Interface Modeling via Tailored Energy Band Alignment: Toward Electrochemically Stabilized All‐Solid‐State Li‐Metal Batteries

• Published in: Advanced functional materials 2022-02, Vol.32 (9), p.n/a
• Main Authors: Kim, Heebae, Im, Changik, Ryu, Seokgyu, Gong, Yong Jun, Cho, Jinil, Pyo, Seonmi, Yun, Heejun, Lee, Jeewon, Yoo, Jeeyoung, Kim, Youn Sang
• Format: Article
• Language: English
• Subjects: all‐solid‐state batteries; Band theory; Batteries; Electric fields; Electron transport; Energy bands; Interface stability; Interfacial energy; Interlayers; Li‐metal anodes; Materials science; Modelling; Rechargeable batteries; solid‐state electrolytes; stable interfaces; Titanium compounds
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202107555

Interfacial instability between Li‐metal anode (LMA) and inorganic solid‐state electrolyte (SSE) is a critical issue in all‐solid‐state Li‐metal batteries (ASSLBs). Previous studies have focused on interface modification methodology to achieve long‐term cycling stability in ASSLBs. However, strategy establishment without an in‐depth understanding of the LMA–SSE interface is limited to a phenomenological solution. Also, the fact that rechargeable batteries are operated by behavior of charges inside electric field is frequently overlooked. Here, it is demonstrated for the first time that interface modeling based on energy band theory does effectively overcome the intrinsic vulnerability of SSE to LMA. The interfacial deterioration, due to undesirable electron transport from LMA to the SSE surface, is precluded by a titanium compound self‐induced interlayer (TSI), which forms an interfacial energy barrier. The Li symmetric cell with a TSI successfully maintains its constant overpotential over 1000 cycles and the significantly reduced impedance, whereas the cell having no interface modification exhibits erratic voltage profiles and is easily failed by repetitive charge–discharge process. This newly introduced approach is an informative tool to substantially reinforce the fundamental understanding of interfacial phenomena in all‐solid‐state batteries. Furthermore, rigorous stability requirements of automotive applications are expected to be fulfilled by the innovative interface modification. All‐solid‐state Li‐metal batteries demonstrate superior energy density and safety to conventional Li‐ion batteries. However, inherent interfacial instability of solid‐state electrolyte and Li‐metal anode expedites the battery's electrochemical degradation. Interface modeling via energy band alignment fundamentally resolves the chronic reliability issue. The revealing results provide comprehensive understanding of interfacial phenomena and fundamental solution applicable to various all‐solid‐state battery types.