Rational Construction and Modulation of Built-In Electric Field for High-Efficiency Alkali Metal-Based Batteries

With the large-scale adoption of electric vehicles and the ongoing integration of renewable energy into the grid, the development of high-performance alkali metal-based batteries (AMBs) has become increasingly important. However, AMBs still face several challenges, such as limited energy density, insufficient rate capability, and short cycle life, which mainly stem from sluggish ionic diffusion kinetics and unstable electrode structural evolution. In recent years, built-in electric field (BIEF) engineering has attracted extensive attention as an effective strategy to enhance battery energy storage performance by regulating the microstructure of materials. This review begins with the key challenges currently faced by AMBs, systematically analyzes the potential of BIEF in addressing these issues, and elaborates on the fundamental principles, evaluation methods, and construction strategies of BIEF. Furthermore, the latest research progress on BIEF engineering for improving the electrochemical activity, reaction kinetics, and cycling stability of AMBs is summarized. Finally, future research directions in BIEF engineering are discussed, providing new insights for designing high-performance AMBs with tunable built-in electric fields.