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In this work, nano LiV3O8(LVO) was synthesized using the rheological phase reaction method. Subsequently, after ultrasonic and heat treatment at 300 °C, the nano LVO Ut-300 was obtained and performed as cathode material in Na-ion batteries for the first time. Brunauer–Emmett–Teller analysis indicated that the specific area increased after ultrasonic treatment, which was conducive to the shuttling of sodium ions and enhancement of the electrochemical performance. The X-ray diffraction patterns displayed stable nano LVO Ut-300 material structure and larger interlayer spacing, and SEM and TEM performed more regular morphology. After the electrochemical tests, the nano LVO Ut-300 cathode delivered a high discharge capacity of 153.8 mA h g–1 in the voltage range of 1.8–4.0 V at 30 mA g–1. Meanwhile, the storage mechanism of Na+ was further explored by XPS, and kinetics characteristics of LVO/Na cells were revealed by pseudocapacitance analysis and galvanostatic intermittent titration technique (GITT) tests. In summary, nano LVO was processed by the ultrasonic method followed by subsequent heat treatment, which could effectively improve the electrochemical behavior of LiV3O8 as cathode materials of secondary Na-ion batteries. [ABSTRACT FROM AUTHOR]

Summary: The carbon layer acting as a conductive medium is beneficial to overcoming the comparatively inferior electronic conductivity of Na3V2(PO4)3. Based on this, Na3V2(PO4)3/C composites with diverse ratios of citric acid are synthetized via rheological phase reaction way in this work. The consequences display that the Na3V2(PO4)3/C‐1.5 composite brings a higher initial discharge capacity of 113.2 mAh g−1 at a current rate of 1 C with coulombic efficiency above 99% during all cycles. The discharge capacity retains at 117.6 mAh g−1 at the 100th cycle. Even at the high current densities of 5 C and 10 C, the composite also shows superior cycling performance with negligible capacity fading. Its discharge capacities decline from 97 to 92.6 mAh g−1 at 5 C and from 85.3 to 83.7 mAh g−1 at 10 C. These remarkable outcomes arise from its preferable morphology with suitable carbon coating because both excess and skimpy carbon seriously affect the microstructure and electrochemical properties of Na3V2(PO4)3/C composites. [ABSTRACT FROM AUTHOR]

Summary: Polyaniline‐derived N‐doped carbon‐composited Na3V2(PO4)3 (NVP@NC) are synthesized by a rheological phase reaction followed by calcination. The NVP@NC composite displays improved cycling and rate properties. Its discharge capacity remains 118.7 mAh g−1 at the 400th cycle at 0.3 C. It also obtains invertible capacities of 93.7 and 91.1 mAh g−1 at 5 and 10 C after 1000 cycles, with capacity retention rates of 92.7% and 98.4%, respectively. These enhanced results due to the N‐doped carbon layer (NC), which restrains the expansion and deformation of the crystal structure, reduce the transport length of sodium ion and electrons and improves the electroconductibility of NVP. [ABSTRACT FROM AUTHOR]

Summary: NaV3O8/polytriphenylamine composites were synthesized by an in situ oxypolymerization way for the first time. Among them, the NaV3O8/20 wt.% polytriphenylamine composite shows better cycling and rate performance. Its discharge capacity retains at 118.9 mAh g−1 after 300 cycles at 120 mA g−1. It also obtains a reversible capacity of 101.7 mAh g−1 at 300 mA g−1 after 100 cycles. These enhanced results arise from the excellent morphology, that is, smaller particles of clear edges and uniform distribution suppress the expansion and deformation of the crystal structure, and avoid large agglomerate particles gathering during the electrochemical reaction. In addition, tight polytriphenylamine (PTPAn) coating also improves the conductivity of NaV3O8 cathode and suppresses the dissolution of NaV3O8 in electrolyte. [ABSTRACT FROM AUTHOR]

