Thermodynamic and Quantum Chemical Investigation and its Material Design of Highly Functional Oxide

高功能氧化物的热力学和量子化学研究及其材料设计

• 批准号: 14550803
• 负责人: IDEMOTO Yasushi
• 金额: $ 1.54万
• 依托单位: Tokyo University of Science
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2002
• 资助国家: 日本
• 起止时间: 2002 至 2003
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-14550803/
• 关键词: Lithium Secondary Battery; Positive electrode material; Thermodynamic data; First-principles_calculation; Electronic structure; Structure analysis; Powder neutron diffraction; Charge-discharge cycle performance; 量子化学計算; 中性子回折; サイクル特性

We investigated the relation between thermodynamic stability, crystal structures, electronic states and electrode performance of LiMn_<2-x>M_xO_4(M=Al, Ni, Co, Cr, Zn, Mg)as cathode materials for lithium secondary batteries.The cycle performance is improved by substitution of Mn with M.The heat of dissolution of these samples was measured by the solution calorimetry method.The enthalpy change per mole of atoms for the formation reaction, ΔH_R, were calculated from the heat of dissolution.The larger |ΔH_R| means a thermodynamically more stable sample.A more thermodynamically stable sample makes a stable crystal structure and leads to a good cycle performance.The crystal structure was determined by Rietveld analysis using powder neutron diffraction.The electron density distribution was obtained by XRD using MEM/Rietveld method and DV-Xα method.The electronic density maps of LiMn_<2-x>M_xO_4 shows the covalent bonding of Mn-O of LiMn_<2-x>M_xO_4 is stronger than that of LiMn2O4.On the other hands, we calculated that the net charge of each atom, the bond overlap population of Li-O, Mn-O, M-O, the density of states, and the electron density of LiMn_<1.75>M_<0.25>O_4 using first principles calculation by DV-Xα method.Li ****y always keeps high and the covalent bonding of Mn-O in the octahedron of each LiMn_<1.75>M_<0.25>O_4 is stronger than that of LiMn_2O_4.****ver, we investigated the electronic states of Li_yMn_<2-x>M_xO_4 dependence of Li content.We calculated the electronic states of Li_yMn_<1.75>M_<0.25>O_4 by DV-Xα method.The net charge of each atom, and the bond overlap populations of Mn-O and M-O were calculated.The strong covalency between Mn and 0 existed in the Li defect model and Li_yMn_<2-x>M_xO_4.The bonding change in Mn-O is small and maintained the spinel structure during the charge-discharge process by substitution of Mn with M.From these results, the stability of the host structure is important for cycle performance.

研究了<2-x>锂二次电池正极材料LiMn_ M_xO_4（M=Al、Ni、Co、Cr、Zn、Mg）的热力学稳定性、晶体结构、电子状态与电极性能之间的关系。用M取代Mn可以改善循环性能。用溶液量热法测量了这些样品的溶解热。由溶解热计算出每摩尔原子的生成反应焓变Δ HR。较大的化合物具有较好的循环性能|ΔH_R| LiMn_ M_xO_4的电子密度图表明，LiMn_<2-x>M_xO_4的Mn-O共价键比LiMn_2O_4强。另一方面，LiMn_M_xO_4的Mn-O共价键<2-x>比LiMn_2O_4强。用DV-Xα方法计算了LiMn_ M_ O_4中各原子的净电荷、Li-O、Mn-O、M-O的键重叠布居数、态密度和电子密度，结果表明：LiMn_<1.75>M_<0.25>O_4中Li *y始终保持较高的值，八面体中Mn-O的共价键<1.75><0.25>比LiMn_2O_4中的强。用DV-Xα方法计算了Li_yMn_ M_xO_4的电子<2-x>态，计算了Li_yMn_<1.75>M_xO_4<0.25>中各原子的净电荷，Mn-O和M-O的键重叠布居，发现Li缺陷模型和Li_yMn_M_xO_4中Mn与O之间存在较强的共价性，Mn与O<2-x>之间的键变化较小，在充放电过程中Mn被M取代后仍保持尖晶石结构。主体结构的稳定性对于循环性能是重要的。

项目成果

井手本 康: "5V級Li二次電池用正極活物質LiMn_<1.5>Ni_<0.5>O_4の酸素量と電極特性"電気化学および工業物理化学. 70巻,8号. 587-589 (2002)

出本靖：“5V级Li二次电池正极活性物质LiMn_<1.5>Ni_<0.5>O_4的氧含量和电极性能”《电化学与工业物理化学》第70卷，第8期。587-589（2002）。

Y.Idemoto: "Dependence of Li content on Crystal Structure during the Charge-Discharge Process of LiMn_<1.5>Ni_<0.5>O_4 as a Cathode Materials for 5V Class Lithium Secondary Battery"Electrochemistry. Vol.71, No.12. 1142-1144 (2003)

Y.Idemoto：“作为5V级锂二次电池正极材料的LiMn_<1.5>Ni_<0.5>O_4充放电过程中Li含量对晶体结构的依赖性”电化学。

井手本 康: "Li-Mn-O系リチウム二次電池正極材料の熱力学的安定性と電極特性"熱測定. 30巻1号. 9-13 (2003)

Yasushi Idemoto：“Li-Mn-O基锂二次电池正极材料的热力学稳定性和电极性能”热测量，第30卷，第1.9-13期（2003年）。

伊藤 由賀: "実験および理論的手法によるLi二次電池用正極材料LiMn系酸化物の検討"表面. 41巻8号. 274-288 (2003)

Yuga Ito：“使用实验和理论方法研究 LiMn 基氧化物作为锂二次电池的正极材料”Surface，第 41 卷，第 8 期。274-288 (2003)。

Yasushi Idemoto: "Oxygen content and Electrode Characteristics of LiMn_<1.5>Ni_<0.5>O_4 as a 5V Class Cathode Material for Lithium Secondaly battery"Electrochemistry. Vol.70,No.8. 587-589 (2002)

Yasushi Idemoto：“LiMn_<1.5>Ni_<0.5>O_4作为5V级锂二次电池正极材料的氧含量和电极特性”电化学。