Effects of rapid quenching on microstructures and electrochemical properties of La0.7Mg0.3Ni2.55Co0.45Bx（x=O-0.2） hydrogen storage alloy

In order to improve the electrochemical performances of La-Mg-Ni based electrode alloys with PuNi3-type structure, a trace of boron was added in La0.7Mg0.3Ni2.55Co0.45 alloy. The La0.7Mg0.3Ni2.55Co0.45Bx（a=0, 0.05, 0.1, 0.15 and 0.2） alloys were prepared by casting and rapid quenching. The electrochemical performances and microstructures of the as-cast and quenched alloys were investigated. The effects of rapid quenching on the microstructures and electrochemical performances of the above alloys were investigated. The results show that the as-cast and quenched alloys are composed of （La, Mg）Ni3 phase, LaNi5 phase and LaNi2 phase. A trace of the Ni2B phase exists in the as-cast alloys containing boron, and the Ni2B phase in the B-contained alloys nearly disappears after rapid quenching. Rapid quenching increases the amount of the LaNi2 phase in the B-free alloy, but it decreases the amount of the LaNi2 phase in the boron-containing alloys. The effects of rapid quenching on the capacities of the boron-containing and boron-free alloys are different. The capacity of the B-free alloy monotonously decreases with increasing quenching rate, whereas the capacities of the B-contained alloys have a maximum value with the change of the quenching rate. The rapid quenching can improve the stability of La-Mg-Ni based electrode alloy but lowers the discharge plateau voltage and decreases the plateau length. The effect of rapid quenching on the activation capabilities of the alloys was complicated.     

快淬工艺对La-Mg-Ni系贮氢合金微观结构及电化学性能的影响

用铸造及快淬工艺制备了La-Mg-Ni系（PuNi3型）贮氢合金La2Mg（Ni0．85Co0.15）9Bx（x=0，0．1，0．2），分析测试了铸态及快淬态合金的微观结构与电化学性能，研究了硼及快淬工艺对合金微观结构及电化学性能的影响。结果表明，铸态合金具有多相结构，主相包括（La，Mg）Ni3相（PuNi3型）和LaNi5相，残余相为一定量的LaNi2相和微量的Ni2B相，经快淬处理后Ni2B相消失，并且其它相的相对量随淬速的变化而变化。不含硼合金的容量随淬速的增加而单调减小，含硼合金的容量随淬速变化有一个极大值。合金的循环寿命随淬速的增加而增加，铸态及快淬态合金均有优良的活化性能。     

铸态及快淬态La2Mg（Ni0.85Co0.15）9Crx（x=0～0.2）电极合金的微观结构及电化学性能

为了提高La-Mg-Ni系（PuNi3）型贮氢合金的电化学循环稳定性,在La2Mg（Ni0.85Co0.15）9合金中加入微量Cr,用铸造及快淬工艺制备了La2Mg（Ni0.85Co0.15）9Crx（x=0,0.1,0.2）贮氢合金.分析测试了铸态及快淬态合金的电化学性能及微观结构,研究了Cr对铸态及快淬态合金微观结构及电化学性能的影响.结果表明,铸态及快淬态合金具有多相结构,包括（La,Mg）Ni3相（PuNi3结构））,LaNi5相和一定量的LaNi2相.快淬对合金的相组成没有影响,但使合金的相丰度产生变化.Cr的加入提高了铸态及快淬态合金的循环稳定性,但使合金的容量下降.合金的循环寿命随淬速的增加而增加,铸态及快淬态合金均有优良的活化性能.     

Effects of substituting Ni with M (M=Cu, Al and Mn) on microstructures and electrochemical characteristics of La-Mg-Ni system (PuNi3-type) electrode alloys

In order to improve the electrochemical cycle stability of La-Mg-Ni system (PuNi3-type) hydrogen storage alloy, Ni in the alloys was partially substituted by M (M=Cu, Al, Mn). A new La-Mg-Ni system electrode alloys La0.7Mg0.3Ni2.55-xCo0.45Mx (M=Cu, Al, Mn;x =0,0.1) were prepared by casting and rapid quenching. The effects of element substitution and rapid quenching on the microstructures and electrochemical performances of the alloys were investigated. The results by XRD, SEM and TEM show that the alloys havea multiphase structure, including the (La, Mg)Ni3 phase, the LaNi5 phase and the LaNi2 phase. The rapid quenching and element substitution have an imperceptible influence on the phase compositions of the alloys, but both change the phase abundance of the alloys. The rapid quenching significantly improves the composition homogeneity of the alloys and markedly decreases the grain size of the alloys. The Cu substitution promotes the formation of an amorphous phase in the as-quenched alloy, and a reversal result by the Al substitution. The electrochemical measurement indicates that the element substitution decreases the discharge capacity of the alloys, whereas it obviously improves the cycle stability of the alloys. The positive influence of element substitution on the cycle life of the alloys is in sequence Al＞Cu＞Mn, and negative influence on the discharge capacity is in sequence Al＞Mn＞Cu. The rapid quenching significantly enhances the cycle stability of the alloys, but it leads to a different extent decrease of thedischarge capacity of the alloys.     

