Co3O4 anode for lithium-ion batteries coupled by polyoxometalates and graphene for boosting ion-/electron-conductivity

Even being promising anode materials for lithium-ion batteries (LIBs), Co3O4 is still hindered by poor redox and large volume change during dis-/charging. Herein, series of PW12 @Co3O4 @GO composites were successfully fabricated to address the aforementioned shortcomings by pinning monodispersed H3PW12O40 (PW12) on Co3O4 and then coating graphene (GO). Results of X-ray photoelectron spectroscopy (XPS) and cyclic voltammograms (CV) show that PW12 was successfully anchored to the macromolecule Co3O4 by covalent Co-O-W bond, where, to improve the ion and charge transfer rate of Co3O4, the excellent ionic conductivity and multi-electron redox of PW12 as "Li+ migration entrance" were explored for the first time, meanwhile, the capacity retention of PW12 was greatly maintained (97.5% after 250 cycles). Moreover, GO as electronic conductor and buffer improves the overall conductivity and copes with large volume changes of Co3O4, which ensures the capacity retention rate of PW12 @Co3O4 @GO-2 of 94.9% after 250 cycles. Finally, we delved into the lithium storage process and proposed a possible lithium storage mechanism of PW12 @Co3O4 @GO-2, which provides a new insight to trigger the electrochemical activity for next-generation anode materials.