Associating and Tuning Sodium and Oxygen Mixed‐Ion Conduction in Niobium‐Based Perovskites

Abstract

Pure ionic conductors as solid‐state electrolytes are of high interest in electrochemical energy storage and conversion devices. They systematically involve only one ion as the charge carrier. The association of two mobile ionic species, one positively and the other negatively charged, in a specific network should strongly influence the total ion conduction. Nb5+‐ (4d0) and Ti4+‐based (3d0) derived‐perovskite frameworks containing Na+ and O2− as mobile species are investigated as mixed ion conductors by electrochemical impedance spectroscopy. The design of Na+ blocking layers via sandwiched pellet sintered by spark plasma sintering at high temperatures leads to quantified transport number of both ionic charge carriers tNa+ and tO2−. In the 350–700 °C temperature range, ionic conductivity can be tuned from major Na+ contribution (tNa+ = 88%) for NaNbO3 to pure O2− transport in NaNb0.9Ti0.1O2.95 phase. Such a Ti‐substitution is accompanied with a ≈100‐fold increase in the oxygen conductivity, approaching the best values for pure oxygen conductors in this temperature range. Besides the demonstration of tunable mixed ion conduction with quantifiable cationic and anionic contributions in a single solid‐state structure, a strategy is established from structural analysis to develop other architectures with improved mixed ionic conductivity.

Additive Engineering by Bifunctional Guanidine Sulfamate for Highly Efficient and Stable Perovskites Solar Cells

“…The R s represents resistance of electrodes, the high‐frequency arc is related to charge‐transport resistance ( R ct ), and low‐frequency arc represents recombination resistance ( R rec ), which are corresponding to the illustration of simplified equivalent circuit diagram. [ 43,44 ] Compared with pristine device, the R ct of 2% GuaSM‐doped device reduces from 49.32 to 24.6 Ω. In addition, the R ct of pristine and 2% GuaSM‐doped devices decreases with the increasing bias (Figure S14b, Supporting Information), and detailed data are summarized in Table S8 in the Supporting Information.…”

Direct evidence of boosted oxygen evolution over perovskite by enhanced lattice oxygen participation

“…The accelerated oxygen ion diffusion is likely associated with the increased crystal lattice symmetry, i.e., from hexagonal symmetry for SCO to tetragonal symmetry for Si-SCO. Although the energy landscape through which the oxygen anions migrate remains quite complex, one general comment is that a higher symmetry could lead to faster oxygen anion transport [59][60][61] . Meanwhile, the fast oxygen ion diffusion in Si-SCO is believed to be related to its unique layered structure 62 , and the presence of partial A-site deficiency further facilitates the oxygen ion diffusion due to the increase in the oxygen vacancy concentration 24,63 .…”

Conduction properties of Ti‐doped NaTaO3 at intermediate temperature

“…For the nature of 4-probe analysis, the profile of the Nyquist plot of A.C. in Figure 6B is distorted and the rising slope from electrodes is A survey of the published literature modeling of CMCs has been studied by a n ers. Processes that have been modeled CVD, 17,18 CVI, [19][20][21][22] and Sol-Gel Infiltrat of alumina matrix in eight-harness satin has been studied numerically in Ref. [ proaches used in the above work general ing the flow of a high viscosity resin thr and modeling the chemical reactions and during processing.…”

“…[6][7][8][9][10][11][12] Even though, some acceptor-doped I-V perovskites have been reported to show notable properties. [13][14][15][16][17][18] For example, (1)…”

“…In their following research, Ti-doped NaNbO 3 was proved to be a pure oxide ion conductor at 400-700°C 1 . 17,18 Same as materials discussed above, NaTaO 3 is also a I-V compound with a perovskite structure. So it is possible that NaTaO 3 has high oxide-ion or proton conductivity after being doped with acceptor element.…”