Investigating the Effects of Lithium Phosphorous Oxynitride Coating on Blended Solid Polymer Electrolytes
Investigating the Effects of Lithium Phosphorous Oxynitride Coating on Blended Solid Polymer Electrolytes
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DOI：
10.1021/acsami.0c09113
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发表时间：
2020-08
影响因子：
9.5
通讯作者：
Jed D. Lacoste;Zhifei Li;Yun Xu;Zizhou He;Drew C Matherne;A. Zakutayev;Ling Fei
中科院分区：
文献类型：
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作者：
Jed D. Lacoste;Zhifei Li;Yun Xu;Zizhou He;Drew C Matherne;A. Zakutayev;Ling Fei
固态电解质在提高锂离子电池安全性方面具有很大的应用前景。两类固体电解质，聚合物和陶瓷，可以组合以产生可以协同地联合收割机组合两种材料的性质的混合电解质。陶瓷电解质抵抗枝晶穿透的化学稳定性、热稳定性和高机械模量可以与聚合物电解质的柔性和易加工性相结合。通过用陶瓷电解质涂覆聚合物电解质，只要施加适当厚度的陶瓷电解质，预期固体电解质的稳定性相对于锂金属提高，并且离子电导率可以保持接近原始聚合物电解质的值。在这里，我们报告了双层锂离子导电混合固体电解质组成的混合聚合物电解质（BPE）涂覆有一层薄的无机固体电解质锂磷氮氧化物（LiPON）。对混合动力系统进行了深入研究。首先，我们研究了聚合物链长和锂盐比例对基于聚环氧乙烷（PEO）和聚碳酸亚丙酯（PPC）的BPE的离子电导率的影响，其中盐锂双（三氟甲磺酰基）酰亚胺（LiTFSI）。优化的BPE由100 k分子量PEO、50 k分子量PPC和25（w/w）% LiTFSI组成（表示为PEO 100 PPC 50 LiTFSI 25），其离子电导率为2.11 × 10-5 S/cm，并且由于PPC和LiTFSI对PEO微晶有很好的破坏作用，因此离子电导率没有表现出热记忆效应。第二，LiPON涂层对BPE的影响作为低至20 nm的厚度的函数进行评估。所得的双层结构显示出从5.2到5.5 V（相对于Li/Li+）的电压窗口和接近BPE的活化能的热活化能的增加，当使用较薄的LiPON层时，导致PEO 100 PPC 50 LiTFSI 25上的30 nm LiPON涂层的类似的离子电导率。研究表明，在BPE上涂覆一层薄薄的LiPON是提高锂长期稳定性的有效策略。
Solid-state electrolytes are very promising to enhance the safety of lithium-ion batteries. Two classes of solid electrolytes, polymer and ceramic, can be combined to yield a hybrid electrolyte that can synergistically combine the properties of both materials. Chemical stability, thermal stability, and high mechanical modulus of ceramic electrolytes against dendrite penetration can be combined with the flexibility and ease of processing of polymer electrolytes. By coating a polymer electrolyte with a ceramic electrolyte, the stability of the solid electrolyte is expected to improve against lithium metal, and the ionic conductivity could remain close to the value of the original polymer electrolyte, as long as an appropriate thickness of the ceramic electrolyte is applied. Here, we report a bilayered lithium-ion conducting hybrid solid electrolyte consisting of a blended polymer electrolyte (BPE) coated with a thin layer of the inorganic solid electrolyte lithium phosphorous oxynitride (LiPON). The hybrid system was thoroughly studied. First, we investigated the influence of the polymer chain length and lithium salt ratio on the ionic conductivity of the BPE based on poly(ethylene oxide) (PEO) and poly(propylene carbonate) (PPC) with the salt lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). The optimized BPE consisted of 100 k molecular weight PEO, 50 k molecular weight PPC, and 25(w/w)% LiTFSI, (denoted as PEO100PPC50LiTFSI25), which exhibited an ionic conductivity of 2.11 × 10–5 S/cm, and the ionic conductivity showed no thermal memory effects as the PEO crystallites were well disrupted by PPC and LiTFSI. Second, the effects of LiPON coating on the BPE were evaluated as a function of thickness down to 20 nm. The resulting bilayer structure showed an increase in the voltage window from 5.2 to 5.5 V (vs Li/Li+) and thermal activation energies that approached the activation energy of the BPE when thinner LiPON layers were used, resulting in similar ionic conductivities for 30 nm LiPON coatings on PEO100PPC50LiTFSI25. Coating BPEs with a thin layer of LiPON is shown to be an effective strategy to improve the long-term stability against lithium.