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Surface chemistry and bulk structure jointly play crucial roles in achieving high-performance supercapacitors. Here, the synergistic effect of surface chemistry properties (vacancy and phosphorization) and structure-derived properties (hollow hydrangea-like structure) on energy storage is explored by the surface treatment and architecture design of the nanostructures. The theoretical calculations and experiments prove that surface chemistry modulation is capable of improving electronic conductivity and electrolyte wettability. The structural engineering of both hollow and nanosheets produces a high specific surface area and an abundant pore structure, which is favorable in exposing more active sites and shortens the ion diffusion distance. Benefiting from its admirable physicochemical properties, the surface phosphorylated MnCo2O4.5 hollow hydrangea-like structure (P-MnCoO) delivers a high capacitance of 425 F g−1 at 1 A g−1, a superior capability rate of 63.9%, capacitance retention at 10 A g−1, and extremely long cyclic stability (91.1% after 10,000 cycles). The fabricated P-MnCoO/AC asymmetric supercapacitor achieved superior energy and power density. This work opens a new avenue to further improve the electrochemical performance of metal oxides for supercapacitors. [ABSTRACT FROM AUTHOR]

Mechanical ball milling is a prevalent technology for material preparation and also serves as a post-treatment method to modify electrode materials, thus enhancing electrochemical performances. This study explores the microstructure modification of commercial activated carbon through mechanical ball milling, proving its efficacy in increasing sodium-ion energy storage. The evolution of activated carbon's physical and chemical properties during ball milling was systematically examined. It was observed that the quantity of closed pores and the graphitization degree in activated carbon increased with extended ball milling duration. The sodium storage mechanism in activated carbon transitions to an insertion-pore filling process, significantly elevating platform capacity. Additionally, ball-milled activated carbon demonstrates remarkable long-term cycling stability (92% capacity retention over 200 cycles at 200 mA g−1) and rate performance. This research offers a novel approach to developing advanced anode materials for sodium-ion batteries. [ABSTRACT FROM AUTHOR]

Phase change materials (PCMs) have garnered significant interest in the field of passive cooling for lithium‐ion batteries in recent years due to their simple structure, low cost, and stable performance. This paper introduces a passive thermal management strategy based on nonuniform paraffin (PA) and glass fiber for battery modules. It explores the impact of glass fiber on the thermal conductivity and structural strength of PA, as well as the thermal management performance of the composite phase change battery module that combines the two materials. The findings reveal that the composite phase change module with a glass fiber mass fraction of 60%, operating at a discharge rate of 3C, maintains a temperature 0.76°C lower than that of the air‐cooling module. This reduction results in a decreased maximum temperature difference between the modules from 7.3 to 5.0°C and a decrease in the maximum temperature ratio from 16.9% to 11.6%. Moreover, compared to the PA phase change module, heat transfer to adjacent cells decreases by approximately 10% during thermal runaway, effectively suppressing thermal propagation. Additionally, the incorporation of glass fiber in this scheme enhances the compressive strength of the module by a factor of 9.81. This study presents a novel method to address the thermal management needs of batteries for heat dissipation and thermal insulation. [ABSTRACT FROM AUTHOR]

The ether electrolytes usually outperform ester electrolytes by evaluating sodium‐ion batteries (SIBs) rate performance, which is a near‐unanimous conclusion of previous studies based on an essential configuration of the half‐cell test. However, here we find that contrary to consensus, the ester electrolyte shows better Na storage capability than the ether electrolyte in full cells. An in‐depth analysis of three‐electrode, symmetric cell, and in situ XRD tests indicates that traditional half‐cell test results are unreliable due to interference from Na electrodes. In particular, Na electrodes show a huge stability difference in ester and ether electrolytes, and ester electrolytes suffer more severe interference than ether electrolytes, resulting in the belief that esters are far inferior to ether electrolytes. More seriously, the more accurate three‐electrode test would also suffer from Na electrode interference. Thus, a "corrected half‐cell test" protocol is developed to shield the Na electrode interference, revealing the very close super rate capability of hard carbon in ester and ether electrolytes. This work breaks the inherent perception that the kinetic properties of ester electrolytes are inferior to ethers in sodium‐ion batteries, reveals the pitfalls of half‐cell tests, and proposes a new test protocol for reliable results, greatly accelerating the commercialization of sodium‐ion batteries. [ABSTRACT FROM AUTHOR]