Supercapacitors are promising energy storage solutions known for their high-power density, fast charge–discharge rates, and long cycle life. Recently, Ti₃C₂T_x MXene, a member of the 2D MXene family, has emerged as a potential electrode material for supercapacitors. However, its limited interlayer spacing hinders broader applications. In this study, we introduce a novel δ-MnO₂@MXene heterostructure with expanded interlayer spacing, synthesized using a hydrothermal approach. This design enhances charge transfer efficiency and improves the contact between the components, significantly boosting supercapacitor performance. The unique nanoflower-like structure of δ-MnO₂ combined with MXene substantially improves capacitance retention and ion diffusion, surpassing the performance of each individual material. The sponge-like architecture of δ-MnO₂ increases accessible charge storage sites and widens the interlayer gaps in MXene, facilitating better ion migration. As a result, the δ-MnO₂@MXene electrode exhibits a capacitance 54 times greater than MXene alone (2.0 F g^-1), an impressive rate capability of 67.3% (after a 20-fold increase in current density), and exceptional cycling stability, maintaining 93% of its capacity after 10,000 cycles. This novel δ-MnO₂@MXene heterostructure significantly enhances electrochemical performance, making it a promising candidate for advanced energy storage applications.

Single-crystal high-nickel cathode (SC-HN) materials are promising candidates for advanced lithium-ion batteries due to their exceptional volumetric and gravimetric energy densities. However, SC-HN materials face air instability, causing distinct storage failure mechanisms compared to polycrystalline high-nickel cathode (PC-HN) materials. The characteristics of SC-HN, such as their lower specific surface area and reduced grain boundaries, make their failure mechanisms distinct and not directly applicable to PC-HN materials. To address these unique degradation pathways, this study systematically investigated the storage failure mechanisms of SC-HN material under ambient air exposure. Using advanced characterization techniques including soft X-ray absorption spectra (sXAS), wide-angle X-ray scattering (WAXS), aberration-corrected scanning transmission electron microscopy (STEM), and etching-based X-ray photoelectron spectroscopy (XPS), we conducted comprehensive multi-dimensional analyses over 6 months to track the evolution of chemical and structural changes. The results reveal that SC-HN materials experience a nonlinear progression of structural and surface composition degradation, and surface structural transformations are found to be the main cause of performance decline. The findings deepen understanding of SC-HN air instability and provide a basis for targeted strategies to enhance storage stability.

Cathode materials play a vital role in determining the electrochemical performance of a lithium-ion battery. They have a direct impact on the energy density, cycle life, rate performance, and safety of the battery. LiMn_yFe_1−yPO₄ (0 < y < 1, LMFP) inherits the advantages of high safety and low cost of LiFePO₄ (LFP) materials and also makes up for the shortcomings of the low energy density of LFP materials to a certain extent. It is considered to be a promising cathode material. However, LMFP exhibits extremely low ionic and electronic conductivity. Due to the Jahn–Teller effect, high Mn content will cause serious Mn dissolution and other problems, which seriously hinder the large-scale application of LMFP. This paper provides a comprehensive review of the structural characteristics, reaction mechanisms, and methods to enhance the electrical conductivity of LMFP cathode materials. It primarily focuses on the effects of particle size optimization, morphology control, surface coating, ion doping, and mixing with other layered cathode materials to improve the electrical conductivity of LMFP and their underlying mechanisms. These modification methods can improve the electron/ion transmission path between material particles and the conductivity of LMFP to a certain extent. However, these methods alone make it difficult to solve the problem of poor conductivity of LMFP cathode materials. To further improve the comprehensive electrochemical performance of LMFP materials, this paper provides a summary of the current research progress and presents future research ideas and development directions for LMFP. The strategy of combined modification by heteroatom-doped carbon material coating, short b-axis, morphology control, and ion doping is proposed, and the main development direction and research ideas of LMFP in the future are pointed out.

