Rechargeable Hybrid Aqueous Battery Research Articles

Performance of Thixotropic Gel Electrolytes in the Rechargeable Aqueous Zn/LiMn2O4 Battery

Novel aqueous gel electrolytes have been prepared using a combination of thixotropic and nonthixotropic gelling agents. These gels are used in rechargeable hybrid aqueous batteries for the first time. Thermogravimetric analysis proves that the retentions of the gel electrolytes in the absorbed glass mat (AGM) separator are significantly higher than that of the conventional liquid electrolyte. Batteries with the gel electrolytes exhibit up to 10% improvement in specific reversible capacity and higher rate capability, and the capacity retention is up to 8% higher than that of the reference battery after 1000 cycles at 4 C. Furthermore, the electrodes of the gel batteries are well-preserved, and dendrite formation on the Zn anode is suppressed as confirmed by scanning electron microscopy and chronoamperometry techniques. These significant improvements are due to the new gel electrolytes and the synergistic effect of a thixotropic and a nonthixotropic gelling agent.

Influence of different silica gelling agents on the performance of aqueous gel electrolytes

In this study, gel electrolytes are prepared from silica gelling agents and aqueous electrolyte for application in the rechargeable hybrid aqueous battery for the first time. The required quantities of silica materials are in the range of 4–15wt.%. The gelling time is in the magnitude of minutes and the ionic conductivities of gel electrolytes are in the range of 50.6–60.6mScm−1. These batteries using these gel electrolytes exhibit higher rate capability, slower self-discharge (ca.15% after 24h), and up to 10–12% higher cyclability compared with the performance of the batteries using the conventional liquid electrolyte.

Binder-free flexible LiMn2O4/carbon nanotube network as high power cathode for rechargeable hybrid aqueous battery

Highly flexible LiMn2O4/carbon nanotube (CNT) electrodes are developed and used as a high power cathode for the Rechargeable Hybrid Aqueous Battery (ReHAB). LiMn2O4 particles are entangled into CNT networks, forming a self-supported free-standing hybrid films. Such hybrid films can be used as electrodes of ARLB without using any additional binders. The binder-free LiMn2O4/CNT electrode exhibits good mechanical properties, high conductivity, and effective charge transport. High-rate capability and high cycling stability are obtained. Typically, the LiMn2O4/CNT electrode achieves a discharge capacity of 72 mAh g−1 at the large-current of 20 C (1 C = 120 mAh g−1), and exhibits good cycling performance and high reversibility: Coulombic efficiency of almost 100% over 300 charge-discharge cycles at 4 C. By reducing the weight, and improving the large-current rate capability simultaneously, the LiMn2O4/CNT electrode can highly enhance the energy/power density of ARLB and hold potential to be used in ultrathin, lightweight electronic devices.

Novel Rechargeable M3V2(PO4)3//Zinc (M = Li, Na) Hybrid Aqueous Batteries with Excellent Cycling Performance.

A rechargeable hybrid aqueous battery (ReHAB) containing NASICON-type M3V2(PO4)3 (M = Li, Na) as the cathodes and Zinc metal as the anode, working in Li2SO4-ZnSO4 aqueous electrolyte, has been studied. Both of Li3V2(PO4)3 and Na3V2(PO4)3 cathodes can be reversibly charge/discharge with the initial discharge capacity of 128 mAh g−1 and 96 mAh g−1 at 0.2C, respectively, with high up to 84% of capacity retention ratio after 200 cycles. The electrochemical assisted ex-XRD confirm that Li3V2(PO4)3 and Na3V2(PO4)3 are relative stable in aqueous electrolyte, and Na3V2(PO4)3 showed more complicated electrochemical mechanism due to the co-insertion of Li+ and Na+. The effect of pH of aqueous electrolyte and the dendrite of Zn on the cycling performance of as designed MVP/Zn ReHABs were investigated, and weak acidic aqueous electrolyte with pH around 4.0–4.5 was optimized. The float current test confirmed that the designed batteries are stable in aqueous electrolytes. The MVP//Zn ReHABs could be a potential candidate for future rechargeable aqueous battery due to their high safety, fast dynamic speed and adaptable electrochemical window. Moreover, this hybrid battery broadens the scope of battery material research from single-ion-involving to double-ions -involving rechargeable batteries.

