Table of Content

20 September 2024, Volume 7 Issue 3

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Advanced Catalyst Design Strategies and In-Situ Characterization Techniques for Enhancing Electrocatalytic Activity and Stability of Oxygen Evolution Reaction

Cejun Hu, Yanfang Hu, Bowen Zhang, Hongwei Zhang, Xiaojun Bao, Jiujun Zhang, Pei Yuan

2024, 7(3):  19.  doi:10.1007/s41918-024-00219-8

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Water electrolysis for hydrogen production holds great promise as an energy conversion technology. The electrolysis process contains two necessary electrocatalytic reactions, one is the hydrogen evolution reaction (HER) at the cathode, and the other is the oxygen evolution reaction (OER) at the anode. In general, the kinetics of OER is much slower than that of HER, dominating the overall of performance electrolysis. As identified, the slow kinetics of catalytic OER is mainly resulted from multiple electron transfer steps, and the catalysts often undergo compositional, structural, and electronic changes during operation, leading to complicated dynamic reaction mechanisms which have not been fully understood. Obviously, this challenge presents formidable obstacles to the development of highly efficient OER electrocatalysts. To address the issue, it is crucial to unravel the origins of intrinsic OER activity and stability and elucidate the catalytic mechanisms across diverse catalyst materials. In this context, in-situ/operando characterization techniques would play a pivotal role in understanding the catalytic reaction mechanisms by enabling real-time monitoring of catalyst structures under operational conditions. These techniques can facilitate the identification of active sites for OER and provide essential insights into the types and quantities of key reaction intermediates. This comprehensive review explores various catalyst design and synthesis strategies aimed at enhancing the intrinsic OER activity and stability of catalysts and examines the application of advanced in-situ/operando techniques for probing catalyst mechanisms during the OER process. Furthermore, the imperative need for developing innovative in-situ/operando techniques, theoretical artificial intelligence and machine learning and conducting theoretical research to better understand catalyst structural evolution under conditions closely resembling practical OER working states is also deeply discussed. Those efforts should be able to lay the foundation for the improved fabrication of practical OER catalysts.



Building the Robust Fluorinated Electrode–Electrolyte Interface in Rechargeable Batteries: From Fundamentals to Applications

Xiangjun Pu, Shihao Zhang, Dong Zhao, Zheng-Long Xu, Zhongxue Chen, Yuliang Cao

2024, 7(3):  21.  doi:10.1007/s41918-024-00226-9

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Endowed by high energy density and high conversion efficiency between chemical and electric energy, rechargeable batteries are indispensable in a variety of different energy-level applications, ranging from portable devices (W-level) to electric vehicles (kW-level) and large-scale energy storage systems (MW-level). However, many lingering scientific and technical challenges still inhibit their wide applications, including low Coulombic efficiency, inferior cycle/rate performance, and safety hazards. After decades of extensive research, it is widely accepted that these challenges are largely influenced by the interfacial chemistry occurring at the electrode-electrolyte interface (EEI). EEI includes both the solid electrolyte interphase on the anode and the cathode electrolyte interphase on the cathode, and the great protective capability of the fluorinated interface is gradually unveiled. Although intensive research efforts have been devoted to fabricating various ex situ artificial and in situ interfacial fluorinated layers, the fundamental approaches to the fluorinated interface are still inferior and not systematically categorized and analyzed. In this contribution, we have confined and proposed five principles regarding obtaining fluorinated interfaces from pretreatment, solvent-separated ion pairs, contact ion pairs, aggregates, and feasible decomposition from numerous reports and built up a systematic design framework to guide the construction of the protective fluorinated interfaces for rechargeable batteries, offering target-oriented guidelines to tackle interface issues in secondary batteries.



