Chunli Wang,Lianshan Sun,Feifei Zhang,Xuxu Wang,Qujiang Sun,Yong Cheng,Limin Wang
Highly uniform hierarchical Mo–polydopamine hollow spheres are synthesized for the first time through a liquid-phase reaction under ambient temperature. A self-assembly mechanism of the hollow structure of Mo–polydopamine precursor is discussed in detail, and a determined theory is proposed in a water-in-oil system. Via different annealing process, these precursors can be converted into hierarchical hollow MoO 2 /C and Mo 2 C/C composites without any distortion in shape. Owing to the well-organized structure and nanosize particle embedding, the as-prepared hollow spheres exhibit appealing performance both as the anode material for lithium-ion batteries and as the catalyst for hydrogen evolution reaction (HER). Accordingly, MoO 2 /C delivers a high reversible capacity of 940 mAh g −1 at 0.1 A g −1 and 775 mAh g −1 at 1 A g −1 with good rate capability and long cycle performance. Moreover, Mo 2 C/C also exhibits an enhanced electrocatalytic performance with a low overpotential for HER in both acidic and alkaline conditions, as well as remarkable stability.
Chenglong Wu,Jiulin Hu,Jing Tian,Fulu Chu,Zhenguo Yao,Yongjian Zheng,Dongguang Yin,Chilin Li
Mg anode has pronounced advantages in terms of high volumetric capacity, resource abundance, and dendrite-free electrochemical plating, which make rechargeable Mg-based batteries stand out as a representative next-generation energy storage system utilized in the field of large-scale stationary electric grid. However, sluggish Mg2+ diffusion in cathode lattices and facile passivation on the Mg anode hinder the commercialization of Mg batteries. Exploring a highly electroactive cathode prototype with hierarchical nanostructure and compatible electrolyte system with the capability of activating both an anode and a cathode is still a challenge. Here, we propose a POM⊂MOF (NENU-5) core–shell architecture as a hybrid precursor template to achieve the stacking of tailored chalcogenide nanosheets around MoO2-C conductive stakes, which can be employed as conversion–insertion cathodes (Cu1.96S-MoS2-MoO2 and Cu2Se-MoO2) for Mg–Li dual-salt batteries. Li-salt modulation further activates the capacity and rate performance at the cathode side by preferential Li-driven displacement reaction in Cu+ extrusible lattices. The heterogeneous conductive network and conformal dual-doped carbon coating enable a reversible capacity as high as 200 mAh/g with a coulombic efficiency close to 100%. The composite cathode can endure a long-term cycling up to 400 cycles and a high current density up to 2 A/g. The diversity of MOF-based materials infused by functional molecules or clusters would enrich the nanoengineering of electrodes to meet the performance demand for future multivalent batteries.
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