Electrical and Structural Properties of Li1.3Al0.3Ti1.7(PO4)3—Based Ceramics Prepared with the Addition of Li4SiO4

Abstract

The currently studied materials considered as potential candidates to be solid electrolytes for Li-ion batteries usually suffer from low total ionic conductivity. One of them, the NASICON-type ceramic of the chemical formula Li1.3Al0.3Ti1.7(PO4)3, seems to be an appropriate material for the modification of its electrical properties due to its high bulk ionic conductivity of the order of 10−3 S∙cm−1. For this purpose, we propose an approach concerning modifying the grain boundary composition towards the higher conducting one. To achieve this goal, Li4SiO4 was selected and added to the LATP base matrix to support Li+ diffusion between the grains. The properties of the Li1.3Al0.3Ti1.7(PO4)3−xLi4SiO4 (0.02 ≤ x ≤ 0.1) system were studied by means of high-temperature X-ray diffractometry (HTXRD); 6Li, 27Al, 29Si, and 31P magic angle spinning nuclear magnetic resonance spectroscopy (MAS NMR); thermogravimetry (TG); scanning electron microscopy (SEM); and impedance spectroscopy (IS) techniques. Referring to the experimental results, the Li4SiO4 additive material leads to the improvement of the electrical properties and the value of the total ionic conductivity exceeds 10−4 S∙cm−1 in most studied cases. The factors affecting the enhancement of the total ionic conductivity are discussed. The highest value of σtot = 1.4 × 10−4 S∙cm−1 has been obtained for LATP–0.1LSO material sintered at 1000 °C for 6 h.

Insights into the Effects of Co-Regulated Factors on Li1.3Al0.3Ti1.7(PO4)3 Solid Electrolyte Preparation: Sources, Calcination Temperatures, and Sintering Temperatures

“…LATP-T calcined at 900 °C and sintered at 950 °C exhibited the highest total ionic conductivity of 0.289 mS/cm among the samples. This value was higher than those of LATP-CK, LATP-L, LATP-A, and LATP-P (0.0117–0.171 mS/cm) and comparable to those reported in other studies (0.140–0.279 mS/cm). ,, The total ionic conductivity of the LATP pellets was strongly influenced by their characteristics, such as secondary phases (e.g., AlPO 4 and LiTiOPO 4 ), grain size, density, and microcracks. ,, These features were in turn affected by the processing parameters (sintering temperature, source, and calcination temperature). Furthermore, the effect of various factors was analyzed using the orthogonal experiment method, which is described in detail below.…”

“…The starting materials (the Ti, Li, Al, and P sources based on a molar ratio of n (Ti): n (Li): n (Al): n (P) of 1.7:1.3:0.3:3) were mixed with the solvent isopropyl alcohol by ball milling (MITR-YXQM-1L, Changsha Minqi Instrument Equipment Co., Ltd., Changsha, China) at 500 rpm for 7.5 h. The mixed powder was calcined at 450 °C for 5 h in air in a nabertherm muffle furnace (The Nabertherm Furnace World, Lilienthal, Germany) to evaporate the gas (e.g., NH 3 , CO 2 , and H 2 O) . The calcined powder was then pulverized and calcined again at different temperatures (700, 800, 900, and 1000 °C) for 10 h in air to obtain the LATP precursor powders. , The precursor powders were ball milled at 500 rpm for 7.5 h, filtered through a 20 μm mesh, and pressed isostatically at 400 MPa to form a pellet with a diameter of 10 mm and a thickness of 1.2 mm. The pellets were placed on an Al 2 O 3 crucible and sintered at 750, 850, 950, and 1050 °C with a ramp rate of 1 °C/min in air to obtain LATP pellets.…”

“…LATP powder was prepared by the solid-state reaction method using the starting materials shown in Table . TiO 2 , Li 2 CO 3 , Al 2 O 3 , and NH 4 H 2 PO 4 were used as sources of Ti, Li, Al, and P, respectively, to prepare LATP. ,,, This sample was designated as LATP-CK and served as a control group. The starting materials (the Ti, Li, Al, and P sources based on a molar ratio of n (Ti): n (Li): n (Al): n (P) of 1.7:1.3:0.3:3) were mixed with the solvent isopropyl alcohol by ball milling (MITR-YXQM-1L, Changsha Minqi Instrument Equipment Co., Ltd., Changsha, China) at 500 rpm for 7.5 h. The mixed powder was calcined at 450 °C for 5 h in air in a nabertherm muffle furnace (The Nabertherm Furnace World, Lilienthal, Germany) to evaporate the gas (e.g., NH 3 , CO 2 , and H 2 O) .…”

Synthesis and Sintering of Li1.3Al0.3Ti1.7(PO4)3@Li2O–2B2O3 Core–Shell Solid Electrolyte Powders Prepared via One‐Pot Spray Pyrolysis

“…[31][32][33][34] Therefore, numerous studies have been performed to minimize the sintering temperature of oxide-based solid electrolytes. [35][36][37][38][39][40][41][42][43] Sintering additives can be used to reduce the sintering temperature via liquid-phase sintering, which accelerates densification. Kwatek et al achieved an ionic conductivity of ≈1.9 Â 10 À4 S cm À1 at a sintering temperature of 800 °C by mixing Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 (LATP) synthesized using the solid-phase method and 10 wt% of 0.75Li 2 O•0.25B 2 O 3 synthesized using melt quenching.…”

Highly stable LiTa2PO8-based hybrid solid electrolytes via the in situ interfacial formation technique for solid-state lithium-metal batteries

“…[10][11][12] LTPO has a monoclinic crystal structure and belongs to the C2/c space group. [13][14][15] It is a quasi-two-dimensional conductor that displays a remarkably high level of ion conductivity along the c-axis and a fairly high level of conductivity along the b-axis. However, ion migration along the a-axis is characterized by sluggishness, as indicated by a diffusion rate that is one order of magnitude lower at all temperatures investigated.…”