A Mn3O4 nanospheres@rGO architecture with capacitive effects on high potassium storage capability.

A two dimensional (2D) Mn3O4@rGO architecture has been investigated as an anode material for potassium-ion secondary batteries. Herein, we report the synthesis of a Mn3O4@rGO nanocomposite and its potassium storage properties. The strong synergistic interaction between high surface area reduced graphene oxide (rGO) sheets and Mn3O4 nanospheres not only enhances the potassium storage capacity but also improves the reaction kinetics by offering an increased electrode/electrolyte contact area and consequently reduces the ion/electron transport resistance. Spherical Mn3O4 nanospheres with a size of 30-60 nm anchored on the surface of rGO sheets deliver a high potassium storage capacity of 802 mA h g-1 at a current density of 0.1 A g-1 along with superior rate capability even at 10 A g-1 (delivers 95 mA h g-1) and cycling stability. A reversible potassium storage capacity of 635 mA h g-1 is retained (90%) after 500 cycles even at a high current density of 0.5 A g-1. Moreover, the spherical Mn3O4@rGO architecture not only offers facile potassium ion diffusion into the bulk but also contributes surface K+ ion storage. The obtained results demonstrate that the 2D spherical Mn3O4@rGO nanocomposite is a promising anode architecture for high performance KIBs.

High Rate Performing in Situ Nitrogen Enriched Spherical Carbon Particles for Li/Na-Ion Cells.

Nitrogen rich, porous spherical carbon particle with the large surface area was synthesized by simple pyrolysis of the amorphous covalent organic framework. The obtained mesoporous spherical carbon particles with dilated interlayer distance (0.377 nm), large surface area (390 m2 g-1) and high level nitrogen doping (10.9%) offer eminent electrochemical performance as an anode for both lithium ion (LIBs) and sodium ion batteries (SIBs). In LIB applications, the synthesized material delivers an average reversible capacity of 820 mAh g-1 after 100 cycles at 0.1 A g-1, superior rate capability of 410 and 305 mAh g-1 at 4.0 and 8.0 A g-1 respectively. In SIBs, the material shows the stable reversible capacity of about 238 mAh g-1 for the studied 500 cycles at 0.5 A g-1. The rate and steady state cycling performance at high current densities are impressive, being as high as 165 mAh g-1 even after 250 cycles at 2.0 A g-1.

Reduced graphite oxide/nano Sn: a superior composite anode material for rechargeable lithium-ion batteries.

The electrochemical performance of reduced graphite oxide (RGO) anchored with nano Sn particles, which are synthesized by a reduction method, is presented. The Sn nanoparticles are uniformly distributed on the surface of the RGO matrix and the size of the particles is approximately 5-10 nm. The uniform distribution effectively accommodates the volume expansion experienced by Sn particles during cycling. The observed electrochemical performance (97 % capacity retention) can be ascribed to the flexible RGO matrix with uniform distribution of Sn particles, which reduces the lithium-ion diffusion path lengths; therefore, the RGO matrix provides more stability to the Sn particles during cycling. Such studies on Sn nanoparticles anchored on RGO matrices have not been reported to date.

High quality NMP exfoliated graphene nanosheet-SnO2 composite anode material for lithium ion battery.

A graphene nanosheet-SnO(2) (GNS-SnO(2)) composite is prepared using N-methylpyrrolidone as a solvent to exfoliate graphene from graphite bar with the aid of CTAB by single phase co-precipitation method. The synthesized composites has been characterised physically by powder XRD which confirms the formation of the composite tetragonal SnO(2) crystal system with the low intense broad 002 plane for GNS. The sandwiched morphology of GNS-SnO(2) and the formation of nanosized particles (around 20 nm) have been confirmed by SEM and TEM images. The presence of sp(2) carbon in the GNS is clear by the highly intense G than D band in laser Raman spectroscopy analysis; furthermore, a single chemical shift has been observed at 132.14 ppm from solid-state (13)C NMR analysis. The synthesized composite has been electrochemically characterized using charge-discharge and EIS analysis. The capacity retentions at the end of the first 10 cycles is 57% (100 mA g(-1) rate), the second 10 cycles is 77.83% (200 mA g(-1)), and the final 10 cycles (300 mA g(-1)) is 81.5%. Moreover the impedance analysis clearly explains the low resistance pathway for Li(+) insertion after 30 cycles when compared with the initial cycle. This superior characteristic of GNS-SnO(2) composite suggests that it is a promising candidate for lithium ion battery anode.

High-performing LiMgxCuyCo1-x-yO2 cathode material for lithium rechargeable batteries.

Sustainable power requirements of multifarious portable electronic applications demand the development of high energy and high power density cathode materials for lithium ion batteries. This paper reports a method for rapid synthesis of a cobalt based layered cathode material doped with mixed dopants Cu and Mg. The cathode material exhibits ordered layered structure and delivers discharge capacity of ∼200 mA h g(-1) at 0.2C rate with high capacity retention of 88% over the investigated 100 cycles.

LiCo(x)Mn(1-x)PO4/C: a high performing nanocomposite cathode material for lithium rechargeable batteries.

Pristine and Co-doped LiMnPO(4) have been synthesized by the sol-gel method using glycine as a chelating agent and the carbon composites were obtained by the wet ball mill method. The advantage of this method is that it does not require an inert atmosphere (economically viable) and facilitates a shorter time for synthesis. The LiCo(0.09)Mn(0.91)PO(4)/C nanocomposites exhibit the highest coulombic efficiency of 99 %, delivering a capacity of approximately 160 mAhg(-1) and retain a capacity of 96.3 % over the investigated 50 cycles when cycled between 3-4.9 V at a charge/discharge rate of 0.1 C.