Unlocking the atomic-scale mechanism of structural evolutions during (de) lithiation and negative-fading in CsPbBr3 anodes

Metal halide perovskite materials have attracted extensive research attention for lithium-ion batteries owing to their distinctive electronic and ionic transport properties. However, the atomic-scale mechanism of phase transformations in metal halide perovskites during lithium storage process remains largely unexplored. Herein, the structural evolution of CsPbBr3 is comprehensively investigated through various in/ex-situ techniques, disclosing the generation of CsBr, LiBr, Pb, and Li22Pb5 phases via intercalation-conversion-alloying reactions during lithiation and the reversible formation of CsPbBr3 upon charging process. Furthermore, CsPbBr3 particles are embedded within conductive carbon nanotubes (o-CNT) to take full advantage of its negative fading phenomenon, which can deliver high specific capacities of 630 mA h g- 1 at 0.1 A g- 1 over 220 cycles and 376 mA h g- 1 upgraded negative fading of CsPbBr3 originates from the enhanced Li-alloying reaction of residual Pb metal loaded on o-CNT and the improved pseudocapacitive contribution from the reduced size of active material during cycles. Thus, this work not only uncovers the electrochemical (de)lithiation mechanism of CsPbBr3 but also proposes an effective strategy to boost the additional "negative fading" effect of halide perovskite materials for superior lithium storage performance. at 1.0 A g- 1 at the 900th cycle. Comprehensive experimental and theoretical analysis identify that the