Developing cost-effective bifunctional electrocatalysts for oxygen reduction and evolution reactions (ORR/OER) is crucial for rechargeable Zn-air batteries. Herein, we synthesize a novel catalyst comprising helical carbonaceous nanotubes encapsulating cobalt nanoparticles, using corn stigma agricultural waste, melamine and cobalt chloride as precursors. The curved surface of helical carbonaceous nanotubes promotes metal ion dispersion and charge separation within the carbon lattice. Applying strain engineering to these curved structures further tunes the electronic configuration of the active centers, boosting electrocatalytic performance. The as-prepared catalyst demonstrates remarkable electrocatalytic performance, achieving a high ORR half-wave potential of 0.869 V with minimal degradation (10 mV shift after 5000 CV cycles), along with a low OER overpotential of 350 mV at 10 mA cm−2. In liquid Zn-air batteries, the catalyst delivers a peak power density of 214.8 mW cm−2 and stable operation for over 390 h at 10 mA cm−2 with negligible voltage decay. Moreover, the corresponding flexible wearable Zn-air battery demonstrates excellent foldability and cyclic stability. These results highlight a promising strategy for designing durable, high-efficiency electrocatalysts for metal-air energy systems.

Calcium-ion batteries (CIBs) have attracted increasing attention owing to the natural abundance and potentially low cost of calcium resources. However, practical CIBs cathodes are broadly hindered by sluggish Ca2+ diffusion, large polarization, and structural instability upon repeated (de)intercalation. Among Mn-based candidates, alpha-MnO2 exhibits a low Ca2+ diffusion barrier, yet its structure suffers irreversible damage during Ca2+ insertion/ extraction. Herein, we propose a Fe-doping strategy to reconstruct the tunnel skeleton of Mn octahedra in alpha-MnO2, which toughens the lattice and regulates its electronic properties, thereby inhibiting the Jahn-Teller effect and preventing Mn dissolution. The strategic incorporation of Fe induces targeted lattice strain, maintaining the long-range skeletal integrity while precisely modifying short-range local distortions. This straindriven regulation significantly expedites Ca2+ transport, yielding a diffusion coefficient of 1.24 & times; 10(-9) cm(2) s(-1), which is the highest recorded value among Mn-based CIB cathodes. Consequently, the optimized Fe-doped alpha-MnO2 delivers high rate performance, achieving capacities of 201, 161, 145, 132, and 111 mAh g(-1) at 0.1, 0.2, 0.3, 0.5, and 1.0 A g(-1), respectively. Furthermore, it exhibits a long-term cycle life by retaining 74 mAh g(-1) after 3000 cycles at 1 A g(-1), providing a rational design paradigm for advanced Mn-based cathodes in CIBs.

Aqueous rechargeable Zn||I2 batteries (ZIBs) offer the combined advantages of high energy density and power density, excellent cycling stability, and superior safety. However, the discontent performance of Zn anodes severely restricts the development of ZIBs. In particular, the uncontrolled growth of Zn dendrites during repeated depositing/stripping cycles often leads to short circuits. In this study, we report a novel zwitterionic salt, 3-(tris (2-hydroxyethyl)ammonio)propane-1-sulfonate (TPS), synthesized via ring-opening reaction, which selectively adsorbs onto the Zn (100) plane through electrostatic interactions, promoting densely packed Zn(100) oriented growth on the anode surface. Moreover, the strong binding energy between TPS and water molecules effectively suppresses the side reactions on the Zn surface, thereby further enhancing the cycling stability of the Zn anode. Benefiting from these positive effects, Zn//Zn symmetrical cells with TPS exhibit remarkable cycling stability over 4000 h under a test condition of 1 mA cm- 2 and 1 mAh cm- 2, greatly outperforming cells with blank electrolytes. Most notably, the ZIBs with TPS deliver a maximum specific capacity of 145.82 mAh g- 1 at 5 A g- 1, and maintain stable performance for 13,000 cycles, significantly surpassing TPS-free counterparts. This chemical synthesis strategy for electrolyte additives offers a promising approach to addressing key challenges in Zn-based energy storage devices.

