LiMn_2O_4正极材料中锰的价态分析

Determination of Different Valence States of Manganese in Cathode Material LiMn_2O_4

研究了采用计算法测定锂离子电池正极材料LiMn2O4中锰的价态的方法及测定条件。用过硫酸铵将低价锰氧化成MnO-4,以硫酸亚铁铵作滴定剂测定锰的总含量;同样以硫酸亚铁铵作滴定剂测定Mn3+和Mn4+的含量;再用乙酰丙酮作络合剂,在Mn3+存在的条件,准确测定Mn4+的含量,通过计算得出其中Mn2+、Mn3+和Mn4+各自含量,并且研究了烧结温度与锰的价态变化关系。本法对锂离子电池正极材料LiMn2O4研制有一定的指导作用。

Optimum conditions for chemical calculation method for Determination of divalent, trivalent and tetravalent manganese in cathode material LiMn2O4 of lithiumion battery were studied in this paper. The total amount of manganese was determined by chemical conversion to permanganic radical using acidified ammonium persulfate, the determination of Mn4+ by the acetylacetoneiodometric method being carried out in the presence of Mn3+ without its interference, and the amount of the tetravalent and trivalent manganese being determined by dissolving the lithium manganese oxides in a known excess of ammonium iron sulfate in 1 mol?L-1 sulfuric acid and backtitrating the unreacted Fe2+ with standardized potassium dichromate. Based on the results obtained, the amount of bivalent manganese and average manganic valence could be calculated. The correlation of sintering temperatures and the average manganic valences was also reported, which is an important guide to the synthesis of cathode material LiMn2O4 of lithiumion battery.