Fabrication Of Batteries Research Articles

Solid-State Lithium Batteries with In Situ Polymerized Acrylate-Based Electrolytes Capable of Electrochemically Stable Operation at 100 °C.

Solid polymer electrolytes (SPEs) typically consist of salts with mobile anions that could cause instabilities and parasitic side reactions in solid-state lithium (Li) batteries. To address this challenge, single-Li-ion conducting (SLIC) SPEs, where anions of Li salts are covalently attached to the polymer backbone, have been utilized to reduce the number of mobile anions. This approach improves the cationic transference number but is accompanied by a loss of ionic conductivity. In this work, we investigate a synergetic approach of using both a polymerizable SLIC salt and a conventional Li salt in a polymer matrix by in situ polymerization of the poly(propylene glycol) acrylate (PPGA) monomer. The synthesized hybrid SPEs show a high ionic conductivity of up to ∼2 × 10-4 S cm-1 and a relatively high Li-ion transference number of ∼0.4. With a significantly reduced fraction of mobile anions in the combined salt SPE, in situ polymerized SPE cells with a LiFePO4 (LFP) cathode achieve a stable performance for over 100 cycles at temperatures as high as 100 °C, which is unattainable with conventional Li salts or electrolytes. Furthermore, solid-state nuclear magnetic resonance spectra provide additional insights into differences in Li nucleus environments and emphasize a reduction in activation energy for hybrid SPEs due to their more open structure. This study opens the path for the fabrication of high-performance solid polymer Li batteries capable of operating at high temperatures using commercial battery fabrication equipment, as in situ polymerized acrylate-based polymers provide drop-in compatibility with conventional battery production, ease of acrylate polymerization, and inexpensive, facile SPE chemistry. We expect that further tuning of the acrylate-based SPE composition may allow further increases in its conductivity without sacrificing its electrochemical stability or mechanical properties.

MnO2/rGO bifunctional catalyst and support materials for gel polymer electrolyte based Zn-air batteries

A high-performance and long-lasting, rechargeable Zn-air battery requires a reliable and effective bifunctional catalyst material to facilitate the oxygen reduction and oxygen evolution reactions during the battery operation. Manganese oxide (MnO2) is a promising non-precious perspective due to its multivalency and various polymorphic structures that effectively catalyze oxygen evolution and reduction. In the present work, MnO2 nanowires (NWs) have been integrated with over-reduced graphene oxide (rGO) in various concentrations via a facile hydrothermal route. The synthesized materials, tested in lab-made zinc-air battery devices fabricated using gel polymer electrolyte, exhibit a significant enhancement in the performance and 2–3 times the cycle life compared to the bare MnO2. The ZAB device was tested for galvanostatic charge-discharge technique, and results exhibit a cycle life of 165 h (495 cycles@20 min per cycle) when discharged up to 1.0 V at a current density of 5.2 mA/cm2 and displayed a capacity of 731 mAh/gZn. Reduced graphene oxide acts as a support material that enhances the conductivity and surface area of the active material and also provides active sites for catalysis. This work signifies the importance of the engineering of the catalyst, support material, and additives, as slight changes may result in a significant enhancement in the cycle life.The appropriate composition of catalyst and support material and a compatible gel polymer electrolyte facilitates the fabrication of flexible zinc-air batteries for various applications.

Improved mechanical and thermal performance of bacterial cellulose paper through cationic cassava starch addition

Cationic particles are commonly used as wet-end additives in papermaking processes. This study evaluates the effects of cationic cassava starch (CCS) on the mechanical strength of paper made from bacterial cellulose (BC). Acetobacter xylinum was utilised in the production of bacterial cellulose (BC) paper, whereas 3‑chloro-2-hydroxypropyl trimethyl ammonium chloride (CHPTAC) was employed in the etherification process of cassava starch to synthesize CCS. Papers containing CCS displayed a more compact surface structure compared to traditional wood-based papers, reaching a brightness level of 97.3 and improving thermal and mechanical characteristics, such as higher tensile strength and is suitable for use as a separator in battery fabrication processes. The results emphasise the possibility of using CCS as a sustainable option in paper production, offering enhanced environmental and mechanical efficiency.

