The effect of relative permittivity of surface supporting materials for high-speed rechargeable LiCoO2 cathode film
The effect of relative permittivity of surface supporting materials for high-speed rechargeable LiCoO2 cathode film
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DOI：
10.1016/j.jpowsour.2019.227194
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发表时间：
2019-11
影响因子：
9.2
通讯作者：
S. Yasuhara;S. Yasui;T. Teranishi;Y. Yoshikawa;T. Taniyama;M. Itoh
中科院分区：
文献类型：
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作者：
S. Yasuhara;S. Yasui;T. Teranishi;Y. Yoshikawa;T. Taniyama;M. Itoh
我们以前报道过BaTiO 3（BTO）-LiCoO 2（LCO）-电解质三相界面（TPI）在C速率增强中发挥重要作用，然而，为什么这种支撑材料对高性能有效仍然未知。我们专注于支持材料的相对介电常数使用有限元方法计算和实验。计算结果表明，随着支撑材料相对介电常数的增加，TPI附近的电场增强。在实验上，我们分别以BTO和CeO 2为支撑材料，在LCO薄膜上制备了纳米点和微垫，以评价其电化学性能和SEI膜的形成机理。CeO 2和BTO纳米点的引入改善了LCO的高C倍率性能;然而，只有沉积在LCO上的BTO纳米点可以在100 C下工作。此外，虽然在CeO 2和BTO的非焊盘区域分别观察到10和300 nm的SEI，但TPI周围的SEI在CeO 2和BTO焊盘周围相当薄。这表明，锂离子在电解质和电极之间的运动可以加速取决于支撑材料的相对介电常数。CeO 2和BTO焊盘TPI附近的低SEI表明，Li+插入/从LCO脱嵌的主要反应可能在TPI区域周围占主导地位。
We previously reported that the BaTiO3(BTO)-LiCoO2(LCO)-electrolyte triple-phase interface (TPI) could play an important role in C-rate enhancement, however, why this supporting material is effective for high performance remains unknown. We focus on the relative permittivity of supporting materials using finite element method calculations and experiments. Calculations revealed that the electric field near the TPI was reinforced as the relative permittivity of supporting materials increased. Experimentally, we prepared nanodots and micropads deposited on LCO thin film using BTO and CeO2as supporting materials to evaluate electrochemical properties and SEI formation mechanisms, respectively. High C-rate performance was improved by the introduction of CeO2and BTO nanodots; however, only the BTO nanodots deposited on LCO could work at 100C. In addition, SEI around the TPI was quite thin around CeO2and BTO pads, although 10 and 300 nm SEI were observed at the non-pad area of CeO2and BTO, respectively. This indicated that the Li+motion between electrolyte and electrode could be accelerated depending on the relative permittivity of supporting materials. The low SEI around the TPI of both the CeO2and BTO pads suggested that the main reactions of Li+insertion/de-insertion into/from LCO might be dominant around the TPI area.