Cathode For Rechargeable Batteries Research Articles

Recent Advances in the Multifunctional Natural Gum-Based Binders for High-Performance Rechargeable Batteries

Natural gum derived from the natural surrounding (gum arabic, guar gum, xanthan gum, gellan gum, fenugreek gum, karaya gum, and acacia gum) is one of the most abundant polysaccharides currently present around the world. As natural gum dissolved solution can be very sticky in nature, its role as a binder for both anodes and cathodes in rechargeable batteries have been recently significantly researched. Although much research has been delved into using natural gum as a feasible binder for rechargeable batteries, little investigation so far has taken place to compile, summarize, analyze, and evaluate the current status-quo of the natural gum-based binder research, as well as understanding some of the obstacles and issues that may need to be addressed. This review gives a comprehensive review on the natural gum-based binder that was used for both anode and cathode in rechargeable batteries and how each kind of natural gum improved the electrochemical performance in terms of cycle retention and rate capabilities. Furthermore, more systematic analysis and future projections for the research on natural gum-based binders are presented, which will serve to further the promising research related to utilizing natural gum as an efficient binder for rechargeable battery systems.

Graphite-Like Carbon-Decorated δ-MnO2 Nanoparticles as a High-Performance Cathode for Rechargeable Zinc-Ion Batteries

Graphite-Like Carbon-Decorated δ-MnO2 Nanoparticles as a High-Performance Cathode for Rechargeable Zinc-Ion Batteries

High-Rate Organic Cathode Constructed by Iron-Hexaazatrinaphthalene Tricarboxylic Acid Coordination Polymer for Li-Ion Batteries.

The sluggish ion-transport in electrodes and low utilization of active materials are critical limitations of organic cathodes, which lead to the slow reaction dynamics and low specific capacity. In this study, the hierarchical tube is constructed by iron-hexaazatrinaphthalene tricarboxylic acid coordination polymer (Fe-HATNTA), using HATNTA as the self-engaged template to coordinate with Fe2+ ions. This Fe-HATNTA tube with hierarchical porous structure ensures the sufficient contact between electrolyte and active materials, shortens the diffusion distance, and provides more favorable transport pathways for ions. When employed as the cathode for rechargeable Li-ion batteries, Fe-HATNTA delivers a high specific capacity (244 mAh g-1 at 50 mA g-1 , 91% of theoretical capacity), excellent rate capability (128 mAh g-1 at 9 A g-1 ), and a long-term cycle life (73.9% retention over 3000 cycles at 5 A g-1 ). Moreover, the Li+ ions storage and conduction mechanisms are further disclosed by the ex situ and in situ characterizations, kinetic analyses, and theoretical calculations. This work is expected to boost further enthusiasm for developing the hierarchical structured metal-organic coordination polymers with superb ionic storage and transport as high-performance organic cathodes.

Superlattice-Stabilized WSe2 Cathode for Rechargeable Aluminum Batteries.

Rechargeable aluminum batteries (RABs), with abundant aluminum reserves, low cost, and high safety, give them outstanding advantages in the postlithium batteries era. However, the high charge density (364 C mm-3 ) and large binding energy of three-electron-charge aluminum ions (Al3+ ) de-intercalation usually lead to irreversible structural deterioration and decayed battery performance. Herein, to mitigate these inherent defects from Al3+ , an unexplored family of superlattice-type tungsten selenide-sodium dodecylbenzene sulfonate (SDBS) (S-WSe2 ) cathode in RABs with a stably crystal structure, expanded interlayer, and enhanced Al-ion diffusion kinetic process is proposed. Benefiting from the unique advantage of superlattice-type structure, the anionic surfactant SDBS in S-WSe2 can effectively tune the interlayer spacing of WSe2 with released crystal strain from high-charge-density Al3+ and achieve impressively long-term cycle stability (110 mAh g-1 over 1500 cycles at 2.0 A g-1 ). Meanwhile, the optimized S-WSe2 cathode with intrinsic negative attraction of SDBS significantly accelerates the Al3+ diffusion process with one of the best rate performances (165 mAh g-1 at 2.0 A g-1 ) in RABs. The findings of this study pave a new direction toward durable and high-performance electrode materials for RABs.

