Aqueous rechargeable lithium battery (ARLB) based on LiV3O8 and LiMn2O4 with good cycling performance

Hierarchical nanostructured hollow core/mesopore shell carbon (HN-HCMSC) represents an innovative concept in electrochemical hydrogen storage. This work deals with physical characteristics and electrochemical hydrogen storage behavior of the HN-HCMSCs, produced by a replica technique using solid core/mesopore shell (SCMS) silica as template. HN-HCMSCs with various core sizes and/or shell thicknesses have been fabricated through the independent control of the core sizes and/or shell thicknesses of the SCMS silica templates. The superb structural characteristics of the HN-HCMSCs including large specific surface area and micropore volume, and particularly well-developed three-dimensionally interconnected hierarchical nanostructure (hollow macroporous core in combination with meso-/microporous shell), provide them with great potential for electrochemical hydrogen storage. A discharge capacity up to 586 mAh/g, corresponding to 2.17 wt % hydrogen uptake, has been demonstrated in 6 M KOH for the HN-HCMSC with a ...

Controllable synthesis of hierarchical nanostructured hollow core/mesopore shell carbon for electrochemical hydrogen storage.

Outlook on K-Ion Batteries

Nanosize crystalline cathode materials of LiNiyMn2 −
					yO4
				(0 < y
				≤ 0.5) composition and spinel-type structure have been obtained by a single-step sucrose-aided self-combustion method. The as-prepared samples contained some amorphous organic impurities that were removed after a short period of heating at 500 °C. The pure single-phase spinels have been characterized by X-ray diffraction, transmission electron microscopy, chemical analysis, and nitrogen sorption isotherms. The samples consist of particles (ca. 24 nm size) that are aggregated in clusters (ca. 1 µm size) in which mesopores (10–80 nm size) appear among the particles. Additional heating at 800° and 1000 °C produces a slight increase in the cubic lattice parameter and a pronounced increase in particle size (>100 nm). Electrical conductivity decreases as the Ni content increases in accordance with an electron hopping mechanism between Mn3+ and Mn4+ ions. The 500 °C- and 800 °C-heated LiNi0.5Mn1.5O4 samples show good electrochemical behaviour at 4.7 V as cathode materials. The capacity (132.7 mA h g−1) found is close to the nominal capacity (146.7 mA h g−1) and remains constant for current densities in the range C/24–2C
				(where C
				= 2.6 mA cm−2). At higher current densities (2C–10C) the capacity decreases progressively. The cyclability at the C current density is ca. 99.7% for both samples.

Nanosize LiNiyMn2 −yO4(0 < y≤ 0.5) spinels synthesized by a sucrose-aided combustion method. Characterization and electrochemical performance

Newly developed LiNi 0 . 7 5 - x Co 0 . 2 5 Mn x O 2 (0.1 ≤ x ≤ 0.25) cathode materials were successfully synthesized by mixing Ni 0 . 7 5 - x Co 0 . 2 5 Mn x (OH) 2 and Li 2 CO 3 via the solid-state reaction followed by heating to elevated temperatures. X-ray diffraction patterns showed that the samples calcined at 900°C exhibited a typical hexagonal α-NaFeO 2 structure without any other impurities present. The ratio of peak intensities of (003) to (104) decreased with the increasing Mn content. The scanning electron microscopy micrograph revealed uniform primary particle size, and the small primary particles agglomerated to form the secondary ones with size distribution in the range of 6-9 μm. The X-ray photoelectron spectroscopy measurement indicated that the valence of Ni ions was a mixture of 2+ and 3+. The amount of Mn substituted for Ni increased proportional to the ratio of Ni 2 + /Ni 3 + in the samples was increased. Besides, for dynamic equilibrium (Ni 2 + + Mn 4 + ↔ Ni 3 + Mn 3 + ), small amount Mn 4 + was reduced to Mn 3 + . After cycling, the cathode materials showed good electrochemical performance, with initial discharge capacity around 170 mAh/g at 0.1 C rate in the voltage range of 3-4.3 V. At a high rate of 1 C, 85% efficiency was still attainable in all samples.

https://iopscience.iop.org/article/10.1149/1.1952687/pdf

Effect of Mn Content on the Microstructure and Electrochemical Performance of LiNi0.75 − xCo0.25MnxO2 Cathode Materials

LiMn 2 O 4 samples were prepared by solid-state reaction at various temperatures between 650 and 900°C from LiOH and MnO 2 (chemical manganese dioxide, CMD). Other samples were also prepared at 750°C with a different cooling rate, or for different periods of time (24 and 72 h), with the other conditions being identical. X-ray diffraction patterns of the prepared samples are identified as the spinel structure with a space group Fd3m. The lattice parameter increases gradually as the sintering temperature rises. The potential vs. lithium ion concentration curves exhibit two distinct plateaus. The sample sintered at 750°C for 48 h (intermediately cooled at a cooling rate of 1°C/min) has the largest first discharge capacity and shows the best cycling performance. It is believed that the best electrochemical properties of this sample result from its crystallinity and its large grain size as compared with other samples. The particles of this sample are relatively large and uniform in size. To investigate the crystallinity of the prepared samples, we introduced a crystallinity index I max /B. where I max is the maximum intensity of a diffraction peak considered and B is the width at an intensity equal to half I max .

Variations of the Electrochemical Properties of LiMn2 O 4 with Synthesis Conditions

Improvement in the cycling performance of LiMn2O4 by the substitution of Fe for Mn

A series of multicomponent Zr 0.5 Ti 0.5 Mn 0.4 V 0.6 Ni 0.85 M 0 15 (M = Fe, Co, Cu, Mo, and Al) alloys are prepared and their crystal structure and pressure-composition-temperature curves are examined. The electrochemical properties of these alloys such as discharge capacity, cycling performance, and rate capability are also investigated. Zr 0.5 Ti 0.5 Mn 0.4 V 0.6 Ni 0.85 M 0.15 (M = Fe, Co, Cu, Mo, and Al) alloys have predominantly C14 Laves phases multiple phase structure, The alloys with M = Co and Fe have relatively larger hydrogen storage capacities. The discharge capacities just after activation are relatively large in the case of the alloys with M = Co and Fe. They are 226 and 225 mAh/g. respectively, at the current density 60 mA/g. The Zr 0.5 Ti 0.5 Mn 0.4 V 0.6 Ni 0.85 Co 0 15 alloy is the best one with a relatively large discharge capacity and good cycling performance. The gradual increases in the discharge capacities of the alloys with the increase in the current density (from 60 to 250 mA/g) are considered to result from the spontaneous hydrogen evolution due to an insufficient hydrogen overvoltage, During activation Ni-rich and Fe-rich regions form on the surface of the Zr 0.5 Ti 0.5 Mn 0.4 V 0.6 Ni 0.85 Fe 0 15 alloy. They may act as active sites for the electrochemical reaction. With the increase in the number of charge/discharge cycles for the Zr 0.5 Ti 0.5 Mn 0.4 V 0.6 Ni 0.85 Fe 0 15 alloy, the quantities of the zirconium and iron dissolved in the solution increase.

DongSu Ahn

Papers

Variations of the Electrochemical Properties of LiMn2 O 4 with Synthesis Conditions

Improvement in the cycling performance of LiMn2O4 by the substitution of Fe for Mn

Development of AB 2-Type Zr-Ti-Mn-V-Ni-M Hydride Electrode for Ni-MH Secondary Battery

Development of AB2-type Zr–Ti–Mn–V–Ni–Fe hydride electrodes for Ni–MH secondary batteries