Ultrasonic Nondestructive Technology For Studying Lithium Plating In Lithium Ion Battery Negative Electrode

Lithium-ion batteries(LIBs)are widely used in various fields due to their high single-cell voltage,no memory effect,and weeny self-discharge.However,LIB's safety performance and energy density are not really satisfactory.Lithium plating is an important factor which limits the development of LIBs.It is also the main reason causing the increase of internal resistance and capacity attenuation of LIBs.But there are still less effective methods for detecting lithium plating of LIBs.Like disassembling the battery to observe the negative surface is inefficient and has certain errors.As an emerging non-destructive testing method,ultrasonic testing has advantages of high efficiency,low cost,no pollution and accurate positioning.This paper innovatively proposes the detection of lithium plating by ultrasonic non-destructive technology,and aims to verify the feasibility of this method.A single point detection system was set up to select the coupling medium suitable for battery detection.A global scanning system was built to scan the battery globally,and the scanning result was compared with the result obtained by the electrochemical voltage relaxation method,then the battery was disassembled to observe the negative electrode surface for verification.Studies have shown that a lithium-ion battery charged at 1.5 C rate shows a large areas blue region in the chromatogram obtained by ultrasonic scanning at 0?.It is determined that lithium plating was appeared.Then,the surface of anodes were observed by disassembling battery,and voltage relaxation method in electrochemistry was used to affirm lithium plating.The feasibility of ultrasonic detection of lithium plating in lithium-ion battery was verified.The cell was placed in a liquid coupling medium,and the temperature of the coupling medium was controlled at 0? through a heat exchange system.The chromatogram of the cell in the state of charge and discharge cycle was collected.After real-time monitoring,the positioning of lithium plating in the battery was verified.