Table of Content

20 November 2021, Volume 4 Issue 4

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Strategies to Solve Lithium Battery Thermal Runaway: From Mechanism to Modification

Lingchen Kong, Yu Li, Wei Feng

2021, 4(4):  633-679.  doi:10.1007/s41918-021-00109-3

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As the global energy policy gradually shifts from fossil energy to renewable energy, lithium batteries, as important energy storage devices, have a great advantage over other batteries and have attracted widespread attention. With the increasing energy density of lithium batteries, promotion of their safety is urgent. Thermal runaway is an inevitable safety problem in lithium battery research. Therefore, paying attention to the thermal hazards of lithium battery materials and taking corresponding preventive measures are of great significance. In this review, the heat source and thermal hazards of lithium batteries are discussed with an emphasis on the designs, modifications, and improvements to suppress thermal runaway based on the inherent structure of lithium batteries. According to the source of battery heat, we divide it into reversible heat and irreversible heat. Additionally, superfluous heat generation has profound effects, including thermal runaway, capacity loss, and electrical imbalance. Thereafter, we emphatically discuss the design and modification strategies for various battery components (anodes, cathodes, electrolytes, and separators) to suppress thermal runaway. Preparation of solid electrolyte interphase layers with excellent thermal stability and mechanical properties is the core of the modification strategy for anode materials. Additives, stable coatings, elemental substitution, and thermally responsive coating materials are commonly used to improve the safety of cathodes. Novel electrolyte additives, solid-state electrolytes, and thermally stable separators provide a good opportunity to solve the thermal runaway problem of next-generation high-performance electrochemical storage devices.



Electrolyzer and Catalysts Design from Carbon Dioxide to Carbon Monoxide Electrochemical Reduction

Jingfu He, Yuanli Li, Aoxue Huang, Qinghua Liu, Changli Li

2021, 4(4):  680-717.  doi:10.1007/s41918-021-00100-y

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Electrochemical CO₂ reduction reaction (CO₂RR) has attracted considerable attention in the recent decade for its critical role in the storage of renewable energy and fulfilling of the carbon cycle, and catalysts with varying morphology and modification strategies have been studied to improve the CO₂RR activity and selectivity. However, most of the achievements are focused on preliminary reduction products such as CO and HCOOH. Development and research on electrochemical CO reduction reaction (CORR) are considered to be more promising to achieve multicarbon products and a better platform to understand the mechanism of C-C formation. In this review, we introduce the current achievements of CO₂RR and emphasize the potential of CORR. We provide a summary of how electrolysis environment, electrode substrates, and cell design affect the performance of CORR catalysts in order to offer a guideline of standard operating conditions for CORR research. The composition-structure-activity relationships for CORR catalysts studied in H-cells and gas-phase flow cells are separately analyzed to give a comprehensive understanding of the development of catalyst design. Finally, the reaction mechanism, latest progress, major challenges and potential opportunities of CORR are also analyzed to provide a critical overview for further performance improvement of CORR.This work reviews the recent progress and potential of carbon monoxide reduction (CORR) research. A comprehensive summary of how electrolysis environment, electrode substrate, and cell design affect the performance of CORR catalysts is performed and the composition-structure-activity relationships for CORR catalysts are analyzed.



Review of Bipolar Plate in Redox Flow Batteries: Materials, Structures, and Manufacturing

