Delika M. Weragoda

Hydrogen energy is considered to be the most potential “ultimate energy source” due to its high combustion calorific value, cleanliness, and pollution-free characteristics. Furthermore, the production of hydrogen via the electrolysis of water has the advantages of simplicity, high efficiency, environmentally safe, and high-purity hydrogen. However, it is also associated with issues such as high-power consumption for the reaction and limited large-scale application of noble metal catalysts. Metal–organic frameworks (MOFs) are porous composite materials composed of metal ions and organic functional groups through orderly coordination with large specific surface areas and large porosity. Herein, we focus on the research status of MOFs and their transition metal derivatives for electrocatalytic water splitting to produce hydrogen and briefly describe the reaction mechanism and evaluation parameters of the electrocatalytic hydrogen evolution and oxygen evolution reactions. Furthermore, the relationship between the catalytic behavior and catalytic activity of different MOF-based catalysts and their morphology, elemental composition, and synthetic strategy is analyzed and discussed. The reasons for the excellent activity and poor stability of the original MOF materials for the electrolysis of water reaction are shown through analysis, and using various means to improve the catalytic activity by changing the electronic structure, active sites, and charge transfer rate, MOF-based catalysts were obtained. Finally, we present perspectives on the future development of MOFs for the electrocatalytic decomposition of water.

•Heat generation of Lithium ion batteries and consequences of thermal instability.•Capability of heat pipes in maintaining thermal stability of Li-ion cells.•Gaps in heat pipe based battery thermal management.•Current status, challenges and future direction of heat pipe based battery thermal management. Heat pipes are currently attracting increasing interest in thermal management of Electric vehicle (EV) and Hybrid electric vehicle (HEV) battery packs due to its superconductive capability, robustness, low maintenance and longevity. With the focus of battery thermal management directed towards both convective and conductive cooling, a significant number of research, both experimental and numerical investigations have been performed during the past decade. However, heat pipe based battery thermal management systems (HP-BTMS) are yet to be commercialized due to lack of understanding their limitations during rapid heat fluctuations and adverse environmental conditions, performance under multiple heat loads, failure criteria in the context of battery thermal management and lack of simple and versatile thermal models to accurately predict the battery thermal performance at module and pack level. This comprehensive review highlights the different heat generation mechanisms of Li-ion batteries and their resulting consequences, followed by the operating principles of heat pipes along with background and shortcomings related to heat pipe based battery thermal management, for the mere purpose of further development of this promising thermal management system. Different heat pipe based thermal management systems developed during the last decade along with their modelling approaches, including the methods adopted for enhancing heat transfer are critically analysed. Heat pipes have demonstrated to be an effective approach in maintaining optimum cell surface temperature, however, several areas require attention if this system is to be commercialized. Niche types of heat pipes such as pulsating heat pipes, loop heat pipe, mini/micro heat pipe have also been reviewed and their advantages, disadvantages, and challenges in the context of BTMS are discussed. Finally, the current status, challenges and prospects of the future direction in HP-BTMS are highlighted.