The Zn anode suffers from severe dendrite growth and side reactions, which restrict its development in the realm of large-scale energy storage. Herein, in this study, we propose a method to create ...surface-microcracks in a Zn foil by 200 MPa cold isostatic pressing. The proposed pressing method can avoid the surface tip effect of Zn, and creates a subtly surface-microcracked zinc structure, providing more zinc ion transport channels, thereby effectively alleviating the dendrite growth and side reactions during the repeated Zn plating and stripping. Benefiting from these advantages, the 200 MPa Zn|Zn symmetric cell can achieve a long cycle life (1525 h) of 1 mA h cm
−2
at 2 mA cm
−2
. The 200 MPa Zn|VO
2
full cell can still maintain a capacity of 110 mA h g
−1
after 1000 cycles at 0.1 A g
−1
. In addition, assembled pouch cells also show excellent cycling stability. The proposed cold isostatic pressing method is compatible with large-scale production applications and provides an effective strategy for realizing high-performance zinc anodes for zinc-ion batteries.
200 MPa cold isostatic pressing creates a surface microcrack Zn foil for scalable and long life zinc anodes that increase zinc ion transport channels and improve zinc ion battery cycling performance.
Practical aqueous zinc‐ion batteries require low‐cost thin zinc anodes with long‐term reversible stripping/depositing. However, thin zinc anodes encounter more severe issues than thick zinc, such as ...dendrites and uneven stripping, resulting in subpar performance and limited lifetimes. Here, this work proposes a three‐in‐one zinc anode obtained by a large‐scale two‐step method to address the above issues. In a three‐in‐one zinc anode, the copper foil as an inactive current collector solves the gradual reduction of the active area when only the pure zinc as an active current collector. This work develops an automatic electroplating device that can continuously deposit a zinc layer on a conducting foil to meet the demand for zinc‐coated copper foils. The sodium carboxymethylcellulose (CMC)‐zinc fluoride (ZnF2) protective layer prevents direct contact between zinc and separator, and provides a uniform and sufficient supply of zinc ions. The CMC‐ZnF2‐coated copper foil performs up to 3000 reversible zinc deposition/stripping cycles with a cumulative capacity of 6 Ah cm−2 and an average Coulombic efficiency of 99.94%. The Zn||ZnVO cell using the three‐in‐one anode achieved a high capacity retention of over 70% after 15 000 cycles. The proposed three‐in‐one anode and the automatic electroplating device will facilitate industrialization of practical thin zinc anodes.
This work reports a Cu‐based Zn anode with a CMC‐ZnF2 coating. This three‐in‐one electrode can be mass‐produced by a two‐step “electroplating and coating” process, where step I is accomplished using an automatic electroplating device. Thanks to the inactive current collector and the protective layer, the anode maintains integrity and deposition uniformity during battery cycling, thereby improving performance and life.
The FeS2 has abundant reserves and a high specific capacity (894 mAh g−1), commonly used to fabricate Li‐FeS2 primary batteries, like LiMx‐FeS2 thermal batteries (working at ≈500 °C). However, ...Li–FeS2 batteries struggle to function as rechargeable batteries due to serious issues such as pulverization and polysulfide shuttling. Herein, highly reversible solid‐state Li‐FeS2 batteries operating at 300 °C are designed. Molten salt‐based FeS2 slurry cathodes address the notorious electrode pulverization problem by encapsulating pulverized particles in time with e− and Li⁺ flow conductors. In addition, the solid electrolyte LLZTO tube serves as a hard separator and fast Li+ channel, effectively separating the molten electrodes to construct a liquid–solid–liquid structure instead of the solid–liquid–solid structure of LiMx‐FeS2 thermal batteries. Most importantly, these high‐temperature Li–FeS2 solid‐state batteries achieve FeS2 conversion to Li2S and Fe at discharge and further back to FeS2 at charge, unlike room‐temperature Li‐FeS2 batteries where FeS and S act as oxidation products. Therefore, these new‐type Li‐FeS2 batteries have a lower operating temperature than Li‐FeS2 thermal batteries and perform highly reversible electrochemical reactions, which can be cycled stably up to 2000 times with a high specific capacity of ≈750 mAh g−1 in the prototype batteries.
