Cheng-Zhang Lu

Tartaric acid-assisted sol–gel synthesis of LiNi0.8Co0.2O2 and its electrochemical properties as a cathode material for lithium batteries

Abstract Polycrystalline, single phase LiNi 0.8 Co 0.2 O 2 was synthesized by a low temperature tartaric acid-assisted sol–gel method under various conditions. The advantages of low temperature solution-based synthesis have been exploited to produce LiNi 0.8 Co 0.2 O 2 by varying the synthesis time and temperature. Also, the effect of different lithium stoichiometry x in Li x Ni 0.8 Co 0.2 O 2 on the electrochemical performance was studied. In the present study, the optimum temperature and time were 800 °C and 12 h. The electrochemical performance of the synthesized material was promising with the first discharge capacity of 174 mAh/g and 165 mAh/g after 10 cycles with a 100% cycling efficiency in the 10th cycle. The synthesis of LiNi 0.8 Co 0.2 O 2 and its improved electrochemical properties have been discussed in detail.

Improved electrochemical properties of Sr2+-doped LiNi0.8Co0.2O2 synthesized via a sol-gel route using tartaric acid as a chelating agent

Single-phase undoped LiNi0.8Co0.2O2 and Sr2+-doped LiNi0.8Co0.2O2 were synthesized by a low temperature tartaric acid assisted sol-gel method. Small quantities of Sr2+ were used as dopants in order to improve the electrochemical characteristics, especially the capacity and cycling performance of LiNi0.8Co0.2O2. The electrochemical performance of the undoped material was promising with a first discharge capacity of 174 mAh/g and 165 mAh/g after 10 cycles with a 100% cycling efficiency in the tenth cycle. Addition of Sr2+ for Li in minimum quantities with the Sr2+/Li+ dopant mole ratio ranging from 10−4 to 10−8 resulted in improved electrochemical properties for dopant mole ratio of 10−6. The first discharge capacity was 182 mAh/g and the tenth was 174 mAh/g at the 10th discharge. The synthesis of Sr2+-doped LiNi0.8Co0.2O2 and its improved electrochemical properties have been discussed for the first time. The improved electrochemical properties of Sr2+-doped LiNi0.8Co0.2O2 system are explained based on defect models.