Fabrication and performances of high lithium-ion conducting solid electrolytes based on NASICON Li1.3Al0.3Ti1.7-xZrx(PO4)3 (0≤ x≤ 0.2)

Solid electrolytes are the key component in designing all-solid-state batteries. The Li_1.3Al_0.3Ti_1.7(PO₄)₃ (LATP) structure and its derivatives obtained by doping various elements at Ti and Al site acts as good solid electrolytes. However, there is still scope for enhancing the ionic conductivity using simple precursors and preparation methods. In this study, the Li superionic conductors Li_1.3Al_0.3Ti_1.7-xZr_x(PO₄)₃ (LATZP) with 0 ≤ x ≤ 0.2 have been successfully prepared by the solid-state reaction route. The structural, morphological, and ionic transport properties were analyzed using several experimental techniques including powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and impedance spectroscopy (IS). The presence of two relaxation processes corresponding to grain and grain boundary was studied using various formalisms. We have observed that grain effects dominate at lower temperatures (<100 °C) while the grain boundary at higher temperatures (> 200 °C) on ionic conductivity. The relaxation mechanisms of grain and grain boundaries were investigated by the Summerfield scaling of AC conductivity. The highest total ionic conductivity of 2.48 × 10^-4 S/cm at 150 °C and 5.50 × 10^-3 S/cm at 250 °C was obtained for x = 0.1 in Li_1.3Al_0.3Ti_1.6Zr_0.1(PO₄)₃ sintered at 950 °C/6 h in the air. The ionic conductivity value was found to be higher than the ionic conductivity reported for LATP prepared via solid-state reaction mechanism using the same precursors and conditions.     

Development of sodium hybrid quasi-solid electrolytes based on porous NASICON and ionic liquids

Lithium-ion batteries are currently the alternative of choice to overcome the increasing demand of energy. However, besides the scarcity of lithium and limited geolocation, it is believed that such batteries have already reached their maximum maturity. Sodium batteries emerge as an alternative to produce the new, so called, post-lithium batteries. In this study, we explore (i) the effect of sodium content and sintering temperature in solid electrolytes based in NASICON-type compounds and (ii) the use of two methodologies to obtain porous NASICON samples: application of natural substances and organic materials as pore-formers and freeze casting. The main purpose is the attainment of hybrid quasi-solid state electrolytes, with enhanced room temperature conductivity, based on porous ceramic electrolyte layers infiltrated with ionic liquids. Using this approach, porous samples with different microstructure and porous morphology and distribution were achieved, providing an enhancement in conductivity (ranging from 0.45 to 0.96 mS cm⁻¹ at 30 °C) of one order of magnitude for infiltrated samples respect to pore-free samples. According to these results the porous NASICON might be considered as a functional macroporous inorganic separator that can act as a Na⁺ reservoir.     

Solid-state potentiometric SO2 sensor combining NASICON with V2O5-doped TiO2 electrode

A compact tubular sensor based on NASICON (sodium super ionic conductor) and V₂O₅-doped TiO₂ sensing electrode was designed for the detection of SO₂. In order to reduce the size of the sensor, a thick-film of NASICON was formed on the outer surface of a small Al₂O₃ tube; furthermore, a thin layer of V₂O₅-doped TiO₂ with nanometer size was attached on the NASICON as a sensing electrode. This paper investigated the influence of V₂O₅ doping and sintering temperature on the characteristics of the sensor. The sensor attached with 5 wt% V₂O₅-doped TiO₂ sintered at 600 °C exhibited excellent sensing properties to 1–50 ppm SO₂ in air at 200–400 °C. The EMF value of the sensor was almost proportional to the logarithm of SO₂ concentration and the sensitivity (slope) was −78 mV/decade at 300 °C. It was also seen that the sensor showed a good selectivity to SO₂ against NO, NO₂, CH₄, CO, NH₃ and CO₂. Moreover, the sensor had speedy response kinetics to SO₂ too, the 90% response time to 50 ppm SO₂ was 10 s, and the recovery time was 35 s. On the basis of XPS analysis for the SO₂-adsorbed sensing electrode, a sensing mechanism involving the mixed potential at the sensing electrode was proposed.     

