LiNi_(0.05)Mn_(1.95)O_4的合成及其对Li^+的离子交换热力学  

Synthesis of LiNi_(0.05)Mn_(1.95)O_4 and Its Ion-Exchange Thermodynamics for Li^+

作　　者：董殿权[1] 刘维娜[1] 刘亦凡[1] 

机构地区：[1]青岛科技大学化工学院,山东青岛266042

出　　处：《物理化学学报》2009年第7期1279-1284,共6页Acta Physico-Chimica Sinica

基　　金：国家自然科学基金(29376245);山东省中青年科学家科研奖励基金(博士基金;2008BS09004);青岛科技大学科研启动基金(0022322)资助项目~~

摘　　要：以乙酸锂、乙酸锰和乙酸镍为原料,采用溶胶-凝胶法合成出掺镍的尖晶石型锂锰氧化物LiNi0.05Mn1.95O4.用0.5mol·L-1的过硫酸铵对其进行酸改性后制得锂离子筛(记作LiNiMn-H).经测定LiNi0.05Mn1.95O4在酸改性过程中Mn2+的溶出率仅为0.31%(w,质量分数),LiNiMn-H对锂离子的饱和交换容量达5.29mmol(36.72mg)Li+/g离子筛.测定了15、25、35、45℃LiNiMn-H在H+-Li+体系吸附锂的离子交换等温线,并利用Pitzer电解质溶液理论计算出该离子交换体系的活度系数,得到H+-Li+交换的平衡常数Ka,△Gm、△Hm和△Sm等热力学参数.结果表明,Ka随温度的升高而降低,LiNiMn-H对Li+的选择性大于原来可交换阳离子(H+)的选择性,吸附锂的过程是自发过程(△Gm<0),该离子交换反应是放热反应.A spinel lithium manganese oxide doped with nickel （LiNi0.05Mn1.95O4） was prepared by a sol-gel method using acetic lithium, nickel and manganese as raw materials. The lithium ion-sieve （denoted as LiNiMn-H） was obtained by acidification of the obtained LiNi0.05Mn1.9504 with 0.5 mol·L-1 （NH4）2S2O4. After testing, we found that the dissolution ratio of Mn2＋ from LiNi0.05Mn1.95O4 during the acid-modification process was only 0.31% （w, mass fraction） and the saturation ion-exchange capacity of LiNiMn-H for Li＋ was 5.29 mmol （36.72 mg） Li＋/g ion-sieve. The exchange isothermal curves of LiNiMn-H in the H＋-Li＋ system were measured at 15, 25, 35 and 45℃ and the average activity coefficients of the electrolyte were calculated using Pitzer electrolyte solution theory. Other thermodynamic constants, such as the equilibrium constantsKa,△Gm、△Hm and △Sm, were calculated during the exchange process. We conclude that the equilibrium constants reduce with the increase in temperature and that the selectivity of LiNiMn-H for Li＋ is higher than the original ion H＋. The exchange process is exothermic and the adsorption process occurs spontaneously （△Gm〈0）.

关 键 词：LiNi0.05Mn1.95O4 锂离子筛 热力学 Pitzer电解质溶液理论 

分 类 号：O614.111[理学—无机化学]