This work reports Li–FeS2 secondary thermal batteries (240–300 °C) with a liquid–solid liquid structure. The liquid lithium anode and FeS2 slurry cathode are isolated using a U‐shaped LLZTO tube. The high battery reversibility is attributed to the reversible transition of Fe and Li2S to FeS2 at high temperatures and FeS2 pulverization. The FeS2 regeneration also avoids the production of polysulfides.
A lithium-ion battery has advantages such as high energy density and long calendar life, but it suffers from the risk of thermal runaway. Overcharge-induced thermal runaway accidents hold a ...considerable percentage. This article discovers that the slope of the dynamic impedance in the frequency band of 30-90 Hz turns positive from negative when the cell just starts to overcharge and proposes the theoretical explanation. Taking 70 Hz impedance as an example, the thermal runaway accident can be successfully avoided by cutting off the charging when the slope turns positive from negative during charging. The warning time is 580 s ahead of the thermal runaway. This feature is easy to identify and requires no complex mathematical models and parameters. Besides, the prediction method based on this feature can be conducted by using an online dynamic impedance measurement device designed by us, which is suitable for large-scale applications. Thus, the overcharge-induced thermal runaway accidents can be avoided.
Aqueous Zn‐ion batteries are plagued by a short lifespan caused by localized dendrites. High‐concentration electrolytes are favorable for dense Zn deposition but have poor performance in batteries ...with glass‐fiber separators. In contrast, low‐concentration electrolytes can wet the separators well, ensuring the migration of zinc ions, but the dendrites grow rapidly. In this work, we propose an electrolyte gradient strategy wherein a zinc‐ion concentration gradient is established from the anode to the separator, ensuring that the separator keeps a good wettability in low‐concentration areas and the zinc anode achieves dendrite‐free deposition in a high‐concentration area. By using this strategy in a common electrolyte, zinc sulfate, a Zn||Zn symmetric cell achieves 14 000 ultralong cycles (exceeding 8 months) at 5 mA cm−2 and 1 mAh cm−2. When the current is further increased to 20 mA cm−2, the symmetric cell could still run for over 10 000 cycles. Assembled Zn||NVO full cells also demonstrate prominent performance. At a high current of 16 mA cm−2, the NVO cathode with high loading (8 mg cm−2) still has a capacity of 58% after 1200 cycles. Overall, the gradient electrolyte strategy provides a promising approach for practical long‐life Zn anodes with the advantages of simple operation and low cost.
A novel gradient electrolyte strategy wherein a concentration gradient of zinc ions is constructed from the anode to the separator enables dense and dendrite‐free Zn deposition. The gradient electrolyte plays dual roles in keeping dense deposition on the zinc surface by the high‐concentration electrolyte containing carboxymethylcellulose and avoiding the water‐poor state of the GF separator by the low‐concentration electrolyte.
Conventional DC-DC converters for renewable energy systems work in large duty cycle conditions, which will lead to the inductor saturations and decrease the system efficiencies and stabilities. In ...this brief, a new fifth-order boost converter, which can work in dual operating modes when different control technologies are adopted, is proposed. To obtain a wider conversion ratio, the required duty cycle for the proposed converter with synchronous controller is smaller than 0.333 while with interleaved controller is smaller than 0.5. Also, dual modes of this converter both have lower switches voltage stress. Then, the inductor saturation issues can be avoided and the system efficiencies and stabilities can be improved. Besides, the lower topological order and simple grounded structure of this converter are benefit to reduce the modeling complexity, topology volume and system noises. Detailed analyses, comparisons and prototype are implemented to study the improved conversion ratio, efficiency and power density of the proposed converter in-depth, and to validate its feasibilities for renewable energy applications.