Ultrathin edge-rich structure of Co3O4 enabling the low charging overpotential of Li-O2 battery

• Ultrathin and edge-rich Co 3 O 4 was fabricated and adopted for Li-O 2 catalyst. • The u-Co 3 O 4 tended to induce the formation of thin and loosely aggregated Li 2 O 2 . • High Co 3+ /Co 2+ ratio was benefit for the decomposition of discharge products. The kinetics of the oxygen reduction reaction and oxygen evolution reaction at the rechargeable lithium-oxygen battery cathode are still need to be greatly improved, and transition metal oxides-based catalysts usually suffer from low conductivity and insufficient active sites. Herein, an ultrathin and edge-rich Co 3 O 4 (u-Co 3 O 4 ) catalyst (thickness 3–4 nm) is proposed to lower the overpotential and enhance the cyclability of non-aqueous Li-O 2 battery. The unique structure endows Co 3 O 4 with high electronic conductivity, high specific surface area and abundant active sites. And the high density of Co 3+ ions exposed on surface can serve as active centers for decomposing the discharge products. This u-Co 3 O 4 catalyst tented to induce forming thin and loosely aggregated Li 2 O 2 as discharge products. Electrochemical impedance spectroscopy reveals that a faster charge transmission realized inside the u-Co 3 O 4 -based cell after discharge. Scanning electron microscopy and X-ray diffraction techniques suggest the u-Co 3 O 4 can perfectly catalyze decomposing the discharge products during recharge. Consequently, this u-Co 3 O 4 provided a ∼0.20 V lowered overpotential and an almost 2-fold cycling life for Li-O 2 battery in comparison with traditional Co 3 O 4 catalyst.

Electrospinning Preparation of a High-Rate Self-Supported Cathode for Rechargeable Aqueous Zinc-Ion Batteries

Electrospinning Preparation of a High-Rate Self-Supported Cathode for Rechargeable Aqueous Zinc-Ion Batteries

Synthesis and electrochemical investigation of lithium and cobalt dual-doped spinel LNMO nanomaterial as cathode for aqueous rechargeable lithium-ion battery

Synthesis and electrochemical investigation of lithium and cobalt dual-doped spinel LNMO nanomaterial as cathode for aqueous rechargeable lithium-ion battery

Highly Stable 4.6 V LiCoO2 Cathodes for Rechargeable Li Batteries by Rubidium-Based Surface Modifications.

Among extensively studied Li-ion cathode materials, LiCoO2 (LCO) remains dominant for portable electronic applications. Although its theoretical capacity (274mAh g-1 ) cannot be achieved in Li cells, high capacity (≤240 mAh g-1 ) can be obtained by raising the charging voltage up to 4.6V. Unfortunately, charging Li-LCO cells to high potentials induces surface and structural instabilities that result in rapid degradation of cells containing LCO cathodes. Yet, significant stabilization is achieved by surface coatings that promote formation of robust passivation films and prevent parasitic interactions between the electrolyte solutions and the cathodes particles. In the search for effective coatings, the authors propose RbAlF4 modified LCO particles. The coated LCO cathodes demonstrate enhanced capacity (>220mAh g-1 ) and impressive retention of >80/77% after 500/300 cycles at 30/45°C. A plausible mechanism that leads to the superior stability is proposed. Finallythe authors demonstrate that the main reason for the degradation of 4.6V cells is the instability of the anode side rather than the failure of the coated cathodes.

