Synthesis, crystal structure of a lithium - zinc bimetal coordination polymer and its graphene composite as anode materials for lithium ion battery

A new bimetal coordination polymer composed of Li+, Zn2+ and 4,5 imidazole dicarboxylic acid (idca) with a molecular formula of Li5Zn6C25H11N10O24 (LiZn1) was prepared via a simple hydrothermal method. The single crystal structure shows that LiZn1 has a 3-D framework consisting of three independent four coordinated Li+ and three independent five coordinated Zn2+ cations, respectively. Topological study indicates the network of LiZn1 is 9-nodal, 3,3,3,3,3,4,5,5,6-connected net, with a point symbol of {4.6.7}(2){4.6(2)}(4){4(2).6(2).7(2).9(3).11}{4(2).6}(2) {4(3).6(3).7(2).8(5).9(2)}(2){4(3).6(3)}(2){6(2).8}{6(5).7(2).8.9(2)}(2). The graphene composite (LiZnl/gr, gr stands for graphene.) was prepared via a sonication treatment of the mixture of LiZn1 and graphene. LiZn1 was employed as the anode of a lithium ion battery, the initial discharge capacity was obtained for 558 mAh/g, after 100 cycles the discharge capacity was decreased to around 75 mAh/g. However, the graphene composite (LiZnl/gr) has improved very much the performance with the initial discharge capacity of 1090 mAh/g and after 100 cycles the discharge capacity could remain about 133 mAh/g. (C) 2018 Elsevier B.V. All rights reserved.