Recently, the research results of the School of Chemistry and Chemical Engineering(SCCE) of IMU has been published in Advanced Materials—a top international journal for material science(Advanced Materials, 2023, DOI: 10.1002/adma.202300687, IF=32). The first author is Tao Fencheng, a master student who was admitted to IMU in 2019. The corresponding authors are Lecturer Kang Xiaomin and Prof. Liu Zhiyu who are with SCCE.

The excellent safety performance of solid-state lithium batteries makes them a new generation of mobile energy storage device to replace the present commercial lithium batteries. The solid-state ion conductive materials(solid-state electrolytes) , are the key materials for solid-state lithium batteries. At present, the solid-state lithium ionic conductive materials that researches have focused on include solid-state organic polymer electrolytes and solid-state inorganic ceramic electrolytes. Although solid-state organic polymer electrolytes are ductile and have good electrode interfacial compatibility, their ionic conductivity and ionic transference number are low. While solid-state inorganic ceramic electrolytes have high ionic conductivity, its electrode interfacial compatibility is very poor. As a result, it is a stressing to find out the ionic conductive materials which have high ionic conductivity , high ionic transference number, broader electrochemical window and good interfacial compatibility.  

With the support of the National Natural Science Foundation of China, the research team has conducted in recent years the systematic research to propose the hollow MOF strategy and harvest the MOF-based ionic conductive material with good performance（Chem. Commun., 2020, 56, 14629—14632；J. Mater. Chem. A, 2022, 10, 14020–14027；Chem. Commun., 2022, 58, 6717–6720）.

On the basis of the previous studies, the research team has attempted structure design and morphology control to harvest the MOF-based hierarchical porous H-ZIF-8 , which is expected to greatly enhance the effective loading of Li+ ions in the solid-state electrolytes. Then, the team synthesized appropriate amount of halloysite nanotube(HNT) to make lithium-loaded anions effectively immobilized by HNT on the basis of the feature that there are positive charges in HNT. The harvested MOF-based composite solid-state electrolytes- H-ZIF-8/HNT, express the conductivity of single Li+ ion. With the electrochemical performance test, H-ZIF-8/HNT shows the outstanding electrochemical performance with the ionic conductivity of as high as 7.74×10-3 S/cm and the ionic transference number of 0.84. And the Li+ ion conductivity of HNT takes lead among the reported electrolytes. The solid-state lithium batteries assembled with the LiFePO 4 as cathode and Li metal as anode, display the charge capacity of 129.22 mA h g-1. After 200 times of charge/discharge cycles, the batteries still have 84% capacity retention, which can still illuminate light-emitting diodes(LED). The research has provided a new strategy for the development of high-performance solid-state electrolytes

Scheme 1. Fabrication procedures of the composite solid-state H-ZIF-8/HNT and illumination of LED by solid-state LiFePO4/electrolyte/Li batteries assembled with HNT