The pre-intercalation of foreign species into zinc-vanadium oxide battery cathodes has been successfully demonstrated to prevent vanadium dissolution owing to the pillar effect strengthening the V-O bond. Here, we challenge this claim and propose a self-inhibition mechanism for cathode dissolution in zinc-vanadium oxide batteries through pre-intercalation of Ca2+ to break the cascade dissolution loop of vanadate cathodes. With the help of the state-of-the-art 3D electron microscopic reconstruction technique, the minor yet key intermediate phase of insoluble calcium vanadate (CaV2O6 & centerdot;2H2O) species is identified on the surface of the electrode at the nanometer scale. In the initial dissolution, Ca-VO2 releases both Ca2+ and vanadium ions, while Ca2+ acts as a solution inhibitor to co-precipitate vanadium ions as a protective layer to prevent further dissolution of the vanadium oxide cathode. As a result, it exhibits ultrahigh cycling stabilities for over 140 cycles at 0.1 A g-1 and 16 500 cycles at 30 A g-1. Particularly, in high mass loadings of 20 mg cm-2, the Ca-VO2 cathode yields a high areal capacity of 8.11 mAh cm-2 at 0.1 A g-1. As a demonstration of the practical applications, an Ah-level pouch cell delivers an average capacity of 1.15 Ah over 200 cycles at 0.5 A g-1. This work provides new insights into the role of pre-intercalated Ca2+ in mitigating vanadium dissolution, paving the way for the development of ultra-stable cathodes in AZIBs.

Sodium sulfur batteries have emerged as a promising candidate for large-scale energy storage, while their practical implementation is severely hindered by sodium dendrite growth, unstable solid-electrolyte interphase (SEI) films, and the polysulfide shuttle effect. Herein, we design a novel local high-concentration electrolyte (LHCE-DEE/TTEE) to balance the ionic conductivity and interfacial stability. This is achieved by replacing the high solvating DME with the moderate solvating diethyl ether (DEE) to mitigate the diluent-solvent interaction and reduce the local dynamic friction for Na+ transport. Additionally, the replacement of DME with DEE weakens the ion-dipole interaction to form stable anion-enriched solvation clusters. Furthermore, the long ethyl chains in DEE provide sufficient steric hindrance to confine sulfur species within the cathode and suppress the polysulfide shuttle effect. Benefiting from these synergistic advantages, the Na||Na symmetric cell in LHCE-DEE/TTEE sustains stable cycling for 2500 h. When coupled with a sulfurized polyacrylonitrile cathode, the designed electrolyte demonstrates robust stability at practical conditions of high sulfur loadings of 8.7 mg cm-2 and lean electrolyte of 4.6 µL mg-1 and this is further validated in pouch cell configurations. This work offers new understanding towards LHCE electrolyte design strategy to balance the ionic conductivity and interfacial stability.

The instable Zn/electrolyte interface due to severe corrosion, especially at high utilization of Zn anode, strongly hindered the practical application of aqueous zinc metal battery. Herein, we report a voltage-driven molecular switch through a reversible transition of the nicotinic molecules between zwitterion and anion to enable deep cycled zinc metal battery. In light of in-situ Raman, the switching mechanism of nicotinic molecules in the electrical double layer is unveiled: during plating, nicotinic molecules switches to zwitterion mode (ON state) with periodical pyridine-ring-substrate adlayer while during stripping, shifts to anion mode with periodical carbonyl group-substrate adlayer (OFF state). The transition of NA molecules enables molecular flipping on the substrate due to the electrostatic force and in this way, in both ON and OFF state, the zinc anode is protected by the adlayer to avoid the zinc corrosion on the anode side. Furthermore, the OTF- decomposition is accompanied by the open ring reaction of N-heterocyclic from nicotinic acid molecules to form highly elastic solid electrolyte interface layer. Benefiting from both the molecular switch function and solid electrolyte interface layer formation, the nicotinic molecules-based electrolyte enables practical zinc metal battery of high energy density (100 Wh/kgelectrode) for over 800 cycles with a cumulative capacity of 2.71 Ah cm- 2 at practical condition of low N/P ratio of 2, and lean electrolyte of 10 mu L mAh- 1, representing the state-of-the-art performance. These findings highlight the utilization of molecular switch and its interfacial protection of the deep cycled zinc anode, and provide a new tactic for the development of high energy metal battery.

