From the whole anode electrode of view, we report in this work a system-level strategy of fabrication of reduced graphene oxide (RGO)/SnO2 composite-based anode for lithium ion battery (LIB) to enhance the capacity and cyclic performance of SnO2-based electrode materials. RGO/SnO2 composite was first coated by a nanothick polydopamine (PD) layer and the PD-coated RGO/SnO2 composite was then cross-linked with poly(acrylic acid) (PAA) that was used as a binder to accomplish a whole anode electrode. The cross-link reaction between PAA and PD produced a robust network in the anode system to stabilize the whole anode during cycling. As a result, the designed anode exhibits an outstanding energy capacity up to 718 mAh/g at current density of 100 mA/g after 200 cycles and a good rate performance of 811, 700, 641, and 512 mAh/g at current density of 100, 250, 500, and 1000 mA/g, respectively. Fourier transform IR spectra confirm the formation of cross-link reaction and the stability of the robust network after long-term cycling. Our results indicate the importance of designing interfaces in anode system on achieving improved performance of electrode of LIBs.

The effect of space accessible to electrolyte ions on the electrochemical activity is studied for a system of transition-metal hydroxide-based pseudocapacitors. Layered α -Co(OH) 2 with various intercalated anions is used as a model material. Three types of layered α -Co(OH) 2 with intercalated anions of dodecyl sulfate, benzoate, or nitrate, are prepared by a simple refl ux and an anionexchange process. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations and X-ray diffraction (XRD) data show the formation of layered α -Co(OH) 2 nanocones with interlayer spacing between adjacent Co(OH) 2 single sheets of 1.6, 0.7, and 0.09 nm, corresponding to the anions as listed above. Electrochemical characterization reveals that interlayer space has a great effect on the electrochemical activity of α -Co(OH) 2 nanocones as an electrode material. For the interlayer spacing of 1.6 nm, in the case of dodecyl sulfate-intercalated α -Co(OH) 2 , the Faradaic reaction takes place more adequately than for benzoate-and nitrate-intercalated α -Co(OH) 2 . As a result, a higher specifi c capacitance and better cycling stability is obtained for the dodecyl sulfate-intercalated α -Co(OH) 2 . The electrochemical activity obviously reduces when the interlayer space decreases to 0.7 nm. Our results suggest the importance of rational designing the interlayer space of layered transition metal hydroxides for high-performance pseudocapacitors. Figure 8 . Schematic drawings of: a) DS-α -Co(OH) 2 , b) NO 3 − -α -Co(OH), and, c) benzoate-α -Co(OH) 2 , where electrolyte ions (OH − ) soak into the interlayer of two adjacent single sheets of Co(OH) 2 .