Hydrogen reduction reaction (HER) and corrosion limit the long‐life cycle of zinc‐ion batteries. However, hydrophilic separators are unable to prevent direct contact between water and electrodes, and ...hydrophobic separators have difficulty in transporting electrolytes. In this work, an inorganic oxide‐based “hydrophobic–hydrophilic–hydrophobic” self‐assembled separator system is proposed. The hydrophobic layer consists of a porous structure, which can isolate a large amount of free water to avoid HER and corrosion reactions, and can transport electrolyte by binding water. The middle hydrophilic layer acts as a storage layer consisting of the GF separator, storing large amounts of electrolyte for proper circulation. By using this structure separator, Zn||Zn symmetric cell achieve 2200 h stable cycle life at 5 mA cm−2 and 1mAh cm−2 and still shows a long life of 1800 h at 10 mA cm−2 and 1mAh cm−2. The assembled Zn||VO2 full cell displays high specific capacity and excellent long‐term durability of 60.4% capacity retention after 1000 cycles at 2C. The assembled Zn||VO2 pouch full cell displays high specific capacity of 172.5mAh g−1 after 40 cycles at 0.5C. Changing the inorganic oxide materials, the hydrophobic–hydrophilic–hydrophobic structure of the separators still has excellent performance. This work provides a new idea for the engineering of water‐based battery separators.
An inorganic oxide‐based “hydrophobic–hydrophilic–hydrophobic” self‐assembled separator system is proposed. The hydrophobic layer consists of a porous structure, which can isolate a large amount of free water to avoid HER and corrosion reactions, and can transport electrolyte by binding water. The middle hydrophilic layer acts as a storage layer consisting of the GF separator, storing large amounts of electrolyte for long battery cycle life.
The thermal runaway of lithium-ion batteries presents a significant threat to electric vehicles by elevating the risk of fires or explosions. Safety warnings based on special gases such as H2 and CO ...are crucial to avoid thermal runaway. However, few studies or applications regarding gas warnings in electric vehicles have been reported. In this study, H2 detection experiments were performed in a real electric vehicle battery pack, and the H2 diffusion behavior was studied. The results showed that H2 can effectively warn about battery faults. In damaged batteries, H2 may be released from the micro-cracks in the battery or the vent. While H2 was detected and the power supply was cut off, the cell surface temperature tended to decrease and thermal runaway did not occur. The installation of the detector affects the detection time. Thus, H2 diffusion simulations starting from different locations were performed, and the installation location was optimized. The results indicated that setting two detectors was optimal, and the optimized detection time (from release to detection of H2) was 60 s shorter than that before optimization. The experimental and simulation results provide an effective msethod for the early warning of thermal runaway and the installation of gas detectors in electric vehicles.
Ammonia (NH3) is one of the most frequently produced chemical products in the world, and it plays an indispensable role in life on Earth. However, its synthesis by the Haber–Bosch (H–B) process is ...highly energy intensive, resulting in extensive carbon emissions that are unsustainable due to their ability to harm the environment. Herein, we propose a facile and mass-producible strategy for increasing the rate and efficiency of nitrogen fixation through the use of copper particle-catalyzed Li nitridation and a solid electrolyte as a medium to reduce Li salt; the above strategy results in the conversion of water and nitrogen into NH3 through the use of renewable electrical energy at room temperature and atmospheric pressure. Copper particles are uniformly pressed into Li metal by a simple rolling method, and their critical role in accelerating the nitrogen fixation process is revealed by both electrochemical tests and simulations. The nitridation of the Li in the composite is reduced to a few minutes instead of the more than 40 h that are needed for bare Li and N2 at room temperature and atmospheric pressure. Our new method provides three important advantages over the H–B method: (1) the new method can be operated at atmospheric pressure, thereby lowering equipment requirements and increasing security; (2) the use of water instead of fossil fuels as a hydrogen source decreases the consumption of these fuels and the emission of CO2; and (3) the low equipment requirements lead to the ready miniaturization and decentralization of the NH3 synthesizing process, thus promoting the possible use of renewable sources of electricity (e.g., wind or solar energy).