Hydrogen-bonded organic frameworks (HOFs) are considered as potential choice for future energy storage systems due to their adjustable chemistry, environmental benignity, and cost-effectiveness. However, the electrochemical reaction mechanisms of the HOFs remain elusive. Herein, we demonstrate the site-selective electrochemical storage of alkaline metal ions (Li+, Na+, and K+) in porphyrin-based hydrogen-bonded organic framework (PFC-72-Co). Through systematic experimental and theoretical investigations, three active sites are identified, namely, carbonyl site (site 1), porphyrin site (site 2), and interstitial site (site 3). The carbonyl functional group can accommodate all alkaline metal ions (Li+, Na+, K+), whereas the porphyrin and interstitial sites are selective only for Li+ ions. As a result, the monomer Co-TCPP, with its abundant active sites, is a promising anode material for potassium-ion batteries, hosting 7 K+ ions and delivering a reversible capacity of 247.6 mAh g-1. In contrast, the PFC-72-Co framework, owing to its low solubility in the electrolyte, serves as a stable anode for lithium-ion batteries, exhibiting ultrahigh cycling stability of over 10,000 cycles. This work provides new understanding of the electrochemical reaction mechanisms of organic materials for alkaline metal-ion batteries.

The aqueous zinc-ion battery is promising as grid scale energy storage device, but hindered by the instable electrode/electrolyte interface. Herein, we report the lean-water ionic liquid electrolyte for aqueous zinc metal batteries. The lean-water ionic liquid electrolyte creates the hydrophobic tri-layer interface assembled by first two layers of hydrophobic OTF − and EMIM + and third layer of loosely attached water, beyond the classical Gouy–Chapman–Stern theory based electrochemical double layer. By taking advantage of the hydrophobic tri-layer interface, the lean-water ionic liquid electrolyte enables a wide electrochemical working window (2.93 V) with relatively high zinc ion conductivity (17.3 mS/cm). Furthermore, the anion crowding interface facilitates the OTF − decomposition chemistry to create the mechanically graded solid electrolyte interface layer to simultaneously suppress the dendrite formation and maintain the mechanical stability. In this way, the lean-water based ionic liquid electrolyte realizes the ultralong cyclability of over 10000 cycles at 20 A/g and at practical condition of N/P ratio of 1.5, the cumulated areal capacity reach 1.8 Ah/cm 2 , which outperforms the state-of-the-art zinc metal battery performance. Our work highlights the importance of the stable electrode/electrolyte interface stability, which would be practical for building high energy grid scale zinc-ion battery.

Advanced battery electrodes require a cautious design of microscale particles with built-in nanoscale features to exploit the advantages of both micro- and nano-particles relative to their performance attributes. Herein, the dynamic behavior of nanosized Sn clusters and their host pores in carbon nanofiber) during sodiation and desodiation is revealed using a state-of-the-art 3D electron microscopic reconstruction technique. For the first time, the anomalous expansion of Sn clusters after desodiation is observed owing to the aggregation of clusters/single atoms. Pore connectivity is retained despite the anomalous expansion, suggesting inhibition of solid electrolyte interface formation in the sub-2-nm pores. Taking advantage of the built-in nanoconfinement feature, the CNF film with nanometer-sized interconnected pores hosting Sn clusters (≈2 nm) enables high utilization (95% at a high rate of 1 A g-1) of Sn active sites while maintaining an improved initial Coulombic efficiency of 87%. The findings provide insights into electrochemical reactions in a confined space and a guiding principle in electrode design for battery applications.

