Decimal Solvent-Based High-Entropy Electrolyte Enabling the Extended Survival Temperature of Lithium-Ion Batteries to−130°C

Freezing and crystallization of commercial ethylene carbonate-based binary electrolytes,leading to irreversible damage to lithium-ion batteries(LIBs),remain a significant challenge for the survival of energy storage devices at extremely low temperatures(<−40°C).Herein,a decimal solvent-based high-entropy electrolyte is developed with an unprecedented low freezing point of−130°C to significantly extend the service temperature range of LIBs,far superior to−30°C of the commercial counterpart.Distinguished from conventional electrolytes,this molecularly disordered solvent mixture greatly suppresses the freezing crystallization of electrolytes,providing good protection for LIBs from possible mechanical damage at extremely low temperatures.Benefiting from this,our high-entropy electrolyte exhibits extraordinarily high ionic conductivity of 0.62 mS·cm−1 at−60°C,several orders of magnitude higher than the frozen commercial electrolytes.Impressively,LIBs utilizing decimal electrolytes can be charged and discharged even at an ultra-low temperature of−60°C,maintaining high capacity retention(∼80%at−40°C)as well as remarkable rate capability.This study provides design strategies of low-temperature electrolytes to extend the service temperature range of LIBs,creating a new avenue for improving the survival and operation of various energy storage systems under extreme environmental conditions.

Failure Analysis of Power Electronic Devices and Their Applications under Extreme Conditions

Power electronic devices are the core components of modern power converters,not only for normal applications,but also for extreme conditions.Current design of power electronic devices require large redundancies for reliability.This results in huge volume and weight for a large-capacity power converter,especially for some extreme applications.Therefore,to optimize the power density,the reliability of power devices needs to be investigated first in order to obtain the accurate operational margin of a power device.Although much research on device failure analysis has been reported,there still lacks efficient failure evaluation methods.This paper first summarizes the current failure research.Then,a three-step failure analysis method of power electronic devices is proposed as:failure information collection,failure identification and mechanism,and failure evaluation.The physics-based modeling method is emphasized since it has a strong relationship with the device fundamentals.After that,power electronic device applications under extreme conditions are introduced and a design method of device under extreme conditions is proposed based on the thermal equilibrium idea.Finally,the challenges and prospects to improve the power device reliability under extreme conditions are concluded.