Thermal runaway caused by overcharging results in catastrophic disasters. The influences of charging rate, ambient temperature and aging on thermal runaway caused by overcharging are studied qualitatively and quantita...Thermal runaway caused by overcharging results in catastrophic disasters. The influences of charging rate, ambient temperature and aging on thermal runaway caused by overcharging are studied qualitatively and quantitatively in this manuscript. The results of overcharging tests indicate that high charging rate and ambient temperature increase thermal runaway risk. Aging in 40 ℃ decreases thermal runaway risk. The risk increase of battery with high overcharging rate and in high ambient temperature is due to fast lithium plating reaction and accelerated SEI decomposition, respectively. The risk decrease of aged battery is due to the occurrence of SEI before overcharging tests. SEI suppresses the side reactions between lithium plating and electrolyte. The results of orthogonal tests indicate that the rank of effect is: discharging rate > ambient temperature > aging. The heat generation is calculated based on the results of overcharging tests. The calculation results indicate that heat generated by side reactions contributes more to the total heat generation. Although thermal runaway does not occur during overcharging with low current, the heat dissipation of the lithium-ion battery is the most and deserves focus. The results are important to the design of battery management system and thermal management system to prevent thermal runaway induced by overcharging in total lifespan of battery.展开更多
Asymmetric behaviors of capacitance and charging dynamics in the cathode and anode are general for nanoporous supercapacitors.Understanding this behavior is essential for the optimal design of supercapacitors.Herein,w...Asymmetric behaviors of capacitance and charging dynamics in the cathode and anode are general for nanoporous supercapacitors.Understanding this behavior is essential for the optimal design of supercapacitors.Herein,we perform constant-potential molecular dynamics simulations to reveal asymmetric features of porous supercapacitors and their effects on capacitance and charging dynamics.Our simulations show that,counterintuitively,charging dynamics can be fast in pores providing slow ion diffusion and vice versa.Unlike electrodes with singlesize pores,multi-pore electrodes show overcharging and accelerated co-ion desorption,which can be attributed to the subtle interplay between the dynamics and charging mechanisms.We find that capacitance and charging dynamics correlate with how the ions respond to an applied cell voltage in the cathode and anode.We demonstrate that symmetrizing this response can help boost power density,which may find practical applications in supercapacitor optimization.展开更多
The thermodynamics and overcharging problem in RN-AdS black holes with a cloud of strings and quintessence are investigated by the absorption of scalar particles and fermions in extended phase space.The cosmological c...The thermodynamics and overcharging problem in RN-AdS black holes with a cloud of strings and quintessence are investigated by the absorption of scalar particles and fermions in extended phase space.The cosmological constant is treated as the pressure of the black hole.The parameters related to quintessence and the cloud of strings are treated as thermodynamic variables.We find that the first law of thermodynamics is satisfied and the second law of thermodynamics is indefinite.Furthermore,we find that near-extremal and extremal black holes cannot be overcharged.展开更多
In a credence goods market,a consumer(he)is unaware of his true need,w hich can be either intense or minor.A n expert(she)designs a menu that either charges a u n iform price to both services,termed pooling pricing,or...In a credence goods market,a consumer(he)is unaware of his true need,w hich can be either intense or minor.A n expert(she)designs a menu that either charges a u n iform price to both services,termed pooling pricing,or varies charges according to service types,termed differential pricing.Learning the menu offered by the expert and anticipating her behavior in serving consumers,a consumer weighs the expected u tility of service provision against the cost incurred in transportation to decide w hether to visit the expert,termed entry decision.Upon arrival of a consumer,the expert discerns his true need and recommends a service along w ith the associated charge.Under the lia b ility assumption,the expert provides a service to satisfy the consumer's need.However,the consumer is unable to discern the nature of the service actually provided.This can induce the expert w ho adopts differential pricing to recommend intense service to a consumer w ith m inor need,termed overcharging.We investigate the effects of consumers'entry decision on the expert's optim al pricing strategy and the occurrence of overcharging,and study the robustness of the main results to practical features.展开更多
基金the support given by National Natural Science Foundation of China(51874184)the Key Natural Science Foundation in Jiangsu Province(18KJA620003)Jiangsu Project Plan for Outstanding Talents Team in Six Research Fields(TD-XNYQC-002)。
文摘Thermal runaway caused by overcharging results in catastrophic disasters. The influences of charging rate, ambient temperature and aging on thermal runaway caused by overcharging are studied qualitatively and quantitatively in this manuscript. The results of overcharging tests indicate that high charging rate and ambient temperature increase thermal runaway risk. Aging in 40 ℃ decreases thermal runaway risk. The risk increase of battery with high overcharging rate and in high ambient temperature is due to fast lithium plating reaction and accelerated SEI decomposition, respectively. The risk decrease of aged battery is due to the occurrence of SEI before overcharging tests. SEI suppresses the side reactions between lithium plating and electrolyte. The results of orthogonal tests indicate that the rank of effect is: discharging rate > ambient temperature > aging. The heat generation is calculated based on the results of overcharging tests. The calculation results indicate that heat generated by side reactions contributes more to the total heat generation. Although thermal runaway does not occur during overcharging with low current, the heat dissipation of the lithium-ion battery is the most and deserves focus. The results are important to the design of battery management system and thermal management system to prevent thermal runaway induced by overcharging in total lifespan of battery.