Development of novel cathode materials for sodium-ion batteries with high capacity and excellent cyclic performance is an exciting and demanding research direction. Herein, we demonstrate the synthesis of NaV3O8 via a rheological phase reaction method. The crystal structure and morphology of synthesized NaV3O8 were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The NaV3O8 powder, calcined at moderate temperature (350 °C) with more uniform and smaller nanorod/nanoplate morphology, and larger d001 spacing, exhibited excellent electrochemical performance as cathode material in sodium ion batteries. A specific discharge capacity of 120 mAh g−1 was achieved at the current density of 120 mA g−1, with exceptional cyclic performance (discharge capacity of 95 mAh g−1 at the 500th cycle). In addition, the NaV3O8 cathode demonstrated excellent rate capability and delivered specific capacity of 80.8 mAh g−1 at current density of 300 mA g−1. The superior electrochemical performance corresponds to the structural stability and faster ionic diffusion. The preliminary results indicate that NaV3O8 can be an alternative cathode material for high-performance sodium-ion batteries. [ABSTRACT FROM AUTHOR]

Li1 .2V3O8 and Cu-doped Li1.2V3O8 were prepared at a temperature as low as 300 °C by a sol-gel method. The structure, morphology, and electrochemical performance of the as-prepared samples were characterized by means of X-ray diffraction, scanning electron microscopy, electrochemical impedance spectroscopy, and the galvanostatic discharge–charge techniques. It is found that the Cu-doped Li1.2V3O8 sample exhibits less capacity loss during repeated cycling than the undoped one. The Cu-doped Li1.2V3O8 sample demonstrates the first discharge capacity of 275.9 mAh/g in the range of 3.8–1.7 V at a current rate of 30 mA/g and remains at a stable discharge capacity of 264 mAh/g within 30 cycles. Furthermore, the possible role that copper plays in enhancing the cycleability of Li1.2V3O8 has also been elucidated. [ABSTRACT FROM AUTHOR]

• 1. For the first time, the Li 7 [V 15 O 36 (CO 3)] and γ -LiV 2 O 5 as host materials to store Zn2+. • 2. A larger voltage window (0.2–1.9 V) than most other aqueous zinc ion batteries. • 3. The energy density and power density of the Li 7 [V 15 O 36 (CO 3)] and the γ -LiV 2 O 5 is high. • 4. The Zn2+ storage mechanisms of the Li 7 [V 15 O 36 (CO 3)] and the γ -LiV 2 O 5 are proved. Recently, many reports have been published about polyoxovanadates (POVs) with multiple electrons redox activity for energy storage. However, they are easily transformed into solid-state oxides after calcination. We noted that although dehydrated Li 7 [V 15 O 36 (CO 3)] (Li 7 V 15) exhibited a high capacity for lithium-ion batteries (LIBs), it was reported that the electrochemical behavior of the dehydrated sample same as γ -LiV 2 O 5 (γ -LVO) which prepared by annealing the cluster and undehydrated Li 7 V 15 was not redox-active. Interestingly, we were surprised to find that undehydrated Li 7 V 15 and its derivative γ -LVO showed better electrochemical performance than LIBs when first proposed as the cathode to store Zn2+. Both Li 7 V 15 and γ -LVO electrodes provided excellent rate performance and satisfied cyclability (135.0 and 214.1 mAh g−1 at 3 A g−1 after 1000 cycles, respectively). The fast kinetics of Li 7 V 15 and γ -LVO were verified by pseudocapacitive analysis, GITT and EIS tests. Moreover, the Zn2+ storage mechanism and redox behavior of Li 7 V 15 and γ -LVO were examined by ex-situ measurements. First-principles calculations revealed that the Zn2+ was chemisorbed on the clusters and physisorbed between the clusters. This work enriches the POVs cathode chemistry in aqueous energy storage. [ABSTRACT FROM AUTHOR]

In this work, nitrogen-doped carbon-coated NaV 3 O 8 (NVO@NC) were successfully synthesized by a simple rheological phase method using melamine as a nitrogen source. X-ray powder diffraction (XRD) and Scanning electron microscopy (SEM) analyses revealed that nitrogen-doped carbon-coated didn't change the crystal structure of NVO but altered the thickness and properties of the surface coating. Among obtained composites, NVO@NC containing a molar ratio of melamine to citric acid of 2.75:1.25 displayed the best electrochemical properties. The electrochemical tests suggested discharge capacity reaching 231.3 mAh g−1 at 150 mA g−1, with discharge capacity remaining at 169.4 mAh g−1 after 100 cycles. Electrochemical impedance spectroscopy (EIS) proved that the coated materials delivered a much lower resistance than that of bulk NVO. Galvanostatic intermittent titration technique (GITT) tests demonstrated sodium ion diffusion coefficient was greatly enhanced after nitrogen-doped carbon coating. In conclusion, nitrogen-doped carbon might increase material conductivity, aid in the formation of SEI films on electrode surfaces, and improve electrode material stability, resulting in NVO materials with high-capacity and ultrafast Na-ion storage. [ABSTRACT FROM AUTHOR]

