Synthesis of Nanocrystal Heterostructures for Li-ion Battery Cathode with Increased Interfacial Stability

Stabilization of electrode-electrolyte interfaces is required to increase the energy stored in battery electrodes. Introducing redox-inactive ions on the electrode surface minimizes deleterious side reactions without affecting the bulk properties. A synthetic challenge exists to grow such layers conformally at each primary particle, to fully passivate interfaces that are buried in the final electrode architecture. Furthermore, matching their structure between active component and the layers, which benefits carrier transport by reducing their strain at the boundaries. The development of methods of sequential colloidal growth of complex oxides and overlayers would provide novel means to advance toward this goal. Post-synthetic annealing was used to produce the final heterostructure and tailor the specific chemistry of the shell. Here, nanocrystals composed of core high energy cathodes were grown with a shell enriched in Al3+, deposited conformally through a one-pot colloidal synthetic method. The finely tailored nanostructures enhanced their capacity retentions compared to the bare counter parts, while minimizing losses of the original properties. Stabilization effects were more apparent on the surface than in the bulk of crystals when it was harvested in extreme conditions, implying the suppression of the side reactions.