Nanoparticle-assembled interconnected PbO _1.44 hollow spheres enabled by PVP-driven transformation of β-PbO ₂ and self-sacrificial templating for superior lithium storage

Lead oxides (PbO_x, 1 ≤ x ≤ 2) are promising high-capacity and low-cost anodes for lithium ion batteries (LIBs). However, the huge lithiation-induced volume expansion of conventional large-sized PbO_x particles leads to severe electrode pulverization with poor cycling stability. Herein, a rare mixed-valence PbO_1.44 with a unique hierarchical architecture of nanoparticle-assembled interconnected hollow spheres (denoted PbO_1.44 NAHSs) is crafted by introducing polyvinylpyrrolidone (PVP) into the solution of generating β-PbO₂ microspheres (MSs), which is exploited for the first time as a potential advanced anode material for LIBs. Notably, an intriguing PVP-driven dissolution-recrystallization transformation process converting β-PbO₂ MSs into PbO_1.44 NAHSs is revealed by PVP-concentration and reaction-time control experiments, demonstrating the dual function of PVP as a mild reducing agent combined with it being a morphology regulator for the construction of PbO_1.44 NAHSs. Furthermore, a self-sacrificial templating mechanism is demonstrated for yielding the interconnected hollow structure of PbO_1.44 NAHSs. Remarkably, PbO_1.44 NAHSs deliver stable capacities of 561 and 453 mA h g^-1 after 100 and 200 cycles at 50 and 500 mA g^-1, respectively, in sharp contrast to the performance of β-PbO₂ MSs (52 and 43 mA h g^-1). Structural and electrochemical measurements of the cycled electrodes indicate that the hollow and nanoarchitectural structure of PbO_1.44 NAHSs enables their superior cycling and rate capabilities, benefiting from the effectively buffered volume expansion and shortened lithium storage distance, respectively. As such, this work highlights a robust PVP-assisted strategy to fabricate rare mixed-valence PbO_1.44 NAHSs with outstanding electrochemical reactivity and mechanical robustness for lithium storage and various potential applications.