Designing Polymer-in-Salt Electrolyte and Fully Infiltrated 3D Electrode for Integrated Solid-State Lithium Batteries.

Solid-state lithium batteries (SSLBs) are promising owing to enhanced safety and high energy density but plagued by the relatively low ionic conductivity of solid-state electrolytes and large electrolyte-electrode interfacial resistance. Herein, we design a poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)-based polymer-in-salt solid electrolyte (PISSE) with high room-temperature ionic conductivity (1.24×10-4  S cm-1 ) and construct a model integrated TiO2 /Li SSLB with 3D fully infiltration of solid electrolyte. With forming aggregated ion clusters, unique ionic channels are generated in the PISSE, providing much faster Li+ transport than common polymer electrolytes. The integrated device achieves maximized interfacial contact and electrochemical and mechanical stability, with performance close to liquid electrolyte. A pouch cell made of 2 SSLB units in series shows high voltage plateau (3.7 V) and volumetric energy density comparable to many commercial thin-film batteries.

Uniform implantation of CNTs on total activated carbon surfaces: a smart engineering protocol for commercial supercapacitor applications.

The main obstacles to building better supercapacitors are still trade-offs between energy and power parameters. To promote commercial supercapacitor behaviors, proper optimization toward electrode configurations/architectures may be a feasible and effective way. We herein propose a smart and reliable electrode engineering protocol, by in situ implantation of carbon nanotubes (CNTs) on total activated carbon (AC) surfaces via a mild chemical vapor deposition process at ∼550 °C, using nickel nitrate hydroxide (NNH) thin films and waste ethanol solvents as the catalyst and carbon sources, respectively. The direct and conformal growth of NNH layers onto carbonaceous scaffold guarantees the later uniform implantation of long and high-quality CNTs on total AC outer surfaces. Such fluffy and entangled CNTs preserve ionic diffusion channels, well connect neighboring ACs and function as superhighways for electrons transfer, endowing electrodes with outstanding capacitive behaviors including large output capacitances of ∼230 F g-1 in 1 M Na2SO4 neutral solution and ∼502.5 F g-1 in 6 M KOH using Ni valence state variation, and very negligible capacity decay in long-term cycles. Furthermore, a full symmetric supercapacitor device of CNTs@ACs//CNTs@ACs has been constructed, capable of delivering both high specific energy and power densities (maximum values reaching up to ∼97.2 Wh kg-1 and ∼10.84 kW kg-1), which holds great potential in competing with current mainstream supercapacitors.

Composite poly(ethylene oxide)-based solid electrolyte with consecutive and fast ion transport channels constructed by upper-dimensional MIL-53(Al) nanofibers.

Novel structural designs for metal organic frameworks (MOFs) are expected to improve ion-transport behavior in composite solid electrolytes. Herein, upper-dimensional MIL-53(Al) nanofibers (MNFs, MIL-53 belongs to the MIL (Material Institute Lavoisier) group) with flower-like nanoflake structures have been designed and constructed via modified hydrothermal coordination. The optimized MNFs with high surface area and porosity can form abundant interfaces with poly(ethylene oxide) (PEO) matrix. The plasticization of MNFs to the PEO matrix will facilitate segmental movement of PEO chains to facilitate Li+ conduction. The unsaturated open metal centers of MNFs can effectively capture bis(trifluoromethanesulfonyl)imide anions (TFSI-) to deliver more free lithium ions for transfer. Moreover, the upper-dimensional nanofiber structure endows lithium ions with a long-range and consecutive transport pathway. The obtained composite solid electrolyte (MNFs@PEO) presents a high ionic conductivity of 4.1 × 10-4 S cm-1 and a great Li+ transference number of 0.4 at 60 °C. The electrolyte also exhibits a stable Li plating/stripping behavior over 1000 h at 0.1 mA cm-1 with inhibited Li dendrite growth. Furthermore, the Li/LiFePO4 and Li/LiNi0.8Mn0.1Co0.1O2 batteries with MNFs@PEO as electrolytes both display great cycling stabilities with high-capacity retention, indicating their potential applications in lithium metal batteries. The study will put forward new inspirations for designing advanced MOF-based composite solid electrolytes.

Engineering of heterointerface of ultrathin carbon nanosheet-supported CoN/MnO enhances oxygen electrocatalysis for rechargeable Zn-air batteries.