Recent Progress and New Horizons in Emerging Novel MXene-Based Materials for Energy Storage Applications for Current Environmental Remediation and Energy Crises

Karim Khan, Ayesha Khan Tareen, Muhammad Iqbal, Ye Zhang, Asif Mahmood, Nasir mahmood, Zhe Shi, Chunyang Ma, J. R. Rosin, Han Zhang

2024, 7(3):  22.  doi:10.1007/s41918-024-00224-x

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Unsustainable fossil fuel energy usage and its environmental impacts are the most significant scientific challenges in the scientific community. Two-dimensional (2D) materials have received a lot of attention recently because of their great potential for application in addressing some of society’s most enduring issues with renewable energy. Transition metal-based nitrides, carbides, or carbonitrides, known as “MXenes”, are a relatively new and large family of 2D materials. Since the discovery of the first MXene, Ti₃C₂ in 2011 has become one of the fastest-expanding families of 2D materials with unique physiochemical features. MXene surface terminations with hydroxyl, oxygen, fluorine, etc., are invariably present in the so far reported materials, imparting hydrophilicity to their surfaces. The current finding of multi-transition metal-layered MXenes with controlled surface termination capacity opens the door to fabricating unique structures for producing renewable energy. MXene NMs-based flexible chemistry allows them to be tuned for energy-producing/storage, electromagnetic interference shielding, gas/biosensors, water distillation, nanocomposite reinforcement, lubrication, and photo/electro/chemical catalysis. This review will first discuss the advancement of MXenes synthesis methods, their properties/stability, and renewable energy applications. Secondly, we will highlight the constraints and challenges that impede the scientific community from synthesizing functional MXene with controlled composition and properties. We will further reveal the high-tech implementations for renewable energy storage applications along with future challenges and their solutions.



Engineering, Understanding, and Optimizing Electrolyte/Anode Interfaces for All-Solid-State Sodium Batteries

Wenhao Tang, Ruiyu Qi, Jiamin Wu, Yinze Zuo, Yiliang Shi, Ruiping Liu, Wei Yan, Jiujun Zhang

2024, 7(3):  23.  doi:10.1007/s41918-024-00228-7

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Rechargeable all-solid-state sodium batteries (ASS-SBs), including all-solid-state sodium-ion batteries and all-solid-state sodium-metal batteries, are considered highly advanced electrochemical energy storage technologies. This is owing to their potentially high safety and energy density and the high abundance of sodium resources. However, these materials are limited by the properties of their solid-state electrolytes (SSEs) and various SSE/Na interfacial challenges. In recent years, extensive research has focused on understanding the interfacial behavior and strategies to overcome the challenges in developing ASS-SBs. In this prospective, the sodium-ion conduction mechanisms in different SSEs and the interfacial failure mechanisms of their corresponding batteries are comprehensively reviewed in terms of chemical/electrochemical stability, interfacial contacts, sodium dendrite growth, and thermal stability. Based on mechanistic analysis, representative interfacial engineering strategies for the interface between SSEs and Na anodes are summarized. Advanced techniques, including in situ/ex situ instrumental and electrochemical measurements and analysis for interface characterization, are also introduced. Furthermore, advanced computer-assisted methods, including artificial intelligence and machine learning (which can complement experimental systems), are discussed. The purpose of this review is to outline the solid-state electrolyte and electrolyte/anode interface challenges, and the potential research directions for overcoming these challenges. This would enable target-oriented research for the development of solid-state electrochemical energy storage devices.



Recent Progress on Designing Carbon Materials by Structural Tuning and Morphological Modulation as K⁺-Storage Anodes

Jiafeng Ruan, Sainan Luo, Qin Li, Han Man, Yang Liu, Yun Song, Fang Fang, Fei Wang, Shiyou Zheng, Dalin Sun