Bonding evolution in PbO@C composites for lead-carbon battery: Implications for HRPSoC performance

Due to the huge density difference between lead and carbon, the strength of the bonding between lead and carbon materials plays a key role in lead-carbon batteries (LCBs). Here, the evolution and transformation of Pb and C bonding in the negative active materials (NAMs) were studied throughout the battery fabrication process of curing, formation and charge/discharge cycles. The results indicate PbC bond in the PbO@C composite is cleaved by chemical reactions during the curing and formation process. In addition, the graphitization degree of the carbon material decreased after charge/discharge cycles. Compared with the blank lead-acid battery, the initial capacity and high-rate partial state of charge (HRPSoC) cycle life of lead-carbon with PbO@C composite significantly increase. The previous sites of Pb and C after the transformation of lead and its compounds can still act as active sites for the reaction of NAMs in curing, formation and charge/discharge cycles. Meanwhile, the porous carbon material in PbO@C can act as a supporting skeleton and a 3D electroosmotic pump, which is beneficial for the interaction between the electrolyte and the negative electrode active substance, attributing to the boosted performance of lead-carbon battery. This work provides theoretical support for understanding the lead-carbon binding mechanism during the operation of lead-carbon batteries.

Unraveling the impact of the design of current collector on dry-processed lithium-ion battery electrodes

Dry processing emerges as a cost-effective technique for achieving high material loading in the field of lithium-ion battery fabrication. Nevertheless, insight into the role of current collectors in this process is still scarce. Herein, a set of dry-processed electrodes with three different current collectors is accordingly prepared and comprehensively studied. This work novelly reveals that the current collectors exhibit significant influence on the interface adhesion strength and the electron conductivity, which leads to difference in the mechanical strength and electrochemical performance of dry-processed electrodes. Consequently, it is recommended that carbon-coated current collector is preferred for dry-processed high energy density lithium-ion battery electrodes.

A Review of Carbon Anode Materials for Sodium-Ion Batteries: Key Materials, Sodium-Storage Mechanisms, Applications, and Large-Scale Design Principles.

Sodium-ion batteries (SIBs) have been proposed as a potential substitute for commercial lithium-ion batteries due to their excellent storage performance and cost-effectiveness. However, due to the substantial radius of sodium ions, there is an urgent need to develop anode materials with exemplary electrochemical characteristics, thereby enabling the fabrication of sodium-ion batteries with high energy density and rapid dynamics. Carbon materials are highly valued in the energy-storage field due to their diverse structures, low cost, and high reliability. This review comprehensively summarizes the typical structure; energy-storage mechanisms; and current development status of various carbon-based anode materials for SIBs, such as hard carbon, soft carbon, graphite, graphene, carbon nanotubes (CNTs), and porous carbon materials. This review also provides an overview of the current status and future development of related companies for sodium-ion batteries. Furthermore, it offers a summary and outlook on the challenges and opportunities associated with the design principles and large-scale production of carbon materials with high-energy-density requirements. This review offers an avenue for exploring outstanding improvement strategies for carbon materials, which can provide guidance for future application and research.

Building aluminium-air battery on waste paper for DIY learning

Abstract Environmental sustainability and the effective use of renewable resources are critical subjects that need to be integrated into our educational systems through practical, hands-on learning. This paper focuses on the fabrication of aluminium-air batteries using waste materials, providing an innovative and cost-effective DIY approach to energy storage education. Utilizing aluminium from food packaging and graphite from pencils, this study demonstrates the construction and functionality of an aluminium-air battery to run an LED, highlighting its potential applications in educational settings and low-cost energy solutions. The paper aims to inspire the adoption of environmentally friendly practices and enhance students’ understanding of electrochemical energy conversion through accessible and engaging DIY projects.

Investigating laser and ultrasonic welding of pouch cell multi-foil current collectors for electric vehicle battery fabrication

The escalating necessity for more efficient and defect-free joining of ‘ultra-thin foil collectors-to-tabs’ in electric vehicle (EV) Li-ion pouch cells motivates this study. The prevalent ultrasonic welding (USW) method for these joint types, faces limitations such as design constraints and access requirements, laser welding (LW) emerges as a promising alternative offering flexibility, one-side access and faster speeds with efficient heat input. This study aims to investigate the feasibility of LW as a viable alternative to USW for joining current collectors-to-tab joints. It compares the mechanical, metallurgical, electrical and thermal analysis of the joints to evaluate both welding techniques for joint defects. The comparison of solid-state material mixing during USW and the intermixing of aluminium (Al) and copper (Cu) during fusion LW using EDX analysis presents interesting observations in the study. The USW generates a thin transition layer with intermetallic compounds (IMCs) attributed to the diffusion of Cu into the Al matrix during joining, which is comparatively lower as in the case of LW with higher material mixing with brittle IMCs like Al2Cu and Al4Cu9. However, the joint strength of LW is comparatively lower than the USW joint attributed to the reduced fusion zone area. Furthermore, from the electrical contact resistance and the joint temperature analysis, it was found that the resistance and temperature vary by as much as 13% and 6%, respectively, for the 50 A and 75 A passing currents when the USW is replaced with the LW process.

