Structure‐Activity Relationships of a Ni‐MOF, a Ni‐MOF‐rGO, and pyrolyzed Ni/C@rGO Structures for Sodium‐ ion Batteries

Abstract

MOF (Metal-Organic Framework) based materials have attracted recent interest as-anode materials for Alkali-ion batteries. However, the insertion reaction that dictates the alkali ion storage in the MOFs being a conversion reaction depicts the drastic drop in cycling and rate stabilities. Herein we report a low-temperature twinning of a representative Ni-MOF with rGO (reduced graphene oxide) by low-temperature processing and through an intermediate physical mixing method to enhance the electrochemical anodic performance of the parent pristine Ni-based MOF that is Ni-MOF. The uniqueness of this process is that low-temperature processing (300 °C) ensures that the identity of MOF is maintained but generates intimate contacts between the Ni-MOF and thermally reduced GO (Graphene Oxide). The Ni-MOF@rGO composite so achieved has delivered a considerably enhanced rate and cycling stability with a capacity of 385 mAhg À 1 (100 mAg À 1 ) which stays consistent till 400 charge-discharge cycles against the pristine MOF which degrades to 272 mAg À 1 in just 250 cycles. The rate enhancements at higher currents are also substantial with the Ni-MOF@rGO composite depicting the capacity of 205 mAhg À 1 at 1 Ag À 1 as against the capacity of 113 mAhg À 1 for pristine Ni-MOF. The Ni-MOF@ rGO also depicts a considerably enhanced performance compared to carbonized (600 °C and 800 °C) control samples.

Synthesis, Properties, and Applications of Metal Organic Frameworks Supported on Graphene Oxide

“…To improve the electrochemical anodic performance of the parent pure Ni-based MOF (Ni-MOF), Haroon et al [76] prepared the Ni-MOF@rGO composite using low temperatures, linked to a representative Ni-MOF with rGO via an intermediary physical mixing method. This method was exceptional because it produced close contacts between the Ni-MOF and thermally regenerated rGO, while maintaining the MOFs' anonymity at low temperatures (300 • C).…”

“…The Ni-BDC/rGO@300 composite displayed a capacity of 205 mAhg −1 at 1 Ag −1 , while the pristine Ni-MOF capacity was 113 mAhg −1 , demonstrating significant rate improvements at higher currents. Scheme 3 illustrates the general synthetic process [76]. Scheme 3.…”