Sulfur Composite Cathodes for High-Capacity Aluminum Metal Anode Rechargeable Batteries

Recently, needs to rechargeable batteries have been diversified into various kinds due to expansion of their application range. Not only future high-performance batteries exceeding Li-ion batteries (LiBs), but also new concept ones, which are composed solely of common elements and have performance comparable to current LiBs, have become one of the important recent research targets in this area. Focusing rich abundance and very-high theoretical capacity (2980 mAh g-1, 8046 mAh cm-3) of aluminum (Al) metal, we have created new concept rechargeable batteries with the following anode reaction in chloroaluminate ionic liquids (ILs):1,2 4[Al2Cl7]- + 3e- ⇌ Al + 7[AlCl4]- Many research groups have also reported similar Al metal anode batteries.3 Herein, some sulfur (S) composite cathodes that enable the use of S(IV)/S electrode reaction are designed to greatly enhance the capacity of Al metal anode battery.The preparation and purification processes for 60.0-40.0 mol% AlCl3–[C2mim]Cl and 61.0-26.0-13.0 mol% AlCl3–NaCl–KCl IL electrolytes were identical with those described in our previous articles.1,2 Three types of cathode active materials, S-coated multi-walled carbon nanotube (S-MWCNT), sulfurized polyethylene glycol (SPEG),4 and sulfurized polyacrylonitrile (SPAN),5 were employed. All the S composite electrodes were prepared by pressing the mixtures of 50 wt% S-based cathode active materials, 45 wt% conductive additive (MWCNT), and 5 wt% polytetrafluoroethylene onto Mo plate current collectors. Al metal plate was employed as the anode active material. Electrochemical experiments were carried out with a commonly used three-electrode cell or a two-electrode sealed cell in an Ar gas-filled glove box with O2 and H2O < 1 ppm.Figure 1 shows multiple cyclic voltammograms recorded at a S-MWCNT composite electrode in a three-electrode cell with 60.0-40.0 mol% AlCl3–[C2mim]Cl at 298 K. When the potential scan was initiated from the rest potential to the negative direction, a pair of reduction and oxidation waves appeared with large over potential. These waves gradually varied with an increase in the number of cycles. Considering the article reported by Gao et al.,6 the redox waves observed in Fig. 1a can be regarded to be the following electrochemical reaction (S/S2-):3S + 8[Al2Cl7]- + 6e- ⇌ Al2S3 + 14[AlCl4]- As for the positive scan from the rest potential (Fig. 1b), several oxidation and reduction waves were observed. Overpotential obviously diminished compared to that for the S/S2-. Similar electrode behavior for S in a Lewis acidic 63-37 mol% AlCl3–NaCl molten salt is reported by Marassi, et al.7 Given that the electrochemical reaction process is the same, the number of electrons involved in the reaction is estimated to be 4. Then, the electrochemical reaction (S(IV)/S) is:[SCl3]+ + 3[Al2Cl7]- + 4e- ⇌ S + 6[AlCl4]- If we can apply this S(IV)/S reaction to the Al metal anode-S cathode rechargeable battery, S cathode capacity becomes double and higher working voltage is expected relative to conventional S/S2- one. Unfortunately, the redox waves for the reaction decrease sharply with increase in the cycle number. The waves almost disappeared at the 5th cycle. Analogous results were also obtained in the 61.0-26.0-13.0 mol% AlCl3–NaCl–KCl. We concluded that the electrode reaction for S(IV)/S on the S-MWCNT composite cathode is not suitable for battery application. However, the use of S-combined active materials, SPEG and SPAN, substantially improved the electrode reaction in the 61.0-26.0-13.0 mol% AlCl3–NaCl–KCl IL at 393 K. Thus, we carried out the charge-discharge test for the Al | SPEG and Al | SPAN batteries with the inorganic IL electrolyte using both S/S2- and S(IV)/S electrode reactions. If SPEG was used, the discharge capacity was ca. 1050 mAh (g-S)-1 at 50th cycle. When using only S/S2- reaction, such high capacity was not attained.2 The S(IV)/S electrode reaction should be directly involved in the capacity increase. Interestingly, the use of SPAN made further improvement possible. One of the typical results is shown in Fig. 2. At the first cycle, the discharge capacity reached ca. 4700 mAh (g-S)-1 and showed ca. 2600 mAh (g-S)-1 even after 50th cycle. These results suggest that the S-combined active material, i.e., SPEG and SPAN, composite electrodes can work as the high-capacity cathodes for Al metal anode rechargeable battery.This research was supported by JST-MIRAI program (JPMJMI17E9). SPAN was provided by ADEKA corporation. References Tsuda, et al., J. Electrochem. Soc., 161, A908 (2014).Tsuda, et al., Chem. Commun., 58, 1518 (2022).Ru, et al., J. Mater. Chem. A, 7, 14391 (2019).Kojima, et al., ECS Trans., 75, 201 (2017).S. Ahmed, et al., Adv. Sci., 8, 2101123 (2021).Gao, et al., Angew. Chem. Int. Ed., 55, 9898 (2016).Marassi, et al., J. Electrochem. Soc., 126, 231 (1979). Figure 1

