Electric Dipoles and Ionic Conductivity in a Na⁺Glass Electrolyte

Abstract

Glass, unlike a crystalline solid, contains atoms and molecules that do not occupy fixed positions. A glass that contains molecules that attract one another can age with time. We report such a glass that contains A 2 O and (OA) − electric dipoles (A = Li or Na). At a temperature T < 1.2T g ≈ 110 • C (T g is the glass transition temperature) the electric dipoles coalesce with time into clusters within which, unlike in ice, some dipoles condense into ferroelectric, negatively charged molecules locally charge-compensated by weakly attracted A + ions. In an applied electric field, the dipoles are oriented and, over time depending on the T < 110 • C, are aligned parallel to the field axis to yield a solid A + electrolyte with an ionic conductivity σ i > 10 −2 S cm −1 and a huge dielectric constant that makes it suitable for many applications, including safe rechargeable batteries of high energy density and long cycle life. The A-glass electrolytes (A = Li or Na) formed from A 2.99 Ba 0.005 ClO + xH 2 O (x < 1) exhibit an unusually high dielectric constant as well as an alkali-ion conductivity σ i > 10 −2 S cm −1 at 25• C after the glass has been conditioned. 1 The solvated water leaves the glass as HCl during heating to 250• C; and most, if not all, of the residual OH − are evaporated as H 2 O above 230Measurement of the inverse loss tangent, tan −1 δ = ε /ε , as a function of frequency at different temperatures showed two resonant frequencies that were coupled to one another. We interpret these resonances to be due to rotational vibrations of the A 2 O and OA − electric dipoles. The vibrations were coupled in the temperature interval 70 < T < 90• C at a frequency 10 < f < 500 Hz, and a chronopotentiometric measurement of the dc current in a symmetric Li/Ca doped Li-glass/Li cell at 44• C 1,2 showed an increase with time of the lithium conductivity in the as-prepared Li-glass. The as-prepared glasses were furnace cooled, not quenched, to 25• C. In this paper we investigate the frequency and temperature dependences of the dielectric constant and how the activation enthalpy H m for a Na + hop in an Au/Na-glass/Au cell is conditioned by an orientation of electric dipoles. We show that a designed thermal history under an applied ac electric field can provide a rapid increase of dc cation conductivity to a σ i > 10 −2 S cm −1 and decrease of an activation energy of mobility to H m = 0.06 eV at 25• C. Materials and MethodsSynthesis.-Nominal glass/amorphous solid electrolytes Na 2.99 Ba 0.005 O 1+x Cl 1-2x were processed in a wet synthesis as described previously 1 from the commercial precursors NaCl (99.9%, Merck), Na(OH) (>99%, Merck), and Ba(OH) 2 · 8H 2 O (98.5%, Merck). The glass products were dried by HCl evaporation at lower temperatures and the loss of the OH − by the reaction 2OH − = O 2− + H 2 O↑ above 230• C as previously shown in Ref. 1; the reaction leaves a glass/amorphous solid containing electric dipoles. Samples "as prepared" were slowly cooled down to room temperature. Some samples were subject to heating ...

Coherence in the Ferroelectric A3ClO (A = Li, Na) Family of Electrolytes

“…In recent years, we have been observing different manifestations of the van der Pol-Duffing Hodgkin-Huxley and FitzHugh-Nagumo oscillators, in different architectures of electrochemical/electrostatic energy harvesting and storage cells [ 65 , 66 , 67 , 68 , 69 , 70 , 71 ]. We have studied what seems to be analogous to Rabi’s oscillations arising from Floquet states, namely, stationary solutions of a quantum system in the presence of a periodic time-dependent perturbation [ 70 ].…”

“…In our previous studies, it was demonstrated that coherence might be observed while discharging electrostatic/electrochemical cells with a load [ 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 ]. In other words, the cells of the type conductor 1 /ferroelectric-electrolyte/conductor 2 with collective electrical self-charge and self-cycling phenomena look like a single macroscopic quantum object while discharging with a load, as observed in Figure 3 and Figure 4 .…”

Stable Dynamics Performance and High Efficiency of ABX3‐Type Super‐Alkali Perovskites First Obtained by Introducing H5O2 Cation

“…More importantly, Fang et al pointed out that the Li 3 O(Ge/SnI 3 ) and Li 3 O[Ge/Sn(BH 4 ) 3 ] perovskites quickly undergo the phase transition to nonperovskite phases, because of the strong interaction between Li 3 O + ions. These calculated results suggest that introducing the super‐alkalis including metal atoms into ABX 3 ‐type perovskites may be difficult, because there is the strong interaction between super‐alkalis . However, super‐alkali anti‐perovskites with the stable dynamics performance can be synthesized.…”

Interphases, Interfaces, and Surfaces of Active Materials in Rechargeable Batteries and Perovskite Solar Cells

“…[140,158] Goodenough and co-workers suggest that amorphization of the SSE could effectively eliminate the grain boundaries and suppress dendrite penetration. [159][160][161] Changing the lattice orientation exposes different ion diffusion channels of the electrode materials, which impacts redox an ideal situation where both materials have the same lattice parameters. ii) Lattice mismatch: the differences between lattice parameters induce dislocations at the interface between the SSE and the electrode materials.…”

“…In addition, crystalline LLZO poses a potential safety risk because Li dendrites can grow along the grain boundaries when the current distribution is uneven during battery operation 140,158. Goodenough and co‐workers suggest that amorphization of the SSE could effectively eliminate the grain boundaries and suppress dendrite penetration 159–161…”