快淬对La0.7Mg0.3Co0.45Ni2.55-xCux (x=0-0.4)电极合金微观结构及电化学性能的影响

应用铸造及快淬工艺制备了La0 7Mg0.3Co0.45Ni2.55-xCux (x=0, 0.1, 0.2, 0.3, 0.4)贮氢电极合金,研究了快淬工艺对合金微观结构及电化学性能的影响.XRD,SEM及TEM的分析结果表明,铸态及快淬态合金具有多相结构,包括(La,Mg)Ni3相,LaNi5相以及LaNi2相.快淬对合金的相组成没有明显影响,但显著地改变了合金的相丰度.快淬还显著地改善合金的成分均匀性,并使合金的晶粒明显细化.电化学测试的结果表明,快淬大幅度提高合金的电化学循环稳定性,但使合金的放电容量和活化性能下降.快淬对合金的放电电压特性具有明显的影响,当淬速大于15m/s时,快淬降低合金的放电电压,并使放电平台的斜率明显增大.     

Effects of rapid quenching on structure and electrochemical characteristics of La0.5Ce0.2Mg0.3Co0.4Ni2.6-xMnx （x=0-0.4） electrode alloys

The La-Mg-Ni system PuNi3-type La0.5Ce0.2Mg0.3Co0.4Ni2.6-xMnx (x=0, 0.1, 0.2, 0.3, 0.4) hydrogen storage alloys were prepared by casting and rapid quenching. The effects of the rapid quenching on the structure and electrochemical characteristics of the alloys were studied. The results obtained by XRD, SEM and TEM indicate that the as-cast and quenched alloys mainly consist of two major phases, (La,Mg)Ni3 and LaNi5, as well as a residual phase LaNi. The rapid quenching does not exert an obvious influence on the phase composition of the alloys, but it leads to an increase of the LaNi5 phase and a decrease of the (La, Mg)Ni3 phase. The as-quenched alloys have a nano-crystalline structure, and the grain sizes of the alloys are in the range of 20-30 nm. The results by the electrochemical measurements indicate that both the discharge capacity and the high rate discharge(HRD) ability of the alloy first increase and then decrease with the variety of quenching rate and obtain the maximum values at the special quenching rate which is changeable with the variety of Mn content. The rapid quenching significantly improves the cycle stabilities of the alloys, but it slightly impairs the activation capabilities of the alloys.     

La0.7Mg0.3Ni2.55-xCo0.45Alx(x=0～0.4)贮氢合金的循环稳定性

为了提高La-Mg-Ni系贮氢合金的循环稳定性,以Al部分替代Ni,采铸造及快淬工艺制备了La0.7Mg0.3Ni2.55-xCo0.45Alx(x=0,0.1,0.2,0.3,0.4)电极合金,研究了Al替代量及快淬工艺对合金微观结构及电化学循环稳定性的影响。X射线衍射分析结果表明:铸态及快淬态合金具有多相结构,包括(La,Mg)Ni3相、LaNi5相和一定量的LaNi2相;Al替代使铸态合金中LaNi2相的量显著增加,但对快淬态合金中LaNi2相的相丰度影响不显著。电化学测试结果表明:随Al替代量的增加,合金的循环寿命大幅度提高;快淬处理可以提高合金的循环寿命,但随Al替代量的增加,淬速对循环寿命的影响减小。     

快淬La—Mg—Ni系贮氢合金的电化学性能及微观结构

采用铸造及快淬工艺制备了La—Mg-Ni系（PuNi3型）贮氢合金La0.7Mg0.3Ni2.55-Co0.45Cux（x=0～0．4），分析测试了铸态及快淬态合金的电化学性能与微观结构，研究了Cu替代Ni及快淬工艺对合金微观结构及电化学性能的影响。结果表明：铸态及快淬态合金具有多相结构，包括（La，Mg）Ni3相和LaNi5相和一定量的LaNi2相。快淬处理对合金的相组成没有影响，但使合会的衍射峰趋于均匀一致。Cu替代Ni使合金的电化学容量下降，但使合金的循环稳定性及放电电压特性得到改善。快淬可提高合金的循环稳定性，但使合金的容量下降。     

