This study aims to apply various interface modifications to the anode of a solid-state battery. The study is divided into four sections, each using a different method of interface modification, including Pt sputtering, co-melting of Li and GaN, co-melting of Li and MAX-MXene followed by Pt modification, and finally spin-coating of CaCl2 on LLZTO followed by co-melting with Li. In the pursuit of cost reduction and interface modification, this research aims to discuss the materials for interface modification that are capable of forming an artificial SEI (Solid Electrolyte Interphase) layer and alloy layer. Additionally, to cater to future industrial applications, the study is dedicated to lowering research costs while selecting appropriate materials. Pt is initially chosen for its high stability, while GaN is selected to facilitate the formation of the alloy anode and artificial SEI layer as an interface transmission layer, blocking electron transport. GaN, being a third-generation semiconductor material with high popularity, has shown promising potential for application in solid-state batteries. Moreover, the application of Mxene involves the use of Ti nanoparticles to enhance the interface's Coulombic repulsion, thereby improving cycling stability and ion transport speed. Furthermore, a Li-C alloy is employed to stabilize the three-dimensional framework. Ultimately, combining the research experiences mentioned above, a low-cost CaCl2 anode is developed, resulting in the optimum interface impedance and overall minimal cost for Li-Ca-Cl solid-state batteries.
The results of each method show a significant reduction in interface impedance, with the lowest impedance of 7 Ω cm2 achieved using the Li-Ca-Cl anode. Symmetric cells also show an increase in cycle life from 90 cycles to 3500 cycles using Li-Pt at a current density of 0.1 mA cm-2, and the full battery can operate for 100 cycles with a discharge capacity retention rate of 93.3% using Li-MXene-Pt. Additionally, the cost of the anode interface modification has been reduced from 983.0 USD g-1 for Pt to 0.7 USD g-1 for CaCl2. Therefore, the ultimate goal of this study is to enhance the wettability of the anode in a solid-state battery at the lowest cost possible and further improve the efficiency of the entire battery, laying the foundation for future application-oriented developments in solid-state batteries.
The future of solid-state batteries lies in the development of high-performance, low-cost anode materials like CaCl2 and ensuring robust interface design for both anode and cathode. The use of Pt and GaN as interface modifiers has shown great promise, but further research is needed to address the cathode's interface challenges. By adopting non-invasive interface research approaches, we can gain a deeper understanding of the underlying processes and unlock the full potential of solid-state batteries for various industrial applications. Collaborative efforts from scholars in these areas will undoubtedly accelerate the advancement of solid-state battery technology.

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