Alginate-Xylan Biopolymer as a Multifunctional Binder for 5 V High-Voltage LNMO Electrodes.

LiNi0.5Mn1.5O4 (LNMO) with a spinel structure is one of the most promising cathode materials choices for Li-ion batteries (LIBs). However, at a high operating voltages, the decomposition of organic electrolytes and the dissolution of transition metals, especially Mn(II) ions, cause unsatisfactory cycle stability. The initial application of a sodium alginate (SA)-xylan biopolymer as an aqueous binder aims to address the aforementioned problems. The SX28-LNMO electrode has a sizable discharge capacity, exceptional rate capability, and long-term cyclability with a capacity retention of 99.8% after 450 cycles at 1C and a remarkable rate capability of 121 mAh g-1 even at 10C. A more thorough investigation illustrated that SX28 binder provides a substantial adhesion property and generates a uniform (CEI) layer on the LNMO surface, suppressing electrolytes' oxidative decomposition upon cycling and improving LIB performances. This work highlights the potential of hemicellulose as an aqueous binder for 5.0 V high-voltage cathodes.

In Situ Preparation of High-Performance Silicon-Based Integrated Electrodes Using Cross-Linked Cyclodextrins.

The strategy of material modification for improving the stability of silicon electrodes is laborious and costly, while the conventional binders cannot withstand the repeated massive volume variability of silicon-based materials. Hence, there is a demand to settle the silicon-based materials' problems with green and straightforward solutions. This paper presents a high-performance silicon anode with a binder obtained by in situ thermal cross-linking of citric acid (CA) and ß-cyclodextrin (ß-CD) during the electrode preparation process. The Si electrode with a binder synthesized by the one-pot method shows excellent cycling performance. It maintains a specific capacity of 1696 mAh·g-1 after 200 cycles at a high current of 0.5 C. Furthermore, the carbonylation of ß-CD to carbonyl-ß-CD (c-ß-CD) introduced better water solubility, and the c-ß-CD can generate multidimensional connections with CA and Si, which significantly enhances the specific capacity to 1941 mAh·g-1 at 0.5 C. The results demonstrate that the prepared integrated electrode facilitates the formation of a stable and controllable solid electrolyte interface layer of Si and accommodates Si's repeated giant volume variations.

N-doped pinecone-based carbon with a hierarchical porous pie-like structure: a long-cycle-life anode material for potassium-ion batteries.

Pinecone-based biomass carbon (PC) is a potential anode material for potassium-ion batteries because it is abundant, cheap, renewable, and easy to obtain. However, because of inferior kinetics and the effects of volume expansion due to the large radius of the K+ ion, it does not meet commercial performance requirements. In this study, nitrogen-doped PC (NPC) was prepared by carbonization in molten ZnCl2 with urea as a nitrogen source. A strategy based on synergistic effects between N doping and ZnCl2 molten salt was used to produce a hierarchically porous pie-like NPC with abundant defects and active sites and an enlarged interlayer distance-properties that enhance K+ adsorption, promote K+ intercalation/diffusion, and reduce the effects of volume expansion. This NPC exhibited a high reversible capacity (283 mA h g-1 at 50 mA g-1) and superior rate performance and cyclic stability (110 mA h g-1 after 1000 cycles at 5 A g-1), demonstrating its potential for use in potassium-ion batteries.

Boron-Doped Pine-Cone Carbon With 3D Interconnected Porosity for Use as an Anode for Potassium-Ion Batteries With Long Life Cycle.

Potassium-ion batteries (KIBs) have received widespread attention as an alternative to lithium-ion batteries because of their low cost and abundance of potassium. However, the poor kinetic performance and severe volume changes during charging/discharging due to the large radius of potassium leading to low capacity and rapid decay. Therefore, development of anode materials with sufficient space and active sites for potassium ion deintercalation and desorption is necessary to ensure structural stability and good electrochemical activity. This study prepared boron-doped pine-cone carbon (BZPC) with 3D interconnected hierarchical porous in ZnCl2 molten-salt by calcination under high temperature. The hierarchical porous structure promoted the penetration of the electrolyte, improved charge-carrier diffusion, alleviated volume changes during cycling, and increased the number of micropores available for adsorbing potassium ions. In addition, due to B doping, the BZPC material possessed abundant defects and active centers, and a wide interlayer distance, which enhanced the adsorption of K ions and promoted their intercalation and diffusion. When used as the anode of a KIB, BZPC provided a high reversible capacity (223.8 mAh g-1 at 50 mA g-1), excellent rate performance, and cycling stability (115.9 mAh g-1 after 2000 cycles at 1 A g-1).

Cross-linked ß-CD-CMC as an effective aqueous binder for silicon-based anodes in rechargeable lithium-ion batteries.

