The extended cycle life of cells is often sacrificed at the expense of high specific energy for high-nickel materials.Cation doping is a promising method to build high-nickel cathode with high energy density and long ...The extended cycle life of cells is often sacrificed at the expense of high specific energy for high-nickel materials.Cation doping is a promising method to build high-nickel cathode with high energy density and long cycle life.Herein,a trace amount of Mg-B co-doping in LiNi_(0.6)Mn_(0.2)Co_(0.2)O_2(NMC622)is investigated in this work,which shows improved structural and electrochemical stability of 1%Mg-0.5%B co-doped material at both 30 and 55℃in coin-cell.Comprehensive chemical composition,structural,and surface analysis are carried out in this paper.It was found that all the selected materials have a similar composition to the target.Moreover,Mg and B doping have different effects on the crystal structural change of NMC622,to be more specific,the c-lattice parameter increases with Mg doping,while the Li^(+)/Ni^(2+)mixing content increases when B was incorporated into the lattice.Furthermore,the microstructure of primary particles was changed by B doping significantly as confirmed by the SEM images.There were marginal benefits in terms of structural and electrochemical stability of materials introduced by Mg or B sole doping.In comparison,incorporating a suitable amount of both Mg and B into NMC622,we found the capacity retention of cells was noticeably improved by reducing the impedance growth and preventing cation mixing during cycling.This study demonstrates the importance of co-incorporation of Mg,B,and optimizing the co-dopant content to stabilize NMC622 as cathode for lithium-ion batteries.展开更多
Amorphous A1MgB thin films were synthesized via a combinatorial sputtering approach. The properties of AIMgB films with the varying deposition temperature was investigated. The deposition temperature was found to domi...Amorphous A1MgB thin films were synthesized via a combinatorial sputtering approach. The properties of AIMgB films with the varying deposition temperature was investigated. The deposition temperature was found to dominate the hardness of the amorphous asdeposited film. The hardness increases with increasing deposition tempera ture and may even exceed that of crystalline A1MgB14 mate rial. The high hardness may be attributed to the existence of randomly distributed B 12 icosahedra structure. Therefore, the thin film that was deposited on cemented carbide shows well cutting performances in turning Ti alloy bar. At the same time, an appropriate method of pretreatment is the key to ensure the coating tool with the excellent adhesion by impact fracture test.展开更多
Al-Cu-Mn-Mg合金因其优异的综合性能,被广泛应用于航空航天和轨道交通等领域。然而,该合金在铸造过程中容易出现热裂缺陷,严重影响铸件的质量和可靠性。因此,提高合金的晶粒细化效果,对于改善合金的铸造性能具有重要意义。Al-Ti-B细化...Al-Cu-Mn-Mg合金因其优异的综合性能,被广泛应用于航空航天和轨道交通等领域。然而,该合金在铸造过程中容易出现热裂缺陷,严重影响铸件的质量和可靠性。因此,提高合金的晶粒细化效果,对于改善合金的铸造性能具有重要意义。Al-Ti-B细化剂是铝合金铸造中最常用的晶粒细化剂,但不同Ti/B质量比的Al-Ti-B细化剂对晶粒细化效果及热裂机制尚未系统研究。采用X射线衍射仪(XRD)、光学显微镜(OM)、扫描电镜(SEM)和CRC(constrained rod cast)金属型约束热裂棒模具等,分析了不同Ti/B质量比的Al-Ti-B细化剂对铸造Al-Cu-Mn-Mg合金微观组织和热裂倾向性的影响。实验结果表明,4种Ti/B比的Al-Ti-B细化剂中Al_3Ti和TiB_2相的含量存在显著差异。在B含量均为0.3%(质量分数)的条件下,添加Al-3Ti-1B、Al-4Ti-1B、Al-5Ti-1B和Al-5Ti-2B的Al-5Cu-0.7Mn-0.55Mg合金的平均晶粒尺寸分别为162.07、113.73、107.81和88.00μm,对应的热裂纹倾向性指数依次为112、136、96和24。微观机制分析表明,Ti B_(2)相的含量对晶粒细化效果和热裂倾向性具有显著影响。特别是Al-5Ti-2B细化剂,在晶粒细化的同时,显著降低了合金的热裂倾向性,展现出优异的性能。展开更多
