Reaction Mechanism of Metal Silicide Mg2Si for Li Insertion
Reaction Mechanism of Metal Silicide Mg2Si for Li Insertion
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DOI：
10.1006/jssc.2000.8787
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发表时间：
2000-09
影响因子：
5.4
通讯作者：
T. Moriga;Kozo Watanabe;D. Tsuji;Shinichi Massaki;I. Nakabayashi
中科院分区：
文献类型：
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作者：
T. Moriga;Kozo Watanabe;D. Tsuji;Shinichi Massaki;I. Nakabayashi
摘要对反萤石型Mg_2Si进行了电化学嵌锂，研究了嵌锂过程中结构的变化。发现锂嵌入Mg 2Si中按照以下反应逐步进行：Mg 2Si +2Li++2e−→ Li 2 MgSi +Mg，和Mg+yLi++ye−→LiyMg。Li 2 MgSi具有空间群为Fm-3 m的2aF ×2aF×2aF结构，其中aF表示基本萤石晶胞的晶格长度。DV-Xα计算结果表明，Li插入Mg_2Si八面体空位时，Mg ~（2+）的电荷补偿是通过引入电子到Mg ~（3+）轨道上而实现的，从而导致Mg ~（2+）离子的还原。因此，一半的Mg 2+离子从Mg 2Si中释放，Li+离子结合到缺失位点中以形成Li 2 MgSi。
Abstract Electrochemical Li insertion into the anti-fluorite-type Mg2Si was performed and the structural variation during the insertion was examined. It was found that lithium insertion into Mg2Si proceeds stepwise according to the following reactions: Mg2Si+2Li++2e−→Li2MgSi+Mg, and Mg+yLi++ye−→LiyMg. Li2MgSi has the 2aF×2aF×2aF structure with space group Fm-3m, where aF represents a lattice length of the fundamental fluorite unit cell. DV-Xα calculation showed that charge compensation in Mg2Si accompanied by the Li insertion into the vacant octahedral site occurs by indroduction of electrons into Mg3s orbitals, resulting in a reduction of Mg2+ ions. Thus, one-half of the Mg2+ ions discharge from Mg2Si and the Li+ ion is incorporated into the missing site to form Li2MgSi.