Point defect engineering has garnered widespread application for enhancing the dynamic behavior of anode materials and improving electrochemical performance. Herein, a hybrid point defect strategy is proposed in Ti-based oxide materials to achieve N doping induced oxygen vacancies (OVs) and subsequently accelerated electron mobility and perform better diffusion kinetics. This methodology culminates in the fabrication of self-supported nanotube arrays comprising N-doped OVs-rich TiO 2 (denoted as N-TNTs). Density functional theory (DFT) calculations and electrochemical characterizations validate that, hybrid point defects lead to high electron mobility and perform better diffusion kinetics, as well as higher Li + /Na + ions adsorption energy barrier and diffusion energy barrier, which in turn improves the rate performance and cycling stability. This research provides a forward-looking and feasible strategy for the application of point defect engineering in anode materials.
Shaohua Wang,Zheng Yi,Xuxu Wang,Qujiang Sun,Yong Cheng,Limin Wang
Carbon coated core-shell structured anode has been reported with advantages to enhance conductivity and partly buffer the volume expansion. However, huge mechanical stress and long lithium/sodium transmission distance also hinder the lithium/sodium storage performances. For maximum buffer effect, we herein design a multicore-shell CoSn@C nanocages with decreased particle size and enhanced extra space in comparison with the monocore-shell sample. This unique structure can effectively buffer the volume expansion in the deintercalation process, alleviate electrode pulverization and improve cyclic stability. Electrochemical tests show that multicore-shell CoSn@C nanocubes have excellent discharge capacities of 1010.9 mAh g −1 at 0.5 A g −1 after 160 cycles and 818 mAh g −1 at 1 A g −1 after 300 cycles for lithium ion battery anode, much higher than that of the monocore-shell sample. The sodium storage performance of the multicore-shell CoSn@C is also far more than the monocore-shell one. Above results suggests that fabrication of multicore-shell structure is an excellent design to buffer volume expansion and enhance performance for lithium and sodium storage.
Xiaoyan Shi,Weiquan Liang,Guoping Liu,Bin Chen,Lianyi Shao,Yanxue Wu,Zhipeng Sun,Felipe García
The development of new energy-related materials is the pinnacle to attaining a sustainable society based on renewable energy. Over the past decades, plenty of electrode materials have been investigated seeking better energy storage properties. However, the often-tedious synthetic procedures and large amounts of solvents utilised during their syntheses incur high costs and severe environmental pollution. Here we present a solvent-free approach to metal–organic-frameworks/MXene-derived carbonaceous metal selenide/MXene composites with unique nanostructures rich in mesopores and macropores. These species can be readily transformed into high-performance electrode materials with enhanced Li/Na ion storage properties compared with their solution-based counterparts. Herein we report not only a unique metal–organic framework/MXene-derived electrode material displaying high-performance for advanced lithium/sodium storage applications but also its novel environmentally benign production process.
A hybrid nanostructure with Co 0.85 Se nanoparticles anchored in nitrogen-doped hollow mesoporous carbon nanospheres/carbon nanotubes (Co 0.85 Se/N-HMCNs/CNTs) is elaborately fabricated by a pyrolysis–reduction–selenization strategy derived from yolk–shell zeolitic imidazolate framework-67 (ZIF-67)@HMCNs, which are synthesized by the confined growth of ZIF-67 inside HMCNs regarded as nanoreactors. Benefitting from the robust hollow carbon frameworks made of nitrogen-doped hollow mesoporous carbon nanospheres, carbon nanotubes, and highly active Co 0.85 Se ultrafine nanoparticles, the as-prepared nanocomposites show greatly enhanced lithium/sodium storage properties. When the Co 0.85 Se/N-HMCNs/CNTs are applied to lithium-ion batteries as anode materials, the advanced nanocomposite delivers excellent cycling stability (286 and 153 mA h g −1 at 10 A g −1 after 5000 and 10 000 cycles) and high rate performance (501 mA h g −1 at 5 A g −1 ). When the Co 0.85 Se/N-HMCNs/CNTs are applied to sodium-ion batteries as anode materials, the material realizes better cycling performance (102 mA h g −1 at 1 A g −1 after 1000 cycles) and excellent rate performance (132 mA h g −1 at 5 A g −1 ).
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