Methods of making and inspecting a web of vitreous lithium sulfide separator sheet and lithium electrode assemblies
A lithium ion-conductive solid electrolyte including a freestanding inorganic vitreous sheet of sulfide-based lithium ion conducting glass is capable of high performance in a lithium metal battery by providing a high degree of lithium ion conductivity while being highly resistant to the initiation and/or propagation of lithium dendrites. Such an electrolyte is also itself manufacturable, and readily adaptable for battery cell and cell component manufacture, in a cost-effective, scalable manner. An automated machine based system, apparatus and methods assessing and inspecting the quality of such vitreous solid electrolyte sheets, electrode sub-assemblies and lithium electrode assemblies can be based on spectrophotometry and can be performed inline with fabricating the sheet or web (e.g., inline with drawing of the vitreous Li ion conducting glass) and/or with the manufacturing of associated electrode sub-assemblies and lithium electrode assemblies and battery cells.
1. A method of inspecting a battery cell, the method comprising:
i) providing an electrode assembly comprising:
a dense solid inorganic electrolyte sheet as an ionically conductive separator layer having first and second opposing principal side surfaces; and
a material layer comprising electroactive lithium disposed on the first principal side surface; and
ii) spectrophotometrically inspecting the electrode assembly for defects or flaws at an interface between the material layer comprising electroactive lithium and the inorganic electrolyte sheet;
wherein the spectrophotometric inspection is an automated inspection comprising:
providing a source of light of a specified wavelength, or the wavelength selectable from a range of wavelengths;
providing sensors for measuring intensity of the light;
providing a computer that interfaces with the sensors for collecting light intensity data;
shining the light at the solid electrolyte sheet for transmission or reflection measurements;
measuring the transmitted or reflected light intensity using said sensors; and
storing data from said sensors using said computer.
2. The method of claim 1 , wherein the material layer is lithium metal.
3. The method of claim 1 , wherein changes in reflectivity of the interface are monitored in order to identify areas of low Li reactivity at the interface.
4. The method of claim 1 , wherein the method involves monitoring reactions at the interface in real time.
5. The method of claim 1 , wherein the spectrophotometric inspection is performed inline with the fabrication of the electrode assembly.
6. The method of claim 1 , wherein the spectrophotometric inspection further comprises inspecting the first and second opposing principal side surfaces and/or interior of the inorganic electrolyte sheet for defects and flaws.
7. The method of claim 6 , wherein the spectrophotometric inspection comprises measuring attenuation of reflected light for inspection of the interface between the inorganic electrolyte sheet and the material layer, and measuring attenuation of transmitted light for inspection of the first and second opposing principal side surfaces and/or interior of the inorganic electrolyte sheet.
8. The method of claim 6 , wherein the spectrophotometric inspection further comprises inspecting an interface between the inorganic electrolyte sheet and a reflective coating layer that is devoid of lithium metal for defects and flaws.