Table of Content

20 December 2025, Volume 8 Issue 4

Previous Issue   

Exploring Degradation Mechanisms and Recent Developments in High Nickel Layered Cathodes for Lithium Batteries

Guiquan Zhao, Yongjiang Sun, Hang Ma, Futong Ren, Wenjin Huang, Pujia Cheng, Genfu Zhao, Qing Liu, Qi An, Li Yang, Lingyan Duan, Mengjiao Sun, Kun Zeng, Xin Wang, Hong Guo

2025, 8(4):  21.  doi:10.1007/s41918-025-00254-z

Asbtract ( 13 )  

Related Articles | Metrics

The Ni-rich layered cathode materials LiNixCoyMn1-x-yO2 (NCM), which have a high energy density, are crucial in the strategic formulation of next-generation high-performance lithium-ion batteries (LIBs), particularly for cathode materials with Ni ≥ 0.9. Although advances in NCM cathodes have made them competitive in terms of capacity and cost, persistent challenges such as surface chemical instability (electrolyte-driven surface degradation) and poor mechanical integrity (lattice oxygen evolution and anisotropic microcracking) of the cathodes remain. Addressing these limitations requires coordinated strategies spanning from atomic-level dopant engineering to macroscopic electrode architectural innovations to enable viable large-scale deployment. Extensive research has been conducted on the structural instability caused by an increase in the Ni content, but a comprehensive understanding of its underlying mechanisms and effective modification strategies for next-generation nickel-rich cathodes is lacking. Hence, we provide a thorough overview of the latest findings on microstructural degradation mechanisms in Ni-rich cathodes, delve into recent effective modification strategies and cutting-edge characterization methods, and finally, examine future research directions and limitations. This review elucidates the challenges facing ultrahigh-nickel cathodes and offers new insights into promising research avenues.



Porous Carbon Supports for Low-Pt Proton-Exchange Membrane Fuel Cells

Jiabin You, Jing Hu, Zhifeng Zheng, Huiyuan Li, Liuxuan Luo, Xiaojing Cheng, Xiaohui Yan, Shuiyun Shen, Junliang Zhang

2025, 8(4):  22.  doi:10.1007/s41918-025-00259-8

Asbtract ( 11 )  

Related Articles | Metrics

Attaining both high performance and long-term durability remains a critical yet challenging objective for low-Pt proton-exchange membrane fuel cells (PEMFCs). The carbon support on which catalysts and ionomers are dispersed strongly affects the cell performance by influencing the Pt activity, mass transport, and degradation. Currently, porous carbons endowed with a high surface area and internally embedded Pt particles are gaining prominence as promising support materials for low-Pt PEMFCs owing to their exceptional catalyst dispersion and kinetic activity. However, challenges in terms of unclear triple-phase boundaries, poor mass transport, and insufficient durability hinder their widespread implementation. Thus, this review provides a comprehensive understanding of and advanced guidelines for the exploration of porous carbons in low-Pt PEMFCs. We begin by analyzing the structures and morphologies of porous carbon catalysts to obtain an overview of their pore structures, Pt deposition, ionomer distribution, and water condensation. We subsequently summarize the mass transport mechanisms involved, exploring state-of-the-art strategies for improving mass transport through engineering accessible pore structures, tailoring uniform ionomer distributions, and incorporating well-defined ionic liquids, among other approaches. Furthermore, we highlight the effects of catalysts and porous carbon degradation on performance loss and introduce recent approaches to mitigate performance loss. Finally, we present conclusions along with outlooks on future exploration priorities. This extensive analysis of current challenges and advances in porous carbon supports is offered to inspire innovative ideas and technologies for the development of next-generation carbon supports for low-Pt PEMFCs.



