Embedded Sensors for In-Situ Cell Monitoring of Batteries

Abstract

The disclosed principles provide for techniques for the 3D fabrication of sensing systems that are embedded inside battery cells and provide cell parameter data for a comprehensive and an robust battery management system. The disclosed principles provide for online and real-time monitoring of battery state-of-health down to the individual cell level of each battery using embedded sensors on one or more of the internal layers of a cell, such as the dielectric separators found in such battery cells. The implementation of the disclosed principles in individual battery cells therefore provides an increased likelihood to mitigate catastrophic failures in batteries. In addition, the disclosed fabrication processes for printing sensors directly on one or more of the components or layers within each individual battery cell, significantly reduce manufacturing steps required by conventional battery management systems. The disclosed principles also provided for a unique silica-based ink for use in the 3D printing of such embedded cell sensing components.

1 . A battery cell monitoring system, comprising:
 an optical fiber formed on a component within the battery cell;   at least one fiber Bragg grating (FBG) sensor formed along the optical fiber by creating a variation in the refractive index of the optical fiber;   wherein the optical fiber is configured to receive therethrough light transmitted from a light source, and to emit light therefrom with one or more shifts in wavelength caused by refraction of the transmitted light by the at least one FBG sensors.   
     
     
         2 . A battery cell monitoring system in accordance with  claim 1 , wherein the optical fiber is formed on a dielectric separator of the battery cell. 
     
     
         3 . A battery cell monitoring system in accordance with  claim 1 , wherein the optical fiber and the at least one FBG sensor are formed via 3D printing. 
     
     
         4 . A battery cell monitoring system in accordance with  claim 1 , wherein the light source comprises battery cell monitoring equipment coupled to the optical fiber and configured to transmit light therethrough and to receive the light emitted therefrom to measure parameters of the battery cell based on the one or more shifts in wavelength caused by refraction of the transmitted light by the at least one FBG sensors. 
     
     
         5 . A battery cell monitoring system in accordance with  claim 4 , wherein one or more of battery cell temperature, strain, pressure, and displacement are measured by the battery cell monitoring equipment based on said one or more shifts in wavelength. 
     
     
         6 . A battery cell monitoring system in accordance with  claim 1 , further comprising at least two metal sleeves formed on the optical fiber proximate ones of the FBG sensors, the at least two metal sleeves configured to detect an internal voltage of the cell. 
     
     
         7 . A battery cell monitoring system in accordance with  claim 6 , further comprising corresponding conductive leads formed in contact with the at least two sleeves, the conductive leads configured to permit voltage measuring across the FBG sensors via the corresponding metal sleeves. 
     
     
         8 . A battery cell monitoring system in accordance with  claim 7 , wherein the at least two sleeves and corresponding conductive leads are formed via 3D printing. 
     
     
         9 . A battery cell monitoring system in accordance with  claim 1 , wherein the optical fiber comprises a cured mixture comprising photopolymer and silica. 
     
     
         10 . A method of forming a battery cell monitoring system, the method comprising:
 forming an optical fiber on a component within the battery cell;   forming at least one fiber Bragg grating (FBG) sensor along the optical fiber by creating a periodic variation in the refractive index of the optical fiber; and   ultraviolet (UV) light curing the optical fiber after its forming;   wherein the optical fiber is configured to receive therethrough light transmitted from a light source, and to emit light therefrom with one or more shifts in wavelength caused by refraction of the transmitted light by the at least one FBG sensors.   
     
     
         11 . A method in accordance with  claim 10 , wherein forming the optical fiber comprises forming the optical fiber on a dielectric separator of the battery cell. 
     
     
         12 . A method in accordance with  claim 10 , wherein forming the optical fiber and the at least one FBG sensor comprises forming via 3D printing. 
     
     
         13 . A method in accordance with  claim 12 , wherein the 3D printing comprises employing aerosol jet technology. 
     
     
         14 . A method in accordance with  claim 10 , further comprising forming at least two metal sleeves on the optical fiber proximate ones of the FBG sensors, the at least two metal sleeves configured to detect an internal voltage of the cell. 
     
     
         15 . A method in accordance with  claim 14 , further comprising forming corresponding conductive leads in contact with the at least two sleeves, the conductive leads configured to permit voltage measuring across the FBG sensors via the corresponding metal sleeves. 
     
     
         16 . A method in accordance with  claim 15 , wherein forming the at least two sleeves and corresponding conductive leads comprises forming via 3D printing. 
     
     
         17 . A method in accordance with  claim 10 , wherein the light source comprises battery management equipment configured to receive the emitted light to measure parameters of the battery cell based on the one or more shifts in wavelength caused by refraction of the transmitted light by the at least one FBG sensors. 
     
     
         18 . An ink mixture for use in 3D printing equipment, the ink mixture comprising:
 a photo-polymer solvent;   silica powder; and   wherein the ink mixture has an overall viscosity sufficient for use in the 3D printing equipment and is UV-curable immediately after deposition.   
     
     
         19 . An ink mixture in accordance with  claim 18 , wherein said ink mixture comprises an overall viscosity of about 75 to 200 cP. 
     
     
         20 . An ink mixture in accordance with  claim 19 , wherein the photo-polymer solvent has an individual viscosity of about 30-55 cP, and wherein the ink mixture comprises about 98% of said photo-polymer solvent and about 2% of said silica powder, and wherein said ink mixture comprises an overall viscosity of about 86 cP. 
     
     
         21 . An ink mixture in accordance with  claim 18 , further comprising an alcohol-based agent. 
     
     
         22 . An ink mixture in accordance with  claim 21 , wherein the ink mixture comprises about 81.667% said photo-polymer solvent, about 1.667% said silica powder, and about 16.667% said alcohol-based agent, and wherein said ink mixture comprises an overall viscosity of about 65 cP. 
     
     
         23 . An ink mixture in accordance with  claim 18 , wherein the 3D printing equipment employs aerosol jet deposition technology. 
     
     
         24 . An ink mixture in accordance with  claim 23 , wherein operating parameters for the aerosol jet equipment comprise: step size of 50 μm; 7 mm/s deposition speed; flow parameters set as 3, 1250, 1300 ccm; standoff distance between the nozzle and a target at approximately 4 mm; and a nozzle size of 200 microns.