Soft-in-Rigid Strategy Promoting Rapid and High-Capacity Lithium Storage by Chemical Scissoring

Large and rapid lithium storage is hugely demanded for high-energy/power lithium-ion batteries; however, it is difficult to achieve these two indicators simultaneously. Sn-based materials with a (de)alloying mechanism show low working potential and high theoretical capacity, but the huge volume expansion and particle agglomeration of Sn restrict cyclic stability and rate capability. Herein, a soft-in-rigid concept was proposed and achieved by chemical scissoring where a soft Sn-S bond was chosen as chemical tailor to break the Ti-S bond to obtain a loose stacking structure of 1D chain-like Sn_1.2Ti_0.8S₃. The in situ and ex situ (micro)structural characterizations demonstrate that the Sn-S bonds are reduced into Sn domains and such Sn disperses in the rigid Ti-S framework, thus relieving the volume expansion and particle agglomeration by chemical and physical shielding. Benefiting from the merits of large-capacity Sn with an alloying mechanism and high-rate TiS₂ with an intercalation mechanism, the Sn_1.2Ti_0.8S₃ anode offers a high specific capacity of 963.2 mA h g^-1 at 0.1 A g^-1 after 100 cycles and a reversible capacity of 250 mA h g^-1 at 10 A g^-1 after 3900 cycles. Such a strategy realized by chemical tailoring at the structural unit level would broaden the prospects for constructing joint high-capacity and high-rate LIB anodes.