The Co-based perovskite La0.6Sr0.4CoO3 has received significant attention as a potential electrocatalyst for its oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) due to its abundance, facile synthesis, and high oxygen kinetics. However, research on the catalytic performance of Ni-doped La0.6Sr0.4Co1−xNixO3 as a bifunctional cathode catalyst for Zn-air batteries (ZABs) is still scarce. In this work, lanthanum strontium cobalt-based perovskite catalysts with various Ni contents (La0.6Sr0.4Co1−xNixO3, x = 0, 0.2, 0.5, and 0.8) were synthesized using a simple combustion method. The effects of Ni doping on the morphology, structure, surface oxygen-related species, and valence states of the transition metals of the perovskite were characterized. The electrochemical behaviors of the perovskite catalysts in both ORR and OER were also assessed. The characterization results revealed that proper Ni doping can decrease particle size, increase surface oxygen vacancies, and create mixed valence states of the transition metal and, thus, lead to improvement of the electrocatalytic activity of perovskite catalysts. Among the different perovskite compositions, La0.6Sr0.4Co0.8Ni0.2O3 exhibited the best ORR/OER activity, with a higher limiting current density, smaller Tafel slope, higher half-wave potential, lower overpotential, and lower potential difference than the other compositions. When La0.6Sr0.4Co0.8Ni0.2O3 was applied as the cathodic catalyst in a primary ZAB, it delivered a peak power density of 81 mW cm−2. Additionally, in rechargeable ZABs, the La0.6Sr0.4Co0.8Ni0.2O3 catalyst exhibited a lower voltage gap (0.94 V) and higher stability during charge–discharge cycling than the commonly used catalyst Pt/C. These results indicate that Ni-doped La0.6Sr0.4Co0.8Ni0.2O3 is a promising bifunctional electrocatalyst for ZAB.

Aqueous rechargeable zinc ion batteries (ZIBs) are regarded as a promising candidates for next‐generation energy storage devices but strongly hindered by the limited utilization of the zinc metal anode (below 5%) due to the active water/anion corrosion. Herein, an ion selective and water‐resistant cellulose nanofiber (CNF)/MXene composite membrane has been developed through molecular sieving to restrict active water and anions from the electrode/electrolyte interface through dehydration of zinc ions, avoiding the water/anion‐induced corrosion/decomposition. In this way, the CNF/MXene@Zn anode exhibits significantly enhanced coulombic efficiency (99.5 % at 10 mA cm‐2) and low voltage hysteresis. Moreover, coated with CNF/MXene composite membrane, zinc symmetric batteries can be operated at the extremely high current of 100 mA cm‐2 and ultra‐high Zn utilization of 88.2% to achieve record‐high cumulative plating capacity of 12 Ah cm‐2. Furthermore, the full vanadium dioxide (VO2) |CNF/MXene@Zn batteries exhibit a high capacity of 357 mAh g‐1 at 2 A g‐1 and retain 93.3% of the capacity after 500 cycles. Moreover, at negative/ positive capacity (N/P) ratio of 2.8, the CNF/MXene membrane coated zinc is able to stably cycle for 100 cycles, demonstrating the potential for high energy zinc battery. This designed CNF/MXene membrane enables ZIBs as viable energy storage devices for practical applications.

The crystallography of the low-temperature phases (β'') for shape memory alloys (NbRu and TaRu) has been debated for decades. Though a P2/m monoclinic structure has been proposed for the β'' phase, the proposed structure is not able to completely represent the measured diffraction data. In this work, the crystallography of the β'' phase was investigated by first-principles calculations. We showed that the previously reported P2/m monoclinic structure was lattice unstable due to the presence of the soft phonon mode. A P21/m monoclinic structure was derived from the P2/m monoclinic structure by displacing its atoms according to the eigenvector of the soft phonon mode at the Γ point. The P21/m and the P2/m monoclinic structures are structurally similar, but the former one is energetically and structurally more favorable than the latter one. We concluded that the β'' phase preferred to crystallize in the P21/m monoclinic structure rather than the previously reported P2/m monoclinic structure. Our results offer guidance for the experimental determination of the crystallography of the β'' phase for NbRu and TaRu.

