High density and safe storage of hydrogen are the preconditions for the large-scale application of hydrogen energy. Herein, the hydrogen storage properties of Ti_0.6Zr_0.4Cr_0.6Mn_1.4 alloys are systematically studied by introducing Y element instead of Ti element through vacuum arc melting. After the partial substitution of Y, a second phase of rare earth oxide is added in addition to the main suction hydrogen phase, C14 Laves phase. Thanks to the unique properties of rare earth elements, the partial substitution of Y can not only improve the activation properties and plateau pressure of the alloys, but also increase the effective hydrogen storage capacity of the alloys. The comprehensive properties of hydrogen storage alloys are improved by multidimensional regulation of rare earth elements. Among them, Ti_0.552Y_0.048Zr_0.4Cr_0.6Mn_1.4 has the best comprehensive performance. The alloy can absorb hydrogen without activation at room temperature and 5 MPa, with a maximum hydrogen storage capacity of 1.98 wt.%. At the same time, it reduces the stability of the hydride and the enthalpy change value, making it easier to release hydrogen. Through theoretical analysis and first-principle simulation, the results show that the substitution of Y element reduces the migration energy barrier of hydrogen and the structural stability of the system, which is conducive to hydrogen evolution. The alloy has superior durability compared to the original alloy, and the capacity retention rate was 96.79% after 100 hydrogen absorption/desorption cycles.

Li-O₂ batteries with extremely high specific energy density have been regarded as a kind of promising successor to current Li-ion batteries. However, the high charge overpotential for the decomposition of Li₂O₂ discharge product reduces the energy efficiency and triggers a series of side reactions that cause the Li-O₂ batteries to have a limited lifetime. Herein, Co-doped C₃N₄ (Co-C₃N₄) photocatalysts were designed by an in situ thermal evaporation method to take advantage of the photo-assisted charging technology to conquer the shortcomings of Li-O₂ batteries encountered in the charge process. Different from the commonly used photocatalysts, the Co-C₃N₄ photocatalysts perform well no matter with and without illumination, owing to the Co doping induced conductivity and electrocatalytic ability enhancement. This makes the Co-C₃N₄ reduce the charge and discharge overpotentials and improve the cycling performance of Li-O₂ batteries (from 20 to 106 cycles) without illumination. While introducing illumination, the performance can be further improved: Charge voltage reduces to 3.3 V, and the energy efficiency increases to 84.84%, indicating that the Co-C₃N₄ could behave as a suitable photocathode for Li-O₂ batteries. Besides, the low charge voltage and the continuous illumination together weaken the corrosion of the Li anode, making the long-term high-efficiency operation of Li-O₂ batteries no longer just extravagant hope.

High-voltage high-nickel lithium layered oxide cathodes show great application prospects to meet the ever-increasing demand for further improvement of the energy density of rechargeable lithium-ion batteries (LIBs) mainly due to their high output capacity. However, severe bulk structural degradation and undesired electrode–electrolyte interface reactions seriously endanger the cycle life and safety of the battery. Here, 2 mol% Ti atom is used as modified material doping into LiNi_0.6Co_0.2Mn_0.2O₂ (NCM) to reform LiNi_0.6Co_0.2Mn_0.18Ti_0.02O₂ (NCM-Ti) and address the long-standing inherent problem. At a high cut-off voltage of 4.5 V, NCM-Ti delivers a higher capacity retention ratio (91.8% vs. 82.9%) after 150 cycles and a superior rate capacity (118 vs. 105 mAh·g⁻¹) at the high current density of 10 C than the pristine NCM. The designed high-voltage full battery with graphite as anode and NCM-Ti as cathode also exhibits high energy density (240 Wh·kg⁻¹) and excellent electrochemical performance. The superior electrochemical behavior can be attributed to the improved stability of the bulk structure and the electrode–electrolyte interface owing to the strong Ti–O bond and no unpaired electrons. The in-situ X-ray diffraction analysis demonstrates that Ti-doping inhibits the undesired H2-H3 phase transition, minimizing the mechanical degradation. The ex-situ TEM and X-ray photoelectron spectroscopy reveal that Ti-doping suppresses the release of interfacial oxygen, reducing undesired interfacial reactions. This work provides a valuable strategic guideline for the application of high-voltage high-nickel cathodes in LIBs.