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Highlights • Biomass anode materials derived from coffee grounds for Li/Na ion batteries are demonstrated. • The electrochemical performance can be enhanced by N doping. • Pyrrolic N and pyridinic N are key factors for electrochemical performance. • First principle calculation of N-doped carbon is displayed. Abstract In this study, we propose a facile process to synthesize nitrogen-doped carbon from agro-food used wastage of coffee grounds and fabricated as anode materials for Li/Na-ion batteries. The coffee grounds derived carbon (CGC) and nitrogen doped (N-CGC) porous carbon materials have been compared by experimental measurements as well as theoretical calculations. The nitrogen doping of 2.23–6.17% are successfully modified into the material. The experimental results indicate that N-CGC exhibits better reversible capacity and excellent rate capability than those of CGC anode due to different distribution functional groups of pyrrolic N and pyridinic N. We also use three different models to demonstrate the differences in carrier transport properties. The difference in electrochemical properties of CGC and N-CGC might be due to the appearance of extra states near the Dirac cone when examining the partial density of states (PDOS) of N-CGC by Density functional theory (DFT) calculations. This investigation is not only solving the problem of biomass waste disposal, also generates valuable functional carbon-based materials for energy storage applications. Graphical abstract Image, graphical abstract [ABSTRACT FROM AUTHOR]

Silicon is growing potential interesting material for high-performance lithium-ion batteries anode, due to its high theoretical specific capacity and vastly abundance elemental. Moreover, for the commercialization of Si-based anode is still suffered by huge volume changes during the lithiation/delithiation cyclic process and low electrical conductivity. Therefore, to address these issues, we demonstrate an approach to anchor silicon particles into porous three-dimensional (3D) graphene aerogels (Si/GA) through a facile hydrothermal followed by freeze-drying techniques. The porous graphene aerogels promote the electrolyte infiltration to enhance Li-ion diffusion and buffer the volume extension of silicon particles to boost the rate capability, cycle stability during (de)lithiation processes. The as-synthesized Si/GA exhibits good cyclic stability and showed the specific capacity of 850 mAh g−1 after 200 cycles with a coulombic efficiency of 99% at a current density of 0.5C. Overall, this work will tenure to protect the volume alteration of Si also enhanced the Li-ion storage for High-performance applications via a simple fabrication of Si/graphene aerogels composite anode. [Display omitted] • 3D porous graphene aerogel wrapped Si composite anode is constructed by hydrothrmal freeze drying route. • The porous structure buffers the volume expansion of Si. • Electrochemical performance of Si is improved by 3D structure graphene aerogel • The Si/GA (1:2) composite anode shows better Li-ion storage cyclic and rate test. [ABSTRACT FROM AUTHOR]

Mesoporous spinel ZnMn 2 O 4 (ZMO) microspheres as potential anode materials for sodium-ion batteries are prepared using the polyvinyl pyrrolidone (PVP)-assisted solvothermal technique. A one-step heat treatment process with heating varying from 1 to 5 °C min−1 is used to reveal the crystal phase purity and tuning of porosity of the as-prepared materials. The ZnMn 2 O 4 synthesized by heating rate of 1 °C min−1 exhibits the highest specific surface area (47.016 m2 g−1) and pore size (23.342 nm). The slow heating rate sample exhibited better capacity and rate capability compared with the sample with the fast heating rate. The electrochemical reaction mechanism is epitomized by ex-situ X-ray powder diffraction/X-ray photoelectron spectroscopy analyses that revealed the conversion mechanism of the ZnMn 2 O 4 electrode during charge and discharge processes. The results indicate that PVP-assisted approach provide porous microspheres of ZnMn 2 O 4 demonstrates enhanced electrochemical performance due to a larger surface area and porosity to facilitate faster Na+ diffusion kinetics. Image 1 • Spinel ZnMn2O4 material produced by solvothermal with post heat treatment route. • PVP assistance with slow heating rate synergistically improves the microstructure. • Superior Na-ion storage exhibits slow ramp rate comparably high ramp rates. • Reaction mechanism was investigated by ex-situ XRD/XPS analyses. [ABSTRACT FROM AUTHOR]

