Recently, Prof. Wu Yuping and Prof. Ma Yuan’s team from the School of Energy and Environment at Southeast University (SEU) published a research paper titled “Insertion-dominated anion redox in high-capacity amorphous sulfide cathodes for solid-state batteries” in the internationally leading energy journal Joule (a Cell Press journal, Impact Factor 37.1). Addressing the challenges faced by cathode materials for sulfide-based all-solid-state batteries, such as insufficient interfacial stability, poor structural stability, and limited capacity, the research team proposed a synergistic design strategy of “structural amorphization, interfacial quasi-homogenization, and anion-enrichment regulation,” constructed a high-performance amorphous titanium sulfide cathode, and revealed an insertion-dominated cation–anion synergistic multi-electron redox lithium storage mechanism.
All-solid-state batteries (ASSBs) are regarded as an important development direction for next-generation energy storage technologies due to their combination of high energy density and high safety. Among them, sulfide solid electrolytes possess high ionic conductivity and good processability. However, when conventional crystalline cathode materials are applied to sulfide all-solid-state batteries, they face problems such as chemical and mechanical mismatch at the cathode/electrolyte interface, unstable lattice structure, and limited solid-phase ion transport, while high-capacity conversion-type materials often suffer from large volume changes and poor cycling stability. Therefore, developing cathode materials with high capacity, fast kinetics, and long-term cycling stability remains a key challenge in the development of all-solid-state batteries.
To address the above issues, the research team proposed a synergistic design strategy of “structural amorphization + interfacial quasi-homogenization + anion enrichment.” Using titanium sulfide as a model system, they constructed an amorphous sulfide cathode highly compatible with sulfide solid electrolytes. The study found that with increasing sulfur content, the lithium storage mechanism of the material expanded from conventional Ti³⁺/Ti⁴⁺ cationic redox to synergistic redox involving Ti³⁺/Ti⁴⁺ and S₂²⁻/S²⁻, achieving an insertion-dominated multi-electron lithium storage mechanism. Among them, amorphous titanium trisulfide (a-TiS₃) maintained a capacity of 556 mAh g⁻¹ after 500 cycles at 0.1 A g⁻¹, and could cycle stably for nearly 2,900 cycles at 2.0 A g⁻¹ with a capacity retention of about 90%. Even at a high rate of 10 A g⁻¹, it still retained about 57% of its initial capacity. Further studies showed that during Li⁺ insertion, a-TiS₃ mainly achieved multi-electron lithium storage through local coordination environment reconstruction, while the host Ti–S network was preserved. At the same time, the cathode/sulfide solid electrolyte interface maintained good chemical and structural stability before and after cycling. Through the synergistic design of interfacial quasi-homogenization, structural amorphization, and anion enrichment, this study broke through the capacity limitation of conventional intercalation cathodes while maintaining the structural advantages of insertion reactions, providing new ideas for the design of cathode materials for high-specific-energy, long-life sulfide all-solid-state batteries.
The School of Energy and Environment and the New Generation Energy Storage Center of Southeast University are the first completing institutions of the paper. Liu Chengyu, a 2024 master’s student, is the independent first author. Prof. Ma Yuan is the Lead Contact and corresponding author, and Prof. Wu Yuping is the co-corresponding author. This research was supported by the National Key R&D Program of China, the National Natural Science Foundation of China, the National High-level Young Talents Fund, the Jiangsu Province Carbon Peaking and Carbon Neutrality Research Project, and the Southeast University High-level Talent Startup Fund, among other projects.
Paper’s link: https://doi.org/10.1016/j.joule.2026.102649
Source: School of Energy and Environment, SEU
Translated by: Melody Zhang
Edited by: Leah Li
