Research progress of the electrochemical impedance technique applied to the high-capacity lithium-ion battery

The world's energy system is changing dramatically.Li-ion battery,as a powerful and highly effective energy storage technique,is crucial to the new energy revolution for its continuously expanding application in electric vehicles and grids.Over the entire lifetime of these power batteries,it is essential to monitor their state of health not only for the predicted mileage and safety management of the running electric vehicles,but also for an"end-of-life"evaluation for their repurpose.Electrochemical impedance spectroscopy(EIS)has been widely used to diagnose the health state of batteries quickly and nondestructively.In this review,we have outlined the working principles of several electrochemical impedance techniques and further evaluated their application prospects to achieve the goal of nondestructive testing of battery health.EIS can scientifically and reasonably perform real-time monitoring and evaluation of electric vehicle power batteries in the future and play an important role in vehicle safety and battery gradient utilization.

Copper corrosion in hot and dry atmosphere environment in Turpan, China

The atmospheric corrosion behavior of pure copper exposed for three years in Turpan, China, which is a typical hot and dry atmosphere environment, was investigated using mass-loss tests, morphology observations, composition analyses, and electrochemical techniques. The results indicated that the annual corrosion rate of pure copper was approximately 2.90 μm/a. An uneven distribution of corrosion products was observed by scanning electron microscopy; this uneven distribution was attributed to the dehydration process during wet–dry and cold–hot cycles, and the compositions mainly consisted of cuprite （Cu2O） and atacamite （Cu2Cl（OH）3）. Electrochemical measurements showed that deposits on copper improved its resistance to corrosion and the protectiveness decreased with increasing temperature. On the other hand, results obtained using the scanning vibrating electrode technique showed that the porous and uneven structure of the deposit layer generated a spatial separation of cathodic and anodic reaction sites, which accelerated the corrosion process in wet and rainy weather.

The emerging hybrid electrochemical energy technologies

Electrochemical energy devices serve as a vital link in the mutual conversion between chemical energy and electrical energy.This role positions them to be essential for achieving high-efficiency utilization and advancement of renewable energy.Electrochemical reactions,including anodic and cathodic reactions,play a crucial role in facilitating the connection between two types of charge carriers:electrons circulating within the external circuit and ions transportation within the internal electrolyte,which ensures the completion of the circuit in electrochemical devices.While electrons are uniform,ions come in various types,we herein propose the concept of hybrid electrochemical energy technologies(h-EETs)characterized by the utilization of different ions as charge carriers of anodic and cathodic reactions.Accordingly,this review aims to explore the fundamentals of emerging hybrid electrochemical energy technologies and recent research advancements.We start with the introduction of the concept and foundational aspects of h-EETs,including the proposed definition,the historical background,operational principles,device configurations,and the underlying principles governing these configurations of the h-EETs.We then discuss how the integration of hybrid charge carriers influences the performance of associated h-EETs,to facilitate an insightful understanding on how ions carriers can be beneficial and effectively implemented into electrochemical energy devices.Furthermore,a special emphasis is placed on offering an overview of the research progress in emerging h-EETs over recent years,including hybrid battery capacitors that extend beyond traditional hybrid supercapacitors,as well as exploration into hybrid fuel cells and hybrid electrolytic synthesis.Finally,we highlight the major challenges and provide anticipatory insights into the future perspectives of developing high-performance h-EETs devices.

Porous polybenzimidazole membranes with positive charges enable an excellent anti-fouling ability for vanadium-methylene blue flow battery

A cost-effective, high-performance and highly stable membrane has always been in intensively needed in aqueous organic-based flow batteries. Here we present a porous polybenzimidazole(PBI) membrane with positive charges that endow the membrane with a high rejection and an excellent anti-fouling ability for target organic molecule and asymmetric structure that affords a high conductivity for vanadiummethylene blue flow battery(V-MB FB). The morphologies and thickness of separating layer in particular of the porous PBI can be well adjusted by simply altering the polymer concentration in the cast solution and further afford the membrane with a controllable property in terms of both ion selectivity and ion conductivity. As a result, a V-MB FB assembled with a porous PBI membrane delivers a coulombic efficiency(CE) of 99.45% and an energy efficiency(EE) of 86.10% at a current density of 40 mA cm^(-2), which is 12% higher than that afforded by a Nafion 212 membrane. Most importantly, the V-MB FB demonstrates a methylene blue(MB) utilization of 97.55% at a theoretical capacity of 32.16 Ah L^(-1)(based on the concentration of MB in the electrolyte) because of the high ion conductivity of the membrane, which favors reducing the cost of a battery. The results suggest that the designed porous PBI membranes exhibit a very promising prospect for methylene blue-vanadium flow battery.

