Lithium-ion batteries(LIBs)undergo various degradation phenomena such as material decomposition,structural change and uneven lithium ion distribution during long-term cycles,which would affect their performance and sa...Lithium-ion batteries(LIBs)undergo various degradation phenomena such as material decomposition,structural change and uneven lithium ion distribution during long-term cycles,which would affect their performance and safety.In order to improve the performance of the LIBs during their life cycle,preload force is preset when the batteries are assembled.Different preload forces will in turn affect the cycle life and heat generation of the battery.In order to address this issue,this work carries out charge/discharge cycle tests on a NCM811 battery under different preload forces.Isothermal calorimetry tests are performed to investigate the battery heat generation under different states of health(SOHs)and preload forces.Based on the test results,an empirical prediction model for heat generation power as a function of SOH is established.Results show that when the preload force is 5 N·m,the battery capacity decreases in the slowest rate and the average heat generation power is the lowest.Changes in peaks of the incremental capacity curve can be used to characterize the loss of lithium at the electrode,which in turn characterizes the change of heat generation power of the battery.The average heat generation power is mainly affected by the SOH,going through a period of trough with the decrease of the SOH and continuing to increase after crossing the critical point.In general,these findings emphasize the relationship between preload force,SOH and heat generation power,which is helpful for the judgment of optimal preload to improve the efficiency of LIBs.展开更多
An electrochemical thermal coupling model of lithium battery was established to study the heat generation characteristic in this study.The simulation results showed that the heat generation density of the battery incr...An electrochemical thermal coupling model of lithium battery was established to study the heat generation characteristic in this study.The simulation results showed that the heat generation density of the battery increased with the discharge rate.With the discharge process,the heat generation density of the battery increased continuously.With 2.5C discharge rate,the heat generation density at the end of discharge was 1.82 times of that at the beginning of discharge.The heat generation density at different areas of the battery was not uniform and 46%of the total ohmic heat was generated near the electrode tabs.A cooling plate with variable mini-channels was designed to improve the temperature non-uniformity caused by the heat generation characteristic.A cooling plate with uniform mini-channels was designed for compared experiment.The experiments were conducted with deionized water and refrigerant R141b and carried out with 1.5C,2C and 2.5C discharge rates.Experimental results showed that the cooling plate with variable mini-channels had a better cooling performance in both single-phase and two-phase cooling conditions.展开更多
基金the financial supports from the National Key R&D Plan of China(No.2021YFB2402001)the Chongqing Municipal Innovation Project(No.CYS23657)。
文摘Lithium-ion batteries(LIBs)undergo various degradation phenomena such as material decomposition,structural change and uneven lithium ion distribution during long-term cycles,which would affect their performance and safety.In order to improve the performance of the LIBs during their life cycle,preload force is preset when the batteries are assembled.Different preload forces will in turn affect the cycle life and heat generation of the battery.In order to address this issue,this work carries out charge/discharge cycle tests on a NCM811 battery under different preload forces.Isothermal calorimetry tests are performed to investigate the battery heat generation under different states of health(SOHs)and preload forces.Based on the test results,an empirical prediction model for heat generation power as a function of SOH is established.Results show that when the preload force is 5 N·m,the battery capacity decreases in the slowest rate and the average heat generation power is the lowest.Changes in peaks of the incremental capacity curve can be used to characterize the loss of lithium at the electrode,which in turn characterizes the change of heat generation power of the battery.The average heat generation power is mainly affected by the SOH,going through a period of trough with the decrease of the SOH and continuing to increase after crossing the critical point.In general,these findings emphasize the relationship between preload force,SOH and heat generation power,which is helpful for the judgment of optimal preload to improve the efficiency of LIBs.
基金supported by the National Key R&D Program of China(2019YFE0104900)。
文摘An electrochemical thermal coupling model of lithium battery was established to study the heat generation characteristic in this study.The simulation results showed that the heat generation density of the battery increased with the discharge rate.With the discharge process,the heat generation density of the battery increased continuously.With 2.5C discharge rate,the heat generation density at the end of discharge was 1.82 times of that at the beginning of discharge.The heat generation density at different areas of the battery was not uniform and 46%of the total ohmic heat was generated near the electrode tabs.A cooling plate with variable mini-channels was designed to improve the temperature non-uniformity caused by the heat generation characteristic.A cooling plate with uniform mini-channels was designed for compared experiment.The experiments were conducted with deionized water and refrigerant R141b and carried out with 1.5C,2C and 2.5C discharge rates.Experimental results showed that the cooling plate with variable mini-channels had a better cooling performance in both single-phase and two-phase cooling conditions.