Improved Cycle Stability of La0.75-xPrxMg0.25Ni3.2Co0.2Al0.1 (x=0-0.4) Electrode Alloys by Melt Spinning

为了改善 La-Mg-Ni 系 A2B7型电极合金的电化学循环稳定性,用 Pr 部分替代合金中的 La,并用熔体快淬工艺制备了La0.75-xPrxMg0.25Ni3.2Co0.2Al0.1(x = 0, 0.1, 0.2, 0.3, 0.4)电极合金。用 XRD、SEM、TEM 分析了铸态及快淬态合金的微观结构。结果表明,铸态及快淬态合金均具有多相结构,包括 2 个主相(La,Mg)Ni3及 LaNi5和 1 个残余相 LaNi2。熔体快淬导致 LaNi5相增加而(La,Mg)Ni3相减少。电化学测试结果表明,熔体快淬显著地提高合金的电化学循环稳定性。当淬速从 0 m/s (铸态被定义为淬速 0 m/s)增加到 20 m/s 时,x=0 合金 100 次充放循环后的容量保持率从 65.32%增加到 73.97%,x=0.4 合金的容量保持率从 79.36%增加到 93.08%。     

Cycle stability of La0.7Mg0.3Ni2.55-xCo0.45Cux （x=0-0.4） electrode alloys

La0.7Mg0.3Ni2.55-xCo0.45Cux（x=0, 0.1, 0.2, 0.3, 0.4） electrode alloys were prepared by casting and rapid quenching. Ni in the alloy was partially substituted by Cu in order to improve the cycle stability of La-Mg-Ni system （PuNi3-type） hydrogen storage alloy. The effects of substituting Ni with Cu on the microstructures and cycle stability of the alloys were investigated in detail. The results obtained by XRD, SEM and TEM show that the substitution of Cu for Ni is favourable for the formation of an amorphous in the as-quenched alloy, and this leads to an obvious refinement of the as-quenched alloy grains and a growth of the lattice constants and cell volumes of the as-cast and quenched alloys. The results obtained by the electrochemical measurement indicate that the cycle stability of the alloys significantly rises with the incremental variety of Cu content. When Cu content changes from 0 to 0.4, the cycle lives of the as-cast and quenched （30 m/s） alloys are enhanced from 72 to 88 cycles and from 100 to 121 cycles, respectively.     

Structures and electrochemical performances of La_(0.75-x)Zr_xMg_(0.25)Ni_(3.2)Co_(0.2)Al_(0.1) (x=0-0.2) electrode alloys prepared by melt spinning

The La-Mg-Ni system A2B7-type electrode alloys with nominal composition La0.75-xZrxMg0.25Ni3.2Co0.2Al0.1(x=0,0.05, 0.1,0.15,0.2)were prepared by casting and melt-spinning.The influences of melt spinning on the electrochemical performances as well as the structures of the alloys were investigated.The results obtained by XRD,SEM and TEM show that the as-cast and spun alloys have a multiphase structure,consisting of two main phases(La,Mg)Ni3 and LaNi5 as well as a residual phase LaNi2.The melt spinning leads to an obvious increase of the LaNi5 phase and a decrease of the(La,Mg)Ni3 phase in the alloys.The results of the electrochemical measurement indicate that the discharge capacity of the alloys(x≤0.1)first increases and then decreases with the increase of spinning rate,whereas for x0.1,the discharge capacity of the alloys monotonously falls.The melt spinning slightly impairs the activation capability of the alloys,but it significantly enhances the cycle stability of the alloys.     

快淬对La-Mg-Ni系A_2B_7型电极合金循环稳定性的影响

用熔体快淬工艺制备了La-Mg-Ni系A2B7型La0.75-xZrxMg0.25Ni3.2Co0.2Al0.1（x=0,0.05,0.1,0.15,0.2）电极合金。用XRD、SEM、TEM分析了铸态及快淬态合金的微观结构,用程控电池测试设备测试了铸态及快淬态合金电极的电化学循环稳定性,研究了快淬工艺对合金结构及电化学循环稳定性的影响,探讨了电极合金的失效机理。结果表明,快淬态合金均具有多相结构,包括两个主相（La,Mg）Ni3及LaNi5和一个残余相LaNi2。快淬处理可以显著改善合金的电化学循环稳定性。导致合金失效的主要原因是电极表面被电解液剧烈腐蚀以及合金电极在电化学循环过程中的粉化。     

