Flocculent Cu Caused by the Jahn–Teller Effect Improved the Performance of Mg-MOF-74 as an Anode Material for Lithium-Ion Batteries

Mg-MOF-74/Cu was synthesized by a one-step method and then using the product as a lithium-ion anode material. The flocculent Cu caused by the Jahn-Teller effect conspicuously improves the electrochemical performance of Mg-MOF-74 by enhancing the conductivity of electrode materials. The as-prepared materials exhibited superior rate performance (298.3 mAh g^-1 at a current density of 2000 mA g^-1) and remarkable cyclability (a specific capacity of 534.5 mAh g^-1 is obtained after 300 cycles at 500 mA g^-1, which remains at 89.1%). In addition, an electrochemical test of coating an anode material on a stainless steel sheet has also been carried out, and the performance is comparable to that of traditional coating on copper foil (a reversible capacity of 531.7 mAh g^-1 is collected, which retains 88.7% of initial capacity). The superior performance, facile one-step synthesis, and low cost of Mg-MOF-74/Cu show promise for practical applications.