High energy density picoliter-scale zinc-air microbatteries for colloidal robotics.

The recent interest in microscopic autonomous systems, including microrobots, colloidal state machines, and smart dust, has created a need for microscale energy storage and harvesting. However, macroscopic materials for energy storage have noted incompatibilities with microfabrication techniques, creating substantial challenges to realizing microscale energy systems. Here, we photolithographically patterned a microscale zinc/platinum/SU-8 system to generate the highest energy density microbattery at the picoliter (10-12 liter) scale. The device scavenges ambient or solution-dissolved oxygen for a zinc oxidation reaction, achieving an energy density ranging from 760 to 1070 watt-hours per liter at scales below 100 micrometers lateral and 2 micrometers thickness in size. The parallel nature of photolithography processes allows 10,000 devices per wafer to be released into solution as colloids with energy stored on board. Within a volume of only 2 picoliters each, these primary microbatteries can deliver open circuit voltages of 1.05 ± 0.12 volts, with total energies ranging from 5.5 ± 0.3 to 7.7 ± 1.0 microjoules and a maximum power near 2.7 nanowatts. We demonstrated that such systems can reliably power a micrometer-sized memristor circuit, providing access to nonvolatile memory. We also cycled power to drive the reversible bending of microscale bimorph actuators at 0.05 hertz for mechanical functions of colloidal robots. Additional capabilities, such as powering two distinct nanosensor types and a clock circuit, were also demonstrated. The high energy density, low volume, and simple configuration promise the mass fabrication and adoption of such picoliter zinc-air batteries for micrometer-scale, colloidal robotics with autonomous functions.

Long-Life All-Solid-State Batteries Enabled by Cold-Pressed Garnet Composite Electrolytes with Enhanced Li+ Conduction.

Garnet Li7La3Zr2O12 (LLZO)-based solid-state electrolytes (SSEs) hold promise for realizing next-generation lithium metal batteries with high energy density. However, the high stiffness of high-temperature sintered LLZO makes it brittle and susceptible to strain during the fabrication of solid-state batteries. Cold-pressed LLZO exhibits improved ductility but suffers from insufficient Li+ conductivity. Here, we report cold-pressed Ta-doped LLZO (Ta-LZ) particles integrated with ductile Li6PS5Cl (LPSC) via a Li+ conductive Li-containing Ta-Cl structure. This configuration creates a continuous Li+ conduction network by enhancing the Li+ exchange at the Ta-LZ/LPSC interface. The resulting Ta-LZ/LPSC SSE exhibits Li+ conductivity of 4.42 × 10-4 S cm-1 and a low activation energy of 0.31 eV. Li symmetric cells with Ta-LZ/LPSC SSE demonstrate excellent Li dendrite suppression ability, with an improved critical current density of 5.0 mA cm-2 and a prolonged cycle life exceeding 600 h at 1 mA cm-2. Our finding provides valuable insights into developing cold-pressed ceramic powder electrolytes for high-performance all-solid-state batteries.

(Battery Student Slam 8 Award Winner) Multi-Clustered Lithium Diffusion in Single-Crystalline NMC Battery Particles

