Thin film resistors are used in many applications. In battery devices, the use of thin film resistors is very high, which can effectively improve the battery usage rate, and can also be used to feedback battery data in the battery management system. Usually based on the value of the film resistance, the true conductivity of the material can be calculated by linear fitting, which provides technical support for product development. While testing resistors in batteries, sampling two- and four-probe testing methods are the most common, and the two methods vary.

First, the film resistance two-needle test method
When the two-probe method is used to test the sheet resistance, the test loading pressure will have a certain effect on the result. Generally, the test loading pressure is increased and the electrode film resistance is lowered. After reaching a certain value, the test result is independent of the pressure. After the rolling, the pole piece, the fresh pole piece after assembling the battery, and the pole piece which has experienced different cycle times show different resistance values and test loading pressure sensitivity differences in different life cycles, and can be calculated through the pressure sensitivity difference of the diaphragm. The difference in the thickness variation of the pole pieces of different life cycles provides a new measurement characterization method for the evaluation of pole piece and lithium battery analysis. 


Second, the film resistance four-needle test
There are many methods for testing the sheet resistance in a battery. The four-probe method and the single-probe method are the most commonly used. These methods have their own characteristics for measuring the sheet resistance, but they all have many shortcomings. Traditional four-probe instruments have been developed for the thin-layer metal coating industry and are primarily used for the measurement of conductive coating resistance on the surface of an insulating substrate. For a battery diaphragm whose underlying collector conductivity is much higher than that of the coating, when the four-probe method tests the resistance, the electron flow direction is parallel to the current collector, and the electron is transmitted perpendicular to the current collector when the battery is actually charged and discharged. Therefore, the resistance tested by this method is different from the actual working condition.
 
In many cases, engineers often use this method to coat the slurry on a non-conductor substrate to test the impedance of the slurry film, and quantitatively analyze the distribution state of the conductive agent in the slurry by resistivity to determine the dispersion effect of the slurry. The film resistance is different in the two methods of testing in the battery. These methods are not the best way to test the thin film battery in the battery industry.