Wood-inspired anisotropic hydrogel electrolyte with large modulus and low tortuosity realizing durable dendrite-free zinc-ion batteries.

While aqueous zinc-ion batteries exhibit great potential, their performance is impeded by zinc dendrites. Existing literature has proposed the use of hydrogel electrolytes to ameliorate this issue. Nevertheless, the mechanical attributes of hydrogel electrolytes, particularly their modulus, are suboptimal, primarily ascribed to the substantial water content. This drawback would severely restrict the dendrite-inhibiting efficacy, especially under large mass loadings of active materials. Inspired by the structural characteristics of wood, this study endeavors to fabricate the anisotropic carboxymethyl cellulose hydrogel electrolyte through directional freezing, salting-out effect, and compression reinforcement, aiming to maximize the modulus along the direction perpendicular to the electrode surface. The heightened modulus concurrently serves to suppress the vertical deposition of the intermediate product at the cathode. Meanwhile, the oriented channels with low tortuosity enabled by the anisotropic structure are beneficial to the ionic transport between the anode and cathode. Comparative analysis with an isotropic hydrogel sample reveals a marked enhancement in both modulus and ionic conductivity in the anisotropic hydrogel. This enhancement contributes to significantly improved zinc stripping/plating reversibility and mitigated electrochemical polarization. Additionally, a durable quasi-solid-state Zn//MnO2 battery with noteworthy volumetric energy density is realized. This study offers unique perspectives for designing hydrogel electrolytes and augmenting battery performance.

Unlocking the Interfacial Adsorption-Intercalation Pseudocapacitive Storage Limit to Enabling All-Climate, High Energy/Power Density and Durable Zn-Ion Batteries.

Sluggish storage kinetics and insufficient performance are the major challenges that restrict the transition metal dichalcogenides (TMDs) applied for zinc ion storage, especially at the extreme temperature conditions. Herein, a multiscale interface structure-integrated modulation concept was presented, to unlock the omnidirectional storage kinetics-enhanced porous VSe2-x ⋅n H2 O host. Theory research indicated that the co-modulation of H2 O intercalation and selenium vacancy enables enhancing the interfacial zinc ion capture ability and decreasing the zinc ion diffusion barrier. Moreover, an interfacial adsorption-intercalation pseudocapacitive storage mechanism was uncovered. Such cathode displayed remarkable storage performance at the wide temperature range (-40-60 °C) in aqueous and solid electrolytes. In particular, it can retain a high specific capacity of 173 mAh g-1 after 5000 cycles at 10 A g-1 , as well as a high energy density of 290 Wh kg-1 and a power density of 15.8 kW kg-1 at room temperature. Unexpectedly, a remarkably energy density of 465 Wh kg-1 and power density of 21.26 kW kg-1 at 60 °C also can be achieved, as well as 258 Wh kg-1 and 10.8 kW kg-1 at -20 °C. This work realizes a conceptual breakthrough for extending the interfacial storage limit of layered TMDs to construct all-climate high-performance Zn-ion batteries.

A 640 nA IQ Output-Capacitor-Less Low Dropout (LDO) Regulator with Sub-Threshold Slew-Rate Enhancement for Narrow Band Internet of Things (NB-IoT) Applications.

An ultra-low quiescent current output-capacitor-less low dropout (OCL-LDO) regulator for power-sensitive applications is proposed in this paper. To improve the gain of the OCL-LDO feedback loop, the error amplifier employs a combination of a cross-coupled input stage for boosting the equivalent input transconductance and a negative resistance technique to improve the gain. Meanwhile, in order to address the issue of transient response of the ultra-low quiescent current OCL-LDO, a sub-threshold slew-rate enhancement circuit is proposed in this paper, which consists of a transient signal input stage and a slew-rate current increase branch. The proposed OCL-LDO is fabricated in a 0.18 µm CMOS process with an effective area of 0.049 mm2. According to the measurement results, the proposed OCL-LDO has a maximum load current of 100 mA and a minimum quiescent current of 640 nA at an input voltage of 1.2 V and an output voltage of 1 V. The overshoot and undershoot voltages are 197 mV and 201 mV, respectively, and the PSR of the OCL-LDO is -72.4 dB at 1 kHz when the load current is 100 µA. In addition, the OCL-LDO has a load regulation of 7.6 µV/mA and a line regulation of 0.87 mV/V.

