NASICON-based H2 Sensor Using CoCrMnO4 Insensitive Reference Electrode and Buried Au Sensing Electrode

This work focuses on the H2 sensing performance of the sensor with buried Au sensing electrode and spi- nel-type oxide CoCrMnO4 insensitive reference electrode within sodium super ionic conductor（NASICON） film. The sensor showed the highest response to H2 gas on the insensitive material sintering at 800 ~C. Compared with those of the traditional structure device, the sensitivity and selectivity of the sensor using buried sensing electrode were greatly improved, giving a response of-177 mV in 9x10 5 g/L H2, which was about 3.5 times higher than that of sensors with traditional structure. Moreover, the AV value of the sensing device exhibited linear relationship to the logarithm of H2 concentration and the sensitivity（slope） was -135 mV/decade. A sensing mechanism related to the mixed potential was proposed for the present sensor.     

Sol-Gel法制备NASICON材料及表征

采用溶胶-凝胶(Sol-gel)法制得了固体电解质NASICON材料.用X射线衍射、红外光谱、拉曼光谱、核磁共振等方法对材料的结构、组成进行了分析,并对材料的电导率进行测量,证明材料具有快离子导电特性.通过对不同烧结温度下材料性质进行比较,发现900℃烧结温度下得到的材料具有更好的晶相结构和电导率.     

掺杂NASICON系统的23Na NMR研究

化合物Na3Zr2Si2PO12。是由ZrO6八面体与SiO4或PO4四面体共角构成的开放三维骨架结构，Na 位于骨架间隙，称之为NASICON（NaSuperIoaicConductor），具有和Na－Al2O3相似的离子电导率（在300℃时，σ＝0．2Ω－1·cm-1［1］但是由于该化合物在100－2000℃间存在单斜一、立方的可逆相变，使其应用受到限制．为了抑制这种相变，已进行了骨架掺杂的研究工作，制备出了多种化学掺杂的NASICON系统［2］．在Na3Zr2Si2PO12化合物中，三个Na十分别位于结构中两个不同的位置，然而掺杂以后，骨架结构发生变化，这时Na十位置，将关系…     

钠快离子导体Na1+xZr2-yTiySixP3-xO12系统研究(Ⅰ)

以Na_3PO_4、ZrP_2O_7、SiO_2、ZrO_2、TiO_2为反应原料,在1173K—1473K的高温下进行固相反应,制备了钠快离子导体Na_(1 x)Zr_(2-y)Ti_ySi_xP_(3-x)O_(12)系统中x=1、y=0—2.0的一系列合成物。研究了它们的相变关系;测定了两个单纯相—211相和202相的电导率和电导激活能。 室温时,211相的电导率σ_(RT)=1.52×10~(-4)(Ω·cm)~(-1),202相的σ_(TR)=0.53×10~(-4)(Ω·cm)~(-1);623K时,211相的电导率σ_(623)=1.21×10~(-1)(Ω·cm)~(-1),202相的σ_(623)=0.88×10~(-2)(Ω·cm)~(-1)。 在523K～673K温区里,211相的电导激活能E_a为31.87kJ/mole,202相的E_a为33.16kJ/mole。     

Development and Investigation of a NASICON‐Type High‐Voltage Cathode Material for High‐Power Sodium‐Ion Batteries

Herein, we introduce a 4.0 V class high‐voltage cathode material with a newly recognized sodium superionic conductor (NASICON)‐type structure with cubic symmetry (space group P2₁3), Na₃V(PO₃)₃N. We synthesize an N‐doped graphene oxide‐wrapped Na₃V(PO₃)₃N composite with a uniform carbon coating layer, which shows excellent rate performance and outstanding cycling stability. Its air/water stability and all‐climate performance were carefully investigated. A near‐zero volume change (ca. 0.40 %) was observed for the first time based on in situ synchrotron X‐ray diffraction, and the in situ X‐ray absorption spectra revealed the V^3.2+/V^4.2+ redox reaction with high reversibility. Its 3D sodium diffusion pathways were demonstrated with distinctive low energy barriers. Our results indicate that this high‐voltage NASICON‐type Na₃V(PO₃)₃N composite is a competitive cathode material for sodium‐ion batteries and will receive more attention and studies in the future.     

A High-Energy NASICON-Type Na3.2MnTi0.8V0.2(PO4)3 Cathode Material with Reversible 3.2-Electron Redox Reaction for Sodium-Ion Batteries

Na superionic conductor (NASICON) structured cathode materials with robust structural stability and large Na⁺ diffusion channels have aroused great interest in sodium-ion batteries (SIBs). However, most of NASICON-type cathode materials exhibit redox reaction of no more than three electrons per formula, which strictly limits capacity and energy density. Herein, a series of NASICON-type Na_3+xMnTi_1−xV_x(PO₄)₃ cathode materials are designed, which demonstrate not only a multi-electron reaction but also high voltage platform. With five redox couples from V^5+/4+ (≈4.1 V), Mn^4+/3+ (≈4.0 V), Mn^3+/2+ (≈3.6 V), V^4+/3+ (≈3.4 V), and Ti^4+/3+ (≈2.1 V), the optimized material, Na_3.2MnTi_0.8V_0.2(PO₄)₃, realizes a reversible 3.2-electron redox reaction, enabling a high discharge capacity (172.5 mAh g⁻¹) and an ultrahigh energy density (527.2 Wh kg⁻¹). This work sheds light on the rational construction of NASICON-type cathode materials with multi-electron redox reaction for high-energy SIBs.     

Development and Investigation of a NASICON-Type High-Voltage Cathode Material for High-Power Sodium-Ion Batteries

Herein, we introduce a 4.0 V class high-voltage cathode material with a newly recognized sodium superionic conductor (NASICON)-type structure with cubic symmetry (space group P2₁3), Na₃V(PO₃)₃N. We synthesize an N-doped graphene oxide-wrapped Na₃V(PO₃)₃N composite with a uniform carbon coating layer, which shows excellent rate performance and outstanding cycling stability. Its air/water stability and all-climate performance were carefully investigated. A near-zero volume change (ca. 0.40 %) was observed for the first time based on in situ synchrotron X-ray diffraction, and the in situ X-ray absorption spectra revealed the V^3.2+/V^4.2+ redox reaction with high reversibility. Its 3D sodium diffusion pathways were demonstrated with distinctive low energy barriers. Our results indicate that this high-voltage NASICON-type Na₃V(PO₃)₃N composite is a competitive cathode material for sodium-ion batteries and will receive more attention and studies in the future.     

Effect of substituting Ce for Zr on the electrical properties of NASICON materials

By investigation of the microstructure of cerium-doped NASICON materials prepared by solid state reaction, we find that variation in the cell parameters a, b and c can affect their activation energy (E_a) of ionic conductance. Furthermore, changes in the grain size and morphology can influence the pre-exponential factor σ₀. Analysis of the electrical conductivity of cerium-doped NASICON grains reveals a decrease from that for the undoped grains. These results suggest that when dealing with Ce-doped NASICON system, the grain size and morphology play a more important role in determining the bulk conductivity than the lattice parameters, at least within a temperature range of 225–350 °C.