Sol-gel synthesis of LixNi0.8Co0.2O2 via an oxalate route and its electrochemical performance as an intercalation material for lithium batteries

LixNi1-yCoyO2 solid solutions have become more important and are being intensively investigated for possible commercial utilization as a cathode material for lithium batteries. The electrochemical performance of these materials greatly depends on the synthesis route. Here, we report the low temperature sol-gel synthesis of LixNi0.8Co0.2O2 (X = 1.0-1.15) using oxalic acid as a chelating agent. Solution-based synthesis of oxides has a number of advantages over conventional synthesis methods, but calcination time and temperature have always influenced electrochemical performance. We report their effects on the electrochemical performance of LiNi0.8Co0.2O2. The discharge capacity was 163 mAh g(-1) in the first cycle and 158 mAh g(-1) after 10 cycles under an optimal synthesis condition for 12 h at 800 degreesC. Li-7 MAS NMR studies were performed to characterize the excess lithium non-stoichiometric phases. Details of the synthesis and improved electrochemical properties are discussed. (C) 2002 Elsevier Science B.V. All rights reserved.