A Review of Diagnostic Tools for Evaluating Porous Transport Layers for Proton Exchange Membrane (PEM) Water Electrolysis

Aroune Ghadbane, Xiao Zi Yuan, Alison Platt, Ali Malek, Nima Shaigan, Marius Dinu, Samaneh Shahgaldi, Khalid Fatih

2025, 8(4):  23.  doi:10.1007/s41918-025-00256-x

Asbtract ( 14 )  

Related Articles | Metrics

As a key component of the proton exchange membrane water electrolyzer (PEMWE), the porous transport layer (PTL) not only provides mechanical support but also facilitates the supply of reactants to the electrode and the removal of produced gases and ensures efficient electrical and thermal management. Commercially available PTLs are often repurposed for other applications, such as filtration, and are not specifically tailored for PEMWE applications. Given this context, research output on PTL development has increased notably in recent years. Optimized, structured PTLs with preferred properties require applicable, relevant, and convenient diagnostic tools for PTL material development. As such, this work aims to identify and review a wide range of techniques for evaluating developed PTLs, including electrochemical techniques, custom-engineered cells, operando diagnosis, ex situ characterization, and postmortem analysis. By providing detailed information on these characterization techniques, this review aims to catalyze further research and development in the academic and industrial sectors, enhancing the understanding, development, and quality control of PTL components.



Ru-Based Catalysts for Oxygen Evolution in Acidic Media: Mechanism and Strategies for Breaking the Activity and Stability Bottlenecks

Zhen Chen, Bihua Hu, Xiaoyu Zhang, Kai Zong, Lin Yang, Yi Wang, Xin Wang, Shuqin Song, Zhongwei Chen

2025, 8(4):  24.  doi:10.1007/s41918-025-00265-w

Asbtract ( 10 )  

Related Articles | Metrics

Productive and economical electrocatalysts for the oxygen evolution reaction (OER) are vital for reducing green hydrogen production costs and advancing the adoption of proton exchange membrane water electrolysis (PEMWE). However, the OER at the PEMWE anode involves complex proton-coupled electron transfer processes, leading to slow kinetics that limits electrolysis efficiency. Moreover, most OER catalysts are highly prone to corrosion in acidic solutions, challenging the long-term stable operation of PEMWE. Currently, OER catalysts rely heavily on iridium-based materials, which are expensive and scarce, hindering large-scale commercialization. Ruthenium, a less expensive platinum group metal, shows promising acidic OER activity but requires improved stability. Therefore, novel ruthenium-based OER catalysts are urgently needed. To achieve these goals, a thorough understanding of the acidic OER mechanisms, clear methods for material design, and the establishment of dependable performance evaluation metrics are necessary. In this review, we systematically summarize the extensively accepted mechanisms for acidic OER activity expression, which include the adsorption-desorption mechanism, multi-active centre mechanism, and lattice oxygen oxidation mechanism, to guide the microstructural design of catalysts. Additionally, we introduce commonly used indicators for evaluating catalytic activity, aiming to provide a basis for catalyst screening. We subsequently discuss and review several types of recently reported Ru-based OER catalysts, namely, Ru metals, Ru alloys, and Ru-based oxide catalysts, with a focus on how their performance can be regulated and the potential structure-performance relationships. Finally, we summarize some important issues that need attention in future research in this field to promote further study of Ru-based acidic oxidation catalysts.



Critical Review of Acid Leaching for Recovery of Valuable Metals from Spent Lithium-ion Batteries

Anil Kumar Vinayak, Mahrima Majid, Liuyin Xia, Xiaolei Wang

2025, 8(4):  25.  doi:10.1007/s41918-025-00266-9

Asbtract ( 11 )  

Related Articles | Metrics

Lithium-ion batteries (LIBs) are an indispensable component of the green revolution, and the growing demand for LIBs reflects this trend. As reliance on LIBs increases, sustainable metal recovery strategies are crucial to mitigating raw material scarcity and environmental concerns. This study examines commonly used and emerging lixiviants for metals extraction, balancing operational efficiency with environmental sustainability. Established mineral acids such as hydrochloric, sulfuric, and nitric acids are effective but pose ecological risks. On the other hand, organic acids present a promising alternative by reducing environmental impact but often compromising process efficiency. In addition to extensively studied organic acids, this review explores the potential of lesser-explored organic acid variants such as propionic and gluconic acids. Biometallurgical recovery, a hybridized alternative methodology to conventional hydrometallurgy, and electrochemical leaching, an emerging metal recovery method, are also explored to enhance sustainability. Furthermore, the review highlights the critical role of policy and regulatory frameworks in aligning recycling practices with circular economy principles and examines spent LIB recycling in China, the USA, and the European Union in this context. By exploring past and future trends, this work underscores the need for innovative, cost-effective, and environmentally responsible solutions in metallurgical processing.