Understanding the diffusion dynamics of lithium within solid-state electrodes is pivotal for developing high-performance batteries. In this context, layered oxides were utilized as a promising cathode material due to their high energy density and fast intraparticle lithium diffusivity. Despite advancements in material composition, coating, and doping, the understanding of intraparticle lithium diffusion has long been described by Fick's law. Conventionally, lithium diffusion is assumed to generate a monotonic lithium concentration gradient within solid-solution single-crystalline battery materials during cycling. This raises fundamental questions about diffusion in layered oxides; (1) Can the diffusion of Li in solids be interpreted as Fickian diffusion, similar to diffusion in gases or liquids, even though it involves structural and phase evolution throughout the battery cycle? and, (2) Does the fast diffusivity (10-11-10-9 cm2/s) support the homogenization of Li?In this study, we address these questions surrounding lithium diffusion in layered oxide by utilizing operando scanning transmission X-ray microscopy. We revealed the formation of mobile Li-dense/-dilute nano-domains within individual single-crystalline LiNi1/3Mn1/3Co1/3O2 (scNMC) during battery cycles. We term this phenomenon ‘multi-clustered lithium diffusion’, distinguishing our findings from the conventionally suggested Fickian diffusion model in solid-solution materials. These domains persist for at least 4 hours during relaxation, accompanied by locally residing strained domains, as confirmed by Bragg coherent diffraction imaging (BCDI), within a single particle. We believe these domains arise due to the compensation of localized chemical potential gradients that are generated by the sustained presence of strain within the battery particles during cycling.While maintaining integrity of Li-dense/-dilute domain at various C-rates, STXM result further show that Li-dilute domains maintain during the discharging. Given the lower concentration of Li at insertion boundaries, which could lower the surface charge transfer impedance of the system, Li-dilute domains facilitate lithium transport by functioning as low-resistance pathways. Through a comprehensive analysis of electrical impedance spectroscopy (EIS), STXM imaging and finite element analysis (FEA), we showed that controlling the local domain fraction is crucial for controlling the overpotential during subsequent charging. Our study introduces new insights into nanoscale solid-state diffusion, thereby enabling the fabrication of high-performance batteries. Figure 1

Thin-Film Embedded Sensors for Battery Health Monitoring

Hybrid or all-electric aircraft are being developed as the next generation of aircraft to both allow new forms of aviation and decrease environmental impact. Since these types of aircraft are based on high-capacity battery technology, safe operation of these batteries becomes increasingly important. In particular, the potential for battery failure due to uncontrolled chemical reactions resulting in thermal runaway, catastrophic failure, and battery fires must be addressed in order for such battery technology to have the level of safety needed for standard aviation implementation. Efforts to ensure battery safety often involve engineering solutions that seek to contain rather than prevent such events by early detection. Such approaches increase the system weight and decrease the power per unit mass provided by the battery system. Existing methods for measuring battery parameters to determine the battery state-of-health are limited. These methods include electrical measurements of the cell current and/or voltage output as well as temperature measurements taken externally on the cell surface. Such external temperature measurements are limited in their ability to provide early warning of impending battery failure. In response, an effort to develop sensors operating internal to battery for health monitoring has been ongoing in the NASA Sensor-based Prognostics to Avoid Runaway Reactions & Catastrophic Ignition (SPARRCI) project [1]. The basic approach associated with this sensor work is the deposition of thin film sensors on the battery separator located between the anode and cathode of the battery. These thin film sensors are then monitored to determine changes in battery parameters and health. Microfabrication techniques are employed to minimize the overall impact of the sensors on battery operation through the implementation of sensors with minimal size, weight, and power consumption. The thickness of the films, which are fabricated through physical vapor deposition (sputtering), are on the order of thousands of angstroms and can have minimal surface area. Thin film sensors for system health management have been implemented for a many decades on complex components for aerospace applications [2,3]. However, the application of thin films of this type on a battery separator for internal battery monitoring applications has not previously been demonstrated to our knowledge. This paper describes the development of sensors for the internal battery monitoring through the use of thin film sensor technology. Thin metal films were successfully deposited on a battery separator polymer material with good adherence and electrical continuity. Multiple types of sensors have been deposited, as well as lead connections from the sensor to the edge of the separator material. The ability of these thin film sensors immersed in electrolyte to perform multiple types of battery parameter measurements has been demonstrated. For example, a multiparameter sensor system measured multiple properties simultaneously inside of a pouch cell over a wide temperature range. Further, real time measurement of interior temperature changes in a battery pouch cell with an integrated interior temperature sensor was demonstrated. These changes include detecting a fault in the battery (shorting) in situ with rapid response time (less than a minute) corresponding to a more limited response by a temperature sensor mounted externally. Other aspects of monitoring battery health were also explored, such as real-time measurement of simulated dendrite growth/metal deposition by sensor on separator material demonstrated. Future efforts will include improvements in the durability of the sensor structure to allow introduction of the approach into standard battery fabrication techniques. Overall, this work is a step forward in providing a method to prevent catastrophic battery failures and provide a foundation for safer, lighter, and higher energy batteries for the electric aircraft industry.[1] B. DeMattia, Daniel Perey, John Lawson, and Gary Hunter, “Advanced Battery Health Approaches for Electric Aircraft”, Energy & Mobility Technology, Systems, and Value Chain Conference & Expo, Cleveland, OH, Sept. 23, 2023.[2] John D. Wrbanek, and Gustave C. Fralick, “Thin Film Physical Sensor Instrumentation Research and Development at NASA Glenn Research Center”, 52nd International Instrumentation Symposium Cleveland, OH, May 2006, NASA TM-2006-214395[3] Lawrence G. Matus (2015) “Instrumentation for Aerospace Applications: Electronic-Based Technologies”, Journal of Aerospace Engineering 26 (2) https://doi.org/10.1061/(ASCE)AS.1943-5525.0000302