Designing bifunctional electrocatalysts with outstanding reactivity and durability towards the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) has remained a long-term aim for metal-air batteries. Achieving the high level of fusion between two distinct metal components to form bifunctional catalysts with optimized heterointerfaces and well-defined morphology holds noteworthy implications in the enhancement of electrocatalytic activity yet challenging. Herein, the fabrication of numerous heterointerfaces of CoN/MnO is successfully realized within ultrathin carbon nanosheets via a feasible self-templating synthesis strategy. Experimental results and theoretic calculations verify that the interfacial electron transfer from CoN to MnO at the heterointerface engenders an ameliorated charge transfer velocity, finely tuned energy barriers concerning reaction intermediates and ultimately accelerated reaction kinetics. The as-prepared CoN/MnO@NC demonstrates exceptional bifunctional catalytic performance, excelling in both OER and ORR showcasing a low reversible overpotential of 0.69 V. Furthermore, rechargeable liquid and quasi-solid-state flexible Zn-air batteries employing CoN/MnO@NC as the air-cathode deliver remarkable endurance and elevated power density, registering values of 153 and 116 mW cm-2 respectively and exceeding Pt/C + RuO2 counterparts and those reported in literature. Deeply exploring the effect of electron-accumulated heterointerfaces on catalytic activity would contribute wisdom to the development of bifunctional electrocatalysts for rechargeable metal-air batteries.

Engineering Sb/Zn4(OH)6SO4·5H2O interfacial layer by in situ chemically reacting for stable Zn anode.

Rechargeable aqueous zinc ion batteries with abundant resources and high safety have gained extensive attention in energy storage technology. However, the cycle stability is largely limited by notorious Zn dendrite growth and water-induced interfacial side reactions. Here, a uniform and robust protection layer consisting of metal antimony (Sb) nanoparticles and micrometer-size sheets Zn4(OH)6SO4·5H2O (ZHS) is purposely designed to stabilize Zn anode via an in situ chemical reaction strategy. The two-phase protection layers (Sb/ZHS) induce a reinforcement effect on the Zn anode (Zn@Sb/ZHS). Specifically, Sb nanoparticles play the part of nucleation sites to facilitate uniform Zn plating and homogenize the electric field around the Zn surface. ZHS micrometer-size sheets possess sufficient electrolyte wettability, fast ion transfer kinetics, and anti-corrosion, thus guaranteeing uniform ion flux and inhibiting H2O decomposition. As expected, the symmetric Zn@Sb/ZHS//Zn@Sb/ZHS cells achieve a minimal voltage hysteresis and a reversible cycle of over 2000 h at 1 mA cm-2. By pairing with the MnO2 cathode, the full cell exhibits a significantly improved stability (∼94.17 % initial capacity after 1500 cycles). This study provides a new strategy to design artificial protection layers.

Ether-Water Co-Solvent Electrolytes Enhanced Vanadium Oxide Cathode Cyclic Behaviors for Zinc Batteries.

Vanadium-based compounds are fantastic cathodes for aqueous zinc metal batteries due to the high specific capacity and excellent rate capability. Nevertheless, the practical application has been hampered by the dissolution of vanadium in traditional aqueous electrolytes owing to the strong polarity of water molecules. Herein, we propose a hybrid electrolyte made of Zn(ClO4)2 salt in tetraethylene glycol dimethyl ether (G4) and H2O solvents to upgrade the cycle life of Zn//K0.486V2O5 battery. The G4 jointly solvates with Zn2+ ions and replaces a portion of the H2O molecules in the Zn2+ solvation sheath. It forms a strong bond with H2O, reducing its activity, and significantly inhibiting vanadium dissolution and water-induced parasitic reaction. Consequently, the optimized electrolyte with H2O and G4 volume ratio of 5 : 5 enhances the cycling stability of Zn//K0.486V2O5 battery, enabling it to reach up to 600 cycles. In addition, the battery demonstrates a satisfactory reversible capacity of 475.7 mAh g-1 and excellent rate performance attributed to the moderate ionic conductivity (28.8 mS cm-1) of the hybrid electrolyte. Last but not least, in the optimized electrolyte, the symmetric Zn//Zn cells deliver a long cycling performance of 400 h, while the asymmetric Zn//Cu cells shows a high average coulombic efficiency of 97.4 %.

Recycling of Zinc-Carbon Batteries into MnO/ZnO/C to Fabricate Sustainable Cathodes for Rechargeable Zinc-Ion Batteries.