Rechargeable hybrid aqueous batteries using silica nanoparticle doped aqueous electrolytes

Silica nanoparticles doped aqueous electrolytes have been prepared and implemented for the first time in rechargeable hybrid aqueous battery systems (ReHABs). The batteries were assembled from a cathode containing LiMn2O4 – a lithium intercalation compound, a zinc metal foil anode and a sulfate electrolyte containing Zn2+ and Li+ ions. Silica nanoparticles were doped into the liquid electrolyte with the initial aim to create a silica containing gel electrolyte. However, the 5% and 10% SiO2 doped electrolytes were viscous and could be easily absorbed in the Absorbed Glass Mat (AGM) separator and the whole system (doped electrolyte+AGM) immobilized after a few minutes. The AGM loaded with silica doped electrolytes remained wet after storage for weeks under ambient condition thanks to the water retention ability of nanoscale silica particles. The doped silica nanoparticles restrained deposition of zinc dendritic crystals, and reduced float charge current and self-discharge. The ReHABs assembled from the silica nanoparticles doped electrolytes provided high specific discharge capacity, up to 140mAh (gLiMn2O4)−1 at 0.2C, and the cyclability of such systems was significantly enhanced compared to the ReHABs assembled from conventional electrolytes. X-ray Diffraction revealed that the anode of the batteries using SiO2 doped electrolytes were protected since only the XRD peaks of Zn were detected after the batteries were running 700 cycles of charge and discharge.

Self-Discharge of Rechargeable Hybrid Aqueous Battery

Self-discharge refers to the loss in stored charge of a battery without connection between its electrodes as a consequence of internal chemical reactions. Self-discharge processes can be tested in a loadfree state for a fixed time. Two self-discharge reactions are possible in a Li-ion cell: one is chemical and the other electrochemical. Because of their reactivity, charged cells can undergo side reactions, and factors such as purity of the active material or electrolyte, the specific surface area of the electrodes, conductors, binders or separators can have effect on the self-discharge performance. These reactions are mostly irreversible while electrochemical reactions can be reversible. For example, lithium re-intercalation can lead to self-discharge of Li-ion batteries, as has been demonstrated by many researchers who have studied the different factors that could affect self-discharge of

Effect of adding various carbon additives to porous zinc anode in rechargeable hybrid aqueous battery

Anodic behavior of porous Zn in rechargeable hybrid aqueous battery is investigated. The battery comprises porous Zn anode and LiMn2O4 cathode. The electrolytes are Li+ and Zn2+ of sulfate salt in aqueous solution. The initial discharge capacity of pure porous Zn is 114 mAh g−1, and the capacity decreases to less than 59 mAh g−1 after 36 cycles. Then, the effects of various carbon additives on the battery performance are studied. The results show that the adding of active carbon increases the initial discharge capacity to 150 mAh g−1, and the capacity maintains above 60 mAh g−1 even after 210 cycles. The reasons for improvement for the battery are investigated by Tafel, scanning electron microscopy, and X-ray Diffraction.

Enhancing rate performance of LiMn2O4 cathode in rechargeable hybrid aqueous battery by hierarchical carbon nanotube/acetylene black conductive pathways

Three-dimensional hierarchical carbon nanotube/acetylene black (CNT/AB) networks are fabricated by a simple mixing method to enhance electronic contact among LiMn2O4 particles in the rechargeable hybrid aqueous battery (ReHAB), an aqueous Zn/LiMn2O4 battery system. The hierarchical and long-range conductive pathways lead to fast electronic transfer in the CNT/AB/LiMn2O4 cathode, which contributes to the outstanding rate performance (specific discharge capacity of 105 mAh g−1 at 10 C). Besides, the stable composite structure contributes to the good cycling performance and high reversibility (Coulombic efficiency of almost 100 % over 300 charge-discharge cycles at 4 C). This hierarchical conductive network design is particularly useful for energy storage applications operated at high charge-discharge rate.