Solid-State Lithium Batteries with in-Situ Polymerized Acrylate-Based Electrolytes Capable of Electrochemically Stable Operation at 100 ℃

In-situ polymerized acrylate-based polymers are very appealing as solid polymer electrolytes (SPEs) in lithium (Li) batteries due to the drop-in compatibility of such in-situ polymerization with conventional battery production, the ease of acrylate polymerization and their inexpensive, facile SPE chemistry. We identified, however, that such SPEs suffer from either a low cationic transference number with dual ion conducting salts (0.12-0.2) or a low ionic conductivity with single Li-ion conducting (SLIC) salts (6·10-6 S cm-1). In this project we overcame these limitations and developed significantly improved SPE with ionic conductivity of up to 2·10-4 Scm-1 and a relatively high Li-ion transference number of 0.4. With a significantly reduced fraction of mobile anions in the hybrid SPE, in-situ polymerized SPE cells with an LiFePO4 (LFP) cathode achieve a stable performance for over 100 cycles at temperatures as high as 100 °C, which is unattainable with conventional Li salts or electrolytes. Furthermore, the motional narrowing observed in the line-shapes of solid-state nuclear magnetic resonance (SS-NMR) spectra provided additional insights of the differences in Li nucleus environments and revealed a reduced activation energy for the hybrid salt SPEs due to their more open structure. This study opens the path for the fabrication of high-performance solid polymer lithium batteries capable of operating at high temperatures using commercial battery fabrication equipment. We expect that further tuning of the acrylate based SPE composition may allow further increases in its conductivity without sacrifices in its electrochemical stability or mechanical properties.

Fabrication of 60μm-Thick Free-Standing Bilayer Solid Electrolytes for Solid-State Batteries Using Solution Processing and Lamination

Development of solid-state batteries with a high voltage cathode and lithium metal anode could enable high energy density while avoiding safety issues of flammable liquid electrolytes. However, the solid electrolyte (SE) should meet multiple requirements, including 1) electrochemical stability at both the cathode and anode side interfaces, 2) small thickness (tens of μm) to maximize energy density of the cell, and 3) fabrication with a scalable manufacturing method. Using bilayer SEs with different electrochemical stability windows could enable stability at both cathode|SE and anode|SE interfaces. In this work, we developed a manufacturing process to fabricate thin (60 μm) free-standing bilayer SE films from slurry casting and lamination, which can be used for large scale manufacturing of SSBs.Halide SE (Li3InCl6) and sulfide SE (Li6PS5Cl) were slurry casted on different substrates, and then were dried in vacuum before being laminated onto each other to make a free-standing bilayer film. The parallel slurry casting approach eliminates cross-compatibility requirements of the solvents used for slurry preparation. The resulting bilayer films after densification were pin-hole free without intermixing between the two phases. The ionic conductivity of the bilayer SE film was ~70% of the bilayer SE pellet (1 mm thickness in total) made with a conventional powder pressing method. However, because the thickness of bilayer SE film (60 μm) was much smaller than the bilayer SE pellet (1 mm), the bilayer SE film had ~10x lower area-specific resistance (ASR) compared to the bilayer SE pellet. Because of the lower total cell resistance, the cell made with the bilayer SE film had a better rate capability compared to the reference cell in pellet geometry.The strategy developed in this work could be integrated into current manufacturing infrastructure of battery fabrication as it is based on slurry casting, which is already a well-established fabrication method for lithium-ion batteries. Moreover, it could be used to fabricate multi-layered solid-state architectures in general, which are challenging to manufacture due to solvent compatibility issues during slurry casting. The study will assist the progress of solid-state battery manufacturing by providing a scalable manufacture method to prepare thin free-standing bilayer SEs.