Current energy storage device has fallen short behind from the fast growing requirement for (hybrid) electric vehicles and portable devices including mobile phones, which drives the lithium metal anode to be a research hot topic. However, the large volume change of lithium metal anode induces instable solid electrolyte interface (SEI) layer, which prevents its further development. A stable SEI layer required flexible surface to accommodate the large volume variation and inorganic core with low Li+ partial molar volume for dendrite suppression. Herein, we achieved a gradient SEI which is composed of flexible surface-rich polycarbonate moieties and low Li+ partial molar volume inorganic LiF-rich core by applying liquid alloy GaSnIn as electrolyte additive. Initially, the calculation verified that liquid alloy GaSnIn as electrolyte additive would facilitate the initial decomposition of LiPF6, and lead to the formation of the gradient SEI layer. In the Li||Li half-cell test, we successfully achieved dense deposition of Li metal and in this way, the cycling performance with liquid alloy GaSnIn as electrolyte additive is greatly improved especially at high rate (10 mA cm 2). Voltage polarization was greatly reduced and Coulombic efficiency was effectively improved due to the gradient SEI layer achieved in the interface of Li anode and electrolyte. In the Li||LFP cell, high average coulombic efficiency (99.06%) at long cycle life (>2500 cycles) is achieved for the liquid alloy GaSnIn-protected Li metal anode at high areal capacity (3 mAh/cm2). These results deepen our understanding on liquid alloy as a promising electrolyte additive for efficient dendrite suppressing, enabling the practical lithium metal batteries (LMBs).

Electrostimulation has been recognized as a promising nonpharmacological treatment in orthopedics to promote bone fracture healing. However, clinical applications have been largely limited by the complexity of equipment operation and stimulation implementation. Here, we present a self-powered implantable and bioresorbable bone fracture electrostimulation device, which consists of a triboelectric nanogenerator for electricity generation and a pair of dressing electrodes for applying electrostimulations directly toward the fracture. The device can be attached to irregular tissue surfaces and provide biphasic electric pulses in response to nearby body movements. We demonstrated the operation of this device on rats and achieved effective bone fracture healing in as short as 6 wk versus the controls for more than 10 wk to reach the same healing result. The optimized electrical field could activate relevant growth factors to regulate bone microenvironment for promoting bone formation and bone remodeling to accelerate bone regeneration and maturation, with statistically significant 27% and 83% improvement over the control groups in mineral density and flexural strength, respectively. This work provided an effective implantable fracture therapy device that is self-responsive, battery free, and requires no surgical removal after fulfilling the biomedical intervention.

Charge separation and transformation are some of the key requirements for high-efficiency photocatalysis. The photocatalytic reaction mechanism provides a guideline for the development and commercialization of high-efficiency photocatalysts. In this study, we designed and favorably synthesized BMO@BOC heterojunctions via a facile solvothermal route and applied the heat treatment method for application in high-efficiency photocatalytic NO removal. More importantly, both continuous stream and intermittent stream methods with in situ diffuse reflectance infrared Fourier transform spectroscopy were applied to intuitively and dynamically investigate the adsorption process and oxidation process of NO removal over the photocatalyst surface. The intermediate products (NO-, NO2-, and NO2) were explicitly detected in both the adsorption process and oxidation process, whilst the final product (NO3-) appeared only in the oxidation process, owing to the separation, migration, and conversion of photoinduced electron-hole pairs.

