GeS2 nanocomposite space-confined in an interconnected spherical graphene framework as advanced anodes for lithium storage

Highlights: • The unique hierarchical GeS₂@PS-G composite is delicately fabricated. • The synergistic strategy of designed structure and optimized composition is illuminated. • The Li⁺-ions storage mechanism is thoroughly investigated by in-situ XRD. • The GeS₂@PS-G anode shows the superior electrochemical properties. Although owing ultrahigh theoretic capacity, the development of germanium sulfide-based anode is severely hindered by its poor conductivity and inferior stability derived from the large volume variation, which is hardly satisfied with the vigorous demand for the high-performance lithium storage. Herein, a reliable and self-assembly synthetic technique is proposed for in-situ growth of GeS₂ nanograins homogeneously distributed on interconnected spherical graphene framework, constructing a three-dimensional (3D) conductive network (GeS₂@PS-G). Benefiting from the synergistic strategy of delicately-designed structure and optimized composition, the unique hierarchical GeS₂@PS-G can effectively relieve the electrode pulverization and agglomeration, thus maintaining the structural integrity. Moreover, the 3D graphene framework provides rapid ions diffusion path, enabling to achieve the maximum conductivity. Systematic electrochemical results demonstrate that such GeS₂@PS-G nanohybrid yields an ultrahigh reversible capacity (1172 mAh g⁻¹ at 0.1 A g⁻¹) and outstanding cycling stability (985 mAh g⁻¹ at 1.0 A g⁻¹ over 1600 cycles) for Li-storage, presenting the best reported performance to date. Notably, the detailed analysis of structural evolution and reaction mechanism of GeS₂@PS-G are clearly articulated by in-situ X-ray diffraction investigation. These findings provide an insight to explore and develop high-performance anodes for next-generation energy storage.