Solid-State Battery Initial Charging Pressure for Anode Adhesion
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Solution Overview
Problem
Low constraining pressure in solid-state batteries with alloy-based anode active materials leads to increased resistance due to inadequate melt adhesion during charging and discharging, resulting in high resistance increase rates.
Innovation Solution
A solid-state battery design with an anode layer containing alloy-based anode active material, specifically silicon, and a sulfide solid electrolyte, where the anode layer has a high void proportion in the stacking direction and an anode current collector with surface roughness between 0.8 μm to 4.0 μm, subjected to initial charging with constraining pressures of at least 30 MPa at the beginning and 40 MPa at the end, then reduced to 10 MPa or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If low constraining pressure is applied during initial charging, then the battery assembly process is simpler and easier to operate, but the melt adhesion of anode active material is insufficient, causing extremely large resistance increase rate
Solution Approach 1:
The patent applies high constraining pressure (at least 30 MPa, preferably 40-100 MPa) during the initial charging step before normal operation. This preliminary action promotes melt adhesion of the alloy-based anode active material particles to the current collector, establishing good electrical contact before the battery enters normal use. After initial charging, the pressure is reduced to normal levels (at most 10 MPa), thus resolving the contradiction between assembly simplicity and reliability.
2Reliability
If high constraining pressure is applied during initial charging, then the melt adhesion of anode active material is promoted and resistance increase rate is suppressed, but the manufacturing process becomes more complex and requires higher equipment capability
Solution Approach 1:
The patent implements dynamic pressure control where the constraining pressure changes at different stages of the manufacturing process. During initial charging, high pressure (at least 30 MPa) is applied to promote melt adhesion. After initial charging completes, the pressure is reduced to normal operating levels (at most 10 MPa). This dynamic adjustment allows the system to achieve high reliability during the critical initial charging phase while maintaining simplicity during normal operation and storage.
3Reliability
If high constraining pressure is applied continuously, then the melt adhesion is continuously maintained, but the manufacturing cost increases and the battery structure becomes more complex
Solution Approach 1:
The patent applies constraining pressure in a periodic manner: high pressure (at least 30 MPa) is applied specifically during the initial charging step, then reduced to low pressure (at most 10 MPa) for subsequent normal operation and storage. This periodic application of high pressure ensures melt adhesion is established when needed most (during initial charging when particles are most mobile), while avoiding the costs and structural complexity of continuously maintaining high pressure throughout the battery lifecycle.
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
This approach suppresses the rise in resistance increase rate by promoting melt adhesion of anode active material particles, reducing inert interfaces, and controlling void arrangement, thereby enhancing the battery's durability and performance.
Implementation Method 1
a low constraining pressure for a solid-state battery that includes an anode layer using an alloy-based anode active material in an initial charging step does not promote the melt adhesion of the anode active material
Implementation Method 2
a solid-state battery that includes a stack including a cathode layer, a solid electrolyte layer, and an anode layer
Data Source
AI summary
In a solid-state battery that includes a stack including a cathode layer, a solid electrolyte layer, and an anode layer, the proportion of voids in the anode layer in a stacking direction, in all voids in the anode layer is more than 36 vol %; or a method of producing a solid-state battery includes: performing initial charging in which a constraining pressure for the stack at the beginning of the charging is at least 30 MPa, and a constraining pressure for the stack at the end of the charging is at least 40 MPa.