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

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• High-energy and high-power lithium-ion batteries (LIBs) require simultaneous large lithium storage and rapid charge/discharge capabilities, which are difficult to achieve.
• Tin (Sn)-based materials offer high theoretical capacity and low working potential for LIB anodes but suffer from significant volume expansion and particle aggregation, limiting their stability and rate performance.
• Existing anode materials struggle to balance high capacity and fast charge/discharge rates, hindering the development of advanced LIBs.

Purpose of the Study:

• To design and synthesize a novel anode material that overcomes the limitations of traditional Sn-based anodes in LIBs.
• To achieve simultaneous high specific capacity and excellent rate capability in LIB anodes through a unique structural design.
• To demonstrate a new strategy for enhancing the electrochemical performance of LIB anodes by controlling structural units.

Main Methods:

• A 'soft-in-rigid' concept was employed using chemical scissoring to break Ti-S bonds, creating a loose stacking structure of 1D chain-like Sn_1.2Ti_0.8S₃.
• In situ and ex situ (micro)structural characterizations were performed to analyze the material's structure and the mechanism of volume expansion mitigation.
• Electrochemical performance testing, including cycling stability and rate capability measurements, was conducted to evaluate the anode's effectiveness.

Main Results:

• The synthesized Sn_1.2Ti_0.8S₃ material effectively disperses Sn domains within a rigid Ti-S framework, mitigating volume expansion and particle agglomeration.
• The anode exhibits a high specific capacity of 963.2 mA h g^-1 at 0.1 A g^-1 after 100 cycles.
• Exceptional rate capability was demonstrated, with a reversible capacity of 250 mA h g^-1 maintained at a high current density of 10 A g^-1 after 3900 cycles.

Conclusions:

• The developed Sn_1.2Ti_0.8S₃ anode material successfully combines the high capacity of Sn with the high-rate performance of TiS₂.
• The 'soft-in-rigid' strategy, achieved through chemical tailoring at the structural unit level, effectively enhances the cyclic stability and rate capability of LIB anodes.
• This approach offers a promising pathway for designing advanced anode materials for next-generation high-energy and high-power LIBs.