Recent Progress in and Future Perspectives on High-Density Single-Atom Electrocatalysts

Yifan Zhang, Ting He, Jing Chen, Dingjie Pan, Xiaojuan Wang, Shaowei Chen, Xiaoping Ouyang

2025, 8(4):  26.  doi:10.1007/s41918-025-00257-w

Asbtract ( 12 )  

Related Articles | Metrics

Single-atom catalysts (SACs) exhibit tremendous potential in electrocatalysis because of their high intrinsic activity and remarkable selectivity arising from their tunable electronic structures and maximal atom utilization. A high density of SACs is fundamental for enhancing the activity and durability during electrochemical reactions. In this review, we first summarize the leading strategies for the synthesis of metal single-atom electrocatalysts and the use of machine learning in the design and screening of SACs, with a focus on maximizing the metal loading through deliberate temperature control, followed by the application of such high-loading SACs to a range of important reactions in electrochemical energy technologies, such as the oxygen reduction reaction (ORR), H2O2 electrosynthesis, the oxygen evolution reaction (OER), the hydrogen evolution reaction (HER), the carbon dioxide reduction reaction (CO2RR), the nitrate reduction reaction (NO3RR), and the reactions in lithium-sulfur batteries. The review concludes with a perspective highlighting the key challenges and future research directions in the development and application of high-density SACs.



Reframing the Corrosion Effects of Silicon Anode Failures: Moving Beyond the Mechanical Paradigm

Qinyi Zhan, Tianze Xu, Ziyun Zhao, Shuoyi Chen, Shichao Wu, Quan-Hong Yang

2025, 8(4):  27.  doi:10.1007/s41918-025-00260-1

Asbtract ( 11 )  

Related Articles | Metrics

High-capacity silicon (Si) is a promising material for manufacturing high-energy-density lithium-ion batteries. However, its practical applicability is severely restricted by the rapid degradation in its cycle life and calendar life. Within the context of the established understanding, Si failures are typically attributed primarily to the notable volume expansion effects of this material. However, the crucial role of chemical corrosion (e.g., hydrofluoric acid-driven corrosion) is frequently underestimated, despite its significant impact on the stability of both Si itself and the solid electrolyte interphase. In this review, the mechanisms of corrosion-induced Si degradation and the limitations of the existing mitigation strategies are systematically examined. More importantly, a novel perspective is proposed, thereby emphasizing galvanic corrosion driven by cathode oxidants, transition metal ion dissolution, and carbon additives, as well as chemical–mechanical coupling failures induced by Si corrosion. Finally, we advocate for the use of advanced characterization techniques, theoretical simulations, and holistic approaches integrating cathode design, auxiliary material optimization, and electrolyte engineering to address coupled chemical–mechanical failures for advancing the practical deployment of Si-based batteries.



Fluoride-Ion Batteries: A Review of Recent Advances and Future Opportunities

Enhao Liu, Youkang Duan, Yu Li, Cong Peng, Wei Feng

2025, 8(4):  28.  doi:10.1007/s41918-025-00268-7

Asbtract ( 12 )  

Related Articles | Metrics

The pursuit of high-energy–density fluoride-ion batteries (FIBs) has been considerably accelerated by the escalating demand for energy storage solutions outperforming existing lithium-ion technologies. As a promising alternative, FIBs leverage fluorine—the most electronegative element—to attain exceptional electrode potentials and energy densities. A comprehensive understanding of the chemistry underlying FIBs is therefore of paramount importance. To this end, this review provides an in-depth examination of the advancements in FIB development, covering cathode materials, anode materials, and electrolytes. Special emphasis is placed on summarizing the types and electrochemical properties of electrode materials. The review concludes with a forward-looking perspective, addressing practical challenges facing FIBs, the future development of electrode and electrolyte materials, advanced in situ characterization techniques, battery reaction mechanisms, and the potential of big data-enabled machine learning (ML). This manuscript seeks to deliver a detailed review of critical areas pivotal to advancing FIB technology, delineating the scope and contributions of this work to furnish theoretical guidance and insights into future trends in the field.