Suppressing Rampant and Vertical Deposition of Cathode Intermediate Product via PH Regulation Toward Large-Capacity and High-Durability Zn//MnO2 Batteries.

Despite great prospects, Zn//MnO2 batteries suffer from rampant and vertical deposition of zinc sulfate hydroxide (ZSH) at the cathode surface, which leads to a significant impact on their electrochemical performance. This phenomenon is primarily due to the drastic increase in the electrolyte pH value upon discharging, which is closely associated with the electrodissolution of Mn-based active materials. Herein, the pH value change is effectively inhibited by employing an electrolyte additive with excellent pH buffering capability. As such, the formation of ZSH at the cathode is postponed, resulting in the deposition of ZSH in a horizontal arrangement. This strategy can significantly enhance the utilization efficiency of cathode active material, while also enabling a solid electrolyte interphase layer at the Zn anode to address low Zn stripping/plating reversibility. With the optimal electrolyte, the Zn//MnO2 battery realizes a 25.6% increase in the specific capacity at 0.2 A g-1 compared to that with the baseline electrolyte, great rate capability (161.6 mAh g-1 at 5 A g-1 ), and superior capacity retention (90.2% over 5,000 cycles). In addition, the pH buffering strategy is highly applicable in hydrogel electrolytes. This work underscores the importance of pH regulation for Zn//MnO2 batteries and provides enlightening insights.

Scalable fabrication of free-standing and integrated electrodes with commercial level of areal capacity for aqueous zinc-ion batteries.

Aqueous zinc-ion batteries (AZIBs) present a highly promising avenue for the deployment of grid-scale energy storage systems. However, the electrodes fabricated through conventional methodologies not only suffer from insufficient mass loadings, but also are susceptible to exfoliation under deformations. Herein, a scalable and cost-effective freezing-thawing method is developed to construct free-standing and integrated electrode, comprising H11Al2V6O23.2, carboxymethyl cellulose, and carbon nanotubes. Benefiting from the synergistic effect of these components, the resultant electrode exhibits superior flexibility and robustness, large tensile strength, exceptional electrical conductivity, and favorable electrolyte wettability. Under a large mass loading of 8 mg cm-2 (corresponding to a negative/positive electrode capacity ratio of 2.09), the electrode achieves remarkable capacity of 345.2 mAh/g (2.76 mAh cm-2) at 0.2 A/g and maintains 235.2 mAh/g (1.88 mAh cm-2) at 4 A/g, while sustaining an impressive capacity retention of 97.7 % over 5000 cycles. These considerably outperform conventional electrodes employing traditional binders. Even at an elevated mass loading of 14 mg cm-2 or when operated at a low temperature of - 30 °C, the electrode continues to deliver excellent electrochemical performance (e.g., extraordinary areal capacity of 4.32 mAh cm-2). In addition, the electrode owns outstanding tolerance to external forces. This research contributes to our understanding of the pivotal challenges within the realm of AZIB technology.

Lanthanum doping and surface Li3BO3 passivating layer enabling 4.8 V nickel-rich layered oxide cathodes toward high energy lithium-ion batteries.

