Phase-junction engineering triggered built-in electric field for fast-charging batteries operated at-30°C

The high operational capability of fast-charging lithium-ion batteries (LIBs) at low temperatures (<-3 degrees C) is essential for frequency regulation and peak-load shifting of power grids in cold regions. However, the low-temperature performance is seriously plagued by the sluggish Li (+) diffusion and high-voltage polarization. Herein, the heterostructure- induced built-in electric field is constructed by selected nitriding of TiNb2O7, which demonstrates high accessibility for accelerated low-temperature dynamics. The introduced charged phase-junction interface enables promoted Li+ diffusion rates, enhanced Li+ adsorption, and reduced lattice strains. The mosaic TiNb2O7/TiNbN2 heterostructure displays an outstanding specific capacity of 241.5 mA h g(-1) at -30 degrees C, corresponding to 89% retention compared with that at 25 degrees C. It even delivers a high-capacity retention of 96% at a 5C rate after approximately 1,000 cycles at -30 degrees C. Our work provides new insight into structure-function relationships for developing fast-charging batteries for cold-region accumulation of electric energy.

Automated summary

The high operational capability of fast-charging lithium-ion batteries at low temperatures is crucial for power grid regulation in cold regions. By introducing a heterostructure-induced built-in electric field, the low-temperature performance of the battery has been significantly improved.