Polyanthraquinonyl sulfide cathodes for rechargeable magnesium batteries: Effect of structure on the performance

Rechargeable magnesium batteries (RMBs) attract special interests as a low-cost and reliable energy-storage technology, but the development is hindered by the low capacities and sluggish Mg2+ diffusion kinetics of the traditional inorganic cathode materials. Organic polymers break the hindrance of inorganic lattice and deliver plenty of candidates for RMB cathodes with the flexible and designable frameworks. Herein, three organic polyanthraquinonyl sulfides (PAQSs) are fabricated and investigated comparatively as RMB cathodes to reveal the effect of structure on the electrochemical magnesium-storage performance. It is demonstrated that the capacity decay is primarily owing to the dissolution of the discharge products (magnesiation state) in the electrolyte. The degree of polymerization is an important factor for the cycling stability. Prominently, poly(2,6-anthraquinonyl sulfide) shows an outstanding comprehensive performance, providing a high capacity (145 mAh g−1 at 50 mA g−1), an outstanding rate capability (74 mAh/g at 10C) and an excellent cyclability (99 % capacity retained after 1000 cycles at 5C). Significantly, poly(2,6-anthraquinonyl sulfide) store Mg2+ rather than MgCl+, and exhibits a considerable specific energy density of 185 Wh kg−1. The present work would assist the rational design of advanced organic RMB electrode materials, and highlights the advantages of organic polymers based on enolization chemistry for high-performance magnesium-storage.

Multifunctional carbon nanofibers coated Co-Zn alloy nanoparticles composite for efficient energy conversion and microwave absorption

Considering the energy crisis and environment pollution, it is urgently to develop multifunctional materials to ensure the sustainable development of human society. Core-shell bimetal/carbon composites have attracted great attention in microwave absorption or electrochemical energy conversion devices, and the composite can overcome the deficient performance of pure carbon materials or pure metal materials. In this work, we proposed a simple method to prepare N-doped carbon nanofibers coated CoZn alloy nanoparticle composites (CoZn/N-CNFs) using CoZn(OH)X nanowires and melamine as precursors through pyrolysis process. The prepared CoZn/N-CNFs exhibited outstanding catalytic property for oxygen reduction reaction (ORR, half-wave potential of 0.814 V vs RHE) in alkaline solution. The CoZn/N-CNFs acted as cathode in rechargeable Zn-air batteries (ZABs) exhibited high open circuit voltage (1.33 V), large output power density (223.8 mW cm−2), and robust stability (87 h, 6 cycles), surpassing the commercial Pt/C-based ZABs. In addition, as an excellent performance electromagnetic wave absorber, CoZn/N-CNFs exhibited favorable impedance matching and electromagnetic wave absorption ability, which has the RLmin of − 33.93 dB under a thickness of 2.1 mm, and the effective bandwidth (RL<−10 dB) of 4.56 GHz with the matching thickness of 2.2 mm. This composite is expected to be a desired metal/carbon composite for ZABs and electromagnetic absorption. This work provides a simple method for the development of multifunctional materials.

