Abstract
LiNi0.8Co0.1Mn0.1O2 cathodes suffer from severe bulk structural and interfacial degradation during battery operation. To address these issues, a three in one strategy using ZrB2 as the dopant is proposed for constructing a stable Ni‐rich cathode. In this strategy, Zr and B are doped into the bulk of LiNi0.8Co0.1Mn0.1O2, respectively, which is beneficial to stabilize the crystal structure and mitigate the microcracks. Meanwhile, during the high‐temperature calcination, some of the remaining Zr at the surface combined with the surface lithium source to form lithium zirconium coatings, which physically protect the surface and suppress the interfacial phase transition upon cycling. Thus, the 0.2 mol% ZrB2‐LiNi0.8Co0.1Mn0.1O2 cathode delivers a discharge capacity of 183.1 mAh g−1 after 100 cycles at 50 °C (1C, 3.0–4.3 V), with an outstanding capacity retention of 88.1%. The cycling stability improvement is more obvious when the cut‐off voltage increased to 4.4 V. Density functional theory confirms that the superior structural stability and excellent thermal stability are attributed to the higher exchange energy of Li/Ni exchange and the higher formation energy of oxygen vacancies by ZrB2 doping. The present work offers a three in one strategy to simultaneously stabilize the crystal structure and surface for the Ni‐rich cathode via a facile preparation process.
Highlights
Ni-rich ternary material, LiNi0.8Co0.1 Mn0.1O2 (NCM811), has attracted considerable attention as a promising cathode due to its high specific discharge capacity (>200 mAh g−1) and low cost, which is considered structure and mitigate the microcracks
Density functional theory confirms that the superior structural stability and excellent thermal stability are attributed to the higher exchange energy of Li/Ni exchange and the higher formation energy of oxygen vacancies by ZrB2 can be occurred accompanied by repeated Li+ insertion/extraction
The (104) peak shifts to the right slightly with increasing ZrB2 content in Figure 1c, while the (104) peak shifts to the left in the sample with only Zr doping according to the www.advancedscience.com previous report.[17]
Summary
Ni-rich ternary material, LiNi0.8Co0.1 Mn0.1O2 (NCM811), has attracted considerable attention as a promising cathode due to its high specific discharge capacity (>200 mAh g−1) and low cost, which is considered structure and mitigate the microcracks. Collector, leading to the loss of active materials and the electrochemical performance deterioration.[9] In response to these problems, many strategies have been proposed to improve the structural and interfacial stability of the electrode. Element doping has been proved to be one of the most effective strategies for mitigating the problems associated with irreversible transition.[10] Doping elements such as Al, Zr, Ti, Nd, Mo, B, and Mg have been reported.[11] Liu et al.[12] confirmed that the lattice expansion can be suppressed when substituting the TMs with Ti. Al has been widely studied in the ternary cathode material due to its superior stability. The as-prepared LiNi0.8Co0.1Mn0.1O2 cathode delivers much higher electrochemical properties at room and elevated temperature This electrode shows superior cycling stability at higher cut-off voltage to 4.4 V, by which higher energy density of LIBs could be achieved. The reasons why the treated sample exhibited superior electrochemical properties have been well explained by experimental characterizations and density functional theory (DFT) calculation
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