Single crystalline Ni-rich layered oxide cathodes show high energy density and low cost, have been regarded as one of the most promising candidates for next generation lithium-ion batteries (LIBs). Extending the cycling voltage window will significantly improve the energy density, however, suffers from bulk structural and interfacial chemistry degradation, leading to rapidly cycle performance deterioration. Here, we propose a dual-modification strategy to synthesize La doping and Li3BO3 (LBO) coating layers modified LiNi0.8Co0.1Mn0.1O2 (NCM811) by a facile one-step heating treatment processing. In-situ EIS and XRD, ex-situ XPS techniques are applied to demonstrate that the La diffused amorphous domains and Li3BO3 passivating layers dampen the lattice distortion, enhance the interfacial chemistry behavior as well as lithium ion transportation kinetics. Specifically, surface La doping amorphous domains successfully suppress the intense lattice stress and volume changes induced by the phase transitions during lithiation/delithiation, thus avoiding the intergranular crack and enhancing the mechanical stability of the material. Moreover, the LBO layer formed by the consumption of residual lithium prevents successive parasitic reactions at the interface as well as provides rapid Li-ion diffusion channels. Furthermore, the coating layer also diminishes the residual lithium compounds, increasing the atmosphere stability and safety of LIBs. Consequently, the La doping and LBO coating NCM811 exhibits an exceptional initial specific capacity (230.6 mAh/g) at 0.5C under a high cutoff voltage of 4.8 V, and a 73.8 % capacity retention following 100 cycles. In addition, a superior specific capacity of 133.8 mAh/g is provided even at a high current density (4C). Our work paves a promising road to tackle the integral structure deterioration and interfacial instability of Ni-rich cathodes.

High-performance Si@C anode for lithium-ion batteries enabled by a novel structuring strategy.

Si anode has drawn growing attention because of its features of large specific capacity, low electrochemical potential, and high natural abundance. However, it suffers from severe electrochemical irreversibility due to its large volume change during cycling. In spite of the achievement of improved electrochemical performance after compositing with carbon materials, most of the reported Si/C composite anodes lack a simple preparation process. To obtain a promising Si-based anode material, both simple preparation process and improved performance are necessary. Herein, inspired by the structure of shock proof foam, a novel structure of Si-based composite (Si@FeNO@P), consisting of Si nanoparticles embedded within a highly graphitized Fe3C/Fe3O4 hybrid nanoparticle-interspersed foam-like porous carbon matrix, has been constructed using a simple method, consisting of simple mixing, drying, and carbonization processes. Thus, the well-designed composite structure effectively mitigates issues resulting from volumetric change of the Si during cycle and hence improves its performance significantly. The research results confirm outstanding performance of the Si@FeNO@P anode in the aspects of cycle durability, specific capacity, and rate capability, with 1116.1 (250th cycle), 858.1 (500th cycle), and 503.1 (500th cycle) mA h g-1 at 100, 1000, and 5000 mA g-1, respectively. By comparing the performance and structure of Si@FeNO@P with other control samples, it was substantiated that the outstanding performances of the Si@FeNO@P anode depend on the synergistic effects of the well-designed unique carbon matrix, conductive Fe3C, and Fe3O4-in situ derived metallic Fe nanoparticles during cycling. The outstanding electrochemical performance and simple preparation route make the Si@FeNO@P anode promising for lithium-ion battery applications. This work also gives useful insights into the development of high-performance Si-based anodes with simple practical methods.

Oriented Zn plating guided by aligned ZnO hexagonal columns realizing dendrite-free Zn metal electrodes.

Aqueous zinc-ion batteries (AZIBs), featuring low cost and high safety, have become a research hotspot in recent years. However, the low Zn stripping/plating reversibility, caused by dendritic growth, harmful side reactions, and Zn metal corrosion, severely influences the applicability of AZIBs. Zincophilic materials have shown great potential to form protective layers at the surface of Zn metal electrodes, whereas those protective layers are usually thick, lack fixed crystalline orientation, and require binders. Herein, a facile, scalable, and cost-effective solution method is used to grow vertically aligned ZnO hexagonal columns with (002) top surface and low thickness of 1.3 µm onto Zn foil. Such oriented protective layer can promote homogenous and nearly horizontal Zn plating not only on the top but also at the side of ZnO columns due to the low lattice mismatch between Zn (002) and ZnO (002) facets and between Zn (110) and ZnO (110) facets. Accordingly, the modified Zn electrode exhibits dendrite-free behavior with considerably suppressed corrosion issue, inert byproduct growth, and hydrogen evolution. Thanks to that, the Zn stripping/plating reversibility is significantly improved in Zn//Zn cell, Zn//Ti cell, and Zn//MnO2 battery. This work provides a promising avenue for guiding metal plating process via oriented protective layer.