基金funding support from the National Natural Science Foundation of China(51876072)the Hubei Provincial Natural Science Foundation of China(2019CFA002,2020CFA093)supported by the Program for HUST Academic Frontier Youth Team
文摘Asymmetric behaviors of capacitance and charging dynamics in the cathode and anode are general for nanoporous supercapacitors.Understanding this behavior is essential for the optimal design of supercapacitors.Herein,we perform constant-potential molecular dynamics simulations to reveal asymmetric features of porous supercapacitors and their effects on capacitance and charging dynamics.Our simulations show that,counterintuitively,charging dynamics can be fast in pores providing slow ion diffusion and vice versa.Unlike electrodes with singlesize pores,multi-pore electrodes show overcharging and accelerated co-ion desorption,which can be attributed to the subtle interplay between the dynamics and charging mechanisms.We find that capacitance and charging dynamics correlate with how the ions respond to an applied cell voltage in the cathode and anode.We demonstrate that symmetrizing this response can help boost power density,which may find practical applications in supercapacitor optimization.
基金Supported in part by NSFC(11747171)Natural Science Foundation of Chengdu University of TCM(ZRYY1729,ZRYY 1921)+1 种基金Discipline Talent Promotion Pro-gram of/Xinglin Scholars(QNXZ2018050)the key fund project for Education Department of Sichuan(18ZA0173)。
文摘The thermodynamics and overcharging problem in RN-AdS black holes with a cloud of strings and quintessence are investigated by the absorption of scalar particles and fermions in extended phase space.The cosmological constant is treated as the pressure of the black hole.The parameters related to quintessence and the cloud of strings are treated as thermodynamic variables.We find that the first law of thermodynamics is satisfied and the second law of thermodynamics is indefinite.Furthermore,we find that near-extremal and extremal black holes cannot be overcharged.
基金the National Natural Science Foundation of China under Grant No.72001115Natural Science Foundation of the Jiangsu Higher Education Institutions of China under Grant No.20KJB410006,Humanities and Social Sciences Foundation of Ministry of Education of China under Grant No.20YJC630041Startup Foundation for Introducing Talent of NUIST under Grant No.2019r067.
文摘In a credence goods market,a consumer(he)is unaware of his true need,w hich can be either intense or minor.A n expert(she)designs a menu that either charges a u n iform price to both services,termed pooling pricing,or varies charges according to service types,termed differential pricing.Learning the menu offered by the expert and anticipating her behavior in serving consumers,a consumer weighs the expected u tility of service provision against the cost incurred in transportation to decide w hether to visit the expert,termed entry decision.Upon arrival of a consumer,the expert discerns his true need and recommends a service along w ith the associated charge.Under the lia b ility assumption,the expert provides a service to satisfy the consumer's need.However,the consumer is unable to discern the nature of the service actually provided.This can induce the expert w ho adopts differential pricing to recommend intense service to a consumer w ith m inor need,termed overcharging.We investigate the effects of consumers'entry decision on the expert's optim al pricing strategy and the occurrence of overcharging,and study the robustness of the main results to practical features.