Nb2CTx MXene Cathode for High-Capacity Rechargeable Aluminum Batteries with Prolonged Cycle Lifetime.

Aluminum-ion batteries have garnered significant interest as a potentially safer and cheaper replacement for conventional lithium-ion batteries, offering a shorter charging time and denser storage capacity. Nonetheless, the progress in this field is considerably hampered by the limited availability of suitable cathode materials that can sustain the reversible intercalation of Al3+/[AlCl4]- ions, particularly after long cycles. Herein, we demonstrate that rechargeable Al batteries embedded with two-dimensional (2D) Nb2CTx MXene as a cathode material exhibit excellent capacity and exceptional long cyclic performance. We have successfully improved the initial electrochemical performance of Nb2CTx MXene after being properly delaminated to a single-layered microstructure and subjected to a post-synthesis calcining treatment. Compared to pristine Nb2CTx MXene, the Al battery embedded with the calcined Nb2CTx MXene cathode has, respectively, retained high capacities of 108 and 80 mAh g-1 after 500 cycles at current densities of 0.2 and 0.5 A g-1 in a wide voltage window (0.1-2.4 V). Noteworthily, the cyclic lifetime of Nb2CTx MXene was extended from ∼300 to >500 times after calcination. We reveal that attaining Nb2CTx nanosheets with a controllable d-spacing has promoted the migration of the [AlCl4]- and Al3+ ions in the MXene interlayers, leading to enhanced charge storage. Furthermore, we found out that the formation of niobium oxides and amorphous carbon after calcination probably benefits the electrochemical performance of Nb2CTx MXene electrode in Al batteries.

Morphology-modulation of (NH4)2V4O9 nanostructures for enhanced electrochemical performance as cathode material for aqueous rechargeable zinc ion batteries

Herein, we report a hydrothermal process to prepare controllable morphology (NH4)2V4O9 nanosheets by adjusting the amount of acetic acid. Further, the structure and electrochemical property of the (NH4)2V4O9 nanosheets are systematically investigated. The electrochemical tests show that the performance of (NH4)2V4O9 nanostructures is greatly dependent on the morphology of (NH4)2V4O9 samples as cathode materials for aqueous rechargeable zinc-ion batteries. In particular, the (NH4)2V4O9 nanosheets own better electrochemical performance compared with nanoparticles, which exhibit high reversible capacity (358.0 mAh·g−1 at 0.3 A·g−1), excellent cycle performance (82.2% capacity retention after 5000 cycles at 10 A·g−1) and as well as rate performance. The outstanding electrochemical performance of the as-prepared nanosheets can be assigned to well-regulated morphology. This work creates a new and efficient way to design cathodes for aqueous rechargeable zinc-ion batteries.

Bulk-phase and interface stability strategies of manganese oxide cathodes for aqueous Zn-MnOx batteries.

The cyclic stability of the MnOx cathodes for rechargeable zinc ion batteries have substantial obstacles due to Mn3+ disproportionation produces Mn2+ caused by Jahn Teller lattice distortion effect in the process of Zn2+ inter/deintercalation. This mini review summarized bulk-phase and interface stability strategies of manganese oxide cathodes for aqueous Zn-MnOx batteries from the regulation of bulk electronic state of manganese oxide improves its structural stability and the formation of beneficial SEI layer at the interface of electrolyte. It provides theoretical support for the design of manganese oxide cathode materials for aqueous zinc ion batteries with high stability.

Stabilizing High-Voltage LiNi0.5 Mn1.5 O4 Cathodes for High Energy Rechargeable Li Batteries by Coating With Organic Aromatic Acids and Their Li Salts.

