Influence of Salt Concentration on the Properties of Sodium‐Based Electrolytes,Small Methods

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Influence of Salt Concentration on the Properties of Sodium‐Based Electrolytes
Small Methods ( IF 10.7 ) Pub Date : 2018-08-27 , DOI: 10.1002/smtd.201800208
Chenxi Geng _{1,

2} , Daniel Buchholz _{1,

2} , Guk‐Tae Kim _{1,

2} , Diogo Vieira Carvalho _{1,

2} , Huang Zhang _{1,

2} , Luciana Gomes Chagas _{1,

2} , Stefano Passerini _{1,

2}

Affiliation

Electrolytes based on organic carbonates are widely used for sodium‐ion batteries (SIBs) due to several advantages such as high ionic conductivity, wide liquidus range, and high electrochemical stability. In this work, this class of electrolyte is investigated focusing on two conductive salts, namely NaPF₆ (sodium hexafluorophosphate) and NaTFSI (sodium bis(trifluoromethanesulfonyl)imide), using PC (propylene carbonate) as solvent. The investigation of different salt concentrations, from rather diluted to highly concentrated (i.e., 0.1, 1, and 3 m), extends from their glass transition temperature to viscosity, ionic conductivity, electrochemical stability window, and electrochemical stability toward Al. Raman spectroscopy discloses the salt–solvent coordination and its possible modification due to changes in temperature, proving that the viscosity played a major role in influencing ionic conductivity rather than ions and molecules' coordination. Finally, the electrochemical performance of half‐cells employing Na _x Ni_0.22Co_0.11Mn_0.66O₂ as the cathode material with the various electrolytes is also reported, and cells containing electrolyte with 1 m salt concentration outperform the other in terms of delivered capacity and rate performance.

中文翻译：

盐浓度对钠基电解质性能的影响

基于有机碳酸盐的电解质由于具有多种优势（例如高离子电导率，宽液相线范围和高电化学稳定性）而被广泛用于钠离子电池（SIB）。在这项工作中，使用PC（碳酸亚丙酯）作为溶剂，研究了这类电解质，重点研究了两种导电盐，即NaPF ₆（六氟磷酸钠）和NaTFSI（双（三氟甲磺酰基）酰亚胺钠）。研究不同盐浓度，从相当稀释到高度浓缩（即0.1、1和3 m），从其玻璃化转变温度延伸至粘度，离子电导率，电化学稳定性窗口和对Al的电化学稳定性。拉曼光谱法揭示了盐与溶剂的配位及其因温度变化而可能发生的变化，证明粘度在影响离子电导率而不是离子和分子配位方面起着主要作用。最后，还报道了使用Na _x Ni _0.22 Co _0.11 Mn _0.66 O ₂作为阴极材料和各种电解质的半电池的电化学性能，以及含1 m电解质的电池就输送能力和速率性能而言，盐浓度优于其他盐浓度。

更新日期：2018-08-27

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