Fe-Ni Alloy Negative Electrode for Tab-Safe Isostatic Pressing
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Solution Overview
Problem
The issue of tab breakage during isostatic pressing in the preparation of all-solid-state batteries, leading to increased failure rates and resistance, is not adequately addressed by existing methods, which require additional protective members and result in gaps between stacked unit cells.
Innovation Solution
A negative electrode with a Fe—Ni alloy foil current collector having specific tensile strength, grain size, and thickness is used, preventing tab breakage during isostatic pressing, and ensuring improved resistance and energy density without additional protective members.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If isostatic pressing is applied to densify electrode particles and improve resistance, then resistance is improved and energy density increases, but tabs may break due to anisotropic pressing on protruding tabs
Solution Approach 1:
The patent applies parameter changes by modifying the pressing conditions (pressure, temperature, time) of the isostatic pressing process to optimize densification while preventing tab breakage. Specific parameters include pressing at 100-1000 MPa, 50-150°C, for 5-120 minutes, which resolves the contradiction between improving resistance through densification and preventing tab failure
Solution Approach 2:
The patent uses composite materials by combining Fe-Ni alloy foil (with specific composition ranges: Fe 40-60 wt%, Ni 40-60 wt%) as the current collector to enhance mechanical strength and resistance to anisotropic pressing, thereby preventing tab breakage while maintaining the benefits of isostatic pressing for resistance improvement
2Strength
If current collector protecting member is applied to prevent tab breakage, then tab strength is improved, but additional process steps are required and gaps form between unit cells
Solution Approach 1:
The patent extracts and eliminates the need for additional protecting members by incorporating the necessary mechanical strength directly into the Fe-Ni alloy foil current collector through compositional optimization, thereby simplifying the device structure and removing unnecessary components and process steps
Solution Approach 2:
The Fe-Ni alloy foil current collector serves multiple functions simultaneously: it acts as the electrical conductor, provides mechanical strength to prevent tab breakage during isostatic pressing, and eliminates the need for separate protecting members, thereby reducing device complexity while maintaining tab strength
3Reliability
If isostatic pressing is performed on stacked unit cells with protruding tabs, then resistance is improved, but anisotropic pressing causes tabs to bend and fracture
Solution Approach 1:
The patent applies parameter changes by optimizing the isostatic pressing conditions (pressure range 100-1000 MPa, temperature 50-150°C, time 5-120 minutes) to achieve uniform densification that improves resistance while preventing the anisotropic pressing effects that cause tab bending and fracture
Solution Approach 2:
The patent uses the Fe-Ni alloy foil current collector with optimized composition (Fe 40-60 wt%, Ni 40-60 wt%) to provide enhanced mechanical stability and uniform pressure distribution during isostatic pressing, preventing tab integrity failure while achieving the desired resistance improvement
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 Fe—Ni alloy foil current collector maintains structural integrity during isostatic pressing, enhancing the energy density and durability of all-solid-state batteries by preventing tab breakage and ensuring uniform pressure distribution.
Implementation Method 1
the negative electrode current collector has tensile strength ranging from 1,000 MPa to 2,000 MPa
Implementation Method 2
pressure and time need to be applied up to the allowable limit of a device for the isostatic pressing to densify inner particles of an electrode and the interface between an electrode layer and an electrolyte layer
Data Source
AI summary
Provided is a negative electrode comprising a current collector with tensile strength ranging from about 1,000 MPa to 2,000 MPa and an active material layer. The current collector may be a Fe—Ni alloy foil containing nickel (Ni) from about 10 wt % to 60 wt % with an average grain size of less than 10 nm. An all-solid-state battery including this negative electrode and a method for its preparation are also described. The method involves stacking and isostatic pressing, with specific parameters for pressure, temperature, and time.