Here, three types of surface coatings based on adsorption of organic aromatic acids or their Li salts are applied as functional coating substrates to engineer the surface properties of high voltage LiNi0.5 Mn1.5 O4 (LNMO) spinel cathodes. The materials used as coating include 1,3,5-benzene-tricarboxylic acid (trimesic acid [TMA]), its Li-salt, and 1,4-benzene-dicarboxylic acid (terephthalic acid). The surface coating involves simple ethanol liquid-phase mixing and low-temperature heat treatment under nitrogen flow. In typical comparative studies, TMA-coated (3-5%) LNMO cathodes deliver >90% capacity retention after 400 cycles with significantly improved rate performance in Li-coin cells at 30 °C compared to uncoated material with capacity retention of ≈40%. The cathode coating also prevents the rapid drop in the electrochemical activity of high voltage Li cells at 55 °C. Studies of high voltage full cells containing TMA coated cathodes versus graphite anodes also demonstrate improved electrochemical behavior, including improved cycling performance and capacity retention, increased rate capabilities, lower voltage hysteresis, and very minor direct current internal resistance evolution. In line with the highly positive effects on the electrochemical performance, it is found that these coatings reduce detrimental transition metal cations dissolution and ensure structural stability during prolonged cycling and thermal stability at elevated temperatures.

Ethynyl and Furyl Functionalized Porphyrin Complexes as New Organic Cathodes Enabling High Power Density and Long-Term Cycling Stability.

Organic cathode materials have recently attracted abundant attention due to their flexible structural tunability and recyclability. However, the low intrinsic electrical conductivity and high solubility in electrolytes of organic electrode materials have significantly limited their practical application. Herein, we present [5,15-bis(ethynyl)-10,20-difurylporphinato] copper(II) (CuDEOP) as a new cathode for rechargeable organic lithium batteries (ROLBs). The combination of both ethynyl and furyl groups of the CuDEOP cathode with a nanorod structure renders it with enhanced structural stability and an extended delocalized π-electron system to deliver excellent cycling stability (capacity retention of 76% after 6000 cycles) and a high power density (16 kW kg-1). The furyl electroactive groups participate in charge storage contribution to achieve a reversible six-electron-transfer redox reaction in a specific voltage range. The mechanism characterizations indicate that the nitrogen atoms on the porphyrin ring act as active sites to alternatively store both PF6- anions and Li+ cations, and the charge storage process is a pseudocapacitive-dominated reaction. This observation will offer a new avenue for designing functionalized molecules for electrochemical energy-storage (EES) systems.

Kinetically optimized copper sulfide cathodes for rechargeable magnesium batteries

Copper sulfides have been recognized as one of the most promising cathode materials for rechargeable magnesium batteries due to their large theoretical capacity and unique conversion-type mechanism. However, the solid-state diffusion of bivalent Mg2+ ions in CuS host lattice is subjected to huge electrostatic interaction and thus sluggish kinetics. Herein, anion substitution strategy and crystal engineering are reported to regulate electrochemical reaction kinetics and reinforce magnesium storage performances of tubular CuS cathodes. Benefitting from anion substitution and crystal facet regulation, the lattice well-exposed Se-substituted CuS nanotube cathodes demonstrate excellent magnesium storage capacity (372.9 mAh g−1 at 100 mA g−1), remarkable cycling stability (1600 cycles at 2.0 A g−1), and a good rate capability (112.4 mAh g−1 at 2.0 A g−1). Electrochemical kinetics investigation further suggests that anionic Se-substitution and crystal facet regulation can significantly optimize electrochemical reaction kinetics and accelerate diffusion rate of Mg2+ ions. Ex-situ X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) characterizations reveal the conversion reaction mechanism of Se-substituted CuS cathodes. These novel findings provide an effective approach to construct high-performance cathode materials for rechargeable magnesium batteries and hold great promise for development of other new battery systems.

