Is it universal that the layered-spinel structure can improve electrochemical performance? |
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作者姓名: | Daqiang Wang Zhenguo Wu Wei Xiang Yuxia Liu Gongke Wang Kanghui Hu Qi Xu Yang Song Xiaodong Guo |
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作者单位: | College of Chemical Engineering;College of Materials and Chemistry&Chemical Engineering;The Key Laboratory of Life Organic Analysis;School of Materials Science and Engineering |
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基金项目: | supported by the National Natural Science Foundation of China (Grant Nos. U20A20145, 21805198, and 21878195);the Distinguished Young Foundation of Sichuan Province (No. 20JCQN0197);the Sichuan Science and Technology Project (No. 2019YFH0149);the Key R&D Project of Sichuan Provincial Department of Science and Technology (No. 2020YFG0471, No. 2020YFG0022);the Sichuan Province Science and Technology Achievement Transfer and Transformation Project (No 21ZHSF0111). |
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摘 要: | The introduction of spinel phase to form the layered-spinel structure(LSS)is an effective way to improve the electrochemical performance of Li-and Mn-rich layered oxides(LMR).But is this structure universal for all LMR systems?In this work,different Mn/Ni ratio systems with the LSS are discussed in detail.It is found that,high discharge capacity(200.8 mA h g-1 at 1C rate;1C=250 mA h g-1)as well as high capacity-retention(94%at 1C rate after 100 cycles)can be achieved by forming the LSS for low-Ni system(Mn/Ni=5.0).However,the capacity retention decreases severely in the high-Ni system(Mn/Ni=3.5,2.6).For example,when the ratio of Mn/Ni is 3.5,the capacity-retention of the layered-spinel sample was only 65.8%,compared to the 83%of the original LMR sample.The Ex-situ XRD,XPS,and HRTEM results demonstrate that the introduction of spinel phase in high-Ni system accelerates the transition and collapse of the crystal structure.This work provides guidance for optimizing the proportions of elements and the design of structures for the LMR.
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关 键 词: | Li-ion battery Li-and Mn-rich layered oxides Spinel phase Mn/Ni ratio |
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