2024, 7(3):  24.  doi:10.1007/s41918-024-00227-8

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Potassium-ion batteries (PIBs) have attracted tremendous attention during the past several years due to their abundant reserves, wide distribution, fast ionic conductivity, and high operating voltage. The primary obstacle impeding the commercialization of rechargeable PIBs is the lack of suitable high-performance anode materials. Carbon materials, known for their environmental friendliness, abundant availability, and outstanding comprehensive performance, have received extensive attention because they can be utilized directly as anodes or serve as a constrained matrix for conversion-/alloying-type anodes to enhance the electrochemical performance. Structural tuning and morphological modulation are two common strategies for modifying carbon materials. In this review, the recent progress in carbon materials aimed at enhancing the performance of PIBs through the utilization of these two strategies is systematically summarized. First, the effects of structural tuning and morphological modulation on the electrochemical properties of carbon materials and the corresponding storage mechanisms are reviewed. Second, the performance improvement mechanisms of conversion-/alloying-type anodes utilizing carbon scaffolds based on these two strategies are systematically discussed. Third, the application of carbon materials based on various modification strategies in various advanced K⁺ storage devices is reviewed. Finally, the challenges and perspectives for the further development of carbon-based materials for PIBs are highlighted.



Flexible Electrodes for Aqueous Hybrid Supercapacitors: Recent Advances and Future Prospects

Siyu Liu, Juan Yang, Pei Chen, Man Wang, Songjie He, Lu Wang, Jieshan Qiu

2024, 7(3):  25.  doi:10.1007/s41918-024-00222-z

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Flexible energy storage systems are promising and efficient technologies for realizing large-scale application of portable, bendable, and wearable electronic devices. Among these systems, aqueous hybrid supercapacitors (AHSs) fabricated using redox-active materials with a positive voltage window in aqueous electrolytes and capacitive carbon materials have attracted enormous attention due to their advantages, including a wide operating voltage, a high energy density, a high power density, a long cycling lifespan, and low cost. Thus far, considerable efforts have been made to develop flexible AHSs constructed from various free-standing and flexible electrodes. However, optimizing the configurations of flexible electrodes and the interfacial interaction between flexible substrates and electroactive materials to fully develop the performance through their synergistic effects remains a major challenge. Herein, we have reviewed and summarized recent advances in flexible electrode materials with a variety of configurations based on porous metal supports, carbon substrates, including carbon nanotube networks, graphene and wearable carbon (carbon fibers, carbon cloth, carbon fabric, etc.), and other flexible materials for high-performance AHSs. These flexible electrodes show unique configurations and optimized interfacial structures, resulting in excellent electrochemical performance and superior mechanical stability in AHSs under various harsh conditions, and have great potential for practical applications. Furthermore, the future directions and perspectives for constructing flexible electrodes with novel configurations and AHSs are outlined and discussed, including (1) fabrication of compressible, ultralight, or transparent flexible electrodes for special needs; (2) tailoring and tuning of interfacial properties with robust adhesion between electroactive materials and flexible substrates; (3) development of advanced in situ characterization techniques to uncover the structure evolution rules of flexible electrodes under the operation conditions; (4) matching and optimization of flexible positive and negative electrode materials to assemble advanced AHS devices; (5) design of multifunctional flexible electrodes and AHSs by integrating other specific functions, etc. This timely review is believed to provide deep insights into the intensive research on flexible aqueous energy storage devices.



Nanoporous Carbon Materials Derived from Biomass Precursors: Sustainable Materials for Energy Conversion and Storage

Zhikai Chen, Xiaoli Jiang, Yash Boyjoo, Lan Zhang, Wei Li, Lin Zhao, Yanxia Liu, Yagang Zhang, Jian Liu, Xifei Li

