Incorporating a selenium (Se) positive electrode into aluminum (Al)-ion batteries is an effective strategy for improving the overall battery performance. However, the cycling stability of Se positive electrodes has challenges due to the dissolution of intermediate reaction products. In this work, we aim to harness the advantages of Se while reducing its limitations by preparing a core–shell mesoporous carbon hollow sphere with a titanium nitride (C@TiN) host to load 63.9wt% Se as the positive electrode material for Al–Se batteries. Using the physical and chemical confinement offered by the hollow mesoporous carbon and TiN, the obtained core–shell mesoporous carbon hollow spheres coated with Se (Se@C@TiN) display superior utilization of the active material and remarkable cycling stability. As a result, Al–Se batteries equipped with the as-prepared Se@C@TiN composite positive electrodes show an initial discharge specific capacity of 377 mAh·g −1 at a current density of 1000 mA·g −1 while maintaining a discharge specific capacity of 86.0 mAh·g −1 over 200 cycles. This improved cycling performance is ascribed to the high electrical conductivity of the core–shell mesoporous carbon hollow spheres and the unique three-dimensional hierarchical architecture of Se@C@TiN.
Wei Lu,Hongpo Liu,Shiquan Li,Jianhua Zhu,Yunfeng Chao,Zhuosen Wang,Yapeng Tian,Xinwei Cui
Sodium selenium (Na-Se) batteries are considered promising candidates for next-generation energy storage devices due to their high volumetric energy density. However, the Se cathode still faces the problems of the shuttling effect and sluggish selenium reduction kinetics. Improving the surface adsorption and catalytic process of selenium cathode can greatly solve the above issues and achieve excellent performance to enhance the application of Na-Se batteries. Herein, experimental and theoretical simulation results indicate that the boron and defects co-doped MXene (BD-MXene) could initiate the redistribution of electrons and improve the surface polarity, promoting chemical adsorption, thus effectively suppressing the shuttle effect. More importantly, the BD-MXene can promote the conversion between polyselenide, accelerating the electrochemical reaction kinetics of Sodium polyselenide. As a result, the obtained Se@BD-MXene exhibits a high rate performance of 502 mAh g −1 at 50 A g −1 (calculated based on Se@BD-MXene) and excellent cycling stability with a decay per cycle of 0.001 % over 4500 at 10 A g −1 . This work provides a viable strategy to design Se cathodes for Na-Se batteries with high-rate capability and long-term cycling.
Selenium cathodes are expected to become next-generation energy storage materials due to their high electronic conductivity and volumetric capacity. However, their commercial applications are hindered by polyselenides dissolution and low Se utilization. Herein, a biomass compound, namely lychee seed, is used as a sustainable precursor to design hierarchically porous carbon by a single-step carbonization activation method. With a unique hierarchical porous structure, the lychee seed–derived activated carbon (LSDAC) used to encapsulate selenium delivers a reversible capacity of 446 mA h g −1 at 2 C and 291 mA h g −1 at 5 C after 1000 cycles. The Se/LSDAC electrodes show the most favorable fast-charging and good cycling behavior compared to the previously reported biomass-based carbon materials. By increasing the Se area loading to 9.5 mg cm −2 , the Se/LSDAC cathode maintains an areal capacity of 3.7 mA h cm −2 (3.2 mA cm −2 areal current density) after 80 cycles. High Se loading and economical and fast-charging cathode designs in Li–Se batteries are inspired.
危险品化学品经营许可证（带存储）