Large-Scale Production of High-Loading Single-Atom Catalysts for Electrochemical Energy Conversion and Storage Applications

Jin Yan, Nadia Batool, Zhangsen Chen, Qian Zhang, Kai Zeng, Tianyi Gu, Chengyi Lu, Jie Guo, Shuhui Sun, Ruizhi Yang

2025, 8(4):  29.  doi:10.1007/s41918-025-00261-0

Asbtract ( 10 )  

Related Articles | Metrics

The development of low-cost and highly efficient electrocatalysts is crucial for the widespread adoption of clean energy technologies. Single-atom catalysts (SACs) have attracted extensive attention because of their exceptional catalytic performance and metal utilization. However, conventional methods for synthesizing SACs often have disadvantages such as an extremely low degree of metal loading and limited yield. Therefore, techniques for the scalable fabrication of SACs with high degrees of metal loading for use in practical applications are strongly needed. In this review, we first explore various design strategies for synthesizing stable SACs. Afterward, we highlight recent advances in improving the mass activity of SACs with high degrees of metal loading and introduce a universal strategy for synthesizing SACs on various supports. Furthermore, we provide a summary of facile strategies for the large-scale preparation of SACs for various electrocatalytic applications, including the oxygen reduction reaction, oxygen evolution reaction, hydrogen evolution reaction, and CO2 reduction reaction. Finally, we discuss the challenges and perspectives of the large-scale production of SACs for use in practical applications. This review offers valuable guidance for the design of high-loading SACs.



Nano-Engineered High-Entropy Intermetallic Compounds for Catalysis: From Designs to Catalytic Applications

Tao Chen, Yang Wang, Weifang Liu, Kaiyu Liu, Dingguo Xia

2025, 8(4):  30.  doi:10.1007/s41918-025-00263-y

Asbtract ( 8 )  

Related Articles | Metrics

The exploration of nanoscale high-entropy intermetallic compounds (HEICs) represents a transformative frontier in materials science, particularly in catalysis. The unique combination of multi-element composition, long-range atomic ordering, and nanoscale dimensions endows HEICs with superior electronic, structural, and catalytic properties that surpass those of traditional metal catalysts. However, achieving both uniform multi-element mixing and long-range ordered structures at the nanoscale is challenging. Building on this, this review highlights the key role of configurational entropy, mixing enthalpy, elemental composition, and size effects in the stable formation of nanoscale HEICs through thermodynamic and kinetic analysis. The latest advancements and existing challenges in the design, synthesis, structure, and applications of HEIC catalysts are discussed, with a focus on exploring their synthesis–structure–performance relationships from multiple perspectives. We hope that this review will offer valuable insights for further exploration and development of HEICs in catalytic applications.



Recent Progress on Constructing Artificial Interfacial Layers for Zinc-Anodes-Stabilizing

Xing Wei, Tian Nian Zhang, Yu Hao Yao, Si Yuan Xuan, Yi Nan Wu, Han Xu, Ye Xing Wang, Song Lin Zhou, Zhenlei Zou, Shi Chao Xing, Wenqiang Zhao, Yang Yi Liu

2025, 8(4):  31.  doi:10.1007/s41918-025-00271-y

Asbtract ( 8 )  

Related Articles | Metrics

Aqueous zinc-ion batteries (AZIBs) are promising to be widely used in large-scale energy storage devices due to their low cost, safety, and environmental friendliness. However, side reactions, including dendrite growth, anode corrosion, and electrode passivation, caused by uneven zinc deposition hinder further practical applications of AZIBs. Constructing artificial interfacial layers (AILs) is an effective strategy to stabilize zinc anodes, which has received significant attention. Herein, this review summarizes the basic principles, design strategies, and electrochemical performances of the AILs for Zn2+ ions. First, the side reactions on Zn anodes and their electrochemical mechanisms are briefly discussed. The classification, components, structural features, synthetic methods, and electrochemical mechanisms of the AILs are then combed in detail with a focus on the interaction between Zn anodes and AILs based on underlying electrochemical processes. Finally, the prospects of the AILs for the future development of AZIBs are proposed.



