Unsymmetrical fluorinated malonatoborate as an amphoteric additive for high-energy-density lithium-ion batteries†,Energy & Environmental Science

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Unsymmetrical fluorinated malonatoborate as an amphoteric additive for high-energy-density lithium-ion batteries†
Energy & Environmental Science ( IF 32.4 ) Pub Date : 2018-04-06 00:00:00 , DOI: 10.1039/c8ee00372f
Jung-Gu Han _{1,

2,

3,

4} , Jae Bin Lee _{1,

2,

3,

4} , Aming Cha _{1,

2,

3,

4} , Tae Kyung Lee _{1,

2,

3,

4} , Woongrae Cho _{1,

2,

3,

4} , Sujong Chae _{1,

2,

3,

4} , Seok Ju Kang _{1,

2,

3,

4} , Sang Kyu Kwak _{1,

2,

3,

4} , Jaephil Cho _{1,

2,

3,

4} , Sung You Hong _{1,

2,

3,

4} , Nam-Soon Choi _{1,

2,

3,

4}

Affiliation

High-capacity Si-embedded anodes and Li-rich cathodes are considered key compartments for post lithium-ion batteries with high energy densities. However, the significant volume changes of Si and the irreversible phase transformation of Li-rich cathodes prevent their practical application. Here we report lithium fluoromalonato(difluoro)borate (LiFMDFB) as an unusual dual-function additive to resolve these structural instability issues of the electrodes. This molecularly engineered borate additive protects the Li-rich cathode by generating a stable cathode electrolyte interphase (CEI) while simultaneously tuning the fluoroethylene carbonate (FEC)-oriented solid electrolyte interphase (SEI) on the Si–graphite composite (SGC) anode. The complementary electrolyte design utilizing both LiFMDFB and FEC exhibited an improved capacity retention of 85%, a high Coulombic efficiency of ∼99.5%, and an excellent energy density of ∼400 W h kg⁻¹ in Li-rich/SGC full cells at a practical mass loading after 100 cycles. This dual-function additive approach offers a way to develop electrolyte additives to build a more favorable SEI for high-capacity electrodes.

中文翻译：

非对称氟化丙二酸硼酸盐作为高能量密度锂离子电池的两性添加剂†

高容量嵌入硅的阳极和富锂阴极被认为是具有高能量密度的后锂离子电池的关键隔室。但是，Si的大量体积变化和富Li阴极不可逆的相变阻碍了它们的实际应用。在这里，我们报告氟代丙二酸二氟硼酸锂（LiFMDFB）作为一种不寻常的双功能添加剂来解决电极的这些结构不稳定性问题。这种分子工程的硼酸盐添加剂可通过生成稳定的阴极电解质中间相（CEI）并同时调节Si-石墨复合材料（SGC）阳极上的碳酸氟乙烯（FEC）取向的固体电解质中间相（SEI）来保护富锂阴极。同时使用LiFMDFB和FEC的互补电解质设计显示出了85％的改进的容量保持率，在100次循环后的实际质量负载下，在富含Li / SGC的全电池中为^-1。这种双重功能的添加剂方法提供了一种开发电解质添加剂的方法，以为大容量电极构建更有利的SEI。

更新日期：2018-04-06

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