The realization of high-efficiency, reversible, stable, and safe Li-O2 batteries is severely hindered by the large overpotential and side reactions, especially at high rate conditions. Therefore, rational design of cathode catalysts with high activity and stability is crucial to overcome the terrible issues at high current density. Herein, we report a surface engineering strategy to adjust the surface electron structure of boron (B)-doped PtNi nanoalloy on carbon nanotubes (PtNiB@CNTs) as an efficient bifunctional cathodic catalyst for high-rate and long-life Li-O2 batteries. Notably, the Li-O2 batteries assembled with as-prepared PtNiB@CNT catalyst exhibit ultrahigh discharge capacity of 20510 mA·h/g and extremely low overpotential of 0.48 V at a high current density of 1000 mA/g, both of which outperform the most reported Pt-based catalysts recently. Meanwhile, our Li-O2 batteries offer excellent rate capability and ultra-long cycling life of up to 210 cycles at 1000 mA/g under a fixed capacity of 1000 mA·h/g, which is two times longer than those of Pt@CNTs and PtNi@CNTs. Furthermore, it is revealed that surface engineering of PtNi nanoalloy via B doping can efficiently tailor the electron structure of nanoalloy and optimize the adsorption of oxygen species, consequently delivering excellent Li-O2 battery performance. Therefore, this strategy of regulating the nanoalloy by doping nonmetallic elements will pave an avenue for the design of high-performance catalysts for metal-oxygen batteries.
Benefiting from the high capacity of Zn metal anodes and intrinsic safety of aqueous electrolytes, rechargeable Zn ion batteries (ZIBs) show promising application in the post-lithium-ion period, exhibiting good safety, low cost, and high energy density. However, its commercialization still faces problems with low Coulombic efficiency and unsatisfied cycling performance due to the poor Zn/Zn2+ reversibility that occurred on the Zn anode. To improve the stability of the Zn anode, optimizing the Zn deposition behavior is an efficient way, which can enhance the subsequent striping efficiency and limit the dendrite growth. The Zn deposition is a controlled kinetics-diffusion joint process that is affected by various factors, such as the interaction between Zn2+ ions and Zn anodes, ion concentration gradient, and current distribution. In this review, from an electrochemical perspective, we first overview the factors affecting the Zn deposition behavior and summarize the modification principles. Subsequently, strategies proposed for interfacial modification and 3D structural design as well as the corresponding mechanisms are summarized. Finally, the existing challenges, perspectives on further development direction, and outlook for practical applications of ZIBs are proposed.
Three-dimensional (3D) printing has the potential to revolutionize the way energy storage devices are designed and manufactured. In this paper, we explore the use of 3D printing in the design and production of energy storage devices, especially zinc-ion batteries (ZIBs) and examine its potential advantages over traditional manufacturing methods. 3D printing could significantly improve the customization of ZIBs, making it a promising strategy for the future of energy storage. In particular, 3D printing allows for the creation of complex, customized geometries, and designs that can optimize the energy density, power density, and overall performance of batteries. Simultaneously, we discuss and compare the impact of 3D printing design strategies based on different configurations of film, interdigitation, and framework on energy storage devices with a focus on ZIBs. Additionally, 3D printing enables the rapid prototyping and production of batteries, reducing leading times and costs compared with traditional manufacturing methods. However, there are also challenges and limitations to consider, such as the need for further development of suitable 3D printing materials and processes for energy storage applications.
Electrocatalytic water splitting that is coupled with electrocatalytic chemical oxidation is considered as one of the promising methods for efficiently obtaining hydrogen energy and fine chemicals. Herein, we focus on an electrochemical redox activation strategy to rationally manipulate the microstructure and surface valence states of copper foam (CF) and boost the corresponding performance towards electrocatalytic benzyl alcohol oxidation (EBA), accompanied by the efficient hydrogen production. Correspondingly, the Cu(II)-dominated species are gradually formed on the CF surface with the dissolution and redeposition of copper in the suitable potential range. The new species containing Cu2O, CuO, and Cu(OH)2 during surface reconstruction process of the CF were confirmed by multiple characterization techniques. After 220-cycled activation (CF-220), the activated CF achieves an increase of current density for EBA in anode from 9.5 for the original CF to 29.3 mmol/cm2, while the pure hydrogen yield increases threefold than that of the original CF at 1.5 VRHE. The produced new species can endow the CF-220 with abundant acidity sites, which can enhance the adsorption toward Lewis-basicity benzyl alcohol, confirmed by NH3-temperature-programmed desorption. In situ Raman result further reveals that the as-produced CuO, Cu(OH)2, and Cu(OH)42− are the main active species toward the EBA process.