High-Entropy Cathode Materials for Sodium-Ion Batteries

Yuncai Chen, Xingxing Yin, Jun Wang, Haohong Chen, Fan Li, Chunhui Zhong, Wenxiang Zhang, Haw Jiunn Woo, Chao Wang, Qingxia Liu

2025, 8(4):  32.  doi:10.1007/s41918-025-00270-z

Asbtract ( 9 )  

Related Articles | Metrics

Portable electrical devices have become integral to our daily lives, with many being powered by rechargeable batteries. The increasing demand for such batteries has prompted a search for alternative options. Among these alternatives, sodium-ion batteries (SIBs) stand out as promising candidates because of their operational similarity to lithium-ion batteries and cost efficiency. Despite the presence of some commercial SIB products, their overall performance falls short of meeting the requirements for large-scale manufacturing. A critical factor influencing the performance of SIBs is the cathode material. Recently, a novel concept involving high entropy has been introduced for use as a cathode material for SIBs. This review begins by introducing the high-entropy concept and then explores the methods used to synthesize cathode materials such as sodium layered oxides, Prussian blue analogs, and NASICON for SIBs. This review also presents state-of-the-art progress in these three types of materials. In the Conclusions section, we outline perspectives for high-entropy materials (HEMs). This comprehensive review aims to serve as a reference for studying HEMs in the context of SIBs.



Solid-State Electrolytes Based on Polyimides for Lithium Batteries: Structures, Key Properties, Synthesis Methods and Applications

Wenzhan Zhang, Ting Xiong, Zhongchao Bai, Huakun Liu, Xiaolin Qiu

2025, 8(4):  33.  doi:10.1007/s41918-025-00267-8

Asbtract ( 8 )  

Related Articles | Metrics

The rapid expansion of markets for new energy power generation systems, electric vehicles, and drones has driven a significant surge in the demand for lithium-ion batteries (LIBs). However, traditional liquid-state LIBs face critical challenges, including a low energy density, significant safety risks, and a limited operational lifespan. Solid-state lithium batteries (SSLBs) have emerged as a promising solution, offering a higher energy density and improved safety, with their industrialization reliant on advancements in solid-state electrolytes (SSEs). Among these, polymer-based SSEs stand out for their lightweight, cost-effective, flexible, and easily processed nature, making them ideal for large-scale production. Notably, polyimide (PI) has gained significant attention as a leading candidate for polymer-based SSEs because of its excellent mechanical properties, thermal stability, flexibility, and flame retardancy. This review systematically examines the application of PI-based solid electrolytes (PISEs) for SSLBs, starting with their structural designs, material types, mechanisms, and key properties. It then delves into preparations, modification strategies, and advanced architectures while presenting application scenarios and performance metrics. Finally, this review highlights potential future directions for the development and optimization of PISEs for SSLBs. It will lay a solid theoretical foundation for the extensive research and application of PI in the field of SSEs and greatly promote the development of high-performance and high-security SSLBs.



Advancements and Challenges in Aqueous Zinc-Iodine Batteries: Strategies for Enhanced Performance and Stability

Ling Wang, Peng Ji, Na Li, Jing Li, Yi Lin Liu, Jinpeng Guan, Zhaoyu Wang, Haiyang Fu, Yongbiao Mu, Lin Zeng

2025, 8(4):  34.  doi:10.1007/s41918-025-00274-9

Asbtract ( 11 )  