Screen-printed graphite electrode on polyvinyl chloride and parchment strips integrated with genetic programming for in situ nitrate sensing of aquaponic pond water

Nitrate is the primary water-soluble macronutrient essential for plant growth that is converted from excess fish feeds,fish effluents,and degrading biomaterials on the aquaponic pond floor,and when aquacultural malpractices occur,large amounts of it retain in the water system causing increase rate in eutrophication and toxifies fish and aquaculture plants.Recent nitrate sensor prototypes still require performing the additional steps of water sample deionization and dilution and were constructed with expensive materials.In response to the challenge of sensor enhancement and aquaponic water quality monitoring,this study developed sensitive,repeatable,and reproducible screen-printed graphite electrodes on polyvinyl chloride and parchment paper substrates with silver as electrode material and 60:40 graphite powder:nail polish formulated conductive ink for electrical traces,integrated with 9-gene genetic expression model as a function of peak anodic current and electrochemical test time for nitrate concentration prediction that is embedded into low-power Arduino ESP32 for in situ nitrate sensing in aquaponic pond water.Five SPE electrical traces were designed on the two types of substrates.Scanning electron microscopy with energy dispersive X-ray confirmed the electrode surface morphology.Electrochemical cyclic voltammetry using 10 to 100 mg/L KNO3 and water from three-depth regions of the actual pond established the electrochemical test time(10.5 s)and electrode potential(0.135 V)protocol necessary to produce peak current that corresponds to the strength of nitrate ions during redox.The findings from in situ testing revealed that the proposed sensors have strong linear predictions(R2=0.968 MSE=1.659 for nSPEv and R2=0.966 MSE=4.697 for nSPEp)in the range of 10 to 100 mg/L and best detection limit of 3.15μg/L,which are comparable to other sensors of more complex construction.The developed three-electrode electrochemical nitrate sensor confirms that it is reliable for both biosensing in controlled solutions and in situ aquaponic pond water systems.

Monitoring stratification of anode biofilms in bioelectrochemical laminar flow reactors using flow cytometry

A laminar flow bioelectrochemical systems(BES)was designed and benchmarked using microbial anodes dominated with Geobacter spp.The reactor architecture was based on modeled flow fields,the resulting structure was 3D printed and used for BES manufacturing.Stratification of the substrate availability within the reactor channels led to heterogeneous biomass distribution,with the maximum biomass found mainly in the initial/middle channels.The anode performance was assessed for different hydraulic retention times while coulombic efficiencies of up to 100%(including also hydrogen recycling from the cathode)and current densities of up to 75 μA cm^(-2) at an anode surface to volume ratio of 1770 cm^(2) L^(-1) after 35 days were achieved.This low current density can be clearly attributed to the heterogeneous distributions of biomass and the stratification of the microbial community structure.Further,it was shown that time and space resolved analysis of the reactor microbiomes per channel is feasible using flow cytometry.

Direct ammonium oxidation to nitrogen gas (Dirammox) in Alcaligenes strain HO-1: The electrode role

It has been recently suggested that Alcaligenes use a previously unknown pathway to convert ammonium into dinitrogen gas(Dirammox)via hydroxylamine(NH2OH).This fact alone already implies a significant decrease in the aeration requirements for the process,but the process would still be dependent on external aeration.This work studied the potential use of a polarised electrode as an electron acceptor for ammonium oxidation using the recently described Alcaligenes strain HO-1 as a model heterotrophic nitrifier.Results indicated that Alcaligenes strain HO-1 requires aeration for metabolism,a requirement that cannot be replaced for a polarised electrode alone.However,concomitant elimination of succinate and ammonium was observed when operating a previously grown Alcaligenes strain HO-1 culture in the presence of a polarised electrode and without aeration.The usage of a polarised electrode together with aeration did not increase the succinate nor the nitrogen removal rates observed with aeration alone.However,current density generation was observed along a feeding batch test representing an electron share of 3%of the ammonium removed in the presence of aeration and 16%without aeration.Additional tests suggested that hydroxylamine oxidation to dinitrogen gas could have a relevant role in the electron discharge onto the anode.Therefore,the presence of a polarised electrode supported the metabolic functions of Alcaligenes strain HO-1 on the simultaneous oxidation of succinate and ammonium.