Building Solid-State Batteries: Insights from Swiss Research Labs

This review article delves into the growing field of solid-state batteries as a compelling alternative to conventional lithium-ion batteries. The article surveys ongoing research efforts at renowned Swiss institutions such as ETH Zurich, Empa, Paul Scherrer Institute, and Berner Fachhochschule covering various aspects, from a fundamental understanding of battery interfaces to practical issues of solid-state battery fabrication, their design, and production. The article then outlines the prospects of solid-state batteries, emphasizing the imperative practical challenges that remain to be overcome and highlighting Swiss research groups’ efforts and research directions in this field.

Recovering Nickel‐Based Materials from Spent NiMH Batteries for Electrochemical Applications

AbstractIn this work, we explored the recovering possibilities of nickel‐based products from the cathode materials of spent nickel‐metal hydride (NiMH) batteries collected from car repair centers in Mongolia. Specifically, nickel‐based by‐products such as metallic nickel, Ni microparticles, nickel oxide, nickel chloride, and betta‐phase (β) nickel hydroxide powders are successfully produced. X‐ray diffraction patterns suggested that all samples show high crystallinity and phase purity. Ni microparticles were recovered using a chemical reduction method from a leachate solution prepared by dissolving the cathode of the spent NiMH battery in hydrochloric acid. Notably, β‐Ni(OH)₂ displayed two redox peaks in KOH electrolyte solution, suggesting that it has excellent electrochemical potential and can be reused for the fabrication of new NiMH batteries. To validate the electrochemical performances, we examined the catalytic activity of nickel microparticles as a catalyst for the degradation of Congo red (CR) dye and oxygen evolution reaction (OER). The reduction reaction rate of CR dye in the presence of a nickel catalyst was 2.17×10−3 s−1, significantly higher than the control experiment without a nickel catalyst. These results provide possible solutions for developing sustainable battery systems by recovering different nickel‐based products from spent NiMH batteries.

Natural low corrosive phytic acid electrolytes enable green, ultrafast, stable and high-voltage aqueous proton battery

Proton is a promising charge carrier for aqueous rechargeable batteries due to its small ionic radius, fast diffusion kinetics and great abundance in nature. However, commonly-used proton battery electrolytes are strong acids, such as sulfuric acid, phosphoric acid, etc., which always leads to the notorious rapid corrosion of electrode and metal components, and thus the poor cyclability, the limited materials option and high maintenance cost. Here, we reported a new-type high-concentration phytic acid (PA) electrolytes, which exhibits marvellous superiorities including environmental friendliness, low corrosiveness, high ionic conductivity (133.3 mS cm−1) and wide working potential window (∼2.9 V) in contrast to conventional acid electrolytes. The experimental and calculation results indicated that the scarcity of free water in high-concentration PA electrolytes and the desolvation effect of the preferentially absorbed PA interfacial layer on the electrode surface work in synergy to inhibit the water activity and thus prevent electrode dissolution and side reactions. Benefiting from this, the assembled K0.2VO0.6[Fe(CN)6]0.8•6H2O (VHCF)//MoO3 button-type proton battery shows an average discharge voltage of 0.7 V with a pair of well-defined redox peak at about 1.4 V, great rate performance, excellent cycling stability (87.9% capacity retention after 1000 cycles at 5 A g−1) and superb coulombic efficiency at various current densities (1 A g−1–50 A g−1). Attributed to good anti-freezing properties of the electrolytes, the proton battery can also run normally at -60 °C and exhibit competent performance (a capacity retention of 45 mAh g−1 at 0.1 A g−1 after 540 cycles). Such green low corrosive electrolyte will be fully compatible with conventional battery fabrication process, and open brand new avenue for the development of aqueous proton battery.

