Heterometallic Metal-Organic Frameworks approach to enhancing lithium storage for their derivatives as anodes materials

Oxalate-derived porous prismatic nickel/nickel oxide nanocomposites toward lithium-ion battery

NiO is a highly appealing anode material for lithium-ion batteries (LIBs) owing to its relatively high Li storage capacity. However, its low electrical conductivity and large volume change during the battery cycling process limit its application. Here, we fabricate a series of porous Ni/NiO (M) nanocomposites through the direct pyrolysis of a nickel oxalate precursor and adjust the Ni(0) content by varying the pyrolysis temperature. The porous architecture is beneficial for alleviating the volume expansion/constriction during cycling. The Ni in the composites accelerates the electrochemical reaction kinetics and enhances the conductivity of the electrode materials. The M-2 electrode with a 17.9% Ni(0) content realizes a high reversible capacity (633.7 mA h g^-1 after 100 cycles at 0.2 A g^-1) and exhibits outstanding rate capability (307.6 mA h g^-1 after 250 cycles at 1 A g^-1). This work can not only supply an approach to adjust the content of an element with specific valence state, but also provide an inspiration for the fabrication of porous metal/metal oxide anode materials in LIBs.

Two-dimensional metal-organic frameworks and their derivatives for electrochemical energy storage and electrocatalysis

Two-dimensional (2D) metal-organic frameworks (MOFs) and their derivatives with excellent dimension-related properties, e.g. high surface areas, abundantly accessible metal nodes, and tailorable structures, have attracted intensive attention as energy storage materials and electrocatalysts. A major challenge on the road toward the commercialization of 2D MOFs and their derivatives is to achieve the facile and controllable synthesis of 2D MOFs with high quality and at low cost. Significant developments have been made in the synthesis and applications of 2D MOFs and their derivatives in recent years. In this review, we first discuss the state-of-the-art synthetic strategies (including both top-down and bottom-up approaches) for 2D MOFs. Subsequently, we review the most recent application progress of 2D MOFs and their derivatives in the fields of electrochemical energy storage (e.g., batteries and supercapacitors) and electrocatalysis (of classical reactions such as the HER, OER, ORR, and CO2RR). Finally, the challenges and promising strategies for the synthesis and applications of 2D MOFs and their derivatives are addressed for future development.