Mesoporous spinel ferrite composite derived from a ternary MgZnFe-layered double hydroxide precursor for lithium storage

Layered double hydroxides (LDHs), also known as hydrotalcite-like anionic clays, are very convenient precursors with a tunable flexibility toward multifunctional nanomaterials, especially in energy storage. Typical methods to improve lithium storage are to introduce additional or self-generating carbonaceous supports to LDH-derived transition metal oxides as anode nanomaterials which can host lithium mainly though a conversion mechanism. Here, we describe a preparation of mesoporous spinel ferrite composite (MgFe2O4/ZnFe2O4) for lithium storage, which is assisted by a combined conversion and alloying mechanism. The composite is derived by a thermal decomposition of a scalablely produced single-resource precursor of ternary Mg2+Zn2+Fe3+-layered double hydroxide (Mg2+Zn2+Fe3+-LDH), and subsequent selective etching. Electrochemical test shows that the electrode delivers an exceptional electrochemical performance, i.e., a reversible capacity of 1190 mA h g−1 after 100 cycles at 100 mA g−1, and, in particular, a reversible capacity of 981 mA h g−1 at 500 mA g−1 after 330 cycles, as well as a reversible capacity of 541 mA h g−1 at 2000 mA g−1 after 1000 cycles. The high electrochemical performance could be attributed to the following features: the combined alloying and conversion mechanisms of ZnFe2O4, synergistic MgFe2O4, and slight-content MgO as a non-active matrix, as well as an appropriate specific area and mesoporous size distribution. Our results show that the cation-tunable LDH precursor-derived synthesis route might be an alternative to prepare multiple-component composites of spinel ferrites and transition metal oxides.