Dendrite-tolerant all-solid-state sodium batteries and an important mechanism of metal self-diffusion

Ionic Conductivity of Na3V2P3O12 as a Function of Electrochemical Potential and its Impact on Battery Performance

“…It is also important to study the potential dependency of NVP's conductivity, since NVP is mainly used as an electrode material with changing potential during battery operation. In our previous work, [9,15] we noted the rapidly increasing polarization of Na‐ASSB cells during high‐rate charge/discharge, which is possibly related to the conducting behavior of NVP.…”

“…The Na electrode is usually undetectable and the Na j NZSP interface usually appears at very low frequencies (~1 Hz). [15] At about 10 kHz, NVP j NZSP j Na shows one obvious process that does not exist in symmetric cells. The real part of the impedance is constantly higher than that of symmetric cells while the imaginary part of this process shows an increasing peak.…”

“…The NVP|NZSP|Na cell, with a similar Au current collector on the positive electrode, also shows a similar process. The Na electrode is usually undetectable and the Na|NZSP interface usually appears at very low frequencies (∼1 Hz) [15] . At about 10 kHz, NVP|NZSP|Na shows one obvious process that does not exist in symmetric cells.…”

“…Compared to batteries with liquid electrolyte, Na‐ASSB cells showed much higher polarization during cycling [12a,13o] . Figure 4a shows typical charge/discharge curves of ASSB cells, obtained from a C‐rate test of an NVP|NZSP|Na cell, prepared by a chemical infiltration method we reported previously [9,15] . For a better comparison of polarization, a shifted capacity, , is chosen as the x‐axis, where the capacity is shifted by half of , the maximum capacity of the respective charge/discharge half cycle.…”

“…[9] Real and imaginary parts of the PEIS results at various potentials are shown in Figure 2b, together with reference plots of an Au j NZSP j Au cell and an Na j NZSP j Na cell (data from previous work). [15,16] At low frequencies (< 10 kHz), the Au j NZSP j Au cell shows a process of increasing impedance, more in the imaginary part and less in the real part, assigned to the ion-blocking effect of the Au electrode. The NVP j NZSP j Na cell, with a similar Au current collector on the positive electrode, also shows a similar process.…”