In-situ ellipsometry for electric vehicle battery cell lithium plating characterization

A method of analyzing lithium plating on anodes of battery cells, comprising:

• providing a battery cell having an aluminum layer, a cathode in contact with the aluminum layer, an anode formed from a powder-based, porous material, a separator layer in contact with the cathode and the anode to electrically insulate the cathode from the anode, and a transparent conductor layer electrically coupled with the anode;
• directing polarized light from a light source at a first angle with respect to a surface of the anode through the transparent conductor layer of the battery cell toward the anode to cause the anode to reflect the polarized light to produce reflected light directed at a second angle with respect to the surface of the anode;
• receiving, by a detector, the reflected light;
• generating, by the detector, an ellipsometry measurement based on the reflected light;
• and
• charging, by a charging circuit, the battery cell while the light source directs the polarized light through the transparent conductor layer of the battery cell toward the anode of the battery cell.

A method, comprising:

• providing a system to detect lithium plating on anodes of battery cells, comprising:
• a battery cell having an aluminum layer, a cathode in contact with the aluminum layer, an anode formed from a powder-based, porous material, a separator layer in contact with the cathode and the anode to electrically insulate the cathode from the anode, and a transparent conductor layer electrically coupled with the anode;
• a light source to direct polarized light at a first angle with respect to a surface of the anode through the transparent conductor layer of the battery cell toward the anode to cause the anode to reflect the polarized light to produce reflected light directed at a second angle with respect to the surface of the anode;
• a detector to:
• receive the reflected light;
• and
• generate an ellipsometry measurement based on the reflected light;
• and
• a charging circuit to charge the battery cell while the light source directs the polarized light through the transparent conductor layer of the battery cell toward the anode of the battery cell.