Abstract

Solid electrolytes have gained attention recently for the development of next-generation Li-ion batteries since they can fundamentally improve the battery stability and safety. Among various types of solid electrolytes, composite solid electrolytes (CSEs) exhibit both high ionic conductivity and excellent interfacial contact with the electrodes. Incorporating active nanofibers into the polymer matrix demonstrates an effective method to fabricate CSEs. However, current CSEs based on traditional poly(ethylene oxide) (PEO) polymer suffer from the poor ionic conductivity of PEO and agglomeration effect of inorganic fillers at high concentrations, which limit further improvements in Li⁺ conductivity and electrochemical stability. Herein, we synthesize a novel PEO based cross-linked polymer (CLP) as the polymer matrix with naturally amorphous structure and high room-temperature ionic conductivity of 2.40 × 10⁻⁴ S cm⁻¹. Li_0.3La_0.557TiO₃ (LLTO) nanofibers are incorporated into the CLP matrix to form composite solid electrolytes, achieving enhanced ionic conductivity without showing filler agglomeration. The high content of Li-conductive nanofibers improves the mechanical strength, ensures the conductive network, and increases the total Li⁺ conductivity to 3.31 × 10⁻⁴ S cm⁻¹. The all-solid-state Li|LiFePO4 batteries with LLTO nanofiber-incorporated CSEs are able to deliver attractive specific capacity of 147 mAh g⁻¹ at room temperature, and no evident dendrite is found at the anode/electrolyte interface after 100 cycles.

Graphic Abstract

A highly ionic-conductive 3-D fiber network composite solid electrolyte is introduced based on Li-ion conducting nanofibers and amorphous poly(ethylene oxide) (PEO) cross-linked polymer. With the reinforcement of Li_0.3La_0.557TiO₃ (LLTO) nanofibers, the continuous 3D conduction network formed within the polymer matrix greatly enhances the electrochemical and mechanical properties of resultant composite solid electrolytes. Consequently, the lithium dendrite is effectively controlled after long cycles, and the all-solid-state Li|LiFePO₄ prototype cells demonstrate excellent cycling stability at room temperature.

中文翻译：

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高性能锂离子导电纳米纤维和非晶态基于PEO的交联聚合物的3-D纤维网络复合电解质，用于全固态锂金属电池

摘要

固体电解质由于可以从根本上提高电池的稳定性和安全性，因此在下一代锂离子电池的开发方面已引起人们的关注。在各种类型的固体电解质中，复合固体电解质（CSE）既显示出高离子电导率，又显示出与电极的出色界面接触。将活性纳米纤维掺入聚合物基体证明了制造CSE的有效方法。但是，当前基于传统聚环氧乙烷（PEO）聚合物的CSE的缺点是PEO的离子电导率很低，并且无机填料在高浓度下会发生团聚作用，这限制了Li ^+的进一步改进。电导率和电化学稳定性。本文中，我们合成了一种新型的基于PEO的交联聚合物（CLP）作为具有天然非晶结构和2.40×10 ^-4  S cm ^-1的高室温离子电导率的聚合物基质。将Li _0.3 La _0.557 TiO ₃（LLTO）纳米纤维掺入CLP基质中以形成复合固体电解质，实现增强的离子电导率而不会出现填料团聚。高含量的锂导电纳米纤维可提高机械强度，确保导电网络，并将总锂⁺导电率提高至3.31×10 ^-4  S cm ^-1。掺有LLTO纳米纤维的CSE的全固态Li | LiFePO4电池在室温下可提供147 mAh g ^-1的有吸引力的比容量，并且在100次循环后在阳极/电解质界面上未发现明显的枝晶。

图形摘要

基于锂离子导电纳米纤维和非晶态聚环氧乙烷（PEO）交联聚合物，引入了高离子导电性的3-D纤维网络复合固体电解质。借助Li _0.3 La _0.557 TiO ₃（LLTO）纳米纤维的增强，在聚合物基体内形成的连续3D导电网络极大地增强了所得复合固体电解质的电化学和机械性能。因此，长周期后可有效控制锂枝晶，并且全固态Li | LiFePO ₄原型电池在室温下表现出出色的循环稳定性。