Nanosheets of earth-abundant jarosite as novel anodes for high-rate and long-life lithium-ion batteries

Facile Synthesis and Phase Stability of Cu-based Na2Cu(SO4)2.xH2O (x = 0-2) Sulfate Minerals as Conversion type Battery Electrodes

Mineral exploration forms a key approach to unveil functional battery electrode materials. Synthetic preparation of naturally found minerals and their derivatives can aid in design of new electrodes. Herein, saranchinaite...

An overview of hydroxy-based polyanionic cathode insertion materials for metal-ion batteries

Rechargeable batteries based on Li-ion and post Li-ion chemistry have come a long way since their inception in the early 1980s. The last four decades have witnessed steady development and discovery of myriads of cathode materials taking into account their processing, economy, and performance along with ecological sustainability. Though oxides rule the battery sector with their high energy and power density, polyanionic insertion compounds work as gold mines for designing insertion compounds with rich structural diversity leading to tuneable redox potential coupled with high structural/chemical/thermal stability. The scope of polyanionic compounds can be taken a step further by combining two or more different types of polyanions to get suites of mixed polyanionic materials. While most cathodes are built with metal polyhedra constituted by oxygen (MO_m|XO_m, M = 3d metals, X = P, S, Si, B, W, etc., m = 3-6), in some cases, selected oxygen sites can form bonding with hydrogen to form OH/H₂O ligands. It can lead to the family of hydroxy-based mixed-polyanionic cathode materials. The presence of hydroxy components can affect the crystal structure, local chemical bonding, and electronic, magnetic, diffusivity and electrochemical properties. Employing a mineralogical survey, the current review renders a sneak peek on various hydroxy-based polyanionic cathode materials for Li-ion and post Li-ion batteries. Their crystal structure, and electrochemical properties have been overviewed to outline future research focus and scope for real-life application.

Synthesis of Hydronium-Potassium Jarosites: The Effect of pH and Aging Time on Their Structural, Morphological, and Electrical Properties

Structural and morphological properties of hydronium-potassium jarosite microstructures were investigated in this work, and their electrical properties were evaluated. All the microstructures were synthesized at a very low temperature of 70 °C with a reduced reaction time of 3 h. An increase in the pH from 0.8 to 2.1 decreased the particle sizes from 3 µm to 200 nm and an increase in the aging time from zero, three, and seven days resulted in semispherical, spherical, and euhedral jarosite structures, respectively. The Rietveld analysis also confirmed that the amount of hydronium substitution by potassium in the cationic site increased with an increase in pH. The percentages of hydronium jarosite (JH)/potassium jarosite (JK) for pH values of 0.8, 1.1, and 2.1 were 77.72/22.29%, 82.44/17.56%, and 89.98/10.02%, respectively. Microstructures obtained in this work were tested as alternative anode materials and the voltage measured using these electrodes made with hydronium-potassium jarosite microstructures and graphite ranged from 0.89 to 1.36 V. The results obtained in this work show that with reduced particle size and euhedral morphology obtained, modified jarosite microstructures can be used as anode materials for improving the lifetime of lithium-ion batteries.

Facile fabrication of a jarosite ultrathin KFe3(SO4)2(OH)6@rGO nanosheet hybrid composite with pseudocapacitive contribution as a robust anode for lithium-ion batteries

Earth-abundant and acid-resistant KFe₃(SO₄)₂(OH)₆@rGO nanosheets deliver stable lithium storage properties, owing to the induced pseudocapacitive contribution.

Homogeneous cationic substitution for two-dimensional layered metal oxide nanosheets via a galvanic exchange reaction

The galvanic exchange reaction of an exfoliated 2D layered metal oxide nanosheet (NS) with excess substituent metal cations enables the synthesis of a mixed metal oxide 2D NS with controllable cation compositions and physicochemical properties. The reaction of the exfoliated MnO₂ NS with Fe²⁺ or Sn²⁺ ions at 90 °C induces the uniform galvanic replacement of Mn ions with these substituent ions, whereas the same reaction at 25 °C results in the intercalative restacking of the negatively-charged MnO₂ NS with Fe²⁺ or Sn²⁺ cations. Upon the galvanic exchange reaction, the highly anisotropic MnO₂ 2D NS retains its original 2D morphology and layered structure, which is in stark contrast to 0D nanoparticles yielding hollow nanospheres via the galvanic exchange reaction. This observation is attributable to the thin thickness of the 2D NS allowing the simultaneous replacement of all the component surface-exposed metal ions. The resulting substitution of the MnO₂ NS with Fe and Sn ions remarkably improves the electrode performance of the carbon-coated derivatives of the MnO₂ NS for lithium ion batteries. The present study clearly demonstrates that the galvanic exchange reaction can provide an efficient method not only to tailor cation compositions but also to improve the functionalities of 2D metal oxide NSs and their carbon-coated derivatives.

In situ formation of flower-like CuCo2S4 nanosheets/graphene composites with enhanced lithium storage properties

Flower-like CuCo₂S₄ nanosheets/graphene composites (abbreviated as CCS–G) were prepared by using a one-pot hydrothermal method.

Two-Dimensional Porous Carbon: Synthesis and Ion-Transport Properties

Their chemical stability, high specific surface area, and electric conductivity enable porous carbon materials to be the most commonly used electrode materials for electrochemical capacitors (also known as supercapacitors). To further increase the energy and power density, engineering of the pore structures with a higher electrochemical accessible surface area, faster ion-transport path and a more-robust interface with the electrolyte is widely investigated. Compared with traditional porous carbons, two-dimensional (2D) porous carbon sheets with an interlinked hierarchical porous structure are a good candidate for supercapacitors due to their advantages in high aspect ratio for electrode packing and electron transport, hierarchical pore structures for ion transport, and short ion-transport length. Recent progress on the synthesis of 2D porous carbons is reported here, along with the improved electrochemical behavior due to enhanced ion transport. Challenges for the controlled preparation of 2D porous carbons with desired properties are also discussed; these require precise tuning of the hierarchical structure and a clarification of the formation mechanisms.

Impact of Morphology of Conductive Agent and Anode Material on Lithium Storage Properties

In this study, the impact of morphology of conductive agent and anode material (Fe₃O₄) on lithium storage properties was throughly investigated. Granular and belt-like Fe₃O₄ active materials were separately blended with two kinds of conductive agents (i.e., granular acetylene black and multi-walled carbon nanotube) as anodes in lithium-ion batteries (LIBs), respectively. It was found that the morphology of conductive agent is of utmost importance in determining LIBs storage properties. In contrast, not as the way we anticipated, the morphology of anode material merely plays a subordinate role in their electrochemical performances. Further, the morphology-matching principle of electrode materials was discussed so as to render their utilization more rational and effective in LIBs.