All Solid State Battery Anode Pressure Stability
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Solution Overview
Problem
The large volume change of Si-based active materials during charge and discharge in all solid state batteries leads to path cut-off, deteriorating battery performance, and the restraining pressure applied to mitigate this change is affected by the expansion and contraction of these materials, necessitating a solution to stabilize the pressure.
Innovation Solution
Incorporating a Si-based active material with an average particle size of 100 nm to 800 nm and a low crystalline sulfide solid electrolyte with specific Raman spectroscopy characteristics, including a peak at 415 cm−1 to 425 cm−1 and a half-value width of 15.5 cm−1 to 20.0 cm−1, to form an anode active material layer, which suppresses the change in restraining pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Si-based active material is used as anode active material, then capacity properties are improved, but volume change during charge and discharge causes path cut-off and battery performance deterioration
Solution Approach 1:
The patent changes the particle size parameter of Si-based active material to a specific range (100 nm to 800 nm average particle size) to reduce volume change during charge-discharge cycles. This parameter optimization allows the material to maintain capacity properties while minimizing expansion and contraction that lead to path cut-off.
Solution Approach 2:
The patent creates a composite anode active material layer combining Si-based active material with sulfide solid electrolyte in specific volume ratios (Si-based: 1-65 vol%, sulfide solid electrolyte: 35-99 vol%). This composite structure mitigates the volume change issue of pure Si-based material while maintaining high capacity properties.
2Reliability
If restraining pressure is applied to suppress path cut-off, then battery performance is improved, but expansion and contraction of Si-based active material causes change in restraining pressure
Solution Approach 1:
The patent optimizes the particle size parameter of Si-based active material (100 nm to 800 nm) to reduce the magnitude of expansion and contraction during charge-discharge cycles. This parameter change directly reduces the fluctuation of restraining pressure while maintaining the ability to suppress path cut-off.
Solution Approach 2:
The composite structure of Si-based active material (1-65 vol%) and sulfide solid electrolyte (35-99 vol%) creates a more stable overall volume during charge-discharge cycles. The sulfide solid electrolyte acts as a buffer that reduces the impact of Si-based material expansion and contraction, thereby stabilizing restraining pressure.
3Reliability
If Si-based active material with small particle size is used, then path cut-off is reduced, but manufacturing precision and particle size control become more difficult
Solution Approach 1:
The patent defines a specific particle size range (100 nm to 800 nm average particle size) that balances the benefits of small particles (reduced path cut-off) with manufacturing feasibility. This parameter specification makes particle size control more manageable while maintaining the advantages of nanoscale materials.
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 specified Si-based active material and low crystalline sulfide solid electrolyte combination effectively reduces the change in restraining pressure caused by expansion and contraction, enhancing battery performance by maintaining a stable ion and electron conducting path.
Implementation Method 1
the sulfide solid electrolyte includes, in a Raman spectroscopy spectrum, a peak in a position of 415 cm−1 or more and 425 cm−1 or less, and a half-value width of the peak is 15.5 cm−1 or more and 20.0 cm−1 or less
Implementation Method 2
a lithium ion conductivity of the sulfide solid electrolyte at 25° C. may be 1.5 mS/cm or more and 3.5 mS/cm or less
Data Source
AI summary
A main object of the present disclosure is to provide an all solid state battery in which change in restraining pressure caused by expansion and contraction of a Si-based active material can be suppressed. The present disclosure achieves the object by providing an all solid state battery including layers in the order of a cathode active material layer, a solid electrolyte layer, and an anode active material layer, wherein: the anode active material layer includes a Si-based active material and a sulfide solid electrolyte; an average particle size D50 of the Si-based active material is 100 nm or more and 800 nm or less; the sulfide solid electrolyte includes, in a Raman spectroscopy spectrum, a peak in a position of 415 cm−1 or more and 425 cm−1 or less, and a half-value width of the peak is 15.5 cm−1 or more and 20.0 cm−1 or less; a volume ratio of the Si-based active material with respect to a total of the Si-based active material and the sulfide solid electrolyte is 1 volume % or more and 65 volume % or less; and a volume ratio of the sulfide solid electrolyte with respect to the total of the Si-based active material and the sulfide solid electrolyte is 35 volume % or more and 99 volume % or less.