Improved Cycling Stability and Fast Charge–Discharge Performance of Cobalt-Free Lithium-Rich Oxides by Magnesium-Doping

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• 作者：Ting-Feng Yi ; Yan-Mei Li ; Shuang-Yuan Yang ; Yan-Rong Zhu ; Ying Xie
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2016
• 出版时间：November 30, 2016
• 年：2016
• 卷：8
• 期：47
• 页码：32349-32359
• 全文大小：907K
• ISSN：1944-8252

文摘

Layered Li-rich, Co-free, and Mn-based cathode material, Li_1.17Ni_0.25–xMn_0.58Mg_xO₂ (0 ≤ x ≤ 0.05), was successfully synthesized by a coprecipitation method. All prepared samples have typical Li-rich layered structure, and Mg has been doped in the Li_1.17Ni_0.25Mn_0.58O₂ material successfully and homogeneously. The morphology and the grain size of all material are not changed by Mg doping. All materials have a estimated size of about 200 nm with a narrow particle size distribution. The electrochemical property results show that Li_1.17Ni_0.25–xMn_0.58Mg_xO₂ (x = 0.01 and 0.02) electrodes exhibit higher rate capability than that of the pristine one. Li_1.17Ni_0.25–xMn_0.58Mg_xO₂ (x = 0.02) indicates the largest reversible capacity of 148.3 mAh g^–1 and best cycling stability (capacity retention of 95.1%) after 100 cycles at 2C charge–discharge rate. Li_1.17Ni_0.25–xMn_0.58Mg_xO₂ (x = 0.02) also shows the largest discharge capacity of 149.2 mAh g^–1 discharged at 1C rate at elevated temperature (55 °C) after 50 cycles. The improved electrochemical performances may be attributed to the decreased polarization, reduced charge transfer resistance, enhanced the reversibility of Li⁺ ion insertion/extraction, and increased lithium ion diffusion coefficient. This promising result gives a new understanding for designing the structure and improving the electrochemical performance of Li-rich cathode materials for the next-generation lithium-ion battery with high rate cycling performance.