Post‐lithium battery materials and technology

Lithium-ion batteries (LIBs) are the most advanced power sources for portable devices and electric vehicles, as well as indispensable for smart grids in the present day. The exponential increase in the use of LIBs causes economical concerns over lithium price and the unevenly distributed lithium resources, not to mentioning their energy density is still inadequate to meet ever-growing demands for energy storage. Therefore, the development of novel electrode materials and the investigation of redox chemistries that enable multielectron transition and new waves of battery technologies are required, presenting a timely issue for the research field of electrochemical energy storage. The search for alternative candidates in the post-LIBs era mainly focuses on sodium-, potassium-, and zinc-ion batteries that are abundant in resources, coupled with high-energy-density cathodes such as sulfur and oxygen. The path to commercialization of these post-LIB systems has been tortuous, along with the obstacles thrown up by complex electrochemistry that leads to irreversibility issue and short lifetime. Thus, suitable electrode structures and electrolytes should be developed to control the electrochemical phase transition, electrode/electrolyte interfacial reactions, volume expansion, and so on. To drive the development of the post-LIBs systems, this special issue highlights the recent advances in the relevant research areas, including high-performance organic carbonyl electrodes and metal/covalent organic frameworks-derived materials, all-climate sodium-ion batteries (SIBs), high-capacity anodes of potassium-ion batteries (PIBs), Zn-based batteries, and potassium/magnesium-sulfur batteries. SIBs hold great promise in the applications of medium- to large-scale energy storage because of the natural abundance and low cost of sodium reserves. Despite their cost advantage, the performance and safety of SIBs are still concerns under extreme conditions. Wang's group has introduced the advances of all-climate SIBs, with an emphasis on the progress and challenges on the electrolytes and electrode materials. High intrinsic ion diffusion coefficients at low temperature and excellent thermal stability are the important features of the electrodes employed in all-climate SIBs. Besides, rational control over the interfacial stability is also deemed critical to improve the stability of SIBs under elevated temperatures. PIBs with high energy density has become one of the viable options for large-scale energy storage. Antimony (Sb)-based materials that are known for their high capacities, suitable potential and low-cost emerged as promising anodes for PIBs. The main challenge of Sb-based anodes is associated with the drastic volume change caused by alloying reaction with potassium, resulting in rapid capacity decay of the battery. Wang's group provided a glimpse of recent progress of PIBs using Sb-base anodes, including metal Sb, Sb-based alloys, Sb chalcogenides, and Sb composite. Despite being extensively investigated, the battery failure mechanism of Sb-based materials has not been fully unveiled. Besides, the investigation of Sb-based full cell is also an interesting direction that is worthy of intensive research exploration. Further improvement and breakthrough can be realized through an optimal combination of reaction chemistry and matching electrolytes in different environments. Zn-ion batteries (ZIBs) are a representative energy storage system with high volumetric capacity, good safety features, low cost, and abundant resources. Wu's group introduced Zn-based microbatteries and microsupercapacitors with representative fiber, in-plane and sandwiched configurations, and their applications in flexible and smart integrated systems are further highlighted. On the other hand, the life span of ZIBs is limited by the dendrite formation, hydrogen evolution, and passivation on the Zn anode. Zhi's group systematically summarized the strategies employed to suppress the dendrite formation on the Zn anode, which include the control of crystallographic orientation, electric field control, ion flux regulation, and mechanical shielding. Combining these technologies under the guidance of theoretical predictions may bring about high improvement in the performance and long-term stability of the battery. To date, ZIBs are still in the early stage of development. Different challenging issues, such as limited cathode capacity, sluggish reaction kinetics, and insufficient mechanical stability, need to be addressed until the seamless integration of flexible and high-energy Zn-based batteries into multifunctional systems can be realized. Potassium sulfur (K-S) battery becomes an intriguing alternative to the commercial LIBs and the Li-S and Na-S counterparts because of the low reduction potential and high theoretical gravimetric energy density (914 Wh kg−1). Guo's group summarized the recent development of cathodes, K anodes and electrolytes for the K-S systems. Strategies in addressing the dissolution of polysulfides intermediates and dendrite formation on the K anode are highlighted. In the future, catalytic cathodes that can promote the reduction kinetics of the polysulfides intermediates and in-depth understanding of their catalytic mechanisms are highly desirable. Besides, more research efforts are needed to understand the formation and composition of SEI layer on the anode surface and customize suitable electrolyte system for K-S battery. The lower tendency of dendrite formation and