Aqueous zinc-ion batteries (ZIBs) with low-priced, high-safety, and high synergistic efficiency have captured an ever-increasing amount of consideration and have been expected to be a promising choice to replace LIBs. However, the cathode materials of ZIBs reported have many shortcomings such as poor electron and zinc ion conductivity and complicated energy storage mechanisms. In this review, several typical cathode materials for ZIBs in recent years and their detailed energy storage mechanisms are summarized, and various improvement methods to enhance the electrochemical properties of ZIBs are briefly introduced. Eventually, the current problems and the expected development foregrounds of ZIBs are proposed. [Display omitted] Although lithium-ion batteries (LIBs) have many advantages, they cannot satisfy the demands of numerous large energy storage industries owing to their high cost, low security, and low resource richness. Aqueous zinc-ion batteries (ZIBs) with low cost, high safety, and high synergistic efficiency have attracted an increasing amount of attention and are considered a promising choice to replace LIBs. However, the existing cathode materials for ZIBs have many shortcomings, such as poor electron and zinc ion conductivity and complex energy storage mechanisms. Thus, it is crucial to identify a cathode material with a stable structure, substantial limit, and suitability for ZIBs. In this review, several typical cathode materials for ZIBs employed in recent years and their detailed energy storage mechanisms are summarized, and various methods to enhance the electrochemical properties of ZIBs are briefly introduced. Finally, the existing problems and expected development directions of ZIBs are discussed. [ABSTRACT FROM AUTHOR]

[Display omitted] Vanadate, as an advanced inorganic material, has been a major object of scientific research due to its flexible valence states and the multi-electron transfer mechanism of vanadium. This review concentrates on the application of vanadates in aqueous ZIBs, which facilitates researchers to understand the latest research progress on vanadate-based cathodes for ZIBs. Furthermore, the limitations of current vanadate-type cathodes are pointed out and the perspectives for their application in emerging energy storage areas are presented. • This work comprehensively summarizes the application of vanadates as aqueous ZIBs cathodes. • Electrochemical performance and energy storage behavior of vanadates cathodes are further discussed. • Current challenges and expected development foregrounds of vanadates cathodes in aqueous ZIBs are proposed. With the increasing pursuit of electronic products with high specific energy and outstanding environmental compatibility, developing advanced new power sources is urgent. As the representative of new energy, rechargeable aqueous zinc ion batteries (ZIBs) have gained much focus recently in the field of energy storage owing to their advantages of safety, cost-effectiveness, and environmental sustainability. Nevertheless, the progression of suitable Zn-storage cathode materials remains a huge challenge, limited by commercial requirements. Vanadate, as an advanced inorganic material, has been a major object of scientific research due to its flexible valence states and the multi-electron transfer mechanism of vanadium. Undeniably, understanding the electrochemical Zn-storage properties and mechanisms of this class of materials plays a crucial role in facilitating their development. However, there is a paucity of reviews on vanadates as cathodes for aqueous ZIBs. This review concentrates on the application of vanadates in aqueous ZIBs, which facilitates researchers to understand the latest research progress on vanadate-based cathodes for ZIBs. Finally, the limitations of current vanadate-type cathodes are pointed out and the perspectives for their application in emerging energy storage areas are presented. [ABSTRACT FROM AUTHOR]

Abstract A series of LiNi 1/3 Co 1/3 Mn 1/3 O 2 /polytriphenylamine composites were successfully synthesized by ultrasound dispersion method. LiNi 1/3 Co 1/3 Mn 1/3 O 2 /polytriphenylamine (5.0 wt%) composite with small and homogeneous particle size exhibited excellent electrochemical performance, which delivered an initial discharge capacity of 223.7 mAh g−1 with a capacity retention of 84.39% after 100 cycles in the voltage range of 2.5–4.5 V and at a current density of 0.2C. Moreover, an excellent specific discharge capacity of 127.3 mAh g−1 at a current density 5C indicates a superior rate performance of the LiNi 1/3 Co 1/3 Mn 1/3 O 2 /polytriphenylamine (5.0 wt%) composite. The good electrochemical performances of the composite can be attributed to the introduction of polytriphenylamine, which increased electrical conductivity, decreased charge transfer resistance and increased Li+ ion diffusion ability. These noteworthy results demonstrated that LiNi 1/3 Co 1/3 Mn 1/3 O 2 /polytriphenylamine composites might be potential cathode materials for lithium ion batteries. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