Salting-Out Effect Realizing High-Strength and Dendrite-Inhibiting Cellulose Hydrogel Electrolyte for Durable Aqueous Zinc-Ion Batteries.

Aqueous zinc-ion batteries are limited by poor Zn stripping/plating reversibility. Not only can hydrogel electrolytes address this issue, but also they are suitable for constructing flexible batteries. However, there exists a contradiction between the mechanical strength and the ionic conductivity for hydrogel electrolytes. Herein, high-concentration kosmotropic ions are introduced into the cellulose hydrogel electrolyte to take advantage of the salting-out effect. This can significantly improve both the mechanical strength and ionic conductivity. Additionally, the obtained cellulose hydrogel electrolyte (denoted as Con-CMC) has strong adhesion, a wide electrochemical stability window, and good water retaining ability. The Con-CMC is also found to accelerate the desolvation process, improve Zn deposition kinetics, promote Zn deposition along the (002) plane, and suppress parasitic reactions. Accordingly, the Zn/Zn cell with Con-CMC demonstrates dendrite-free behavior with prolonged lifespan and can endure extremely large areal capacity of 25 mAh cm-2. The Con-CMC also enables a large average Coulombic efficiency of 99.54% over 500 cycles for the Zn/Cu cell. Furthermore, the assembled pouch-type Zn/polyaniline full battery provides great rate capability, superior cyclability (even with limited Zn anode excess), a slow self-discharge rate, and outstanding affordability to external forces. Overall, this work extends our knowledge of the rational design of hydrogel electrolytes.

Simplified Synthesis of Fluoride-Free Ti3C2Tx via Electrochemical Etching toward High-Performance Electrochemical Capacitors.

MXenes have been intensively studied for electrochemical energy storage and other applications. However, time-consuming multistep procedures involving hypertoxic HF or alike are utilized in conventional synthesis methods of MXenes. Besides, -F terminal functional groups inevitably exist in these MXenes, detrimental to supercapacitor and battery performances. Herein, we develop a facile and time-saving electrochemical etching method to synthesize F-free and Cl-containing Ti3C2Tx in a mixed LiOH and LiCl aqueous solution with an etching efficiency of 92.2%. During the synthesis, sonification alone is able to delaminate Ti3C2Tx without using any hazardous organic intercalant. The obtained delaminated Ti3C2Tx flakes are ∼3.8 µm in lateral size and ∼3.9 nm in thickness, and can be stable in an aqueous dispersion for at least 15 days. The filtrated Ti3C2Tx film is 20.5 MPa in tensile strength, 13.4 GPa in Young's modulus, and 1663 S cm-1 in electrical conductivity, and exhibits specific capacitances of 323.7 F g-1, 1.39 F cm-2, and 1160 F cm-3 for supercapacitors. Also, a flexible zinc-ion hybrid capacitor with energy density values of 20.8 mWh cm-3 and 249.9 µWh cm-2 is assembled by using the Ti3C2Tx film as the cathode, and can maintain almost all its capacity under bending.

Facile and green synthesis of nanocellulose with the assistance of ultraviolet light irradiation for high-performance quasi-solid-state zinc-ion batteries.