Combination of flexible multifunctional stealth technology properties such as electromagnetic (EM) and infrared (IR) stealth is crucial to the development of aerospace, military, and electronic fields, but the synthesis technology still has a significant challenge. Herein, we have successfully designed and synthesized highly flexible MXene@cellulose lamellae/borate ion (MXCB) sheets with strong high-temperature EM-IR bi-stealth through sequential bridging of hydrogen and covalent bonds. The resultant MXCB sheets display high conductivity and good mechanical features such as flexibility, stretchability, fatigue resistance, and ultrasonic damage. MXCB sheets have a high tensile strength of 795 MPa. Furthermore, MXCB sheets with different thicknesses indicate exceptional high-temperature thermal-camouflage characteristics. This reduces the radiation temperature of the target object (>300 °C) to 100 °C. The conductivity of MXCB sheet with 3 μm thickness is 6108 S/cm and the EM interference (EMI) shielding value is 39.74 dB. The normalized surface-specific EMI SE absolute shielding effectiveness (SSE/t) is as high as 39312.78 dB·cm2/g, which remained 99.39% even after 10,000 times repeated folding. These multifunctional ultrathin MXCB sheets can be arranged by vacuum-assisted induction to develop EM-IR bi-stealth sheet.
Flexible aqueous zinc batteries (FAZBs) with high safety and environmental friendliness are promising smart power sources for smart wearable electronics. However, the bare zinc anode usually suffers from damnable dendrite growth and rampant side reaction on the surface, greatly impeding practical applications in FAZBs. Herein, a composite polymer interface layer is artificially self-assembled on the surface of the zinc anode by graft-modified fluorinated monomer (polyacrylic acid-2-(Trifluoromethyl)propenoic acid, PAA-TFPA), on which an organic–inorganic hybrid (PAA-Zn/ZnF2) solid electrolyte interface (SEI) with excellent ionic conductivity is formed by interacting with Zn2+. Both the pouch cell and fiber zinc anode exhibit excellent plating/stripping reversibility after protecting by this organic–inorganic SEI, which can be stably cycled more than 3000 h in symmetric Zn||Zn cells or 550 h in fiber Zn||Zn cells. Additionally, this interface layer preserves zinc anode with excellent mechanical durability under various mechanical deformation (stably working for another 1200 h after bending 100 h). The corresponding PAA-Zn/ZnF2@Zn||MnO2 full cell displays an ultra-long life span (79% capacity retention after 3000 cycles) and mechanical robustness (85% of the initial capacity for another 3000 cycles after bending 100 times). More importantly, the as-assembled cells can easily power smart wearable devices to monitor the user's health condition.
Intelligent ion gels, which possess highly tunable mechanical, electrical, and stimulus-responsive properties, have emerged as powerful candidates in the field of artificial intelligence, telemedicine, and health monitoring. To enrich the functionality of ion gels, it is critical to explore the link between the structure and function of ion gels. In this review, we provide an overview of the synthesis path and functional derivatives of ion gels. The conformational relationships of ion gels have been discussed, such as the effect of structure on electrical conductivity as well as sensing properties. From the perspective of stimulus response, the role of ion gels in areas such as bionic haptics, neural devices, artificial muscles, and intelligent displays has also been explored. It is possible that smart ion gels will open up a new horizon in the upcoming smart era, especially after the current challenges are resolved.
Aqueous zinc-ion batteries (ZIBs) are regarded as among the most promising candidates for large-scale grid energy storage, owing to their high safety, low costs, and environmental friendliness. Over the past decade, vanadium oxides, which are exemplified by V2O5, have been widely developed as a class of cathode materials for ZIBs, where the relatively high theoretical capacity and structural stability are among the main considerations. However, there are considerable challenges in the construction of vanadium-based ZIBs with high capacity, long lifespan, and excellent rate performance. Simple widenings of the interlayer spacing in the layered vanadium oxides by pre-intercalations appear to have reached their limitations in improving the energy density and other key performance parameters of ZIBs, although various metal ions (Na+, Ca2+, and Al3+) and even organic cations/groups have been explored. Herein, we discuss the advances made more recently, and also the challenges faced by the high-performance vanadium oxides (V2O5-based) cathodes, where there are several strategies to improve their electrochemical performance ranging from the new structural designs down to sub-nano-scopic/molecular/atomic levels, including cation pre-intercalation, structural water optimization, and defect engineering, to macroscopic structural modifications. The key principles for an optimal structural design of the V2O5-based cathode materials for high energy density and fast-charging aqueous ZIBs are examined, aiming at paving the way for developing energy storage designed for those large scales, high safety, and low-cost systems.