fluid filling the inside of the case and pressing the battery cell, wherein the fluid isotropically presses the battery cell during at least one of charging and discharging of the battery cell
Data Source
AI summary
A method of controlling a cycling pressure of a secondary battery can include assembling the secondary battery by stacking a cathode, a separator, and an anode in order; activating the secondary battery by applying a pressure of about 5 MPa or less; and cycling the secondary battery by applying the pressure of about 5 MPa or less.