The study demonstrates unusual capabilities of phospho-olivine NaMnPO4 to intercalate lithium and sodium reversibly, which makes it attractive electrode material instead of the conventional lithium analogue LiMnPO4.
revealed the crystalstructure and lattice parameters of NaMPO4 (M = Mn, Co and Ni). For the first time, the crystalstructure parameters of the orthorhombic NaNiPO4 maricite-type phase were evaluated. Similarly, it was identified that the NaCoPO4 and NaMnPO4 have high temperature hexagonal and maricite phases, respectively. The calculated BET specific surface areas (SBET) of NaMnPO4, NaCoPO4 and NaNiPO4
以硝酸甘氨酸为前体,通过固溶燃烧合成(SCS)方法成功合成了金属钠盐NaMPO 4(M = Mn,Co和Ni)。XRD Rietveld精炼方法揭示了NaMPO 4的晶体结构和晶格参数(M = Mn,Co和Ni)。首次评估了斜方晶NaNiPO 4镁铁矿型相的晶体结构参数。类似地,已确定NaCoPO 4和NaMnPO 4分别具有高温六方相和马氏体相。计算出的NaMnPO 4,NaCoPO 4和NaNiPO 4的BET比表面积(S BET)分别为17.7、22.6和18.7 m 2 g -1。与1 M Na 2 SO 4,1 M NaNO 3和1 M NaCl相比,NaMPO 4(M = Mn,Co和Ni)电极在1 M NaOH电解质中显示出良好的比电容。基于电解质阴离子的影响在特定电容的这种差异进行了分析(CL -,SO 4 2-,OH -和NO 3 - )和电解质溶液的pH条件。总体而言,maricite-NaNiPO
Syntheses, crystal structures, optical, Raman spectroscopy, and magnetic properties of two polymorphs of NaMnPO4
Abstract The monophasic natrophilite form of NaMnPO4 was synthesized using a simple and scalable one-step hydrothermal method. The heat treatment of the natrophilite NaMnPO4 in the air resulted in the formation of the high-temperature maricite polymorph of NaMnPO4. The crystalstructures of these two polymorphs were confirmed by the Rietveld refinements and Raman spectroscopy. The DSC study of the
obtained at an optimized polyaniline (PANi) percentage of 30 wt%, where a specific capacitance of 201 F g−1 at 1 A g−1 current density was observed. This is more than twice the value obtained by pure NaMnPO4. The fabricated supercapacitors also deliver 26.5 W h kg−1 specific energy and high cycling stability.
提出了一种加入导电添加剂以提高基于 NaMnPO 4的钠离子超级电容器性能的新策略。据观察,与导电聚合物形成复合材料会导致基于钠离子的系统的比电容增加近两倍。更高的电导率、快速的法拉第响应以及更多的离子传输通道导致了这种改进。在此,最佳性能是在 30 wt% 的优化聚苯胺 (PANi) 百分比下获得的,其中观察到在 1 A g -1电流密度下的比电容为 201 F g -1 。这是纯 NaMnPO 4获得的值的两倍多。制造的超级电容器还提供 26.5 Wh kg -1 比能量和高循环稳定性。
Peculiarities of Phase Formation in Mn-Based Na SuperIonic Conductor (NaSICon) Systems: The Case of Na<sub>1+2<i>x</i></sub>Mn<sub><i>x</i></sub>Ti<sub>2–<i>x</i></sub>(PO<sub>4</sub>)<sub>3</sub> (0.0 ≤ <i>x</i> ≤ 1.5)
stoichiometric Na3MnTi(PO4)3 (x = 1.0) and NaTi2(PO4)3 for x < 1.0 or NaMnPO4 for x > 1.0. The theoretical predictions are corroborated by experiments obtained using X-ray diffraction and Raman spectroscopy on solid-state and sol–gel prepared samples. The results confirm that this system does not show a solid solution type behavior but phase-separates into thermodynamically more stable sodium ordered monoclinic
NAtrium SuperIonic CONductor (NASICON) 结构的磷酸盐骨架化合物作为“摇椅”型电池的合适电极材料引起了人们的极大兴趣。锰基电极材料由于其优异的稳定性、资源非关键性和高电极电势而成为最受欢迎的电极材料之一。尽管大部分研究致力于锂离子和钠离子电池的锰基氧化物,但对富锰聚阴离子的热力学和相形成的理解仍然普遍缺乏。在本研究中,我们研究了基于NASICON结构的Na 1+2 x Mn x Ti 2– x (PO 4 ) 3 (0.0 ≤ x ≤ 1.5)的双功能钠离子电池电极系统。为了分析热力学和相形成特性,我们使用密度泛函理论、簇展开和半正则蒙特卡罗方法的计算采样构建了成分-温度相图。结果表明该系统中可能的 Mn 浓度存在有限的热力学极限,这主要是由化学计量的 Na 3 MnTi(PO 4 ) 3 ( x = 1.0) 和 NaTi 2 (PO 4 ) 3 ( x