Effect of the Sintering Agent, B[sub 2]O[sub 3], on Li[Ni[sub x]Co[sub 1−2x]Mn[sub x]]O[sub 2] Materials

Li [ Ni x Co 1 − 2 x Mn x ] O 2 electrode materials prepared at 900°C show good performance and are less reactive with electrolyte at elevated temperatures than LiCoO 2 when charged to 4.2 V ( vs. Li) and above. However, the tap density and the resulting electrode density of samples reported previously are lower than required for some industrial applications in Li-ion batteries. One way to increase the density while preserving a 900°C heating temperature is to use a sintering agent. A few weight percent of B 2 O 3 was added during the synthesis of Li [ Ni x Co 1 − 2 x Mn x ] O 2 as a sintering agent. The preparation, structure, morphology, density, and electrochemical behavior of the resulting materials, for several compositions, including x = 0 ( i.e. , LiCoO 2 ) , are presented as a function of B 2 O 3 content. We found that denser Li [ Ni x Co 1 − 2 x Mn x ] O 2 ( x > 0 ) could be obtained using B 2 O 3 as a sintering agent. The presence of a lithium borate impurity in LiCoO 2 samples and an increase in the amount of Ni in the Li layer for Li [ Ni x Co 1 − 2 x Mn x ] O 2 with x > 0 are induced by B 2 O 3 additions. For x = 0.1 , and for up to 1 wt % added B 2 O 3 , the electrochemical behavior remains quite good while the sintering significantly improves the density of the powder.