Acidic zinc-carbon dry batteries have been widely used in life because of their low cost. However, a great quantity of used batteries is discarded as refuse, which not only wastes resources but also leads to environmental contamination. To reuse spent batteries on a large scale, this study concerns a simple, effective, and sustainable strategy to turn them into MnO/ZnO/C composites. After a conventional leaching treatment followed by pyrolysis, the rust cathode materials can be reduced to MnO/ZnO/C. When serving as a rechargeable zinc-ion battery cathode, this electrode provides a maximum reversible capacity of around 362 mAh g-1 MnO ) and a rate capability of 191 mAh g-1 MnO at a high current rate of 1.20 A g-1 . Furthermore, ZnO gradually dissolves in the electrolyte with the increase of discharge cycles, replenishing the Zn2+ content in the electrolyte and further enhancing cycling stability (98.02 % after 500 cycles). The device also exhibits a remarkable energy density of 336.37 Wh kg-1 , low self-discharge rate, and can efficiently power a LED panel. This strategy offers an economical and facile route to convert zinc-carbon battery waste into useful materials for aqueous rechargeable zinc ion batteries.

Surface and Interface Engineering of Nanoarrays toward Advanced Electrodes and Electrochemical Energy Storage Devices.

The overall performance of electrochemical energy storage devices (EESDs) is intrinsically correlated with surfaces and interfaces. As a promising electrode architecture, 3D nanoarrays (3D-NAs) possess relatively ordered, continuous, and fully exposed active surfaces of individual nanostructures, facilitating mass and electron transport within the electrode and charge transfer across interfaces and providing an ideal platform for engineering. Herein, a critical overview of the surface and interface engineering of 3D-NAs, from electrode and interface designs to device integration, is presented. The general merits of 3D-NAs and surface/interface engineering principles of 3D-NA hybrid electrodes are highlighted. The focus is on the use of 3D-NAs as a superior platform to regulate the interface nature and unveiling new mechanism/materials without the interference of binders. The engineering and utilization of the surface of 3D-NAs to develop flexible/solid-state EESDs with 3D integrated electrode/electrolyte interfaces, or 3D triphase interfaces involving other active species, which are characteristic of (quasi-)solid-state electrolyte infiltration into the entire device, are also considered. Finally, the challenges and future directions of surface/interface engineering of 3D-NAs are outlined. In particular, potential strategies to obtain electrode charge balance, optimize the multiphase solid-state interface, and attain 3D solid electrolyte infiltration are proposed.

Electrolyte Concentration Regulation Boosting Zinc Storage Stability of High-Capacity K0.486V2O5 Cathode for Bendable Quasi-Solid-State Zinc Ion Batteries.

Vanadium-based cathodes have attracted great interest in aqueous zinc ion batteries (AZIBs) due to their large capacities, good rate performance and facile synthesis in large scale. However, their practical application is greatly hampered by vanadium dissolution issue in conventional dilute electrolytes. Herein, taking a new potassium vanadate K0.486V2O5 (KVO) cathode with large interlayer spacing (~ 0.95 nm) and high capacity as an example, we propose that the cycle life of vanadates can be greatly upgraded in AZIBs by regulating the concentration of ZnCl2 electrolyte, but with no need to approach "water-in-salt" threshold. With the optimized moderate concentration of 15 m ZnCl2 electrolyte, the KVO exhibits the best cycling stability with ~ 95.02% capacity retention after 1400 cycles. We further design a novel sodium carboxymethyl cellulose (CMC)-moderate concentration ZnCl2 gel electrolyte with high ionic conductivity of 10.08 mS cm-1 for the first time and assemble a quasi-solid-state AZIB. This device is bendable with remarkable energy density (268.2 Wh kg-1), excellent stability (97.35% after 2800 cycles), low self-discharge rate, and good environmental (temperature, pressure) suitability, and is capable of powering small electronics. The device also exhibits good electrochemical performance with high KVO mass loading (5 and 10 mg cm-2). Our work sheds light on the feasibility of using moderately concentrated electrolyte to address the stability issue of aqueous soluble electrode materials.

Phase Transition Triggers Explosion-like Puffing Process to Make Popcorn-Inspired All-Conductive Anodes for Superb Aqueous Rechargeable Batteries.

