Homogeneous and Fast Ion Conduction of PEO‐Based Solid‐State Electrolyte at Low Temperature,Advanced Functional Materials

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Homogeneous and Fast Ion Conduction of PEO‐Based Solid‐State Electrolyte at Low Temperature
Advanced Functional Materials ( IF 18.5 ) Pub Date : 2020-09-16 , DOI: 10.1002/adfm.202007172
Shengjun Xu _{1,

2} , Zhenhua Sun _{1,

2} , Chengguo Sun ₁ , Fan Li _{3,

4} , Ke Chen _{1,

5} , Zhihao Zhang _{1,

2} , Guangjin Hou ₃ , Hui‐Ming Cheng _{1,

6} , Feng Li _{1,

2}

Affiliation

Poly(ethylene oxide) (PEO)‐based electrolytes are promising for all‐solid‐state batteries but can only be used above room temperature due to the high‐degree crystallization of PEO and the intimate affinity between ethylene oxide (EO) chains and lithium ions. Here, a homogeneous‐inspired design of PEO‐based solid‐state electrolytes with fast ion conduction is proposed. The homogeneous PEO‐based solid‐state electrolyte with an adjusted succinonitrile (SN) and PEO molar ratio simultaneously suppresses the PEO crystallization and mitigates the affinity between EO and Li⁺. By adjusting the molar ratio of SN to PEO (SN:EO ≈ 1:4), channels providing fast Li⁺ transport are formed within the homogeneous solid‐state polymer electrolyte, which increases the ionic conductivity by 100 times and enables their application at a low temperature (0–25 °C), together with the uniform lithium deposition. This modified PEO‐based electrolyte also enables a LiFePO₄ cathode to achieve a superior Coulombic efficiency (>99%) and have a long life (>750 cycles) at room temperature. Moreover, even at a low temperature of 0 °C, 82% of its room‐temperature capacity remains, demonstrating the great potential of this electrolyte for practical solid‐state lithium battery applications.

中文翻译：

低温下基于PEO的固态电解质的均质和快速离子导电

基于聚环氧乙烷（PEO）的电解质有望用于全固态电池，但由于PEO的高度结晶以及环氧乙烷（EO）链与锂之间的亲和力，因此只能在室温以上使用离子。在此，提出了一种基于PEO的具有快速离子传导性的固态电解质的均质设计。具有均一的丁二腈（SN）和PEO摩尔比调节的均质PEO基固态电解质同时抑制PEO结晶并减轻EO和Li ⁺之间的亲和力。通过调整SN与PEO的摩尔比（SN：EO≈1：4），通道可提供快速的Li ⁺在均匀的固态聚合物电解质中形成了电迁移，这使离子电导率提高了100倍，并使其能够在低温（0-25°C）下应用，并且锂沉积均匀。这种改性的基于PEO的电解质还使LiFePO ₄阴极在室温下能够实现优异的库仑效率（> 99％）并具有长寿命（> 750次循环）。此外，即使在0°C的低温下，其室温容量仍可保持82％，这表明这种电解质在固态锂电池的实际应用中具有巨大的潜力。

更新日期：2020-09-16

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