采用共沉淀高温固相反应法合成锂离子电池正极材料LiNi_(0.8)Co_(0.1)Mn_(0.1)O_2(811),通过掺入Li、Mg和Al元素,并采用SEM、XRD、电化学测试,研究掺杂对材料晶体结构和电化学性能影响规律.实验结果表明:共沉淀过程中三价金属离子(Mn^(...采用共沉淀高温固相反应法合成锂离子电池正极材料LiNi_(0.8)Co_(0.1)Mn_(0.1)O_2(811),通过掺入Li、Mg和Al元素,并采用SEM、XRD、电化学测试,研究掺杂对材料晶体结构和电化学性能影响规律.实验结果表明:共沉淀过程中三价金属离子(Mn^(3+)、Al^(3+))出现会促使少量α-Ni(OH)2形成,而Li^+、Mg^(2+)和Al^(3+)均溶入晶格无杂相析出.高温融锂反应中,三种掺杂元素显著削弱Ni^(2+)出现数量,抑制Ni^(2+)混排进入Li^+格位,大幅提升811基体可逆容量;Mg^(2+)、Al^(3+)掺杂进一步增强基体晶格稳定性,改善其循环性能;Li^+-Al^(3+)共掺杂使之达到最佳:首次充电效率ICE超过90%,0.2C倍率下50次循环容量达195.8 m Ah/g、容量保持率为96.2%.展开更多
In this paper, in-situ coagulation of 0.9Al_2O_3–0.1TiO_2 suspension and microwave dielectric properties of 0.9Al_2O_3–0.1TiO_2 ceramics prepared by a novel direct coagulation casting via high valence counter ions(D...In this paper, in-situ coagulation of 0.9Al_2O_3–0.1TiO_2 suspension and microwave dielectric properties of 0.9Al_2O_3–0.1TiO_2 ceramics prepared by a novel direct coagulation casting via high valence counter ions(DCC-HVCI) method were proposed. The 0.9Al_2O_3–0.1TiO_2 suspension could be coagulated via controlled release of calcium ions from calcium iodate at an elevated temperature. The influence of tri-ammonium citrate(TAC) content, solid loading, and calcium iodate content on the rheological properties of the suspension was investigated. In addition, the influence of coagulation temperature on coagulation time and properties of green bodies was also studied. It was found that the stable 0.9Al_2O_3–0.1TiO_2 suspension could be successfully prepared by adding 0.3 wt% TAC and adjusting pH value to 10–12 at room temperature. 0.9Al_2O_3–0.1TiO_2 green bodies with uniform microstructures were coagulated by adding 8.0 g/L calcium iodate after treating at 70 ℃ for 1 h. 0.9Al_2O_3–0.1TiO_2 ceramics, sintered at 1500 ℃ for 4 h and annealed at 1100 ℃ for 5 h, showed uniform microstructures with density of 3.62±0.02 g/cm^3. The microwave dielectric properties of 0.9Al_2O_3–0.1TiO_2 ceramics prepared by DCC-HVCI method were: ε_r = 11.26±0.06, Q×f = 11569± 629 GHz, τ_t = 0.93±0.60 ppm/℃. The DCC-HVCI method is a novel and promising route without binder removal process to prepare complex-shaped microwave dielectric ceramics with uniform microstructures and good microwave dielectric properties.展开更多
文摘采用共沉淀高温固相反应法合成锂离子电池正极材料LiNi_(0.8)Co_(0.1)Mn_(0.1)O_2(811),通过掺入Li、Mg和Al元素,并采用SEM、XRD、电化学测试,研究掺杂对材料晶体结构和电化学性能影响规律.实验结果表明:共沉淀过程中三价金属离子(Mn^(3+)、Al^(3+))出现会促使少量α-Ni(OH)2形成,而Li^+、Mg^(2+)和Al^(3+)均溶入晶格无杂相析出.高温融锂反应中,三种掺杂元素显著削弱Ni^(2+)出现数量,抑制Ni^(2+)混排进入Li^+格位,大幅提升811基体可逆容量;Mg^(2+)、Al^(3+)掺杂进一步增强基体晶格稳定性,改善其循环性能;Li^+-Al^(3+)共掺杂使之达到最佳:首次充电效率ICE超过90%,0.2C倍率下50次循环容量达195.8 m Ah/g、容量保持率为96.2%.
基金supported by National Natural Science Foundation of China(No.51501066)China Postdoctoral Science Foundation(Nos.2015M572136,2017T100550,and 2016M602290)the Fundamental Research Funds for the Central University(No.2017JYCXJJ002)
文摘In this paper, in-situ coagulation of 0.9Al_2O_3–0.1TiO_2 suspension and microwave dielectric properties of 0.9Al_2O_3–0.1TiO_2 ceramics prepared by a novel direct coagulation casting via high valence counter ions(DCC-HVCI) method were proposed. The 0.9Al_2O_3–0.1TiO_2 suspension could be coagulated via controlled release of calcium ions from calcium iodate at an elevated temperature. The influence of tri-ammonium citrate(TAC) content, solid loading, and calcium iodate content on the rheological properties of the suspension was investigated. In addition, the influence of coagulation temperature on coagulation time and properties of green bodies was also studied. It was found that the stable 0.9Al_2O_3–0.1TiO_2 suspension could be successfully prepared by adding 0.3 wt% TAC and adjusting pH value to 10–12 at room temperature. 0.9Al_2O_3–0.1TiO_2 green bodies with uniform microstructures were coagulated by adding 8.0 g/L calcium iodate after treating at 70 ℃ for 1 h. 0.9Al_2O_3–0.1TiO_2 ceramics, sintered at 1500 ℃ for 4 h and annealed at 1100 ℃ for 5 h, showed uniform microstructures with density of 3.62±0.02 g/cm^3. The microwave dielectric properties of 0.9Al_2O_3–0.1TiO_2 ceramics prepared by DCC-HVCI method were: ε_r = 11.26±0.06, Q×f = 11569± 629 GHz, τ_t = 0.93±0.60 ppm/℃. The DCC-HVCI method is a novel and promising route without binder removal process to prepare complex-shaped microwave dielectric ceramics with uniform microstructures and good microwave dielectric properties.