Benefiting from excellent mechanical properties, large surface area, rich hydroxyl groups, good sustainability, etc., nanocellulose is highly promising for various applications. However, intense chemical treatment and long-term processing are usually required to fabricate nanocellulose. Herein, a new synthesis method of nanocellulose is developed by using ultraviolet light irradiation-assisted delignification and subsequent sonification. This method is more cost-effective, time-saving, and environmentally benign compared to most of previously reported synthesis methods of nanocellulose. The obtained nanocellulose contains a small amount of lignin, which is unfavorable for high-temperature stability and optimal transparency. However, a small amount of lignin is beneficial to mechanical properties and in-water stability. With this nanocellulose, flexible MnO2 cathode film and hydrogel electrolyte are constructed and a quasi-solid-state zinc-ion battery is assembled. The battery exhibits 233.3 mAh g-1 after 1000 cycles at 1 A g-1 and 20 ℃. And more than half of that capacity can be maintained at -20 ℃. The battery also possesses great rate capability and good endurance to external forces. This work provides new insights into the synthesis and application of nanocellulose.

Flexible Ti3C2Tx/Nanocellulose Hybrid Film as a Stable Zn-free Anode for Aqueous Hybrid Zn-Li Batteries.

Aqueous zinc-based batteries are a very promising technology in the post-lithium era. However, excess zinc metals are often used, which results in not only making a waste but also lowering the actual energy density. Herein, a Ti3C2Tx/nanocellulose (derived from soybean stalks) hybrid film is prepared by a facile solution casting method and employed as the zinc-free anode for aqueous hybrid Zn-Li batteries. Benefiting from the ultra-low diameter and rich hydroxyl groups of nanocellulose, the hybrid film exhibits better mechanical properties, superior electrolyte wettability, and more importantly, significantly improved zinc plating/stripping reversibility compared to the pure Ti3C2Tx film. The hybrid film also dramatically overwhelms the stainless steel as the electrode for reversible zinc deposition. Further analysis shows that the hybrid film can lower the zinc deposition overpotential and promote the desolvation process of hydrated Zn2+ ions. In addition, it is found that hexagonal Zn thin flakes are horizontally deposited onto the hybrid film owing to the low lattice mismatch between the Ti3C2Tx surface and the (002) facet of Zn. Consequently, zinc dendritic growth and accompanied harmful side reactions can be considerably inhibited by the hybrid film, and the assembled Zn-Li hybrid batteries exhibit excellent electrochemical performances. This work might inspire future work on zinc-based batteries.

Large areal capacity all-in-one lithium-ion battery based on boron-doped silicon/carbon hybrid anode material and cellulose framework.

Si, featuring ultra-large theoretical specific capacity, is a very promising alternative to graphite for Li-ion batteries (LIBs). However, Si suffers from intrinsic low electrical conductivity and structural instability upon lithiation, thereby severely deteriorating its electrochemical performance. To address these issues, B-doping into Si, N-doped carbon coating layer, and carbon nanotube conductive network are combined in this work. The obtained Si/C hybrid anode material can be "grown" onto the Cu foil without using any binder and delivers large specific capacity (2328 mAh g-1 at 0.2 A g-1), great rate capability (1296.8 mAh g-1 at 4 A g-1), and good cyclability (76.7% capacity retention over 500 cycles). Besides, a cellulose separator derived from cotton is found to be superior to traditional polypropylene separator. By using cellulose as both the separator host and the mechanical skeleton of two electrodes, a flexible all-in-one paper-like LIB is assembled via a facile layer-by-layer filtration method. In this all-in-one LIB, all the components are integrated together with robust interfaces. This LIB is able to offer commercial-level areal capacity of 3.47 mAh cm-2 (corresponding to 12.73 mWh cm-2 and 318.3 mWh cm-3) and good cycling stability even under bending. This study offers a new route for optimizing Si-based anode materials and constructing flexible energy storage devices with a large areal capacity.

Stabilizing zinc deposition with sodium lignosulfonate as an electrolyte additive to improve the life span of aqueous zinc-ion batteries.