Zhining Duan, Zhiguo Qu, Qinlong Ren, Jianfei Zhang

2021, 4(4):  718-756.  doi:10.1007/s41918-021-00108-4

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Interest in large-scale energy storage technologies has risen in recent decades with the rapid development of renewable energy. The redox flow battery satisfies the energy storage demands well owing to its advantages of scalability, flexibility, high round-trip efficiency, and long durability. As a critical component of the redox flow battery, the bipolar plates provide mechanical support for the electrodes and act as a physical separator between adjacent cells, as well as constructing the internal circuit and guiding the electrolyte flow. The present work offers a comprehensive review of the development of bipolar plates in redox flow batteries, covering materials, structures, and manufacturing methods. In terms of materials, the effects of material types and composition on the compactness, mechanical strength, and electrical conductivity are summarized in detail. Furthermore, the corrosion mechanisms of bipolar plates and the corresponding detection and mitigation methods are discussed. In addition, the structures of the bipolar plates refer to the flow field designs on the surface. The advantages and disadvantages of these existing flow fields are described, and the tendencies for further optimization are also discussed. The manufacturing of composite bipolar plates in terms of material cost and preparation methods is also outlined. Based on the summary of previous research, this work provides suggestions for the future development of high-performance bipolar plates.



Semiconductor Electrochemistry for Clean Energy Conversion and Storage

Bin Zhu, Liangdong Fan, Naveed Mushtaq, Rizwan Raza, Muhammad Sajid, Yan Wu, Wenfeng Lin, Jung-Sik Kim, Peter D. Lund, Sining Yun

2021, 4(4):  757-792.  doi:10.1007/s41918-021-00112-8

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Semiconductors and the associated methodologies applied to electrochemistry have recently grown as an emerging field in energy materials and technologies. For example, semiconductor membranes and heterostructure fuel cells are new technological trend, which differ from the traditional fuel cell electrochemistry principle employing three basic functional components:anode, electrolyte, and cathode. The electrolyte is key to the device performance by providing an ionic charge flow pathway between the anode and cathode while preventing electron passage. In contrast, semiconductors and derived heterostructures with electron (hole) conducting materials have demonstrated to be much better ionic conductors than the conventional ionic electrolytes. The energy band structure and alignment, band bending and built-in electric field are all important elements in this context to realize the necessary fuel cell functionalities. This review further extends to semiconductor-based electrochemical energy conversion and storage, describing their fundamentals and working principles, with the intention of advancing the understanding of the roles of semiconductors and energy bands in electrochemical devices for energy conversion and storage, as well as applications to meet emerging demands widely involved in energy applications, such as photocatalysis/water splitting devices, batteries and solar cells. This review provides new ideas and new solutions to problems beyond the conventional electrochemistry and presents new interdisciplinary approaches to develop clean energy conversion and storage technologies.



Sodium Superionic Conductors (NASICONs) as Cathode Materials for Sodium-Ion Batteries

Qingbo Zhou, Linlin Wang, Wenyao Li, Kangning Zhao, Minmin Liu, Qian Wu, Yujie Yang, Guanjie He, Ivan P. Parkin, Paul R. Shearing, Dan J. L. Brett, Jiujun Zhang, Xueliang Sun

2021, 4(4):  793-823.  doi:10.1007/s41918-021-00120-8

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Sodium-ion batteries (SIBs) have developed rapidly owing to the high natural abundance, wide distribution, and low cost of sodium. Among the various materials used in SIBs, sodium superion conductor (NASICON)-based electrode materials with remarkable structural stability and high ionic conductivity are one of the most promising candidates for sodium storage electrodes. Nevertheless, the relatively low electronic conductivity of these materials makes them display poor electrochemical performance, significantly limiting their practical application. In recent years, the strategies of enhancing the inherent conductivity of NASICON-based cathode materials have been extensively studied through coating the active material with a conductive carbon layer, reducing the size of the cathode material, combining the cathode material with various carbon materials, and doping elements in the bulk phase. In this paper, we review the recent progress in the development of NASICON-based cathode materials for SIBs in terms of their synthesis, characterization, functional mechanisms, and performance validation/optimization. The advantages and disadvantages of such SIB cathode materials are analyzed, and the relationship between electrode structures and electrochemical performance as well as the strategies for enhancing their electrical conductivity and structural stability is highlighted. Some technical challenges of NASICON-based cathode materials with respect to SIB performance are analyzed, and several future research directions are also proposed for overcoming the challenges toward practical applications.