As a non-active material component, the binder can effectively maintain the integrity of battery electrodes. In this work, based on the inspired structure of fishing nets, a three-dimensional mesh adhesive using widely sourced raw materials CMC and ß-CD was designed. These cross-linked cyclodextrins have the advantage of dispersing the stress at the anchor point and moderating the significant volume changes of the Si anode. The Si/ß-CD-CMC electrode maintains a reversible capacity of 1702 mA h g-1 even after 200 cycles at a high current of 0.5C. This work represents a significant step forward in Si anode binders and enables the cross-linked cyclodextrins to have potential applications in energy storage systems.

Proton solvent-controllable synthesis of manganese oxalate anode material for lithium-ion batteries.

Manganese oxalates with different structures and morphologies were prepared by the precipitation method in a mixture of dimethyl sulfoxide (DMSO) and proton solvents. The proton solvents play a key role in determining the structures and morphologies of manganese oxalate. Monoclinic MnC2O4·2H2O microrods are prepared in H2O-DMSO, while MnC2O4·H2O nanorods and nanosheets with low crystallinity are synthesized in ethylene glycol-DMSO and ethanol-DMSO, respectively. The corresponding dehydrated products are mesoporous MnC2O4 microrods, nanorods, and nanosheets, respectively. When used as anode material for Li-ion batteries, mesoporous MnC2O4 microrods, nanorods, and nanosheets deliver a capacity of 800, 838, and 548 mA h g-1 after 120 cycles at 8C, respectively. Even when charged/discharged at 20C, mesoporous MnC2O4 nanorods still provide a reversible capacity of 647 mA h g-1 after 600 cycles, exhibiting better rater performance and cycling stability. The electrochemical performance is greatly influenced by the synergistic effect of surface area, morphology, and size. Therefore, the mesoporous MnC2O4 nanorods are a promising anode material for Li-ion batteries due to their good cycle stability and rate performance.

Deep Eutectic Solvent Synthesis of LiMnPO4/C Nanorods as a Cathode Material for Lithium Ion Batteries.

Olivine-type LiMnPO4/C nanorods were successfully synthesized in a chloride/ethylene glycol-based deep eutectic solvent (DES) at 130 °C for 4 h under atmospheric pressure. As-synthesized samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR) and electrochemical tests. The prepared LiMnPO4/C nanorods were coated with a thin carbon layer (approximately 3 nm thick) on the surface and had a length of 100-150 nm and a diameter of 40-55 nm. The prepared rod-like LiMnPO4/C delivered a discharge capacity of 128 mAh·g-1 with a capacity retention ratio of approximately 93% after 100 cycles at 1 C. Even at 5 C, it still had a discharge capacity of 106 mAh·g-1, thus exhibiting good rate performance and cycle stability. These results demonstrate that the chloride/ethylene glycol-based deep eutectic solvents (DES) can act as a new crystal-face inhibitor to adjust the oriented growth and morphology of LiMnPO4. Furthermore, deep eutectic solvents provide a new approach in which to control the size and morphology of the particles, which has a wide application in the synthesis of electrode materials with special morphology.

Fast Preparation of Porous MnO/C Microspheres as Anode Materials for Lithium-Ion Batteries.

Porous MnO/C microspheres have been successfully fabricated by a fast co-precipitation method in a T-shaped microchannel reactor. The structures, compositions, and electrochemical performances of the obtained MnO/C microspheres are characterized by X-ray diffraction, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (HRTEM), Brunauer-Emmett-Teller analysis, charge-discharge testing, cyclic voltammograms, and electrochemical impedance spectra. Experimental results reveal that the as-prepared MnO/C, with a specific surface area of 96.66 m²·g-1 and average pore size of 24.37 nm, exhibits excellent electrochemical performance, with a discharge capacity of 655.4 mAh·g-1 after cycling 50 times at 1 C and capacities of 808.3, 743.7, 642.6, 450.1, and 803.1 mAh·g-1 at 0.2, 0.5, 1, 2, and 0.2 C, respectively. Moreover, the controlled method of using a microchannel reactor, which can produce larger specific surface area porous MnO/C with improved cycling performance by shortening lithium-ion diffusion distances, can be easily applied in real production on a large scale.

Enhanced supercapacitor performance of Mn3O4 nanocrystals by doping transition-metal ions.

Pristine and transition-metal-doped Mn3O4 nanocrystals shaped in octahedrons have been synthesized by hydrothermal reduction of potassium permanganate and characterized by SEM/TEM, X-ray diffraction, X-ray photoelectron spectroscopy, and electrochemical experiments. The results reveal that a multistep reduction process is taking place, and the introduction of doping ions causes a direct synthesis of single-phase Mn3O4 nanocrystals. To assess the properties of Mn3O4 nanocrystals for their use in supercapacitors, cyclic voltammetry and galvanostatic charging-discharging measurements are performed. The phase stability during cycling and charge-transfer behavior are greatly improved by doping with transition metal, and Cr-doped Mn3O4 nanocrystals exhibit a maximum specific capacitance of 272 F g(-1) at a current density of 0.5 A g(-1). These doped Mn3O4 nanocrystals could be a promising candidate material for high-capacity, low-cost, and environmentally friendly electrodes for supercapacitors. In addition, these results have verified the ability of doping to improve capacitive performances of spinel-structured transition-metal oxides.