Li-rich Cathode Materials for Rechargeable Na Batteries: Ion exchange Method

The relatively low capacity and limited cycling retention of many known Na-ion battery prototypes are presumably due to the fact that most of the cathode materials undergo multiple phase transformations which lead to the cathodes’ instability during cycling (due to stresses that challenge their crystal structure). Such structural transformations and the consequent instability of Na ions insertion cathodes could be one of the major problems that limit the practical development of Na-ion batteries since they deteriorate the cycle life and rate capabilities.

To overcome this issue, we investigated new cathode compounds that are synthesized through Li–Na ion exchange. We starting from O3-Li rich cathode materials and produced by electrochemical ion exchange the new cathode material Na_0.95Li_0.05Mn_0.54Co_0.13Ni_0.13O_w.

This cathode material was characterized electrochemistry by voltammetry and galvanometric measurements by spectroscopy, microscopy and diffractomety including EDS, SEM and XRD. The results are shown in the poster.

Measurements of these cathodes in half cells (vs. Na) as well as in full cells (vs. hard carbon anodes) showed a specific capacity of 170 mAh/g after 50 cycles for these cathodes (considered to be high for sodium ion batteries.

Preliminary results show that the cathode‘s lithium sites remain populated by 5 percent of lithium ions. These lithium ions may occupy the tetrahedral sites, what maybe necessary for the cathodes’ stabilization.