Sodium-ion batteries have become a significant research focus in academia. As a novel sodium anode material, layered NbOPO₄, consisting of octahedral NbO₆ units sharing oxygen atoms with tetrahedral PO₄ units, exhibits stability due to strong phosphorus-oxygen covalent bonds that prevent oxygen loss from the framework. However, its inherently low electrical conductivity and sluggish charge transfer kinetics limit its electrochemical performance. To address these challenges, we designed and synthesized vanadium-doped niobium oxyphosphate coated with reduced graphene oxide (V-NbOPO₄@rGO) via a microwave hydrothermal method followed by calcination. Vanadium doping effectively modulated the electronic structure of NbOPO₄ and significantly enhanced its conductivity, as corroborated by density functional theory (DFT) calculations. Consequently, the V_0.15-NbOPO₄@rGO electrode demonstrated exceptional rate capability, achieving 418 mAh g⁻¹ at a low current density of 0.1 A g⁻¹ and maintaining a reversible capacity exceeding 100 mAh g⁻¹ even at an ultrahigh current density of 50 A g⁻¹. Furthermore, the reversible sodium storage mechanism of V_0.15-NbOPO₄@rGO was validated through in-situ XRD, TEM, and XPS analyses. This study provides an effective strategy for improving the electrochemical performance of NbOPO₄based anodes and deepens understanding of the sodium storage mechanism in V-doped NbOPO₄, emphasizing its potential for practical application in sodium-ion batteries.

Lithium–sulfur (Li–S) batteries are proposed as next-generation energy storage devices due to their high theoretical capacity and specific energy. However, the actual capacity utilization is greatly limited by the poor reactivity of the sulfur reduction reaction (SRR), which motivates us to develop corresponding high-efficient catalysts. Inspired by the application of MXene and single-atom catalysts (SACs) in improving SRR, a virtual screening on the MXene-supported SACs from the imp2d database is carried out. Finally, six kinds of top catalysts are identified for SRR, and most of them can be considered as variants of the previous representative SRR catalysts, which reflects the rationality of our screening. Meanwhile, the stability and reactivity metrics of the SACs are calculated by density functional theory (DFT) and show obvious trends depending on the type of adatom/MXene. For the critical intermediate binding that can tune SRR activity, further electronic structure analysis reveals the so-called 10-electron count rule, whose decisive role is also reflected by the Shapley value analysis from machine learning (ML). It is noteworthy that this count rule was used to analyze the SACs for hydrogen/carbon/nitrogen-related reactions before, and our successful attempt to optimize SRR further indicates its universality in catalysis fields. Overall, the 10-electron count rule not only rationalizes the nature of SAC–adsorbate interactions but also provides intuitive design guidance for novel SRR catalysts.

Molybdenum dioxide (MoO₂) is a hopeful anode material for high-performing lithium-ion batteries (LIBs), but the practical application is still impeded due to its huge volume variation and degraded capacity upon the cycling process. Herein, we present a reasonable design and synthesis of amorphous carbon matrix-confined MoO₂ yolk–shell microspheres (MoO₂/C-YSMs) by a simple solvothermal strategy and in situ carbonizing process. This unique carbon-restrained yolk–shell architecture can not only shorten Li⁺ ion/electron transfer pathways, but also relieve the large volume change of anode materials and further improve battery performance. Profit from steady yolk–shell structure and conductive carbon matrix, the obtained MoO₂/C-YSMs electrode demonstrates a high reversible specific capacity of 1034 mA h g^–1 at 100 mA g⁻¹ and 504 mA h g⁻¹ at 2000 mA g⁻¹ with good rate capability and long cycle performance. The study demonstrates a facile, feasible, and low-cost method to prepare high-performing electrodes via structural design, which reveals the potential of MoO₂/C-YSMs for using high-performance anode material for LIBs.

The lattice distortion resulting from the Jahn–Teller effect (JTE) at the Mn redox center typically induces irreversible phase transitions and structural degradation, which in turn diminishes the reversible capacity and long-term cycling performance. Here, N-doped carbon quantum dots (N-CDs) grafted to the surface of 3 × 3 tunnel todorokite-type MnO₂ (TMO) nanosheet (abbreviated to TMO@N-CDs) are designed. The adsorption of N-CDs promoted the charge transfer and redistribution between Mn and O and promoted the closer electron cloud overlap between Mn and O, thus enhancing the bonding strength of Mn–O bonds, stabilizing the lattice structure, inhibiting JTE, and realizing reversible H⁺/Zn²⁺ storage. Meanwhile, a significant amount of N-CDs can increase active sites of TMO nanosheet, enhance the binding ability with metal ions, and accelerate the ion diffusion kinetics, thus realizing stable electrochemical performances. The density functional theory (DFT) calculation shows that there is obvious orbital overlap between Mn and O in [MnO6] octahedron, which further quantifies the strong interaction between Mn and O through interphase synergy between N-CDs and TMO. The reversible (de)insertion behavior dominated by H⁺ during charging and discharging was proved by operando XRD and ex-situ SEM. As expected, the obtained TMO@N-CDs cathode exhibits remarkable electrochemical properties in terms of high reversible capacity, good rate performance, and satisfactory cycling stability (after 1000 cycles, the specific capacity remains 96.02%).