divalent charges of magnesium make magnesium-sulfur (Mg-S) battery a safer and higher energy density alternative to the commercial LIBs. By comparing electrode materials and cell parameters from different literature, Bo's group has identified the performance gap of Mg-S cells between academia and industry. Despite substantial progress has been made over the past years, critical issues such as the low discharge potential, passivation layer on the Mg surface, sluggish ion transfer, and shuttling effect of polysulfies have not been effectively addressed, though the construction of solid-state Mg-S battery could be the feasible solution when both energy density and cost are taken into consideration. Metal/covalent organic frameworks (MOFs/COFs), which can be either porous or crystalline in structure, have attracted high attention in energy storage and conversion systems owing to their high surface area, well-aligned pore and tailorable structure and function. In addition, electrode materials derived from MOFs and COFs, including metal oxide, sulfides, phosphides, carbons and other composites, exhibit better electrochemical performances compared to their counterparts synthesized by traditional methods owing to the structural advantages of MOFs/COFs derivatives. Cao et al systematically summarized the application of MOFs/COFs and their derivatives in energy storage system. Besides, the inherent strengths and weaknesses of MOFs/COFs were also discussed, along with the possible solutions to their existing challenges. Organic electrode materials are promising candidates for electrochemical storage devices owing to their abundance, low cost and environmental friendliness. Among this family, carbonyl-based organic compounds tick all the right boxes as highly desirable materials for rechargeable batteries due to their unique properties, including fast-redox kinetics and structural diversity in design. Some intrinsic shortcomings of organic electrode materials limit their further development, such as low conductivity and solubility. Seferos's group systematically summarized the recent development about carbonyl-based organic materials for rechargeable batteries, focusing on the strategies to overcome their shortcomings. It is hoped that the novel insight into the optimization of carbonyl materials can be harnessed for the future design of high-performance rechargeable batteries. Overall, we have witnessed remarkable achievements beyond LIBs technology. As the guest editors, we hope that this special issue can help the readers to understand the electrochemical mechanisms that drive the progress of the post-LIBs systems. Meanwhile, the theoretical models here can be used as the fundamental guidance for structural design of active materials and device manufacture, as well as to promote the commercialization of the post-LIBs. Last but not least, the contributions from all authors, referees, and the EcoMat editorial team are heartily appreciated. Yan Yu is a professor of material science at the University of Science and Technology of China (USTC). She received her PhD in material science at USTC in 2006. From 2007 to 2008, she worked as a postdoctoral researcher at Florida International University. After that she received a Humboldt Research Fellowship and the Sofja Kovalevskaja award from the Alexander von Humboldt Foundation and worked at the Max Planck Institute for Solid-State Research in Stuttgart, Germany. Her current research interests mainly include the design of novel nanomaterials for clean energy, especially for batteries and the fundamental science of energy-storage systems. Zaiping Guo is currently a distinguished professor at the University of Wollongong, Australia. She received her PhD in materials engineering from the University of Wollongong in December 2003. After her Australian Postdoctoral (APD) fellowship in the Institute for Superconducting & Electronic Materials, she joined the Faculty of Engineering and Information Sciences, University of Wollongong as a lecturer in 2008, was promoted to professor in 2012, and then distinguished professor in 2019. Her primary research interests are in the fields of energy storage and electrochemistry, such as lithium ion batteries, sodium ion batteries, potassium ion batteries, and hydrogen storage. Yifei Mo is a professor of Materials Science and Engineering at the University of Maryland, College Park. He received his PhD from the University of Wisconsin Madison (2010), and conducted his postdoctoral research at Massachusetts Institute of Technology (2010-2013). His research aims to advance the understanding, design, and discovery of engineering materials through computational techniques, with current emphases on critical materials problems in solid-state devices for energy storage and conversion. Yong Lei is a professor at the Technical University of Ilmenau in Germany. He received his PhD from the Chinese Academy of Sciences in 2001. He worked at the Karlsruhe Institute of Technology as an Alexander von Humboldt Fellow and the University of Muenster as a junior professor. In 2011, he joined the Technical University of Ilmenau as Professor and Leader (Fachgebietsleiter) of the Group of Applied Nano-Physics (Fachgebiet Angewandte Nanophysik). His research focuses on template nanostructuring, and energy-related (mainly batteries, supercapacitors, and PEC cells) and optoelectronic applications of functional nanostructures. He received some prestigious funding from European Research Council and BMBF (Federal Ministry of Education and Research of Germany).