Na3Zr2Si2PO12固态电解质研究进展

钠离子电池具有资源丰富、能量密度高等优点,使用固态电解质的固态钠电池兼具高安全性成为研究热点。固态电解质是超离子导体,是固态电池关键材料。Na₃Zr₂Si₂PO₁₂是钠超离子导体（NASICON）中最具代表性的固态电解质材料。总结了Na₃Zr₂Si₂PO₁₂材料的结构、离子传输机制及其相互关系,旨在从机理上理解Na₃Zr₂Si₂PO₁₂固态电解质中钠离子传输性能;总结了主要制备方法,指出了不同方法的优缺点;在提升离子电导率方面,对合成工艺、掺杂、界面因素进行了总结,力求归纳和探索合成高性能钠离子固态电解质的途径。     

低功耗微型CO2传感器的研制

制作了一种新型微型结构CO2传感器,该传感器采用Al2O3陶瓷片作为衬底,sol-gel法制备的固体电解质NASICON(sodiumsuperionicconductor)材料为离子导电层,复合碳酸盐Li2CO3-BaCO3(摩尔比为1:1.5)为敏感电极。该传感器在CO2浓度为(500~5000)×10–6体积分数范围内表现出良好的敏感特性,灵敏度达到67.3mV/decade(毫伏/10×10–6体积分数),并且功耗由原来的1.08W降到0.72W。微型元件的响应恢复时间分别为20s和58s。     

NASICON基NO_2气体传感器

文中介绍了一种管式结构的固体电解质NO_2气体传感器.该传感器是用溶胶–凝胶法制备的NASICON(钠离子导体) 为导电层材料,利用化学沉淀法制备的NiO和贵金属Au作为敏感电极材料制得的.文中研究了不同敏感电极材料对气体传感器性能的影响.以NiO+Au 作为敏感电极材料的传感器具有较大的灵敏度,当工作温度在300 ℃时,对浓度为(5～200)×10-6的NO_2表现出了良好的气敏性能,传感器的灵敏度大于70 mV/decade.     

NASICON固体电解质气体传感器的研究进展

采用高温固相法、溶胶-凝胶法制备了NASICON固体电解质材料,并利用XRD、IR、Raman、SEM等现代分析手段对NASICON材料进行了分析表征,优选出NASICON材料制备的工艺条件.对制备不同检测气体所需的敏感电极材料组份及制备方法进行了比较系统的研究.并以NASICON为离子导电层,以BaCO3-Li_2CO_3、Na_2SO_4-Li_2SO_4等复合盐以及单一或复合金属氧化物为敏感电极材料,制作出了具有良好性能的CO_2、CO、SO_2、NO_2、H_2S、Cl_2、NH_3等分立器件和集成一体化的CO-C_7H_8(甲苯)、NH_3-C_7H_8两种双功能器件.     

Liquid‐phase sintering of highly Na+ ion conducting Na3Zr2Si2PO12 ceramics using Na3BO3 additive

Na₃Zr₂Si₂PO₁₂ (NASICON) is a promising material as a solid electrolyte for all‐solid‐state sodium batteries. Nevertheless, one challenge for the application of NASICON in batteries is their high sintering temperature above 1200°C, which can lead to volatilization of light elements and undesirable side reactions with electrode materials at such high temperatures. In this study, liquid‐phase sintering of NASICON with a Na₃BO₃ (NBO) additive was performed for the first time to lower the NASICON sintering temperature. A dense NASICON‐based ceramic was successfully obtained by sintering at 900°C with 4.8 wt% NBO. This liquid‐phase sintered NASICON ceramic exhibited high total conductivity of ~1 × 10^?3 S cm^?1 at room temperature and low conduction activation energy of 28 kJ mol^?1. Since the room‐temperature conductivity is identical to that of conventional high‐temperature‐sintered NASICON, NBO was demonstrated as a good liquid‐phase sintering additive for NASICON solid electrolyte. In the NASICON with 4.8 wt% NBO ceramic, most of the NASICON grains directly bonded with each other and some submicron sodium borates segregated in particulate form without full penetration to NASICON grain boundaries. This characteristic composite microstructure contributed to the high conductivity of the liquid‐phase sintered NASICON.     

Synthesis of Na ion-electron mixed conductor Na3Zr2Si2PO12 by doping with transition metal elements (Co,Fe, Ni)

NASICON solid electrolyte Na₃Zr₂Si₂PO₁₂ (NZSP) exhibits high chemical stability and can be utilized as cladding materials of cathodes to improve battery cycle stability. However, the electronic conductivity of NZSP is extremely low (∼10⁻⁹ S cm⁻¹), which will hinder the electron conduction of cathode materials. To address this issue, the electronic conductivity of NZSP is improved by doping with transition metal elements (Co, Fe, Ni). Co-doped NZSP has an electronic conductivity of 5.03 × 10⁻⁶ S cm⁻¹. On the other hand, the ionic conductivity of doped samples remains stable, even slightly increased. The mechanical properties of pristine and doped samples are characterized with a micro indenter, which is also a key parameter for coating materials.