Lithium metal batteries (LMBs) have great significance in enhancing energy density. However, low ion diffusion in bulk electrolytes, high desolvation energy of Li⁺, and sluggish ion transport kinetics in electrode interphases at low temperatures cause LMBs to have a short cycle life (usually below 300 cycles). In this study, we designed a low-temperature electrolyte to overcome these issues. The medium-chain length isopropyl formate (IPF) was employed as main solvent in the designed electrolyte. Especially, the hydrogen bonding between non-solvating cosolvent (1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether [TFE]) and IPF can be formed, leading to the weakened interaction between Li⁺ and the solvents. Thus, a fast Li⁺ desolvation can be achieved. Additionally, the designed electrolyte can maintain a high conductivity (6.37 mS cm⁻¹) at −20°C and achieve higher Li⁺ transference numbers (0.62). Finally, Li||LiFePO₄ full cells using the designed electrolyte exhibit a capacity of 113 mAh g⁻¹ after 480 cycles at 0.1C under −20°C. Meanwhile, Li||LiFePO₄ can deliver 150 mAh g⁻¹ after 120 cycles at 50°C. This study provides a novel pathway for optimizing electrolytes for next-generation LMBs during low-temperature operations.

2D COF-based photocatalysts exist as insoluble and difficult-to-process blocks, the layered stacking buries active sites, hindering water molecule access, while crystal defects restrict charge carrier migration/penetration. The well-defined sub-nanostructures with distinct configurations (C₂, C₃) can construct multiple pathways and intramolecular electric fields, which promote electron separation and transfer. Hence, we develop a kind of heteropore-conjugated reticular oligomers (CROs) subnano-crystals with well-defined structures, which can be regarded as a defect-free COFs segment. These sub-nanometer dots ensure sufficient exposure of active sites, enhance processability, form a “homogeneous catalyst” and consequently increase the accessibility of water molecules. Accordingly, the photocatalytic performance of series CROs is up to 129.33 μmol h^–1, improving 3–5 times over bulk COFs. Theoretical calculation shows that: Electron transfer number (ET) increased from 0.43 to 0.99 e, charge transfer distance (D) increases from 2.467 to 10.319 Å, while electron–hole overlap integral (S_r) decreases from 0.495 to 0.023, and exciton binding energy (E_b) decreases from 6.28 to 4.28 eV. The statistical product and service solutions (SPSS) method indicates that extending electron–hole separation distances and reducing exciton binding energy play a pivotal role in achieving effective electron delocalization and efficient charge transfer, thus significantly promoting the photocatalytic process.

The electrocatalytic two-electron oxygen reduction reaction (2e⁻ ORR) has emerged as a pivotal strategy for sustainable hydrogen peroxide (H₂O₂) synthesis, offering a carbon-neutral alternative to the energy-intensive anthraquinone process. This review critically synthesizes recent breakthroughs in catalyst design, mechanistic understanding, and system integration to address the persistent selectivity–stability trade-off. Key advances include atomic-level engineering of electronic modulation and surface functionalization and hydrophobicity control, which achieve > 95% H₂O₂ selectivity by precisely tuning *OOH adsorption energy and suppressing 4e⁻ pathways. Hierarchical architectures, such as flow-through electrodes and catalytic membranes, extend operational stability beyond 500 h at industrial current densities (> 200 mA cm⁻²) through confinement effects and interfacial engineering. Emerging operando characterization techniques coupled with machine learning-accelerated simulations now enable dynamic mapping of active-site evolution and degradation mechanisms. System-level innovations integrating renewable energy input and circular carbon strategies demonstrate pilot-scale feasibility for net-negative emission H₂O₂ production. However, persistent challenges in scalability, long-term catalyst durability under fluctuating loads, and techno-economic gaps between laboratory and industrial implementations require urgent attention. We propose a multidisciplinary roadmap combining materials genome initiatives, modular reactor design, and policy-driven lifecycle assessment frameworks to accelerate the deployment of 2e⁻ ORR systems. This work provides actionable guidance for advancing carbon-neutral chemical manufacturing through electrochemical routes aligned with global net-zero goals.