以Na_2CO_3、(CH_3CO_2)2Mn·4H_2O、Y_2O_3和CH_3COOLi·2H_2O为原料,采用高温固相法经过2次灼烧和水热离子交换法得到一系列钇掺杂的LiMn_(1-x)Y_xO_2(x:0.01,0.02,0.03,0.05)化合物.通过XRD、XPS、循环伏安及恒电流充放电测试技术,研究了钇掺杂离子对合成正极材料结构及电化学性能的影响.结果表明,所得产物均具有单斜层状结构.合适的钇掺杂可以起到扩展锂离子脱嵌通道和稳定骨架结构的作用,钇离子的引入部分取代原有的三价锰离子,由于钇离子的离子半径较三价锰离子大,因此稀土掺杂锰酸锂材料的晶胞参数比未掺杂材料大,在一定程度上扩充了锂离子迁移的三维通道,更有利于锂离子的嵌入与脱嵌,提高单斜层状LiMnO_2材料的电化学循环可逆性及循环稳定性.通过对所得化合物进行了钇掺杂量及电化学性能的研究,得到性能比较优良的LiY_(0.021)Mn_(0.979)O_2化合物,其首次放电比容量为125.7 mA·h/g,100次循环以后,放电比容量达212.1 mA·h/g,远高于未掺杂材料的放电容量138 mA·h/g.交流阻抗测试结果表明,Y~(3+)的掺入能降低材料的电化学反应阻抗和提高材料中Li~+的扩散能力.
A series of yttrium(Ⅲ) ion doped layered lithium manganese oxides LiY_xMn_(1-x)O_2(x:0.01, 0.02, 0.03 and 0.05) compounds was synthesized with Na_2CO_3, (CH_3COO)_2 Mn·4H_2O, CH_3COOLi·2H_2O and Y_2O_3 as the starting materials by means of two-step high temperautre solid state reaction and hydrothermal ion exchange method. The Y~(3+) -doping effect on the structure and the electrochemical performances of the samples were investigated by XRD, XPS, cyclic voltammetry and charge-discharge tests. The XRD results show that the samples exhibit the same phase as pure monoclinic layered sturcture. Electrochemical performances indicate that the yttrium ions can partially replace Mn~(3+) in monoclinic structure LiMnO_2 materials. Because the radius of Y~(3+) is bigger than that of Mn~(3+) , samples doped with yittrium elements have larger lattice constant compared with that of undoped sample. Doping enables lithium ions to transport more freely in the three dimensional pathway, and all yittrium element doped materials show good cycle stability. Experiments of doping ratio and electrochemistry performance were carried out. The compound LiY_(0.021)Mn_(0.979)O_2 obtained exhibited a better performance whose initial discharge specific capacity reached 123.4 mA·h/g respectively. After 100 cycles, the discharge capacity maintained 212.1 mA·h/g, which is much higher than the discharge capacity 138 mA·h/g of the undoped monoclinic structure LiMnO_2 materials. AC analysis shows lower electrochemical impedance and the diffusibility of lithium ions is clearly improved due to Y~(3+) doping.
参考文献
| [1] | Armstrong A R,Bruce P G.Natrue[J],1996,381:197 |
| [2] | Capitare F,Gravereall P,Delmas C.Solid State Ionics[J],1996,89:197 |
| [3] | Tabuchi M,Ado K,Kobayashi H,Kageyama H.J Electrochem Soc[J],1998,145(4):L49 |
| [4] | Chiang Y M,Wang H F,Jang Y-II.Chem Mater[J],2001,13:53 |
| [5] | Choi J,Taackery M M.J Electrochem Soc[J],1999,146(10):59 |
| [6] | Zhong H,Xu H,Zhou Y F.J Inorg Chem[J],2004,20:261 |
| [7] | Li D C,Takahisa M T,Hideyuki N C.J Power Sources[J],2004,135:262 |
| [8] | Komaba S,Yoshii K,Ogata A,Nakai I.Electrochim Acta[J],2009,54(8):2 353 |
| [9] | Patoux S,Doeff M M.Electrochem Commun[J],2004,6:767 |
| [10] | Na S H,Kim H S,Seong M I.Solid State Ionics[J],2005,176:313 |
| [11] | Velikokhatnyi O I,Choi D,Kumta P N.Mater Sci Eng[J],2006,B128:115 |
| [12] | Su Z,Ye S H,Yan T Y,Gao X P,Shen P W.J Electrochem Soc[J],2008,155:A839 |
| [13] | Dou Z H,Zhang T A,Hou C.J Rare Earth[J],2004,22(5):644 |
| [14] | Ghosh P,Mahanty S,Basu R N.Electrochim Acta[J],2009,54(5):1 654 |
| [15] | Xie Y T,Xu Y B,Yan L,Yang Z Y,Yang R D.Solid State Ionics[J],2005,176:2 563 |
| [16] | Amatucci G G,Badway F,Singhal A.J Electrochem Soc[J],2001,148(8):A940 |
| [17] | Liu H W,Zhang K L.Mater Lett[J],2004,28(24):3 049 |
| [18] | Thirunakaran R,Sivashanmugam A,Gopukumar S,Rajalakshmi R.J Power Sources[J],2009,187:565 |
| [19] | Huang Z F,Zhang H Z,Wang D P,Meng X,Ming X,Chen G.Solid State Sci[J],2009,11(1):271 |
| [20] | Liu H Y,Deng G Q,Guo Y L.J Rare Earths[J],2008,26:722 |
| [21] | Singhal R,Das S R,Tomar M S,Ovideo O,Nieto S,Melgarejo R E,Katiyar R S.J Power Sources[J],2007,164(2):857 |
| [22] | Chitrakar R,Kanoh H,Kim Y S,Miyai Y,Ooi K.J Solid State Chem[J],2001,160:69 |
| [23] | Horn Y S,Hackney S A,Armstrong A R.J Electrochem Soc[J],1999,146(7):2 404 |
| [24] | Ceder G,Mishra S K.Electrochem Solid State Lett[J],1999,2(11):550 |
| [25] | Bacj S,Pereira J P,Willmann P.Electrochim Acta[J],2006,52:504 |
| [26] | Bard A J,Faulkner L R.Electrochemical Methode:Fundamentals and Application[M],2nd.New York,John Wiley and Sons INC.,2001:368 |
| [27] | Tan B J,Klabunde K J,Sherwood P M A.J Am Chem Soc[J]1991,113:855 |
| [28] | Ingo G M,Parazzo E,Bagnarelli O,Zaccnetti N.Surf Interface Anal[J],1990,16:515 |
| [29] | Vasquez R P,Foote M L,Hunt B D.J Appl Phys[J],1989,66:4 867 |
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