基金financially supported by the National Natural Science Foundation of China(Project numbers.51834004,51774076,51704062)the Fundamental Research Funds for the Central Universities(N2025019)。
文摘The extended cycle life of cells is often sacrificed at the expense of high specific energy for high-nickel materials.Cation doping is a promising method to build high-nickel cathode with high energy density and long cycle life.Herein,a trace amount of Mg-B co-doping in LiNi_(0.6)Mn_(0.2)Co_(0.2)O_2(NMC622)is investigated in this work,which shows improved structural and electrochemical stability of 1%Mg-0.5%B co-doped material at both 30 and 55℃in coin-cell.Comprehensive chemical composition,structural,and surface analysis are carried out in this paper.It was found that all the selected materials have a similar composition to the target.Moreover,Mg and B doping have different effects on the crystal structural change of NMC622,to be more specific,the c-lattice parameter increases with Mg doping,while the Li^(+)/Ni^(2+)mixing content increases when B was incorporated into the lattice.Furthermore,the microstructure of primary particles was changed by B doping significantly as confirmed by the SEM images.There were marginal benefits in terms of structural and electrochemical stability of materials introduced by Mg or B sole doping.In comparison,incorporating a suitable amount of both Mg and B into NMC622,we found the capacity retention of cells was noticeably improved by reducing the impedance growth and preventing cation mixing during cycling.This study demonstrates the importance of co-incorporation of Mg,B,and optimizing the co-dopant content to stabilize NMC622 as cathode for lithium-ion batteries.
基金supported by the Fundamental Research Funds for the Central Universities(No.DUT10JN08)the Natural Science Foundation of Jiangsu Province(No.BK2011252)the Industry Science and Technology Supported Plan of Changzhou(No.CE20110012)
文摘Amorphous A1MgB thin films were synthesized via a combinatorial sputtering approach. The properties of AIMgB films with the varying deposition temperature was investigated. The deposition temperature was found to dominate the hardness of the amorphous asdeposited film. The hardness increases with increasing deposition tempera ture and may even exceed that of crystalline A1MgB14 mate rial. The high hardness may be attributed to the existence of randomly distributed B 12 icosahedra structure. Therefore, the thin film that was deposited on cemented carbide shows well cutting performances in turning Ti alloy bar. At the same time, an appropriate method of pretreatment is the key to ensure the coating tool with the excellent adhesion by impact fracture test.
文摘Al-Cu-Mn-Mg合金因其优异的综合性能,被广泛应用于航空航天和轨道交通等领域。然而,该合金在铸造过程中容易出现热裂缺陷,严重影响铸件的质量和可靠性。因此,提高合金的晶粒细化效果,对于改善合金的铸造性能具有重要意义。Al-Ti-B细化剂是铝合金铸造中最常用的晶粒细化剂,但不同Ti/B质量比的Al-Ti-B细化剂对晶粒细化效果及热裂机制尚未系统研究。采用X射线衍射仪(XRD)、光学显微镜(OM)、扫描电镜(SEM)和CRC(constrained rod cast)金属型约束热裂棒模具等,分析了不同Ti/B质量比的Al-Ti-B细化剂对铸造Al-Cu-Mn-Mg合金微观组织和热裂倾向性的影响。实验结果表明,4种Ti/B比的Al-Ti-B细化剂中Al_3Ti和TiB_2相的含量存在显著差异。在B含量均为0.3%(质量分数)的条件下,添加Al-3Ti-1B、Al-4Ti-1B、Al-5Ti-1B和Al-5Ti-2B的Al-5Cu-0.7Mn-0.55Mg合金的平均晶粒尺寸分别为162.07、113.73、107.81和88.00μm,对应的热裂纹倾向性指数依次为112、136、96和24。微观机制分析表明,Ti B_(2)相的含量对晶粒细化效果和热裂倾向性具有显著影响。特别是Al-5Ti-2B细化剂,在晶粒细化的同时,显著降低了合金的热裂倾向性,展现出优异的性能。
