Supercapacitors or ultracapacitors are considered as one of the potential candidates in the domain of energy storage devices for the forthcoming generations. These devices have earned their significance in numerous applications, viz., to power hybrid electric/electric vehicles and other power and electronic systems which require electrical energy for their operation. Supercapacitors are the most versatile devices which are most widely used for delivery of electrical energy in short time and in arenas which demand long shelf life. Therefore, the development of supercapacitors has huge market requirements, and long-term progress is needed for their successful advancement and commercialization. Meanwhile, supercapacitors are also facing challenges such as technical problems, establishing electrical parameter models, consistency testing, and establishing industrial standards. In this paper, the above challenges and the future development opportunities of supercapacitors are introduced in detail. This perspective will provide corresponding guidance and new directions for the development of supercapacitors.

Sodium-ion batteries are renowned for their abundant reserves, cost-efficiency, safety, and eco-friendliness and are prime candidates for large-scale energy storage applications. The development of cathode materials plays a crucial role in shaping both the commercialization path and the ultimate performance capabilities of SIBs. To overcome the intricate synthesis challenges associated with pure-phase sodium-ion cathode materials, this study introduces an innovative and streamlined electrochemical Li⁺/Na⁺ exchange process, successfully fabricating a high-capacity Ni-rich cathode material. This cathode material boasts a remarkable reversible capacity of 180 mAh g⁻¹ at 0.1 C and retains a high-rate capacity of 115 mAh g⁻¹ even at 5 C. Additionally, it exhibits exceptional cycling stability, retaining about 85% of its capacity at 1 C after 50 cycles and still maintaining a capacity greater than 60% after 100 cycles. The Na-NMA85 full cell preserves a discharge capacity of 110 mAh g⁻¹ after 100 cycles, with a capacity retention rate of 80%. This research underscores innovative strategies for designing ion-intercalation-based cathode materials that enhance battery performance, providing fresh perspectives for advancing high-performance battery technologies.

Sodium-ion batteries (SIBs), benefiting from abundant sodium resources, cost-effectiveness, high safety, and environmental friendliness, are emerging as vital supplements to lithium-ion batteries (LIBs) in various fields, including electric vehicles, portable power sources, and stationary energy storage stations. The performance of SIBs largely hinges on cathode materials. Among them, Ni-based layered oxide cathode materials (Na1-δNixMyO2; M=Co, Mn, Al, Fe, and/or other elements; x + y = 1, y ≤ x ≤ 1; Ni-rich, 0.6 ≤ x ≤ 1) have exhibited distinctive advantages and enhancement potential due to the unique arrangement of Na and Ni ions within their layered structures. Na1-δNixMyO2 can significantly increase the specific discharge capacity by increasing the Ni content, which is of great significance for improving the energy density of SIBs. However, increasing the Ni content of Na1-δNixMyO2 also brings challenges, namely a decrease in structural stability, cycle durability, and thermal safety. In this paper, a comprehensive review is provided to understand the relationship between material structure and electrochemical performance. The degradation mechanism and modification strategies to further improve the performance and mitigate the degradation of SIB cathode materials of Ni-based cathodes such as Na1-δNixMyO2 are emphasized. This paper also analyzes the technical challenges and proposes future research directions to overcome them toward practical SIB applications.

Ni-rich layered oxide LiNi_0.91Co_0.06Al_0.03O₂ (NCA91) with high specific capacity has emerged as a leading cathode candidate for advanced lithium-ion batteries (LIBs). Nevertheless, increase in Ni content triggers structural instability and fast capacity degradation, which severely impedes the practical application of Ni-rich materials. Herein, a comprehensive study is conducted to explore the structural evolution and electrochemical behaviors of NCA91 cathodes with precisely tuned Li/TMs (transition metals) molar ratios spanning from 1.01 to 1.07. Results reveal that the NCA91 electrode with an optimal Li/TMs ratio of 1.03 exhibits outstanding structural integrity, coupled with remarkable cycling durability and rate capability. Specifically, the cathode with Li/TMs = 1.03 retains 88% of its initial capacity after 100 cycles at 1 C, and maintains ~130 mAh g⁻¹ even at 10 C. This work establishes a quantitative structure–composition–performance correlation that offers critical design principles for developing ultrahigh-nickel cathode materials.

Two‐dimensional (2D) transition‐metal carbides and nitrides (MXenes) exhibit high electronic conductivity, large volumetric capacitance, and excellent mechanical robustness, making them attractive for electrochemical actuators (ECAs). However, the fundamental link between surface chemistry, charge‐storage mechanism, and macroscopic actuation remains unclear, limiting their full potential. Here, we elucidate the actuation mechanism of Ti ₃ C ₂ ‐based ECAs, revealing that actuation is driven by pseudocapacitive reactions rather than by simple ion intercalation. Controlled hydrothermal treatment of Ti ₃ C ₂ T _x can tailor oxygen functional groups, boosting pseudocapacitive activity and interlayer adjustability. In situ structural analysis reveals that anomalous interlayer expansion arises from multiple hydrated ions accumulating at confined Ti─O─Ti active sites during pseudocapacitive reactions. Coupled with a beneficial wave‐like cross‐section morphology, the oxygen‐functionalized Ti ₃ C ₂ ‐based solid‐state ECA achieves a peak‐to‐peak strain of ∼1% at 0.05 Hz under a ±1 V square‐wave voltage, which is four times greater than the pristine Ti ₃ C ₂ T _x device, while maintaining excellent cycling stability. These findings culminate in a mechanistic framework linking atomic‐scale surface chemistry to macroscopic device performance, providing critical insights for designing advanced 2D material‐based actuators.