Carbon materials are the most important anode materials used in supercapacitors. However, there are still great challenges in improving their low specific capacitance and energy density. In this study, a fast molten salt method was developed for the preparation of a super-high capacity activated carbon cloth anode. The nitrogen-activated carbon cloth electrode (NCC) showed better electrochemical performance than most of the carbon-based materials reported on previously. The maximum areal capacitance of the nitrogen-activated carbon cloth electrode was 6.72 F cm−2 at the current density of 2 mA cm−2. By employing the first-principle calculations method, it was derived that the adsorption energy of the K atoms on the graphite increased with the increase in nitrogen doping, especially on the pyridinic nitrogen (N-6). In addition, when the NCC and Ni-Co-S@CC electrodes were assembled into an asymmetric supercapacitor (ASC), the ASC demonstrated an operation in a large potential window of 1.8 V, and it achieved a high volumetric energy density of 23.51 mWh cm−3 at a power density of 1808 mW cm−3. This work showed the super high capacity of activated carbon cloth as a new anode material for high-performance supercapacitors prepared using a simple molten salt method.

Multi-ion batteries and supercapacitors are promising as energy storage devices. However, the intercalation/deintercation of various cations on the electrodes in the hybrid electrolytes is not clearly understood. Herein, the selectivity of different cations (viz., K+, Na+, Li+) in hybrid aqueous electrolytes based on hierarchical 2H-phase MoS2 is investigated by combining experimental and theoretical methods. A quantitative method based on first-principles calculations is proposed to enumerate the cation selectivity in hybrid aqueous electrolytes. It indicates that the eventual intercalation of various cations in the MoS2 interlayer space is mainly reliant on the competition reactions of the various cations in the hybrid electrolytes into the electrode. The chemical potentials related to the molar ratio and the binding energy of different cations into the electrode play a pivotal role in such selectivity of the cations. This mechanism is tested using the MoS2@ACC (flower-like MoS2 grown on the active carbon cloth substrate) electrode, which is fabricated in one-step using the simple hydrothermal technique. The theoretical cation selectivity is also reinforced by the experimental results based on the 2H-MoS2@ACC electrodes. Overall, this study provides a fundamental understanding of the electrochemical storage behavior between electrolytes and electrodes for multi-ion capacitors.

Understanding and establishing a specific relationship between modified structures and photocatalytic reaction process has a profound significance for designing catalysts with preferable activity. In this study, we have favorably synthesized the bismuth oxyhalides (BiOClxBr1-x, 0 <= x <= 1) photocatalysts by utilizing the ethylene glycol assisted solvothermal method and the calcination procedure for photocatalytic nitric oxide oxidation. By regulating the halogen proportion in anions layer, the lattice strain has been induced in the structure, specifically the tensile strain in c axis. By virtue of in situ DRIFTS and DFT calculation, we found that the optimized surface reaction thermodynamic process should be the main factors response for prominent enhanced photocatalytic activity, rather than the light absorption and separation of carriers. The bismuth oxyhalides with Cl/Br ratios of 3:1 (BiOClxBr1-x-3:1) possess the lowest thermodynamic energy barrier for photocatalytic nitric oxide oxidation reaction, whilst both associative and dissociative reaction process exist in the initial elementary reaction about oxygen reduction. Finally, we develop a feasible strategy to depress thermodynamic energy barriers via tuning the ratio of halogen in anions layer and bringing the lattice strain, as well build relationship between the adjusted structures and surface reaction process.

Flexible bioelectronics, including wearable and implantable electronics, have revolutionized the way of human-machine interaction due to the fact that they can provide natural and seamless interactions with humans and keep stable and durable at strained states. As sensor elements or biomimetic actuators, flexible bioelectronics can dynamically sense and monitor physiological signals, reveal real-time physical health information and provide timely precise stimulations or treatments. Thus, the flexible bioelectronics are playing increasingly important roles in human-health monitoring and disease treatment, which will significantly change the future of healthcare as well as our relationships with electronics. This review summarizes recent major progress in the development of flexible substrates or encapsulation materials, sensors, circuits and energy-autonomous powers toward digital healthcare monitoring, emphasizing its role in biomedical applications in vivo and problems in practical applications. A future perspective into the challenges and opportunities in emerging flexible bioelectronics designs for the next-generation healthcare monitoring systems is also presented. (C) 2019 The Chinese Ceramic Society. Production and hosting by Elsevier B.V.