Structure and electrochemical performance of hydrogen storage alloy La0.7Mg0.3Ni2.875Co0.525Mn0.1-boron composite

The structure and electrochemical characteristics of La0.7Mg0.3Ni2.875Co0.525Mn0.1-boron composite was studied systematically. The AB3 type hydrogen storage alloys La0.7Mg0.3Ni2.875Co0.525Mn0.1 were successfully synthesized by means of inter-media alloy La2Mg17 . The alloys were composited with boron at different weight rate. From the XRD analyses, each alloy of this series is mainly composed of (La,Mg)Ni3 phase and the LaNi5 phase, and the phase abundance of each phase varies with the boron weight rate, moreover, after composition, the c and cell volumes of (La,Mg)Ni3 phase increase, and the LaNi5 phase keep the same, which indicate that the boron may enter (La,Mg)Ni3 phase. The electrochemical studies show that the maximum discharge capacity of the composites decreases, but the cycling life improved. And the high rate discharge ability and exchange impendence spectroscopy (EIS) of the AB3 alloys and its composite were also studied.     

Zr替代La对快淬态A2B7型电极合金结构及电化学性能的影响

用铸造及快淬工艺制备了A2B7型电极合金,合金的名义成分为La0.75-xZrxMg0.25Ni3.2Co0.2Al0.1 (x = 0, 0.05, 0.1, 0.15, 0.2)。深入研究了Zr替代La对合金微观结构及电化学性能的影响。用XRD、SEM、TEM分析了合金的结构。结果表明,铸态及快淬态合金均具有多相结构,含有两个主相(La,Mg)Ni3和LaNi5以及一个残余相LaNi2。Zr替代La使合金中LaNi5相明显增加,并促进快淬态合金中形成非晶相。电化学测试的结果表明,Zr替代La明显降低合金的放电容量,但显著改善合金的电化学循环稳定性。当Zr含量小于0.1时,合金的放电容量随淬速的增加而先增加后减小,合金的循环稳定性随淬速的增加而单调增加。     

Effects of Rapid Quenching on Structure and Hydrogen Storage Characteristics of Mg20Ni10-xMnx (x=0-4) Alloys

为了改善Mg2Ni型合金的贮氢性能,用Mn部分替代合金中的Ni,并采用快淬工艺制备Mg20Ni10-xMnx(x=0, 1, 2, 3, 4)合金。用XRD和HRTEM分析了铸态及快淬合金的微观结构,用自动控制Sieverts设备测试合金的吸放氢动力学,并采用程控电池测试仪测试合金的电化学性能。结果表明,当淬速为20 m/s时,快淬(x=4)合金中出现非晶相,且非晶化程度随淬速的增加而增加。合金的吸放氢量及动力学性能随淬速的增加而增加。此外,快淬显著地改善了合金的电化学性能,包括放电容量及含Mn合金的循环稳定性。     

快淬对RE-Mg-Ni系A_2B_7型贮氢合金动力学性能的影响(英文)EI北大核心CSCD

合金的电化学贮氢动力学性能是其应用于动力电池的重要因素。为了提高RE-Mg-Ni系A2B7型贮氢合金的动力学性能,用M(M=Pr,Zr)部分替代La,并采用快淬处理制备了La0.65M0.1Mg0.25Ni3.2Co0.2Al0.1(M=Pr,Zr)电极合金。研究了元素替代和快淬处理对合金结构及电化学贮氢动力学性能的影响。XRD及TEM结果显示,铸态及快淬态合金均为多相结构,包含(La,Mg)2Ni7和LaNi5主相以及少量的残余相LaNi2。Pr替代快淬态合金为纳米晶结构,而Zr替代快淬态合金为类非晶结构,说明Zr部分替代La促进了非晶的形成。电化学测试表明合金的高倍率放电性能(HRD)随着快淬速度的增加先增大后减小。此外,电化学阻抗谱(EIS),塔菲尔极化曲线以及电势阶跃测试均表明合金的电化学动力学性能随着快淬速度的增加先增大后减小。     

添加Si对A_2B_7型电极合金结构及电化学贮氢性能的影响(英文)

