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Advanced hierarchical hybrid nanostructures of polar, conductive and catalytic chemical traps/carbon with rationally tailored components, structures, and chemistries are important in determining the performance of lithium-sulfur (Li–S) batteries. Herein we propose a facile strategy to prepare 3D-structured CNF@graphene-CoSe (CNF@G L -CoSe) cable/sheath heterostructure with the in-situ formed CoSe as a catalyst for graphene-like carbon growth and Se as a catalyst promoter. The architecture integrates high electrical conductivity, effective ion transport, notable polysulfide entrapment, and polysulfide redox kinetics, availing lithium/sulfur conversion when applied as an interlayer in a Li–S battery. As expected, the battery delivered a low decay of 0.053% per cycle over 700 cycles at 1 C. The capacity even remained 649.4 and 524.5 mA h g−1 at 4 and 6 C, respectively. Furthermore, an areal capacity of about 3 mA h cm−2 at 0.1 C after long-term tests can still maintain with sulfur loading of 4.5 mg cm−2. A facile effective strategy to prepare 3D-structured CNF@graphene-CoSe cable/sheath heterostructure with the in situ formed CoSe as a catalyst for graphene-like carbon growth and Se as a catalyst promoter, achieving significant enhancement in electrochemical performance of Li–S batteries. [Display omitted] • In situ constructing CNF@graphene-CoSe cable/sheath heterostructure. • CoSe catalyzes the growth of graphene sheath and Se as a catalyst promoter. • Synergism of conductivity, absorption and catalysis. • Enabling excellent performance as an interlayer. [ABSTRACT FROM AUTHOR]

Abstract The micro-mechanical responses of an electrode dominate its electrochemical performance and lifetime. Herein, an experimental method is proposed to investigate the micro-strain/stress of graphene electrodes during galvanostatic charge/discharge cycling. The characteristic Raman peak of the graphene electrode is acquired in situ in a modified coin cell as a function of time. And two mechanical models are established, including microscale plane strain and plane stress with Li-induced-stiffening. Combining the mechanical models and the measured 2D peak, the micro-strain and micro-stress of the graphene electrode are quantitatively characterized. Furthermore, the deformation mechanism and rate-dependent characteristics are discussed. Excepting slight compressive loads by the solid–electrolyte interface film, the graphene experiences an increasing tensile strain/stress with increasing capacity. The stresses significantly depend on the charge/discharge rate, where higher stresses are induced at higher currents with a multiplicative relationship between the stress and current increments. The origins of the stress differences between macroscale and microscale involve the elongation of the intralayer C−C bonds caused by intercalated Li between the graphene layers and a microscopic concentration gradient. This work enhances the understanding of the microscopic mechano-electro-chemical mechanism of graphene electrodes and facilitates theoretical modeling of the stress with Li concentration and current. Graphical abstract Image 106365 [ABSTRACT FROM AUTHOR]