Pyrolyzed Bacterial Cellulose as the Backbone of the Cathode Catalyst-CoFe2O4 for the Li-O2 Battery

In this paper, CoFe2O4@pyrolyzed bacterial cellulose (CFO@PBC) nanocomposites were synthesized by a hydrothermal process and an in situ composite technique as the cathode for rechargeable Li-O2 batteries (LOB). CoFe2O4@Ketjenblack (CFO@KB) were prepared in the same way as the comparison. The as-prepared materials were characterized by SEM, XRD, and BET. The LOB with CFO@PBC-3 showed a maximum initial discharge capacity of 2660 mAh g−1 (electrode) at the current density of 100 mAg−1, while the mass ratio of CoFe2O4 and pyrolyzed bacterial cellulose was 3. The cyclic voltammetry of the CFO@PBC nanocomposite electrodes was investigated at 0.1 mVs−1 in the voltage window of 2.0–4.5 V. With the limited capacity of 640 mAh g−1 (electrode), the CFO@PBC-3 electrode showed the best cycle stability and higher cutoff voltage of discharging. The pyrolyzed bacterial cellulose, as the fibrous 3D backbone in CFO@PBC nanocomposite electrodes, produced better results than the CFO@KB.

Pyrazine and crown ethers: functional covalent organic polymers for (solar-assisted) high capacity and rate performance lithium-organic battery

Multifunctional two-dimensional (2D) covalent organic polymers (COPs) benefiting from unique features display great potential in lithium-organic batteries yet are rarely reported. In this work, we fabricate a novel conjugated polymer (TQ-COP) functioned with flexible crown ethers and pyrazine redox-active sites, used as an organic rechargeable battery cathode. The Fourier transform infrared spectroscopy (FT-IR) and 13C cross-polarization and magic-angle spinning nuclear magnetic resonance (MAS NMR) verify the chemical identity of redox-active units formed during polymerization. In this structure, pyrazine-redox components exhibit a maximum six-electron transfer per active site, resulting in an initial specific capacity of 162 mA h/g(20 mA/g). Because of macrocyclic cavities and preferential coordination with the alkali metal ions of crown ethers, the rate determining step is changed into a charge transfer process, urging TQ-COP to emerge with a superior rate performance (132 mA h/g at 2 C, 81% vs. 0.1 C). Furthermore, the introduction of crown ethers facilitates photo-excited charge-carriers transfer by narrowing the HOMO-LUMO gap, rendering a photo-assisted lithium-organic battery with significant photovoltage responses and ∼10% improvement of battery round-trip efficiency under illumination, demonstrating its promising capability of solar energy utilization. This work proposes new insights into multifunctional COPs for advanced lithium-organic batteries.

Simply Prepared Magnesium Vanadium Oxides as Cathode Materials for Rechargeable Aqueous Magnesium Ion Batteries.

Vanadium-oxide-based materials exist with various vanadium oxidation states having rich chemistry and ability to form layered structures. These properties make them suitable for different applications, including energy conversion and storage. Magnesium vanadium oxide materials obtained using simple preparation route were studied as potential cathodes for rechargeable aqueous magnesium ion batteries. Structural characterization of the synthesized materials was performed using XRD and vibrational spectroscopy techniques (FTIR and Raman spectroscopy). Electrochemical behavior of the materials, observed by cyclic voltammetry, was further explained by BVS calculations. Sluggish Mg2+ ion kinetics in MgV2O6 was shown as a result of poor electronic and ionic wiring. Complex redox behavior of the studied materials is dependent on phase composition and metal ion inserted/deinserted into/from the material. Among the studied magnesium vanadium oxides, the multiphase oxide systems exhibited better Mg2+ insertion/deinsertion performances than the single-phase ones. Carbon addition was found to be an effective dual strategy for enhancing the charge storage behavior of MgV2O6.