Low-temperature sintering effects on NASICON-structured LiSn2P3O12 solid electrolytes prepared via citric acid-assisted sol-gel method

Abstract

LiSn 2 P 3 O 12 with sodium (Na) super ionic conductor (NASICON)-type rhombohedral structure was successfully obtained at low sintering temperature, 600°C via citric acid-assisted sol-gel method. However, when the sintering temperature increased to 650°C, triclinic structure coexisted with the rhombohedral structure as confirmed by X-ray diffraction analysis. Conductivity-temperature dependence of all samples were studied using impedance spectroscopy in the temperature range 30 to 500°C, and bulk, grain boundary and total conductivity increased as the temperature increased. The highest bulk conductivity found was 3.64×10 −5 S/cm at 500°C for LiSn 2 P 3 O 12 sample sintered at 650°C, and the lowest bulk activation energy at low temperature was 0.008 eV, showing that sintering temperature affect the conductivity value. The voltage stability window for LiSn 2 P 3 O 12 sample sintered at 600°C at ambient temperature was up to 4.4 V. These results indicated the suitability of the LiSn 2 P 3 O 12 to be exploiting further for potential applications as solid electrolytes in electrochemical devices.

Analysis of thermal and electrical conductivity properties of Al substitution LiHf2(PO4)3 chemical solid electrolyte

“…However, the observed absorption bands in region III from 643 to 750 cm −1 are assigned to the symmetry stretching vibration of P-O-P and region IV is the absorption band in the range 553-630 cm −1 due to the asymmetry bending vibration modes of O-P-O bonds. Similar behavior for NASICON-type materials were also reported [21][22][23]. In another observation, the modes slightly shifted towards higher wave number as Al content is increased in the basic LHP structure.…”

Essential structural and experimental descriptors for bulk and grain boundary conductivities of Li solid electrolytes

“…The final 17 descriptors applied in the machine learning were categorized into material, experimental, chemical and structural properties (see Figure 1). The additives (0: absent; 1: present), content of additives (wt%), sintering temperature (°C), sintering time (h), pellet diameter (mm), method type, grain size (μm) and phase type were collected along with the ionic conductivities from various published papers [8,[10][11][12]14,15,[30][31][32][33][34][35][36][37][38][39][40][41][42]. The method types were ball mill/ solid-state (0), melt quench (1), liquid phase (2), and sol-gel techniques (3).…”

Electrical Properties of Li-based NASICON Structured Ceramic Electrolytes Substituted With Chromium

“…AC conductivity values are determined from the dielectric data as discussed in [8]. Figure 6 displays log σ AC vs log ω plots of a Li 1+x Cr x Sn 2-x P 3 O 12 system with x = 0.1 to 0.9.…”

“…AC conductivity spectra can also be used to estimate the ionic hopping rate, ω p in the prepared system. The ionic hopping rate, ω p can be determined from the graph of log σ AC versus log ω by extrapolating at twice the value of DC conductivity from the vertical axis horizontally towards the graph and then extrapolating downwards vertically to the horizontal axis [8]. Meanwhile, the relation of ionic hopping rate, ω p and the magnitude of the charge carrier concentration, K then can be obtained using the following equation [28-29; 31-32] (3) where (4)…”

“…al (1976) [3] in the system of Na 1+x Zr 2 Si x P 3-x O 12 [2] . Since then, various studies have focused on lithium analogous NASICON structured with the general formula LiM 2 P 3 O 12 with M = Ti [4,5], Zr [6,7],Sn [8][9][10] and etc. Lithium analogous NASICON structured electrolytes are made of a three−dimensional framework of TiO 6 octahedra and PO 4 tetrahedra with interstitial tunnels in which Li-ions can hop easily [11][12][13].…”