Tuning the Morphologies of MnO/C Hybrids by Space Constraint Assembly of Mn-MOFs for High Performance Li Ion Batteries.

Abstract

Morphology controllable fabrication of electrode materials is of great significance but is still a major challenge for constructing advanced Li ion batteries. Herein, we propose a novel space constraint assembly approach to tune the morphology of Mn(terephthalic acid) (PTA)-MOF, in which benzonic acid was employed as a modulator to adjust the available MOF assembly directions. As a result, Mn(PTA)-MOFs with microquadrangulars, microflakes, and spindle-like microrods morphologies have been achieved. MnO/C hybrids with preserved morphologies were further obtained by self-sacrificial and thermal transformation of Mn(PTA)-MOFs. As anodes for Li ion batteries, these morphologies showed great influence on the electrochemical properties. Owing to the abundant porous structure and unique architecture, the MnO/C spindle-like microrods demonstrated superior electrochemical properties with a high reversible capacity of 1165 mAh g-1 at 0.3 A g-1, excellent rate capability of 580 mAh g-1 at 3 A g-1, and no considerable capacity loss after 200 cycles at 1 A g-1. This strategy could be extended to engineering the morphology of other MOF-derived functional materials in various structure-dependent applications.