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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]

In this work, we report a facile approach to synthesis of highly fluffy and wrinkled reduced graphene oxide by simple freeze-drying and microwave-expanding method in vacuum. Compared with thermal reduced graphene oxide (RGO), the as-synthesized freeze drying and microwave reduced graphene oxide (FMGO) electrodes exhibit an improved electrochemical performance with high specific capacitance of 246 F g −1 at scan rate 5 mV s −1 and good cycle stability for application in supercapacitors. The outstanding performance of FMGO as a supercapacitor is attributed to the highly fluffy and wrinkled graphene which permits the creation of three-dimensional networks to induce fast electron and ion transport, thus eventually leading the significantly improved electrochemical capacitive behaviors. [ABSTRACT FROM AUTHOR]