Thanks to high safety and low cost, rechargeable zinc-ion batteries (RZIBs) have become a promising candidate for grid-scale energy storage systems. However, zinc anodes suffer from severe dendrite growth and irreversible side reactions, leading to poor cyclability of RZIBs. In this work, low-cost sodium lignosulfonate (SL) is utilized as the electrolyte additive to solve this problem. The added amount of SL is optimized to be 0.02%, which enables the Zn//α-MnO2 battery to deliver a large capacity of 146 mAh g-1 after 1000 cycles at 1 A g-1, corresponding to a high capacity retention of 83.5%. The Zn//Zn symmetric cell with the modified electrolyte also shows excellent cyclability even under a commercial level of areal specific capacity (4 mAh cm-2). Overall, the results of this study confirm that the SL additive can improve the ionic conductivity of electrolyte, restrict the two-dimensional planar diffusion of Zn2+ ions at the electrode/electrolyte interface, lower the nucleation overpotential of Zn2+ ions, prevent side reactions, and inhibit the corrosion of Zn metal. Therefore, the dendrite growth and byproduct formation can be effectively suppressed. This study provides new insights into protecting metal electrodes of electrochemical energy storage devices.

Interface Engineering of Silicon and Carbon by Forming a Graded Protective Sheath for High-Capacity and Long-Durable Lithium-Ion Batteries.

Silicon is one of the most promising anode materials for lithium-ion batteries, whereas its low electronic conductivity and huge volumetric expansion upon lithiation strongly influence its prospective applications. Herein, we develop a facile method to introduce a graded protective sheath onto the surface of Si nanoparticles by utilizing lignin as the carbon source and Ni(NO3)2 as the auxiliary agent. Interestingly, the protective sheath is composed of NiSi2, SiC, and C from the interior to the exterior, thereby guaranteeing excellent compatibility between the neighboring components. Thanks to this unique coating layer, the obtained nanocomposite delivers a large reversible specific capacity (1586.3 mAh g-1 at 0.2 A g-1), excellent rate capability (879.4 mAh g-1 at 5 A g-1), and superior cyclability (88.2% capacity retention after 500 cycles at 1 A g-1). Such great performances are found to derive from a slight volumetric expansion, high Li+ ion diffusion coefficients, good interface stability, and fast electrochemical kinetics. These properties are obviously superior to those of their counterparts, benefiting from the interface engineering. This study offers new insights into constructing high-capacity and long-durable electrode materials for energy storage.

Integrated design of aqueous zinc-ion batteries based on dendrite-free zinc microspheres/carbon nanotubes/nanocellulose composite film anode.

With the booming development of wearable electronics, flexible zinc-based batteries are attracting significant attention due to their high safety, low cost, environmental benignity, and relatively large energy/power densities. However, in a conventional segregated configuration, the electrodes could be easily detached from the separator when the battery is subjected to bending strain, which would dramatically depress electrochemical performances. Moreover, severe zinc dendrite growth and parasitic side reactions at the anode are extremely detrimental to the durability and the reliability of zinc-based batteries. Herein, a flexible self-standing composite film anode consisting of zinc microspheres, carbon nanotubes, and nanocellulose is constructed to replace the conventional Zn foil. It is found that the use of this anode can effectively inhibit the dendrites and side reactions, thereby substantially improving the cyclability. In addition, a layer-by-layer vacuum filtration method is used to integrate the composite film anode with a cellulose separator and a MnO2-based composite film cathode into a single matrix. The unique integrated battery realizes great rate capability and cycling stability, and more importantly, superior affordability to bending deformations. Besides, the commonly used thick, heavy, and expensive current collectors are no longer required in the integrated configuration, therefore enabling the battery to be smarter and cheaper. This study not only opens a new option for building dendrite-free zinc anodes but also discloses a facile strategy to achieve integrated configuration for energy storage devices.

High lithium storage performance of CoO with a distinctive dual-carbon-confined nanoarchitecture.

