Du Hongwei, Zhang Xianhui, Chen Zhenlian, Wu Dongyang, Zhang Zhifeng, Li Jun
Nano Science and Technology Institute, University of Science and Technology of China Suzhou 215123 China
Ningbo Institute of Material Technology & Engineering, Chinese Academy of Sciences Ningbo 315201 China.
RSC Adv. 2018 Jun 21;8(40):22813-22822. doi: 10.1039/c8ra02555j. eCollection 2018 Jun 19.
LiCoSiO has the potential for use as a high safety, high energy-density cathode material for lithium-ion batteries but suffers from bad electrochemical performance. Herein, we demonstrate a profound study on the effects of carbon coating and Al-doping on the electrochemistry of LiCoSiO synthesized by a two-step method. The synthesized 4 at% Al-doped LiCoSiO/C allows two lithium removals between 2.5 and 4.6 V, showing a first charge and discharge capacity of 331 and 140 mA h g, respectively, and a high capacity retention in cycling with no voltage degradation. The relationship between the improved performance and the supporting structural characteristics was studied by galvanostatic charge/discharge measurements and electrochemical impedance spectroscopy, coupled with material characterizations. This work demonstrates that electrical conductivity plays a central role in controlling the electrochemical performance of the modified LiCoSiO. Both the reversibility of delithiation and the irreversible capacity loss are strongly dependent on the electrical condition of the particles, which can be modified by Al-doping and carbon coating. The characteristics of carbon layers are analyzed because of their importance in improving the electrical properties and achieving a solution to the challenges with LiCoSiO. We that show LiCoSiO could have unique electrochemical characteristics that satisfy all the requirements of high safety, high energy density, and high compatibility with the current organic electrolytes if appropriately modified.
LiCoSiO有潜力用作锂离子电池的高安全性、高能量密度正极材料，但存在电化学性能不佳的问题。在此，我们对碳包覆和铝掺杂对两步法合成的LiCoSiO电化学性能的影响进行了深入研究。合成的4 at%铝掺杂LiCoSiO/C在2.5至4.6 V之间可实现两次锂脱除，首次充电和放电容量分别为331和140 mA h g，且循环过程中具有高容量保持率，无电压衰减。通过恒流充放电测量、电化学阻抗谱以及材料表征研究了性能改善与支撑结构特征之间的关系。这项工作表明，电导率在控制改性LiCoSiO的电化学性能中起着核心作用。脱锂的可逆性和不可逆容量损失都强烈依赖于颗粒的电学状态，而这可以通过铝掺杂和碳包覆来改变。由于碳层在改善电学性能以及解决LiCoSiO面临的挑战方面的重要性，对其特性进行了分析。我们表明，如果进行适当改性，LiCoSiO可能具有满足高安全性、高能量密度以及与当前有机电解质高兼容性所有要求的独特电化学特性。