Spinel structure comprising Co and Mn with formula of Co (1− x) Mn x V 2 O 4 (x = 0, 0.25, 0.50, and 0.75) nanocomposite materials were successfully synthesized using solvothermal technique and incorporated in anode material for Li-ion storage for the first time. The specific surface area was tuned by altering the Co and Mn atomic ratios in the CoV 2 O 4 structure. The specific surface areas of 26.94, 25.49, 29.82, and 8.54 m2/g were obtained for CoV 2 O 4 , Co 0.75 Mn 0.25 V 2 O 4 , Co 0.50 Mn 0.50 V 2 O 4 , and Co 0.75 Mn 0.25 V 2 O 4 , respectively. Besides, the resultant product physicochemical and electrochemical properties were systematically characterized. An eco-friendly and water-based carboxyl methyl cellulose with styrene butadiene rubber (CMC/SBR) binder was used to prepare an active electrode. The sample with equal concentrations of Co and Mn in the V O matrix exhibited a higher reversible specific capacity and rate performance than other concentration of Mn-doped samples. A specific capacity of 1364.47 mAh/g was obtained at a current density of 0.1 A/g over 100 cycles. The high cyclic and rate performance were mainly attributed to a large surface area with fine adhesion between active materials and a current collector. The theoretical calculations of CoV 2 O 4 and Co 0.5 Mn 0.5 V 2 O 4 indicated that band gaps decreased after Mn substitution, which could explain rate capability of Mn-substitute one demonstrate much better performance. The results indicate that composition-optimized Co 0.5 Mn 0.5 V 2 O 4 anode is a potential candidate for Li-ion battery applications. Unlabelled Image • Mn-modified cobalt vanadate materials for novel anodes in Li-ion batteries through solvothermal technique • Sample with equal proportion of Mn and Co content exhibited excellent electrochemical performance. • Co0.5Mn0.5V2O4 anode exhibited the reversible capacity of 1364 mAh/g at a current density of 0.1 A/g over 100 cycles. [ABSTRACT FROM AUTHOR]

Binary mixed transition-based metal oxides have some of the most potential as anode materials for rechargeable advanced battery systems due to their high theoretical capacity and tremendous electrochemical performance. Nonetheless, binary metal oxides still endure low electronic conductivity and huge volume expansion during the charge/discharge processes. In this study, we synthesized a reduced graphene oxide (rGO)-wrapped CoV2O4 material as the anode for sodium ion batteries. The X-ray diffraction analyses revealed pure-phased CoV2O4 (CVO) rGO-wrapped CoV2O4 (CVO/rGO) nanoparticles. The capacity retention of the CVO/rGO composite anode demonstrated 81.6% at the current density of 200 mA/g for more than 1000 cycles, which was better than that of the bare one of only 73.5% retention. The as-synthesized CVO/rGO exhibited remarkable cyclic stability and rate capability. The reaction mechanism of the CoV2O4 anode with sodium ions was firstly studied in terms of cyclic voltammetry (CV) and ex situ XRD analyses. These results articulated the manner of utilizing the graphene oxide-coated spinel-based novel anode-CoV2O4 as a potential anode for sodium ion batteries. [ABSTRACT FROM AUTHOR]

In this study, ZnIn 2 S 4 (B-ZIS) and ZnIn 2 S 4 /C (S-ZIS) composites anode are synthesized using hydrothermal method and followed by ball-milling process. The initial discharge/charge capacities for bare ZnIn 2 S 4 (B-ZIS) are 524 and 378 mAh g−1 under a current density of 1 A g−1, which suffers from gradually capacity fading. To improve its cycle stability, high-energy ball-milling process (HEBM) with carbon black is applied to fabricate S-ZIS spherical particles. The as-obtained composite anode exhibits enhanced electrochemical performances not only on cycle stability, but also reversible capacity. The discharge and charge capacity of S-ZIS approach to 823 and 679 mAh g−1 at the first cycle and retain 468 and 459 mAh g−1 after 500 cycles at the high current density of 1 A g−1. Furthermore, ex situ X-ray diffraction (XRD) and ex situ X-ray photoelectron spectroscopy (XPS) techniques are used to monitor the evaluation of crystal structure of B-ZIS during charge and discharge processes. The results indicate that the metallic Zn and In were observed at low potential voltage during sodiation process and successfully converted back to spinel phase at above 0.5 V. The presence of high reversibility nature of B-ZIS may leads to the superior cycling and excellent rate capability of S-ZIS which makes ZnIn 2 S 4 a potential anode material of sodium ion batteries. [Display omitted] [ABSTRACT FROM AUTHOR]