Currently, the energy density of lithium ion batteries has reached a level of about 200 300 Wh kg-1, but the current energy density is still unable to meet the needs of long distance electric vehicles. In the future, the energy density of lithium ion batteries will need to continue to increase to more than 500 Wh kg-1 to meet the longer range and higher drive performance of electric vehicles. A lithium metal anode has the potential to increase the energy density and reduce the weight of batteries, making them more efficient and practical for use in electric vehicles and other applications. The advantages of lithium metal anodes include higher energy density, longer cycle life, and lower cost compared to other types of anodes. This is because lithium metal has a higher theoretical capacity (3860 mAh g-1) than graphite (372 mAh g-1), which is commonly used as an anode material in commercial lithium ion batteries. Additionally, the use of lithium metal anodes can reduce the weight of batteries and increase their energy efficiency, making them more practical for use in electric vehicles and portable electronic devices. However, there are still significant challenges that need to be overcome in order to fully realize the potential of lithium metal anodes. One major challenge is the formation of dendrites, which are branching structures that can grow from the surface of the lithium metal and cause short circuits within the battery. This can result in safety hazards and reduced cycle life. Another challenge is the issue of lithium metal oxidation and degradation during cycling, which can reduce the performance and cycle life of the battery. To overcome these challenges, researchers are exploring various strategies such as using protective coatings, designing new electrolytes, and optimizing the battery architecture. However, since there are so many factors affecting lithium dendrite generation, such as local current density, current density, flatness of lithium foil surface, homogeneity of SEI, lithium ion concentration, electronic conductivity, and ionic conductivity, etc., the existing protection strategies and means still cannot cope with all of the above factors. Therefore, multi functional protection strategies are necessary to enhance the protection effect and promote the adoption of lithium metal.

All solid state electrolytes are special compared with other protection strategies. It offers several advantages over conventional liquid electrolytes, including improved mechanical strength, and enhanced stability against lithium metal. These characteristics make all solid state electrolytes a potential solution to prevent dendrite formation in lithium metal batteries. One approach to achieve this is using ceramic based solid electrolytes, such as lithium garnet or sulfide based materials. These materials have high ionic conductivity and excellent stability against lithium metal, which can prevent dendrite formation and improve battery performance. However, the contact between ceramic electrolyte and lithium metal is not ideal. Due to the better interface contact, polymer based solid electrolytes were explored, which offer further advantages such as improved flexibility, processability, and scalability. However, polymer based electrolytes still face challenges such as lower ionic conductivity and limited stability against lithium metal.

In this project, we proposed the multi-functional lithium metal protective strategies, which guiding four independent works referred to various factors affecting the dendrite growth: preparing the artificial SEI to flatten lithium anode surface by using CuCl2 and furfuryl alcohol; employing the polymeric additive to adjust the lithium ions flux; and functionalizing the solid state electrolyte for lithium dendrite resistance. […]