锂离子在石墨中的嵌入特性研究

Study on intercalation characteristics of lithium ion in graphite

研究了锂离子在人造石墨（ＡＧ）中的电化学嵌入特性和用它作负极材料时的电池性能。Ｌｉ－ＡＧ试验电池在ＬｉＡｓＦ６－ＥＣ＋ＤＥＣ电解液中充电时，依次形成Ｌｉ０．５Ｃ６和ＬｉＣ６两种化合物，这可由ＸＲＤ图谱及碳电极贮存期间电极电位的变化曲线获得证明。ＡＧ颗粒表面使用ＰＡＮ在１２００℃氮气中分解碳的包覆试验表明，这种无定形碳层可提高材料的放电率，降低自放电率。制成了额定容量为４００ｍＡｈ和５００ｍＡｈ的两种ＡＡ型ＡＧ－ＬｉＣｏＯ２电池；４００ｍＡｈ容量的电池以０．５Ｃ，１００％ＤＯＤ充放电寿命超过４００次，同样条件下。

Electrochemical intercalation characteristics of lithium ion in artificial graphite (AG) and the performances of AA size cell with it as the anode were studied in this paper.Both Li 0.5 C 6 and LiC 6 compounds were successively formed during charge process of AG electrode in Li AG cell using LiAsF 6 EC+DEC electrolyte,this result was proved by XRD patterns and the potential variation of AG electrode with storage time.The test results of encapsulation of AG particles showed that this amorphous carbon coating formed by PAN decomposition at 1200℃ in N 2 was able to improve both discharge and self discharge rates.AA size cell with 400mAh and 500mAh nominal capacity were fabricated with AG anodes and LiCoO 2 cathodes.The cyclic life of cells with 400mAh capacity at 0.5C rate and 100% DOD is more than 400 cycles and it is about 300 cycles for cells with 500mAh capacity at same conditions.