### 高倍率球形锂离子电池正极材料LiNi0.5Co0.2Mn0.3O2的制备及其电化学性能研究

1. a. 四川大学高分子研究所 成都 610065;
b. 四川大学化学工程学院 成都 610065;
c. 成都理工大学材料与化学化工学院 成都 610065
• 投稿日期:2016-11-10 发布日期:2017-04-25
• 通讯作者: 郭孝东 E-mail:xiaodong2009@scu.edu.cn
• 基金资助:

项目受国家自然科学基金（No.21506133）资助.

### Preparation and Electrochemical Performance of High Rate Spherical Layered LiNi0.5Co0.2Mn0.3O2 Cathode Material for Lithium-Ion Batteries

Zheng Zhuoa, Wu Zhenguob, Xiang Weic, Guo Xiaodongb

1. a. Polymer Research Institute, Sichuan University, Chengdu 610065;
b. School of Chemical Engineering, Sichuan University, Chengdu 610065;
c. College of Materials and Chemistry & Chemical Engineering, Chengdu University of Technology, Chengdu 610065
• Received:2016-11-10 Published:2017-04-25
• Contact: 10.6023/A16110594 E-mail:xiaodong2009@scu.edu.cn
• Supported by:

Project supported by the National Natural Science Foundation of China (No. 21506133).

Layered Ni-rich compound LiNi0.5Co0.2Mn0.3O2 has drawn considerable attention recently because high Ni content contributes to the improvement of specific capacity and the reduction of cost. However, it is a challenge to obtain the Ni-rich LiNi0.5Co0.2Mn0.3O2 cathode with both high rate performance and high tap density because the rate capability is often improved at the expense of volumetric energy density, which is mostly dependent on the tap density. In our work, an uniform Ni-rich LiNi0.5Co0.2Mn0.3O2 microsphere with an average diameter of ca. 5 μm and tap density of 2.1 g·cm-3 was successfully prepared using carbonate co-precipitation method, which can meet the commercial requirement for lithium-ion batteries (tap density≥2.1 g·cm-3, Lithium Nickel Cobalt Manganese Oxides from CETC International Co., Ltd). In this synthetic route, the 2 mol·L-1 mixture of NiSO4·6H2O, MnSO4·H2O and CoSO4·7H2O (Ni:Co:Mn=5:2:3, molar ratio) are the starting materials, 2 mol·L-1 Na2CO3 and 4 mol·L-1 NH3·H2O are the precipitant and chelating agent, respectively. In order to achieve high tap density, the stirring speed of continuous stirred tank reactor (CSTR) is as high as 1500 r/min, and the powder was preheated at 550 ℃ for 6 h and then calcined at 850 ℃ for 14 h in flowing oxygen. Powder X-ray diffraction (XRD) and transmission electron microscopy (TEM) results indicate that the microsphere LiNi0.5Co0.2Mn0.3O2 material has a well-ordered α-NaFeO2 structure with stable in-plane [√3×√3]R30° ordering in the transition-metal layers. Electrochemical results also confirm that this cathode has excellent cycling stability and high rate capability. Specifically, it exhibits a discharge capacity of 150 mAh·g-1 between 2.7 and 4.3 V at 1C after 100 cycles, with outstanding capacity retention of 94.6%. At 30C rate, it can still deliver a high discharge capacity of 96 mAh·g-1. Meanwhile, the energy storage capacity for this cathode is also encouraging. At 0.1C rate, the specific energy (Es) is 687.83 Wh·kg-1 (volumetric energy density is 1444.45 Wh·L-1); at 30C rate, the specific energy (Es) is 335.27 Wh·kg-1 (volumetric energy density is 704.07 Wh·L-1). These excellent features will make this microsphere LiNi0.5Co0.2Mn0.3O2 material as a potential positive electrode material for commercial high energy density lithium-ion batteries.