Li2ZnTi3O8 anode: design from material to electrode and devices

Abstract

Spinel Li₂ZnTi₃O₈, as a zero volumetric change material, is a promising anode for electrochemical energy storage devices. Compared with commercial graphite, Li₂ZnTi₃O₈ provides high operating potentials of 0.5 and 1 V, offering high safety. Compared with commercial Li₄Ti₅O₁₂, Li₂ZnTi₃O₈ possesses relatively large theoretical specific capacity of 229 mA h g⁻¹ and low synthesis cost. However, Li₂ZnTi₃O₈ suffers low electronic conductivity, resulting in poor electrochemical performance. A material modification process is a common strategy to overcome the issue of Li₂ZnTi₃O₈ and has been mainly focused on in previous reviews. The investigations and achievements are rarely summarized for research on subsequent processes after a material modification process, such as electrode and device designs. In this review, the designs from material to electrode and device are completely reviewed. The design schemes mainly include (1) modifying the surface, doping by heterogeneous ions, and shortening the diffusion distance of Li⁺ ions by designing nanostructure or porous structure on the material level, (2) optimizing binder and Cu current collector and designing flexible electrode structure on the electrode level, and (3) rational construction of lithium-ion full cells and lithium-ion capacitors on the device level. It is believed that rational designs can ensure superior performance for Li₂ZnTi₃O₈-based energy storage and conversion devices. In addition, the work sums up theoretical studies on the basic structure and electronic properties via the first principles calculations and mechanism of capacity-rising of Li₂ZnTi₃O₈ upon cycling, which will provide much comprehensive knowledge and understanding of Li₂ZnTi₃O₈.