The major accomplishment of electrochemical energy-storage devices is closely linked to the advent of state-of-the-art techniques to make optimal electrode systems. Herein, we demonstrate a unique popcorn-inspired strategy to develop all-conductive and highly puffed Fe⊂carbon nanopopcorns as superb anodes for rechargeable Ni/Fe batteries. Temperature-dependent systematic studies show that the nanopopcorn evolution mechanism is governed by typical phase variation from Fe2O3 nanospheres to dispersed Fe0 nanodebris, whose formation induces catalytic reconstruction/conversion from hydrocarbons to graphitic nanolayers while triggering the explosion-like instant puffing process beyond 700 °C. The as-built Fe⊂carbon hybrids with favorable loosened structures, open-up/enlarged surface areas, and intrinsically conducting nature enable great electrochemical reactivity and cyclic stability (reversible capacity higher than ∼420 mA h g-1 in all cycles without obvious capacity decay), as well as outstanding rate behaviors (∼300 mA h g-1 is still retained at ∼20 A g-1). Full-cell devices of NiO@carbon (+)//Fe⊂carbon (-) can exhibit Max. energy/power densities of up to ∼140.8 W h kg-1 and ∼15.6 kW kg-1, respectively. This work sheds a fundamental light on arts to configure puffed electrodes for advanced electrodes in various important applications while holding great promise for high-rate/capacity aqueous rechargeable batteries.

Building better rechargeable Zn-Mn batteries with a highly active Mn3O4/carbon nanowire cathode and neutral Na2SO4/MnSO4 electrolyte.

A more reliable/eco-friendly secondary Zn-Mn battery system is built with highly active Mn3O4@carbon nanowires and near-neutral electrolytes. Such configured batteries show high reversibility and superior behavior in terms of both stored capacity and cycling durability, holding great promise in near-future power-supply applications.

One-Dimensional Integrated MnS@Carbon Nanoreactors Hybrid: An Alternative Anode for Full-Cell Li-Ion and Na-Ion Batteries.

Manganese sulfide (MnS) has triggered great interest as an anode material for rechargeable Li-ion/Na-ion batteries (LIBs/SIBs) because of its low cost, high electrochemical activity, and theoretical capacity. Nevertheless, the practical application is greatly hindered by its rapid capacity decay lead by inevitable active dissolutions and volume expansions in charge/discharge cycles. To resolve the above issues in LIBs/SIBs, we herein put forward the smart construction of MnS nanowires embedded in carbon nanoreactors (MnS@C NWs) via a facile solution method followed by a scalable in situ sulfuration treatment. This engineering protocol toward electrode architectures/configurations endows integrated MnS@C NWs anodes with large specific capacity (with a maximum value of 847 mA h g-1 in LIBs and 720 mA h g-1 in SIBs), good operation stability, excellent rate capabilities, and prolonged cyclic life span. To prove their potential real applications, we have established the full cells (for LIBs, MnS@C//LiFePO4; for SIBs, MnS@C//Na3V2(PO4)3), both of which are capable of showing remarkable specific capacities, outstanding rate performance, and superb cyclic endurance. This work offers a scalable, simple, and efficient evolution method to produce the integrated hybrid of MnS@C NWs, providing useful inspiration/guidelines for anodic applications of metal sulfides in next-generation power sources.

Putting Nanoarmors on Yolk-Shell Si@C Nanoparticles: A Reliable Engineering Way To Build Better Si-Based Anodes for Li-Ion Batteries.

Practical utilization of silicon (Si) for Li-ion batteries (LIBs) still remains sluggish because of its formidable kinetic problems of huge volume expansions over 300%, instable solid electrolyte interphase (SEI), and unsatisfactory electrical conductivity. Though using a yolk-shell (Y-S) Si@C nanodesign indeed helps to mitigate active changes, optimize SEI properties, and lower intrinsic charge-transfer impedances, the total anodic behaviors in reversibility, rate capabilities, and long-lasting cyclability are still far from perfect. To settle the above issues, we herein propose a reliable and effective way by putting tough and malleable Ni nanoarmors on Y-S Si@C nanoparticles (Si@C⊆Ni). The unique functionalized configurations endow such hybrid systems with superb reversible capacity retention (almost no capacity decay emerges in 600 cycles, retaining a reversible capacity beyond ∼1307 mA h g-1), prominent cyclic stability, and rate behaviors. To justify their potential usage, full cells of (-)Si@C⊆Ni//LiFePO4(+) are further constructed, delivering impressive specific energy and power densities (max. VALUES: ∼423 W h kg-1/∼497.8 W kg-1). This paradigm work may offer a highly feasible engineering protocol to push forward Si anode performances for next-generation LIBs.

