SURFACE MODIFICATION OF SPINEL LiMn{sub}2O{sub}4 CATHODE MATERIAL BY Li{sub}2O-2B{sub}2O{sub}3 GLASS IN LITHIUM-ION BATTERIES

摘要

Lithium borate glass, Li{sub}2O-2B{sub}2O{sub}3, coated on the surface of the lithium manganese oxide cathode material in Li-ion batteries was synthesized to achieve electrochemical cyclability and structural stability. The heat treatment temperature was evaluated according to TG/DTA analysis. The commercial cathode material powder km 110 coated under various weight percent of Li{sub}2O-B{sub}2O{sub}3 glass was calcined to form fine-coated powder of single spinel phase, exhibiting different particle size, size distribution and morphology. The km 110 powder coated with LBO glass was successfully obtained by solid-state method. The structure was confirmed by XRD along with the composition measured by EPMA and ICP-AES. From FESEM image and Laser Scattering measurements, the average particle size was 11 μm. The electrochemical behavior was examined by using two-electrode test cells consisted of a cathode, metallic lithium anode, and an electrolyte of 1M LiPFg in a 1:1 (volume ratio) mixture of EC/DMC. Cyclic charge/discharge testing of the coin cells, fabricated by both base km 110 and LBO-coated km 110 cathode material showed the capacity between 109 mAh/g and 95 mAh/g. Furthermore, the LBO-coated km 110 exhibited better cyclability than the base km 110 after 16 cycles test. The introduction of LBO-coated km 110 apparently decreased the decay rate after cyclic test.