2024, 7(3):  26.  doi:10.1007/s41918-024-00223-y

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Biomass, which is derived from abundant renewable resources, is a promising alternative to fossil-fuel-based carbon materials for building a green and sustainable society. Biomass-based carbon materials (BCMs) with tailored hierarchical pore structures, large specific surface areas, and various surface functional groups have been extensively studied as energy and catalysis-related materials. This review provides insights from the perspectives of intrinsic physicochemical properties and structure-property relationships for discussing several fundamental yet significant issues in BCMs and their consequences. First, the synthesis, properties, and influencing factors of BCMs are discussed. Then, the causes and effects of the poor mechanical properties of biochar are explored. The factors affecting the properties of BCMs are presented, and the approaches for tuning these properties of biochar are summarized. Further, the applications of BCMs in energy storage and conversion are highlighted, including hydrogen storage and production, fuel cells, supercapacitors, hybrid electrodes, catalytic reforming, oxygen and CO2 reduction, and acetylene hydrochlorination. Finally, the future trends and prospects for biochar are proposed. This review aims to serve as a useful, up-to-date reference for future studies on BCMs for energy and catalytic applications.



Safety Issues and Improvement Measures of Ni-Rich Layered Oxide Cathode Materials for Li-Ion Batteries

Baichuan Cui, Zhenxue Xiao, Shaolun Cui, Sheng Liu, Xueping Gao, Guoran Li

2024, 7(3):  27.  doi:10.1007/s41918-024-00211-2

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Ni-rich layered oxide cathode materials hold great promise for enhancing the energy density of lithium-ion batteries (LIBs) due to their impressive specific capacity. However, the chemical and structural stability issues associated with the materials containing a high Ni content have emerged as a primary safety concern, particularly in the context of traction batteries for electric vehicles. Typically, when these materials are in a highly charged state, their metastable layered structure and highly oxidized transition metal ions can trigger detrimental phase transitions. This leads to the generation of oxygen gas and the degradation of the material’s microstructure, including the formation of cracks, which can promote the interactions between Ni-rich materials and electrolytes, further generating flammable gases. Consequently, various strategies have been devised at the material level to mitigate potential safety hazards. This review begins by providing an in-depth exploration of the sources of instability in Ni-rich layered oxides, drawing from their crystal and electronic structures, and subsequently outlines the safety issues that arise as a result. Subsequently, it delves into recent advancements and approaches aiming at modifying Ni-rich cathode materials and electrolytes to enhance safety. The primary objective of this review is to offer a concise and comprehensive understanding of why Ni-rich cathode materials are susceptible to safety incidents and to present potential methods for improving the safety of Ni-rich cathode materials in high-density LIBs.



Towards High Value-Added Recycling of Spent Lithium-Ion Batteries for Catalysis Application

Ruyu Shi, Boran Wang, Di Tang, Xijun Wei, Guangmin Zhou

2024, 7(3):  28.  doi:10.1007/s41918-024-00220-1

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With the proposal of the global carbon neutrality target, lithium-ion batteries (LIBs) are bound to set off the next wave of applications in portable electronic devices, electric vehicles, and energy-storage grids due to their unique merits. However, the growing LIB market poses a severe challenge for waste management during LIB recycling after end-of-life, which could cause serious environmental pollution and resource waste without proper treatment. Pyrometallurgical, hydrometallurgical, and direct recycling of spent LIBs have been developed, guided by the “waste to wealth” principle, and were applied to LIB remanufacturing. However, some spent LIB materials with low values or great direct regeneration difficulties may not be suitable for the above options, necessitating expanded application ranges of spent LIBs. Considering their unique compositions, using waste electrode materials directly or as precursors to prepare advanced catalysts has been proposed as another promising disposal technology for end-of-life LIBs. For example, transition metal elements in the cathode, like Ni, Co, Mn, and Fe, have been identified as catalytic active centers, and graphite anodes can serve as the catalyst loading matrix. This scheme has been adopted in various catalysis applications, and preliminary progress has been made. Therefore, this review summarizes and discusses the application of spent LIB recycling materials in catalysis and classified it into three aspects: environmental remediation, substance conversion, and battery-related catalysis. Moreover, the existing challenges and possible foci of future research on spent LIB recycling are also discussed. This review is anticipated to mark the start of close attention to the high-value-added applications of spent LIB products, enhancing economic efficiency and sustainable development.