Metallic Fe nanoparticles trapped in self-adapting nanoreactors: a novel high-capacity anode for aqueous Ni-Fe batteries.

Metallic Fe nanoparticles trapped in thick carbon nanoreactors are realized in situ via conventional gas-phase reactions. These derived nanohybrids exhibit unique self-adapting properties, with prominent anodic performance in terms of both stored capacity and cyclic durability when serving as anodes for Ni-Fe batteries.

In Situ Engineering Toward Core Regions: A Smart Way to Make Applicable FeF3@Carbon Nanoreactor Cathodes for Li-Ion Batteries.

Iron fluorides (FeFx) have attracted great interest in Li-ion batteries due to their high theoretical capacity, low cost, and preferable cell safety. However, their practical utilization is severely impeded by inferior electrode kinetics, leading to poor electrode cyclability and rate capabilities. The major bottleneck should be lack of any effective engineering techniques to make reliable encapsulation and conducting matrix on soluble FeFx species. Herein, we propose an applicable synthetic strategy where the massive production of FeF3@carbon nanoreactors (total size: ∼60 nm) can be easily achieved by in situ engineering toward the core regions in hybrids, with the iron rust wastes and common solvents as raw materials. Such functionalized configurations can well make up for the shortcomings of FeF3 species, enabling them with outstanding cathode behaviors involving excellent reversible capacity retention (∼270% higher than that of a bare FeF3 electrode after 600 cycles) and drastically enhanced rate performance. This paradigm work provides a facile and scalable method to make superior and sustainable cathodes and, moreover, offers a feasible engineering protocol to make water-soluble species encapsulated into carbon matrix, not merely for batteries but also for other wide range of fields like catalysis, nanomedicine, etc.

In Situ Packaging FeFx into Sack-like Carbon Nanoreactors: A Smart Way To Make Soluble Fluorides Applicable to Aqueous Batteries.

Ferruginous materials have long attracted great interest in aqueous batteries since Fe is an earth-abundant and low toxic element. However, their practical application is severely hindered by their poor structural stability during deep cycling. To maximize their cyclability, we herein propose a simple and effective method, by in situ packaging Fe-based materials into carbon nanosacks via a facile CVD approach. To verify our strategy, we purposely choose water-soluble Fe2F5 as a study paradigm. The in situ formed Fe2F5@C nanosacks product exhibits prominent anodic performance with high electrochemical activity and capacity, obviously prolonged cyclic lifetime, and outstanding rate capabilities. Besides, by pairing with the cathode of α-Co(OH)2 nanowire arrays@carbon cloth, a full device of rechargeable aqueous batteries has been developed, capable to deliver both high specific energy and power densities (Max. values reaching up to ∼163 Wh kg(-1) and ∼14.2 kW kg(-1)), which shows great potential in practical usage. Our present work may not only demonstrate the feasibility of using soluble fluorides as anodes for aqueous batteries but also provide a smart way to upgrade cyclic behaviors of Fe-based anodes.

FeF3@Thin Nickel Ammine Nitrate Matrix: Smart Configurations and Applications as Superior Cathodes for Li-Ion Batteries.

Iron fluorides (FeFx) for Li-ion battery cathodes are still in the stage of intensive research due to their low delivery capacity and limited lifetime. One critical reason for cathode degradation is the severe aggregation of FeFx nanocrystals upon long-term cycling. To maximize the capacity and cyclability of these cathodes, we propose herein a novel and applicable method using a thin-layered nickel ammine nitrate (NAN) matrix as a feasible encapsulation material to disperse the FeF3 nanoparticles. Such core-shell hybrids with smart configurations are constructed via a green, scalable, in situ encapsulation approach. The outer thin-film NAN matrix with prominent electrochemical stability can keep the FeF3 nanoactives encapsulated throughout the cyclic testing, protecting them from adverse aggregation into bulk crystals and thus leading to drastic improvements of electrode behaviors (e.g., high electrode capacity up to ∼423 mA h g(-1), greatly prolonged cyclic period, and promoted rate capabilities). This present work may set up a new and general platform to develop intriguing core-shell hybrid cathodes for Li-ion batteries, not only for FeFx but also for a wide spectrum of other cathode materials.