(1. 遼寧工程技術(shù)大學(xué) 材料科學(xué)與工程學(xué)院，阜新 123000；
2. 東北師范大學(xué) 化學(xué)學(xué)院，長春 130024)
摘 要: 采用基于密度泛函理論的第一性原理平面波贗勢方法，計(jì)算鋰離子電池負(fù)極材料金屬Sn在嵌Li過程中形成LixSn合金(0≤x≤4.4)的形成能、嵌Li電位、晶體結(jié)構(gòu)、電子結(jié)構(gòu)和彈性性質(zhì)。結(jié)果表明：隨著嵌Li量的增加，LixSn合金的平均嵌Li電位逐漸降低，體積膨脹率呈現(xiàn)線性增大，費(fèi)米能態(tài)密度整體上呈現(xiàn)增大的趨勢，導(dǎo)電性增強(qiáng)。隨著嵌Li量的增加，LixSn合金中Sn—Li金屬鍵的離子性特征逐漸增強(qiáng)，導(dǎo)致體積模量(B)、剪切模量(G)和彈性模量(E)幾乎呈線性降低。G/B值表明，隨著嵌Li量的增加，LixSn合金由延性轉(zhuǎn)變?yōu)榇嘈裕瑢?dǎo)致LixSn合金容易發(fā)生脆性破壞。同時(shí)，采用電池程控測試儀測得金屬Sn的充放電曲線，發(fā)現(xiàn)理論計(jì)算的嵌Li電位與實(shí)驗(yàn)測得充放電電壓具有良好的一致性。
關(guān)鍵字: 鋰離子電池；Sn-Li合金；嵌鋰性能；彈性性質(zhì)；第一性原理
（1. College of Materials Science and Engineering, Liaoning Technical University, Fuxin 123000, China;
2. College of Chemistry, Northeast Normal University, Changchun 130024, China）
Abstract:The lithium insertion properties, including formation energy, average intercalation voltage, crystal structure, electronic structure and elastic properties of LixSn phase, for pure tin anode material for lithium ion battery were investigated by means of the first-principles plane-wave pseudopotentials method based on the density functional theory(DFT). The calculation results show that the average lithium intercalation potential of LixSn alloy decreases gradually with Li concentration increasing, the volume expansion rate increases linearly and the density of states at the Fermi level increases, indicating the improvement of electrical conductivity of LixSn phase. The ionic nature of Sn—Li metallic band for LixSn alloy enhances with Li concentration increasing, resulting in declining of bulk modulus (G), shear modulus (B) and elastic modulus (E). The G/B value shows that mechanical property of LixSn alloy changes from toughness to brittleness in high lithium concentration, suggesting that LixSn alloy suffer from brittle fracture. On the other hand, the charging-discharging curves of pure tin were measured by battery test instrument. The values of calculated Li intercalated potential obtained DFT calculations are well consistent with the experimental values.
Key words: lithium-ion battery; Sn-Li alloy; lithium insertion property; elastic property; first-principle