LiV 3 O 8 /poly (3, 4-ethylenedioxythiophene) (LVO/PEDOT) composites were synthesized via an in-situ oxidative polymerization process. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, galvanostatic discharge/charge tests, and electrochemical impedance spectroscopy techniques are used to characterize the as-prepared samples. The results demonstrated that the electrochemical performances of LVO/PEDOT composites have greatly improved in comparison with bare LVO. The discharge capacities of 20 wt% LVO/PEDOT composite are 270, 265, 252, 240, and 229 mAh g − 1 and ˃95% capacity retention is maintained after the charge-discharge 50 cycles at the current densities of 60, 90, 120, 180, and 240 mA g − 1 , respectively. A high reversible capacity of 176 mAh g − 1 (only 58 mAh g − 1 for the bare LVO) can be maintained after 50 cycles at a very high current rate of 2000 mA g − 1 . Electrochemical impedance spectra results implied that the 20 wt% LVO/PEDOT composite revealed a decreased charge transfer resistance and increased Li + ions diffusion ability. This noteworthy improvement is ascribed to the combination of PEDOT, which can act just as a defending layer to inhibit the LVO from direct contact with electrolyte and buffer volume change, and act just as a conductive network to improve the electronic conductivity, thus cycling stability and rate capability are improved. [ABSTRACT FROM AUTHOR]

[Display omitted] • Na 2 THBQ were combined with CDs as cathode materials in SIBs for the first time. • o -Na 2 THBQ/CDs-2 performed good cycling stability and rate performance. • The mechanism of o -Na 2 THBQ/CDs-2 was explored by ex-situ tests. • The sodium ion diffusion coefficient of the materials was tested by GITT. Organic compounds are considered auspicious due to their widespread presence in nature, low cost, and sustainability. However, the inherent drawbacks of these organics' compounds, like low-conductivity and high-solubility, restrict their large-scale application. To solve these problems, we innovatively combined carbon quantum dots (CDs) with active substances (tetrahydroxybenzoquinone ortho -disodium salt (o -Na 2 THBQ)) at different mass ratios. The optimized o -Na 2 THBQ/CDs-2 (the mass ratio of o -Na 2 THBQ to CDs is 10:2) exhibited excellent electrochemical performance, the first-cycle discharge specific capacity was 410 mAh g−1 and maintained 182 mAh g−1 after 500 cycles, and the Coulombic efficiency was nearly 100 %. After 1300 cycles, the o -Na 2 THBQ/CDs-2 composite demonstrated a high specific capacity of 63 mAh g−1 at 500 mA g−1. This work provides a reference to design an optimal composite ratio of carbon dots (CDs) and organics to fabricate cathode materials for high-performance sodium-ion batteries. [ABSTRACT FROM AUTHOR]

Conjugated carbonyl compounds with high theoretical capacity, low cost, structural flexibility and abundant resources are potential cathodes in metal-ion batteries (lithium-LIBs, sodium-SIBs, kalium-KIBs). Regrettably, their inherent drawbacks of high solubility and low electrical conductivity limit their further application. Herein, different mass ratios of reduced graphene oxide wrapped poly (1,5-anthraquinonyl sulfide) (PAQS/rGO) composites were prepared through a calcination-treatment process aiming at decreasing the dissolution and enhancing the conductivity. XRD, FTIR and Raman analysis confirmed the successful synthesis of PAQS. XRD analysis also confirmed the conversion of GO to rGO. Four-probe test results showed that the conductivity of composites increased as the rGO ratio increased. SEM images showed that PAQS/rGO composites presented microsphere morphologies. Profiting from the enhanced conductivity and limited dissolution in electrolyte, the PAQS2 (the mass ratios of PAQS and rGO is 10:2) composite exhibited outstanding performance both in half- and full-batteries. In LIBs/SIBs, PAQS2 exhibited reservable discharge capacities of 121 and 115 mAh g−1 at 50 mA g−1 after 200 and 400 cycles, respectively. In PTPAn/PAQS2 all-organic Li/Na-ion batteries, reservable charge/discharge capacities of 42.1/39 and 42.1/40.4 mAh g−1 were retained at 50 mA g−1 after 200 cycles, respectively. Ex-situ FT-IR analysis further performed the redox reaction of carbonyl groups during charging and discharging. [ABSTRACT FROM AUTHOR]

