Besides Li＋ and Mg2＋, the electrochemical behavior of Na^＋ and K＋ in LiFePO4/FePO4 structures was studied since they naturally coexist with Li＋ and Mg2＋ in brine. The cyclic voltammogram （CV） results indicated...Besides Li＋ and Mg2＋, the electrochemical behavior of Na^＋ and K＋ in LiFePO4/FePO4 structures was studied since they naturally coexist with Li＋ and Mg2＋ in brine. The cyclic voltammogram （CV） results indicated that Na＋ exhibits some reversibility in LiFePO4/FePO4 structures. Its reduction peak appears at -0.511 V, more negative than that of Li＋ （-0.197 V）, meaning that a relatively positive potential is beneficial for decreasing Na＋ insertion. The reduction peak of K＋ could not be found clearly, indicating that K＋ is difficult to insert into the FePO4 structure. Furthermore, technical experiments using real brine with a super high Mg/Li ratio （493） at a cell voltage of 0.7V showed that the final extracted capacity of Li＋, Mg2＋ and Na＋ that can be attained in 1 g LiFePO4 is 24.1 mg, 7.32 mg and 4.61 mg, respectively. The Mg/Li ratio can be reduced to 0.30 from 493, and the Na/Li ratio to 0.19 from 16.7, which proves that, even in super high Mg/Li ratio brine, if a cell voltage is appropriately controlled, it is possible to separate Li^＋ and other impurities effectively.展开更多
基金Project(K1205034-11) supported by Technology Program of Changsha,China
文摘Besides Li＋ and Mg2＋, the electrochemical behavior of Na^＋ and K＋ in LiFePO4/FePO4 structures was studied since they naturally coexist with Li＋ and Mg2＋ in brine. The cyclic voltammogram （CV） results indicated that Na＋ exhibits some reversibility in LiFePO4/FePO4 structures. Its reduction peak appears at -0.511 V, more negative than that of Li＋ （-0.197 V）, meaning that a relatively positive potential is beneficial for decreasing Na＋ insertion. The reduction peak of K＋ could not be found clearly, indicating that K＋ is difficult to insert into the FePO4 structure. Furthermore, technical experiments using real brine with a super high Mg/Li ratio （493） at a cell voltage of 0.7V showed that the final extracted capacity of Li＋, Mg2＋ and Na＋ that can be attained in 1 g LiFePO4 is 24.1 mg, 7.32 mg and 4.61 mg, respectively. The Mg/Li ratio can be reduced to 0.30 from 493, and the Na/Li ratio to 0.19 from 16.7, which proves that, even in super high Mg/Li ratio brine, if a cell voltage is appropriately controlled, it is possible to separate Li^＋ and other impurities effectively.