Related Articles | Metrics

Aqueous zinc-iodine batteries (AZIBs) offer intrinsic safety, low cost, and high theoretical capacity, yet their practical performance is hindered by three coupled challenges: polyiodide shuttling that depletes active material and reduces coulombic efficiency; sluggish I2/I-/I3- redox kinetics that limit rate capability; and uncontrolled zinc dendrite growth that causes anode instability and parasitic reactions. This review summarizes recent advances addressing these issues across four domains. Cathode strategies include carbon-based hosts (hierarchical porosity, heteroatom doping, surface functionalization, electrocatalyst integration), ordered mesoporous frameworks, polymer matrices, iodine-containing perovskites, and emerging carriers. Anode designs involving artificial interfacial layers, three-dimensional zinc scaffolds, and anode-free configurations are evaluated for their ability to regulate Zn2+ flux and suppress dendrites. Separator and membrane modifications that block iodide crossover while maintaining ion transport are evaluated. Electrolyte developments encompass aqueous formulations with functional additives, water-in-salt systems, and solid/quasi-solid electrolytes that enhance stability and mechanical robustness. The review concludes with perspectives on key research priorities, including complete shuttle suppression, accelerated redox kinetics, durable dendrite control, and system-level feasibility through integrated material and interface engineering. This concise overview aims to guide the rational design of next-generation AZIBs with enhanced performance and durability.



Two-in-One Integrated CO2/N2 Conversion and Related Systems: Potential, Status, and Future

Changfan Xu, Ningxiang Wu, Yan Ran, Ping Hong, Yong Lei

2025, 8(4):  35.  doi:10.1007/s41918-025-00264-x

Asbtract ( 10 )  

Related Articles | Metrics

Electro-conversion of CO2, N2, or NOx into valuable chemicals, e.g., CO, HCOOH, and NH3, has become a favorite for mitigating environmental pollution and addressing the energy crisis. Typical electrolysis systems, which pair a cathodic CO2, N2, or NOx reduction reaction (CO2RR, NRR, or NOxRR) with an anodic oxygen evolution reaction (OER), hinder the economic viability and efficiency of the overall system due to the energy-intensive OER process. Innovative “Two-in-One” systems that integrate CO2RR, NRR, or NOxRR with a value-added oxidation process or energy storage unit, rather than OER, within a single device have emerged as promising alternatives. However, these “Two-in-One” integrated systems still face numerous pressing challenges in advancing the industrialization of CO2-, N2-, and NOx-related conversion technologies, such as limited application scenarios, low efficiency, and restricted products. Herein, we discuss the technological breakthroughs of “Two-in-One” systems from the perspective of value-added chemical co-production, environmental remediation, and energy storage, aiming to provide readers with fresh research viewpoints to improve efficiency, increase product variety and selectivity, maximize product value, and reduce costs. Specifically, the design principles of “Two-in-One” systems, specific design strategies for dual-value-added chemical co-production, environmental pollutant recycling, and energy storage applications, along with techno-economic and environmental impacts, are discussed in detail. Finally, key research opportunities and challenges are highlighted to facilitate further developments.



Vacancy Engineering Strategies for Water Splitting Electrocatalysts

Qing Zhang, Yuhai Dou, Cong Liu, Haining Fan, Mingjin Cui, Porun Liu, Hua Kun Liu, Shi Xue Dou, Ding Yuan

2025, 8(4):  36.  doi:10.1007/s41918-025-00262-z

Asbtract ( 8 )  

Related Articles | Metrics

With the increasing demand for sustainable energy solutions, electrocatalysis has become an essential technology for energy conversion and storage. Despite significant advancements, traditional electrocatalysts still face persistent challenges in enhancing activity and improving stability. Recent studies have shown that vacancy engineering—modifying the atomic structure of materials through the introduction of vacancies—can significantly enhance catalytic efficiency and durability. As such, this approach provides a promising pathway to advance electrocatalysis. This review first explains the mechanisms of the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) and then provides a comprehensive overview of the application synthesis and characterization of various vacancies strategies, including anionic vacancies, cationic vacancy, and combined anionic–cationic vacancies. The review deeply analyzes the role of vacancies in the electrocatalysts for HER, OER, and overall water splitting. Moreover, the advanced characterization techniques for vacancies are introduced to demonstrate the effects of vacancies from the atomic level. Finally, the review addresses the current challenges and limitations associated with vacancy engineering and proposes potential directions for future research.