Elastic Layer in All-Solid-State Battery Stack for Contact Stability
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Solution Overview
Problem
All-solid-state secondary batteries face reduced coulombic efficiency due to thickness variations of the anode active material layer during charging and discharging, leading to stress on the solid electrolyte and anode current collector, which disrupts the ion and electron conduction paths.
Innovation Solution
A unit stack-cell structure is designed with a laminate configuration including a cathode layer, a solid electrolyte layer, and an elastic layer with specific compressive strength and stress relaxation properties to improve the followability of the anode current collector, thereby maintaining a stable contact between the solid electrolyte and anode current collector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the anode active material layer thickness varies during charging and discharging, then the battery capacity increases, but the contact between solid electrolyte and anode current collector deteriorates
Solution Approach 1:
An elastic layer is introduced as an intermediary component between the anode current collector and solid electrolyte. This elastic layer absorbs the thickness variations of the anode active material during charging and discharging, maintaining stable contact between the solid electrolyte and anode current collector while allowing the battery to operate at high capacity.
2Reliability
If the elastic layer compressive strength is increased, then the contact stability improves, but the stress on solid electrolyte increases
Solution Approach 1:
The compressive strength of the elastic layer is optimized to a specific range (0.28-0.6 MPa at 40-70% compressibility) to balance two opposing requirements: providing enough force to maintain stable contact between solid electrolyte and anode current collector, while limiting the stress transmitted to the solid electrolyte to prevent damage.
3Stress or pressure
If the elastic layer compressive strength is decreased, then the stress on solid electrolyte is reduced, but the contact stability deteriorates
Solution Approach 1:
The compressive strength of the elastic layer is optimized to a specific range (0.28-0.6 MPa at 40-70% compressibility) to balance two opposing requirements: providing enough force to maintain stable contact between solid electrolyte and anode current collector, while limiting the stress transmitted to the solid electrolyte to prevent damage.
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 elastic layer absorbs volume changes in the anode layer, ensuring a stable contact and increasing the coulombic efficiency of the all-solid-state secondary battery by uniformly distributing stress and maintaining a good contact state during charging and discharging.
Implementation Method 1
an elastic layer having a compressive strength of greater than or equal to about 0.28 MPa and less than about 0.6 MPa in a compressibility interval in a range of about 40% to about 70%
Implementation Method 2
The elastic layer may have a stress relaxation rate in a range of about 5% to about 20%
Data Source
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AI summary
A unit stack-cell structure and an all-solid-state secondary battery including the same, the unit stack-cell structure includes a plurality of stacked unit cells, each unit cell of the plurality of stacked unit cells including a laminate in which a cathode layer; a solid electrolyte layer; an anode layer; and an elastic layer are sequentially arranged, wherein the elastic layer has a compressive strength of greater than or equal to about 0.28 MPa and less than about 0.6 MPa in a compressibility interval in a range of about 40 % to about 70 %.