Synthesis and electrochemical properties of LiFePO4/graphene composite as a novel cathode material for rechargeable hybrid aqueous battery

A novel self-assembled LiFePO4/graphene composite is successfully prepared by a facile template-free hydrothermal approach. Physical and electrochemical properties of the LiFePO4/graphene composite as cathode material in rechargeable hybrid aqueous batteries are firstly investigated. The LiFePO4/graphene composite exhibits a high discharge capacity of 145.8mAhg−1 at 0.2C, which is 40% higher than that of pristine LiFePO4. Moreover, LiFePO4/graphene shows much better rate capability and excellent cyclability. This enhanced electrochemical performance could be attributed to the positive effects of graphene nanosheets, which create a flexible electrical conductive matrix, ensuring a continuous electron pathway in bulk electrode and absorbing the volume change during lithium intercalation/de-intercalation of LiFePO4.

Experimental and mathematical studies on cycle life of rechargeable hybrid aqueous batteries

Rechargeable hybrid aqueous batteries (ReHABs) were constructed from LiMn2O4 cathode, aqueous electrolyte containing ZnSO4 and Li2SO4, and polished zinc foil anode. Cyclability data were obtained from a Neware battery tester and the data were modeled by the particle filter method. This method exhibits superior performance in both tracking and predicting the cyclability behavior of ReHABs. Data from both Swagelok and coin cells are modeled successfully and the results show that the non-linear term in the model of Swagelok batteries is larger than that in the model of coin cells. This nonlinear term is varied versus battery types. This fact shows the versatility of the particle filter method in modeling different types of batteries. This finding is crucial because it proves the suitability of particle filter method as a promising candidate in the evaluation of battery cycle life, without the need for running batteries till the end of life, which may take up to a few thousands of cycles and last for several months or years.

Synthesis and electrochemical investigation of nanosized LiMn2O4 as cathode material for rechargeable hybrid aqueous batteries

Single phase cubic spinel LiMn2O4 nanosized particles are synthesized by a novel solution-mediated solid state method. The obtained LiMn2O4 nanoparticles have a narrow particle size distribution in a range from 100 to 300nm. Cyclic voltammetry and galvanostatic charge–discharge tests of the LiMn2O4 samples are performed in an aqueous solution of lithium and zinc acetates, using zinc as anode. Cells containing nanosized LiMn2O4 cathodes have higher specific discharge capacity, coulombic efficiency, better cyclability and rate capability than the cells containing conventional bulk LiMn2O4. The superior electrochemical performance can be ascribed to the much smaller particle size and less agglomeration, which not only shorten the diffusion pathway for electrons and lithium ions but also provide a larger specific surface area for lithium transportation during high C-rate charge–discharge cycling.

Rechargeable hybrid aqueous batteries

A new aqueous rechargeable battery combining an intercalation cathode with a metal (first order electrode) anode has been developed. The concept is demonstrated using LiMn2O4 and zinc metal electrodes in an aqueous electrolyte containing two electrochemically active ions (Li+ and Zn2+). The battery operates at about 2 V and preliminarily tests show excellent cycling performance, with about 90% initial capacity retention over 1000 charge–discharge cycles. Use of cation-doped LiMn2O4 cathode further improves the cyclability of the system, which reaches 95% capacity retention after 4000 cycles. The energy density for a prototype battery, estimated at 50–80 Wh kg−1, is comparable or superior to commercial 2 V rechargeable batteries. The combined performance attributes of this new rechargeable aqueous battery indicate that it constitutes a viable alternative to commercial lead-acid system and for large scale energy storage application.