Importance of Halide Ions in the Stabilization of Hybrid Sn-Based Coatings for Lithium Electrodes

Low-Temperature-Sensitivity Materials for Low-Temperature Lithium-Ion Batteries

High-energy low-temperature lithium-ion batteries (LIBs) play an important role in promoting the application of renewable energy storage in national defense construction, including deep-sea operations, civil and military applications, and space missions. Sn-based materials show intrinsic low-temperature-sensitivity properties and promising applications in the field of subfreezing energy storage and conversion. In the past decade, our group has studied the intrinsic properties and fundamental applications of Sn-based materials in low-temperature LIBs. In this spotlight, we first discuss the principles on limiting the operation performance of LIBs under cool environments, including the decreased Li-ion diffusion in electrode materials, increased viscosity of the electrolyte, and large electrochemical impedance. Then, we mainly introduce our strategies to improve the low-temperature performance of LIBs based on a series of Sn-based materials, including material phase transition regulation, interfacial structural engineering, and targeted control of the electrolyte composition. Finally, we discuss the further development and directions of low-temperature LIBs based on several aspects of extending cycle life, introducing inorganic components in the solid electrolyte interphase (SEI), and testing the low-temperature performance with large pouch cells. This feature article aims to provide insights into the unique low-temperature properties of Sn-based materials and the potential to improve the low-temperature performance of LIBs through advanced material design and engineering.

The mechanism of water oxidation using transition metal-based heterogeneous electrocatalysts

The water oxidation reaction, a crucial process for solar energy conversion, has garnered significant research attention. Achieving efficient energy conversion requires the development of cost-effective and durable water oxidation catalysts. To design effective catalysts, it is essential to have a fundamental understanding of the reaction mechanisms. This review presents a comprehensive overview of recent advancements in the understanding of the mechanisms of water oxidation using transition metal-based heterogeneous electrocatalysts, including Mn, Fe, Co, Ni, and Cu-based catalysts. It highlights the catalytic mechanisms of different transition metals and emphasizes the importance of monitoring of key intermediates to explore the reaction pathway. In addition, advanced techniques for physical characterization of water oxidation intermediates are also introduced, for the purpose of providing information for establishing reliable methodologies in water oxidation research. The study of transition metal-based water oxidation electrocatalysts is instrumental in providing novel insights into understanding both natural and artificial energy conversion processes.

Oxygen Evolution/Reduction Reaction Catalysts: From In Situ Monitoring and Reaction Mechanisms to Rational Design

The oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) are core steps of various energy conversion and storage systems. However, their sluggish reaction kinetics, i.e., the demanding multielectron transfer processes, still render OER/ORR catalysts less efficient for practical applications. Moreover, the complexity of the catalyst-electrolyte interface makes a comprehensive understanding of the intrinsic OER/ORR mechanisms challenging. Fortunately, recent advances of in situ/operando characterization techniques have facilitated the kinetic monitoring of catalysts under reaction conditions. Here we provide selected highlights of recent in situ/operando mechanistic studies of OER/ORR catalysts with the main emphasis placed on heterogeneous systems (primarily discussing first-row transition metals which operate under basic conditions), followed by a brief outlook on molecular catalysts. Key sections in this review are focused on determination of the true active species, identification of the active sites, and monitoring of the reactive intermediates. For in-depth insights into the above factors, a short overview of the metrics for accurate characterizations of OER/ORR catalysts is provided. A combination of the obtained time-resolved reaction information and reliable activity data will then guide the rational design of new catalysts. Strategies such as optimizing the restructuring process as well as overcoming the adsorption-energy scaling relations will be discussed. Finally, pending current challenges and prospects toward the understanding and development of efficient heterogeneous catalysts and selected homogeneous catalysts are presented.

Recent Advances in Solid-Electrolyte Interphase for Li Metal Anode

Lithium metal batteries (LMBs) are considered to be a substitute for lithium-ion batteries (LIBs) and the next-generation battery with high energy density. However, the commercialization of LMBs is seriously impeded by the uncontrollable growth of dangerous lithium dendrites during long-term cycling. The generation and growth of lithium dendrites are mainly derived from the unstable solid–electrolyte interphase (SEI) layer on the metallic lithium anode. The SEI layer is a key by-product formed on the surface of the lithium metal anode during the electrochemical reactions and has been the barrier to development in this area. An ideal SEI layer should possess electrical insulating, superior mechanical modulus, high electrochemical stability, and excellent Li-ion conductivity, which could improve the structural stability of the electrode upon a long cycling time. This mini-review carefully summarizes the recent developments in the SEI layer for LMBs, and the relationship between SEI layer optimization and electrochemical property is discussed. In addition, further development direction of a stable SEI layer is proposed.