Herein, a distinctive dual-carbon-confined nanoarchitecture, composed of an inner highly conductive, robust carbon nanotube (CNT) support and outer well-designed porous carbon (PC) coating, was demonstrated to efficiently improve the electrochemical properties of CoO nanoparticles for the first time, and the CoO nanoparticles were confined between the CNTs and porous carbon. The well-designed porous carbon coating showed significant superiority compared to common non-porous carbon coatings, due to its distinctive characteristics such as high flexibility, rich free space and open tunnel-like structure. Therefore, the synergistic effects of the CNT core and the porous carbon sheath endowed the CoO-based composite (CNTs@CoO@PC) with improved electrochemical reaction kinetics, large pseudocapacitive contribution and superior structural stability. As a result, the CNTs@CoO@PC showed outstanding performance with 1090, 571 and 242 mA h g-1 at 200, 1000 and 5000 mA g-1 after 300, 600 and 1000 cycles, respectively. Furthermore, this strategy may be used to improve other metal oxide anode materials for lithium storage.

Realizing an All-Round Hydrogel Electrolyte toward Environmentally Adaptive Dendrite-Free Aqueous Zn-MnO2 Batteries.

Flexible energy storage devices are at the forefront of next-generation power supplies, one of the most important components of which is the gel electrolyte. However, shortcomings exist, more or less, for all the currently developed hydrogel electrolytes. Herein, a facile and cost-effective method is developed to construct an all-round hydrogel electrolyte by using cotton as the raw material, tetraethyl orthosilicate as the crosslinker, and glycerol as the antifreezing agent. The obtained hydrogel electrolyte has high ionic conductivity, excellent mechanical properties (e.g., high tensile strength and elasticity), ultralow freezing point, good self-healing ability, high adhesion, and good heat-resistance ability. Remarkably, this hydrogel electrolyte can provide a record-breaking high ionic conductivity of 19.4 mS cm-1 at -40 °C compared with previously reported aqueous electrolytes for zinc-ion batteries. In addition, this hydrogel electrolyte can significantly inhibit zinc dendritic growth and parasitic side reactions from -40 to 60 °C. With this hydrogel electrolyte, a flexible quasi-solid-state Zn-MnO2 battery is assembled, which shows remarkable energy densities from -40 to 60 °C. The battery also exhibits outstanding cycling durability and has high endurance under various harsh conditions. This work opens new opportunities for the development of hydrogel electrolytes.

Developing improved electrolytes for aqueous zinc-ion batteries to achieve excellent cyclability and antifreezing ability.

Due to their low cost, high safety, environmental friendliness, and impressive electrochemical performances, aqueous zinc-ion batteries are considered promising alternative technologies to lithium-ion batteries for use in large-scale applications. However, existing aqueous zinc-ion batteries usually suffer from poor cyclability and cannot operate at subzero temperatures. Herein, to solve these problems, the electrolyte in aqueous zinc-ion batterie is optimized by adding the appropriate amounts of diethyl ether and ethylene glycol. Results show that the addition of 1% diethyl ether contributes to the best cyclability at 25 °C. Furthermore, the addition of 30% ethylene glycol results in the best electrochemical performances at 0 and - 10 °C. This significant performance improvement at low temperatures is ascribed to the high ionic conductivity of the modified electrolyte and the low charge transfer impedance of the battery with the modified electrolyte at 0 and -10 °C. It is also shown that the modified electrolyte can decrease the nucleation overpotential of zinc plating, enhance the interfacial stability between the zinc metal and electrolyte, suppress the zinc dendritic growth and side reactions, and decrease the self-corrosion rate of the zinc anode. This work offers a facile strategy to realize aqueous zinc-ion batteries with excellent cyclability and antifreezing ability and may inspire research on other aqueous energy storage systems.

Facile fabrication of hierarchical hollow microspheres assembled by titanate nanotubes.

Hierarchical hollow microspheres assembled by titanate nanotubes were fabricated via a hydrothermal process. During the entire process, the hydrous titanium oxide microspheres served as a template and source of titanate ions and H(2)O(2) was used to facilitate the conversion of titanate sheets into nanotubes in low-concentration NaOH (0.1 M). Furthermore, this synthesis route is more friendly than the previous hydrothermal synthesis of TiO(2)-derived nanotubes in a highly alkaline (10-15 M) medium.