Theoretical study of adsorption of sodium, lithium, magnesium and calcium chloride and sulfate salts by pure and Sc-doped B12N12 nanocages and pure boron nitride nanosheet

High concentrations of water-soluble chloride and sulfate salts may cause adverse effects to humans and plants. Boron nitride (BN) nanostructures seem able to remove these water-soluble salts. In addition, Li+, Mg2+, Ca2+, and Na2+ interactions with BN nanostructures have received much attention in fabricating high-performance metal-ion batteries. Accordingly, this study investigated the adsorption of chloride and sulfate salts of Li, Mg, Ca, and Na on pristine and scandium (Sc)-doped B12N12 nanocages and pure BN nanosheet through DFT calculations. Optimizing the structures at the B3LYP/6-31 g (d, p) and M062X/6-311 g (d, p) computational levels indicated very exothermic chemisorption of chloride and sulfate salts on the pure and Sc-doped B12N12 nanocages. The B12N12-LiCl and Sc@B11N12-LiCl complexes showed the highest negative adsorption energies of −26.33 and −57.30 kcal/mol among the chloride salts. The B12N12-MgSO4 and Sc@B12N12-MgSO4 complexes showed the highest adsorption energies of −69.27 and −102.70 kcal/mol among the sulfate salts. Studying the effect of the adsorption process on the electronic properties of the B12N12 nanocage showed a reduction in the energy gap upon the adsorption of all salts on the pure B12N12 nanocage with the lowest energy gap of 3.98 eV for B12N12-MgSO4. The adsorption energies of the individual salts and their complexes on the B12N12 nanosheet at the B3LYP/6-311 g (d, p) level imply the occurrence of physisorption. A significant reduction was observed in the energy gap by adsorbing the salts on the BN nanosheet. Adsorbing CaSO4 and MgSO4 on the BN nanosheet caused the largest variation of 1.71 and 1.56 eV in the energy gap, respectively. The promising results of our study highlight the potential application of BN nanostructures in the removal of various soluble salts and the fabrication of metal-ion batteries.

Two-electron conversion nitroxide radicals-based electrode synergistically enhancing charge storage in water-in-salt electrolyte

Water-in-salt electrolytes (WISEs) are attractive in aqueous batteries due to their non-flammability, environmental friendliness, and wide electrochemical stability window. Stable nitroxide radicals with fast electron transfer rate and good cycling stability are promising electrode materials applied for WISEs, while their limited conductivity and high solubility in electrolytes are still challenges. Here, porous carbon with high specific area is used as conductive substrate for the deposition of 4-amino-TEMPO (TEMPO = 2,2,6,6-tetramethylpiperidine-1-oxyl), and MXene nanosheets are employed as their conductive binder to construct freestanding electrode with “hyacinth bean-like” structure. Nitroxide radicals undergo a two-step two-electron reversible redox reaction and MXene exhibits pseudocapacitive ion intercalation, leading to synergistically enhanced discharge capacity in WISE (19.8 m LiCl). The incorporated redox active nitroxide radicals in MXene/porous carbon-TEMPO electrode boost the surface pseudocapacity and the rationally designed three-dimensional structure further facilitates the ions diffusion and electrons transfer, endowing the composite electrode with fast charge storage kinetic. This work provides a promising potential for the design and fabrication of high-performance aqueous batteries.

The effects of fluorine doping on the structure, interface and electrochemical properties of lithium titanate

Enhancing the electronic and ionic conductivity of Li4Ti5O12 electrode materials, as well as suppressing the interface reaction between Ti4+ on the surface of Li4Ti5O12 and the electrolyte, is one of the key factors in preparing high-power and long-life Li4Ti5O12 lithium-ion batteries. To tackle these challenges, fluorine ions with strong electronegativity was chosen as dopants to engineer fluorine-doped Li4Ti5O12 electrode materials. Fluorine ion doping changes the surface state of Li4Ti5O12, increases the interface compatibility, suppresses the reactivity between Li4Ti5O12 and the electrolyte, and forms a uniform SEI film during cycling. Moreover, fluorine ion doping induces the generation of oxygen vacancies and improves the crystallinity of Li4Ti5O12, thereby fostering improved electronic and ionic transport kinetics. The above appealing features enables the prepared fluorine-doped Li4Ti5O12 material demonstrates exceptional high-rate performance, delivering specific capacities of 175 mAh·g−1/0.5C, 159 mAh·g−1/10C, and 138 mAh·g−1/50C. In essence, the fluoride ion doping strategy holds profound implications for enhancing electrode interface characteristics, transport kinetics, and the fabrication of high-power lithium-ion batteries.