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 −1 (100 mAg −1 ) which stays consistent till 400 charge‐ discharge cycles against the pristine MOF which degrades to 272 mAg −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 −1 at 1 Ag −1 as against the capacity of 113 mAhg −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.