Boosting Lithium Storage of a Metal-Organic Framework via Zinc Doping

Lithium-ion batteries (LIBs) as a predominant power source are widely used in large-scale energy storage fields. For the next-generation energy storage LIBs, it is primary to seek the high capacity and long lifespan electrode materials. Nickel and purified terephthalic acid-based MOF (Ni-PTA) with a series amounts of zinc dopant (0, 20, 50%) are successfully synthesized in this work and evaluated as anode materials for lithium-ion batteries. Among them, the 20% atom fraction Zn-doped Ni-PTA (Zn_0.2-Ni-PTA) exhibits a high specific capacity of 921.4 mA h g^-1 and 739.6 mA h g^-1 at different current densities of 100 and 500 mA g^-1 after 100 cycles. The optimized electrochemical performance of Zn_0.2-Ni-PTA can be attributed to its low charge transfer resistance and high lithium-ion diffusion rate resulting from expanded interplanar spacing after moderate Zn doping. Moreover, a full cell is fabricated based on the LiFePO₄ cathode and as-prepared MOF. The Zn_0.2-Ni-PTA shows a reversible specific capacity of 97.9 mA h g^-1 with 86.1% capacity retention (0.5 C) after 100 cycles, demonstrating the superior electrochemical performance of Zn_0.2-Ni-PTA anode as a promising candidate for practical lithium-ion batteries.