The development of lithium-ion batteries is hindered by the lack of appropriate low-cost cathode materials with high performance. Here, the preparation of Cu-coated Li 3 V 2 (PO 4) 3 /C (x % Cu-LVPC) composites is reported via a chemical precipitation and self-reduction method. With an optimized Cu coating content of 2.0 wt%, the 2.0% Cu-LVPC composite displays the best electrochemical properties. The initial discharge capacity of 2.0% Cu-LVPC is 175 mA h g−1 at 0.15 C (30 mA g−1) in the voltage range from 3.0 to 4.8 V and the capacity retention is 86.3% after 50 cycles, whereas pristine LVPC has an initial capacity of 163 mA h g−1 and retains 82.2% of the capacity after 50 cycles. Moreover, the rate capacity of 2.0% Cu-LVPC is also increased under different current densities and 2.0% Cu-LVPC exhibits excellent long-term cycling performance of 89 mA h g−1 after 1000 cycles at 10 C. The enhanced electrochemical properties are attributed to the uniform coating of the metal conductor Cu on the LVPC surface, which is conducive to electron transfer and extraction/insertion of Li+ ions. • Cu-coated Li 3 V 2 (PO 4) 3 /C (LVPC) was prepared via a chemical precipitation and self-reduction method. • The 2.0% Cu-coated LVPC composite exhibits significantly improved electrochemical performance. • Cu coating can effectively increase the conductivity of LVPC. • Cu coating on the surface of LVPC can reduce the polarization. [ABSTRACT FROM AUTHOR]

• LZO-LVPC composites were prepared by a simple mechanical ball-milling method. • 4.0 wt% LZO-LVPC exhibit a significant improved electrochemical performance. • LZO compensate for the transfer of Li+ between the cathode material and the electrolyte. • LZO protect the cathode material from side reactions with electrolyte. A simple and efficient synthetic route was developed to obtain composites by mechanically ball-milling Li 2 ZrO 3 (LZO) with Li 3 V 2 (PO 4) 3 /C (LVPC). LZO improves the ionic conductivity of LVPC, compensates for the transfer of Li+ between the LVPC and the electrolyte, reduces the impedance of LVPC, and protects LVPC from side reactions caused by direct contact with the electrolyte. The composite consisting of 4.0 wt% of LZO exhibited a considerable electrochemical performance. The 1st discharge capacity reached 192 mAh g−1 at 30 mA g−1 between 3.0 and 4.8 V, and remained at 153 mAh g−1 after 50 cycles. The EIS analysis showed that the charge transfer and diffusion of Li+ in the LZO-LVPC composites were more favorable than those of pristine LVPC. The synthetic method proposed in this work is simple and efficient, which is convenient for large-scale production. [ABSTRACT FROM AUTHOR]

Lithium-ion batteries (LIBs) have garnered significant academic and industrial focus because of their excellent merits, like high voltage, high energy density, excellent cyclic performance, no memory effect and environment-friendly nature. So far, the electrochemical properties of LIBs are restricted by the capacity of cathode materials and various novel compositions and designed architectures have been proposed to enhance the energy density and cyclic performance of LIBs cathodes. Recently, lithium nickel cobalt manganese oxides have attracted extensive research interest owing to the united advantages of LiCoO 2 , LiNiO 2 and LiMnO 2. Herein, we have reviewed the recent developments of LiNi 1/3 Co 1/3 Mn 1/3 O 2 from the viewpoint of synthesis processes and structural designs. The electrochemical properties of LiNi 1/3 Co 1/3 Mn 1/3 O 2 depend on particle size, morphology, ion doping and surface coating of the as-prepared cathode powder. The present article summarizes the recent developments and provides an insight into the future roadmap for the realization of high energy density LIBs. • Main synthesis methods of NCM cathodes are summarized and analyzed. • Partial ionic substitution enhances the structural stability and electronic conductivity. • Surface coating can prevent the side reactions, improved the electronic and ion migration rate. • Composite structure can increase the structure constancy and the electronic conductivity. [ABSTRACT FROM AUTHOR]