| Solid-state lithium ion batteries have attracted extensive attention due to their higher energy density and safety properties.As a critical material of solid-state lithium ion battery,the electrochemical performance of solid-state electrolyte affects the use of the battery.Traditional inorganic ceramic electrolytes have poor contact with the electrode interface,while organic polymer electrolytes have low ionic conductivity at room temperature.It makes a key technology for the development of a new generation of solid-state lithium-ion batteries to study solid-stste electrolytes with high ionic conductivity and good mechanical properties.Metal-Organic Frameworks(MOFs)are an emerging class of porous crystal materials with high porosity and tunable pore morphology,which have great candidate in ion conduction.In this paper,five kinds of Zn-MOFs with different pore size and functionalization were synthes ized act as solid-state ionic conduction materials which have high lithium ionic conductivity,high lithium ion transference number and wide electrochemical windows.The main contents are as follows:1.Compound Zn-MOF-74 and Zn-MOF-74-II with pore sizes of 14(?)and 19(?)were synthesized by using organic bridging ligands of different molecular lengths.Compound Zn-MOF-74-II with large porosity to load more lithium ions and improve the conductivity of lithium ions.Compared with Zn-MOF-74,the lithium ionic conduction properties of Zn-MOF-74-II have a significant improvement.The lithium ion conductivity reaches 1.46×10–3 S·cm–1 at room temperature,which is twice that of MOF-74.The lithium ion transference number increases to 0.68 and activation energy decreases to 0.06 e V in a wide stable electrochemical window of 2.0-5.0 V.2.Hollow ZIF-8 was synthesized by exterior-template method.As-synthesized hollow ZIF-8 has a large cavity with a diameter of 1?m,which could store more lithium ions in large cavity effectively and further to migrate lithium ions through lattice and cavity wall and promote lithium ion conduction.Compared with non-hollow ZIF-8,the lithium ionic conduction properties of hollow ZIF-8 have a significant improvement.The lithium ion conductivity reaches 7.36×10–4 S·cm–1 at room temperature,which is two orders of magnitude higher than that of non-hollow ZIF-8.The lithium ion transference number increases to 0.83 with an activation energy of 0.15 e V in a wide stable electrochemical window of 2.0-6.5V.3.A unique multiple carboxylic zinc metal-organic framework(Zn-MOF-COOH)containing uncoordinated carboxylic acid groups was synthesized by the hydrothermal method.Zn-MOF-COOLi was synthesized through deprotonation using Li OH via a straightforward acid-base reaction at room temperature,thereby exhibiting better lithium ionic conduction properties.Compared with Zn-MOF-COOH,the lithium ionic conduction properties of Zn-MOF-COOLi improved remarkable.The lithium ion conductivity is 1.65×10–4 S·cm–1 at room temperature,which is one order of magnitude higher than that of Zn-MOF-COOH.The lithium ion transference number increases to 0.77 with an activation energy of0.12 e V in a wide stable electrochemical window of 1.5-6.5V.4.A three-dimens ional compound Zn-MOF with a pore size of 11(?)was synthesized by the hydrothermal method.Li Cl,Li Br and Li I were loaded into the pore of compound Zn-MOF for post-modification to generate Li Cl@Zn-MOF,Li Br@Zn-MOF and Li I@Zn-MOF,respectively.Compared with Zn-MOF,the lithium ionic conduction properties of Li X@Zn-MOF have improved effectively,and the comprehensive lithium ionic conduction performance of Li Br@Zn-MOF was the best.At room temperature,the lithium ion conductivity of Li Br@Zn-MOF is4.47×10–4 S·cm–1,the lithium ion transference number reaches 0.80 and activation energy is 0.10 e V in a wide stable electrochemical window of 0.8-6.8V.5.Five types of PVDF-HFP/MOF-5 composite electrolyte membranes were synthesized using phase inversion method.The inclus ion of MOF-5 effectively improves the porosity,mechanical properties and affinity with electrolyte of the electrolyte membranes.Compared with pure PVDF-HFP,the lithium ionic conduction properties of PVDF-HFP/MOF-5-X(X=I,II,III,IV,V)have an obvious enhancement,especially the PVDF-HFP/MOF-5-II.At room temperature,PVDF-HFP/MOF-5-II composites has a lithium ionic conductivity of 1.20×10–3S·cm–1,a lithium ion transference number of 0.90 and an activation energy of 0.17 e V in a wide stable electrochemical window of 3.8–6.8 V. |
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