Ion-conducting polymer membranes are essential in many separation processes and electrochemical devices, including electrodialysis¹, redox flow batteries², fuel cells³ and electrolysers^4,5. Controlling ion transport and selectivity in these membranes largely hinges on the manipulation of pore size. Although membrane pore structures can be designed in the dry state⁶, they are redefined upon hydration owing to swelling in electrolyte solutions. Strategies to control pore hydration and a deeper understanding of pore structure evolution are vital for accurate pore size tuning. Here we report polymer membranes containing pendant groups of varying hydrophobicity, strategically positioned near charged groups to regulate their hydration capacity and pore swelling. Modulation of the hydrated micropore size (less than two nanometres) enables direct control over water and ion transport across broad length scales, as quantified by spectroscopic and computational methods. Ion selectivity improves in hydration-restrained pores created by more hydrophobic pendant groups. These highly interconnected ion transport channels, with tuned pore gate sizes, show higher ionic conductivity and orders-of-magnitude lower permeation rates of redox-active species compared with conventional membranes, enabling stable cycling of energy-dense aqueous organic redox flow batteries. This pore size tailoring approach provides a promising avenue to membranes with precisely controlled ionic and molecular transport functions.

The current collector is a crucial component in lithium‐ion batteries and supercapacitor setups, responsible for gathering electrons from electrode materials and directing them into the external circuit. However, as battery systems evolve and the demand for higher energy density increases, the limitations of traditional current collectors, such as high contact resistance and low corrosion resistance, have become increasingly evident. This review investigates the functions and challenges associated with current collectors in modern battery and supercapacitor systems, with a particular focus on using carbon coating methods to enhance their performance. Surface coating, known for its simplicity and wide applicability, emerges as a promising solution to address these challenges. The review provides a comprehensive overview of carbon‐coated current collectors across various types of metal and nonmetal substrates in lithium‐ion batteries and supercapacitors, including a comparative analysis of coating materials and techniques. It also discusses methods for manufacturing carbon‐coated current collectors and their practical implications for the industry. Furthermore, the review explores prospects and opportunities, highlighting the development of next‐generation high‐performance coatings and emphasizing the importance of advanced current collectors in optimizing energy device performance.

The battery system, as the core energy storage device of new energy vehicles, faces increasing safety issues and threats. An accurate and robust fault diagnosis technique is crucial to guarantee the safe, reliable, and robust operation of lithium-ion batteries. However, in battery systems, various faults are difficult to diagnose and isolate due to their similar features and internal coupling relationships. In this paper, the current research of advanced battery system fault diagnosis technology is reviewed. Firstly, the existing types of battery faults are introduced in detail, where cell faults include progressive and sudden faults, and system faults include a sensor, management system, and connection component faults. Then, the fault mechanisms are described, including overcharge, overdischarge, overheat, overcool, large rate charge and discharge, and inconsistency. The existing fault diagnosis methods are divided into four main types. The current research and development of model-based, data-driven, knowledge-based, and statistical analysis-based methods for fault diagnosis are summarized. Finally, the future development trend of battery fault diagnosis technology is prospected. This paper provides a comprehensive insight into the fault and defect diagnosis of lithium-ion batteries for electric vehicles, aiming to promote the further development of new energy vehicles.

Water electrolysis, a key enabler of hydrogen energy production, presents significant potential as a strategy for achieving net‐zero emissions. However, the widespread deployment of water electrolysis is currently limited by the high‐cost and scarce noble metal electrocatalysts in hydrogen evolution reaction (HER). Given this challenge, design and synthesis of cost‐effective and high‐performance alternative catalysts have become a research focus, which necessitates insightful understandings of HER fundamentals and material engineering strategies. Distinct from typical reviews that concentrate only on the summary of recent catalyst materials, this review article shifts focus to material engineering strategies for developing efficient HER catalysts. In‐depth analysis of key material design approaches for HER catalysts, such as doping, vacancy defect creation, phase engineering, and metal‐support engineering, are illustrated along with typical research cases. A special emphasis is placed on designing noble metal‐free catalysts with a brief discussion on recent advancements in electrocatalytic water‐splitting technology. The article also delves into important descriptors, reliable evaluation parameters and characterization techniques, aiming to link the fundamental mechanisms of HER with its catalytic performance. In conclusion, it explores future trends in HER catalysts by integrating theoretical, experimental and industrial perspectives, while acknowledging the challenges that remain.

Rapid uptake of lithium‐centric technology, e.g., electric vehicles and large‐scale energy storage, is increasing the demand for efficient technologies for lithium extraction from aqueous sources. Among various lithium‐extraction technologies, membrane processes hold great promise due to energy efficiency and flexible operation in a continuous process with potential commercial viability. However, membrane separators face challenges such as the extraction efficiency due to the limited selectivity toward lithium relative to other species. Low selectivity can be ascribed to the uncontrollable selective channels and inefficient exclusion functions. However, recent selectivity enhancements for other membrane applications, such as in gas separation and energy storage, suggest that this may also be possible for lithium extraction. This review article focuses on the innovations in the membrane chemistries based on rational design following separation principles and unveiling the theories behind enhanced selectivity. Furthermore, recent progress in membrane‐based lithium extraction technologies is summarized with the emphasis on inorganic, organic, and composite materials. The challenges and opportunities for developing the next generation of selective membranes for lithium recovery are also pointed out.