为改善La–Mg–Ni系A2B7型合金的电化学贮氢性能,在合金中添加一定量的Si元素,通过真空熔炼及退火处理的方法制备La0.8Mg0.2Ni3.3Co0.2Six(x=0-0.2)电极合金。研究Si元素的添加对合金结构及电化学贮氢性能的影响。结果表明,铸态及退火态合金均为多相结构,分别为Ce2Ni7型的(La,Mg)2Ni7相和CaCu5型的LaNi5相以及少量的残余相LaNi3。Si元素的添加没有改变合金的主相,但使得合金中的(La,Mg)2Ni7相减少而LaNi5相增加。添加Si显著地影响了合金的电化学性能。随着Si含量的增加,铸态及退火态合金的放电容量逐步降低,但循环稳定性却随着Si含量的增加而增强。此外,合金电极的高倍率放电性能、极限电流密度、氢扩散系数以及电化学交流阻抗谱的测试均表明合金的电化学动力学性能随着Si含量的增加先增加而后减小。     

La0.67Mg0.33Ni3.0-xAlx（x=0.0-0.35）贮氢合金相结构和电化学性能研究

采用X射线衍射、电子探针和电化学测试研究了La0.67Mg0.33Ni3.0-xAlx（x=0.0-0.35）合金的相结构和电化学性能。XRD结果和EPMA观察表明：La0.67Mg0.33Ni3.0合金由LaNi3相和La2Ni7相组成。然而La0.67Mg0.33Ni3.0-xAlx（x=0．1，0．2，0．35）合金不含LaNi3相。研究结果表明Al替代Ni改变了La0．67Mg0．33Ni3.0合金的相结构，Al替代Ni不利于La0．67Mg0．33Ni3.0合金中LaNi3相的形成。此外，随Al含量的增加，La0.67Mg0.33Ni3.0-xAlx（x=0．1，0．2，0．35）合金的相结构也发生了变化。WDS分析表明：随La0.67Mg0.33Ni3.0-xAlx合金中X的增加，Al在LaNis相中的含量增加，但Al在LaNi2相的含量很少并且几乎不随X变化。电化学性能测试表明：Al替代Ni提高了La0.67Mg0.33Ni3.0合金电极的循环稳定性。但La0.67Mg0.33Ni3.0-xAlx合金电极的放电容量却随Al含量的增加而明显降低。     

Influences of the substitution of Fe for Ni on structures and electrochemical performances of the as-cast and quenched La0.7Mg0.3Co0.45Ni2.55−xFex (x = 0–0.4) electrode alloys

In order to improve the cycle stability of the La–Mg–Ni system PuNi₃-type hydrogen storage electrode alloys, Ni in the alloy was partially substituted by Fe. The La_0.7Mg_0.3Co_0.45Ni_2.55−xFe_x (x = 0, 0.1, 0.2, 0.3, 0.4) hydrogen storage alloys were prepared by casting and rapid quenching. The effects of the substitution of Fe for Ni on the structures and electrochemical performances of the as-cast and quenched alloys were investigated in detail. The results of the electrochemical measurement indicate that the substitution of Fe for Ni obviously decreases the discharge capacity, high rate discharge capability (HRD) and discharge potential of the as-cast and quenched alloys, but it significantly improves their cycle stabilities, and its positive impact on the cycle life of as-quenched alloy is much more significant than on that of the as-cast one. The microstructure of the alloys analyzed by XRD, SEM and TEM show that the as-cast and quenched alloys have a multiphase structure which is composed of two major phases (La, Mg)Ni₃ and LaNi₅ as well as a residual phase LaNi₂. The substitution of Fe for Ni helps the formation of a like amorphous structure in the as-quenched alloy. With the increase of Fe content, the grain sizes of the as-quenched alloys significantly reduce, and the lattice constants and cell volumes of the alloys obviously increase.     

Fe替代Ni对铸态及快淬态La0.7Mg0.3Co0.45Ni2.55-xFex (x = 0-0.4)电极合金循环稳定性的影响

用铸造及快淬工艺制备了La0.7Mg0.3Co0.45Ni2.55-xFex(x=0,0.2,0.3,0.4)电极合金,研究了Fe替代Ni对合金循环稳定性及微观结构的影响。结果表明,Fe替代Ni显著地改善合金的循环稳定性,且Fe替代Ni对快淬态合金的循环稳定性具有更加显著的作用。试验合金具有多相结构,包括2个主相(La,Mg)Ni3和LaNi5以及1个残余相LaNi2。Fe替代Ni促进快淬态合金形成类非晶结构,随Fe含量的增加,快淬态合金的晶粒显著细化,合金的晶格常数及晶胞体积显著增大。