Design and Mechanism Investigation of High-voltage Solid-state Non-lithium Alkali Metal-ion Batteries

Description

While lithium ion batteries have been extensively applied, the earth’s lithium reserve is limited. It is thus urgent for the development of alternative battery systems. Sodium and potassium (the sixth and eighth most abundant element on earth), featuring abundant materials-availability, similar physical and chemical properties compared with lithium, have good potential for making practical ion battery systems. Recently, researchers, including the principle investigators, have developed feasible sodium/potassium based battery systems based on high capacity alloying-type anodes and anion-intercalation-type graphite cathode. While these batteries have merits of high working voltages, low cost and easy recycling, their further commercial applications are limited by: 1) poor cycling stability of the alloying anodes; 2) low capacity of the graphite cathode; 3) possibility of leaking and explosion associated with liquid electrolytes at high working voltages.  In this project, the principles investigators will study and address these issues to design high performance high-voltage solid state sodium and potassium ion batteries. On one hand, high voltage layered cathode materials (modified graphite, transition metal sulfide, nitride, oxide, MXene, etc.), modified alloying anodes (Sn, Ge, Sb, and Bi) and novel solid-state gel polymer electrolytes will be developed. On the other hand, by combining theoretical calculation with in-situ/ex-situ characterizations, we will clearly reveal following problems: 1) pulverization failure mechanisms and mechanical alloying-electrochemical coupling mechanisms of the alloying-type anodes; 2) anion intercalation mechanisms of new layered cathode materials; 3) ion transportation mechanisms and interface stabilities of polymer electrolytes. Upon success of this project, the PI team will be able to develop a wide range of high performance sodium and potassium solid state batteries with good safety (with no electrolyte leaking and explosion concerns), high working voltage (> 4.2 V), high reversible capacities (> 120 mAh g-1), high energy density (> 180 Wh kg-1) and good cycling stabilities (capacity retention > 90% after 1000 cycles at 5C). Additionally, the obtained knowledge will be used for design and preparation of other full cells with high capacities, high energy densities, good rate capabilities, and long cycling lives. When these batteries become more matured, companies on knowledge transfer, technology investment and batteries manufacture will be benefited.