Anodic Research Articles

On the Practicability of the Solid‐State Electrochemical Pre‐Sodiation Technique on Hard Carbon Anodes for Sodium‐Ion Batteries

AbstractHard carbon (HC) with low cost and high specific capacity is considered the appropriate anode material for sodium‐ion batteries (SIBs), but the low initial coulombic efficiency (ICE) caused by solid electrolyte interface (SEI) formation and inherent active defects impede its practical battery application. Here, the practicability of solid‐state electrochemical (SSE) pre‐sodiation technique for hard carbon anode is assessed to conquer such challenges. The uniformly pre‐sodiated HC (Pre‐HC) can be fabricated through the SSE reaction between the HC and preloaded sodium metal film without introducing a liquid electrolyte. After being immerged in the electrolyte, a thin artificial SEI with abundant inorganic species is formed on the surface of Pre‐HC due to the spontaneous chemical reaction, and the ICE of HC is improved from 76.0% to 107.9%. Full cell paired with Na3V2(PO4)3 cathode exhibits a high ICE of 94.0% with 70% of energy density augment (from 126.5 to 214.4 Wh kg−1) after anode pre‐sodiation. Pre‐HC anode still retains the pre‐sodiation capacity of 671.1 mAh gNa−1 after being stored in the dry air for 2 h. This work demonstrates the practical applicability of this SSE pre‐sodiation strategy to enhance the energy density of SIBs.

N, S co-doped coal-based hard carbon prepared by two-step carbonization and a molten salt template method for sodium storage

Hard carbon, known for its abundant resources, stable structure and high safety, has emerged as the most popular anode material for sodium-ion batteries (SIBs). Among various sources, coal-derived hard carbon has attracted extensive attention. In this work, N and S co-doped coal-based carbon material (NSPC1200) was synthesized through a combination of two-step carbonization process and heteroatom doping using long-flame coal as a carbon source, thiourea as a nitrogen and sulfur source, and NaCl as a template. The two-step carbonization process played a crucial role in adjusting the structure of carbon microcrystals and expanding the interlayer spacing. The N and S co-doping regulated the electronic structure of carbon materials, endowing more active sites. Additionally, the introduction of NaCl as a template contributed to the construction of pore structure, which facilitates better contact between electrodes and electrolytes, enabling more efficient transport of Na+ and electrons. Under the synergistic effect, NSPC1200 exhibited exceptional sodium storage capacity, reaching 314.2 mAh g-1 at 20 mA g-1. Furthermore, NSPC1200 demonstrated commendable cycling stability, maintaining a capacity of 224.4 mAh g-1 even after 200 cycles. This work successfully achieves the strategic tuning of the microstructure of coal-based carbon materials, ultimately obtaining hard carbon anode with excellent electrochemical performance.

The effect of time and heat exposure on the wettability and glossiness of CAA and FPL coatings for aluminum substrates

The use of anodized coatings as a substrate for adhesive bonding of aluminum is widespread and generally accepted. However, with time and exposure to heat, the coating’s behavior changes and its wettability decrease. We examine the coating’s wettability by measuring the contact angle. Aluminum sheets are coated with two types of anodizing and FPL coatings for this study. The results indicate that the wettability of all coatings remains stable for 16 h post application. However, there is a significant decrease in wettability over extended time periods, with the anodized coating exhibiting more pronounced changes after 30 days compared to the FPL coating. Also, in both types of coatings, as the heating temperature increases, the wettability decreases and the contact angle increases. The changes in the anodized coatings are more pronounced than in FPL coatings. Measuring the glossiness of the coating before and after heating shows that the gloss and the surface roughness of the coating remain unchanged.

Lignin‐derived hard carbon anode with a robust solid electrolyte interphase for boosted sodium storage performance

AbstractHard carbon is regarded as a promising anode candidate for sodium‐ion batteries due to its low cost, relatively low working voltage, and satisfactory specific capacity. However, it still remains a challenge to obtain a high‐performance hard carbon anode from cost‐effective carbon sources. In addition, the solid electrolyte interphase (SEI) is subjected to continuous rupture during battery cycling, leading to fast capacity decay. Herein, a lignin‐based hard carbon with robust SEI is developed to address these issues, effectively killing two birds with one stone. An innovative gas‐phase removal‐assisted aqueous washing strategy is developed to remove excessive sodium in the precursor to upcycle industrial lignin into high‐value hard carbon, which demonstrated an ultrahigh sodium storage capacity of 359 mAh g−1. It is found that the residual sodium components from lignin on hard carbon act as active sites that controllably regulate the composition and morphology of SEI and guide homogeneous SEI growth by a near‐shore aggregation mechanism to form thin, dense, and organic‐rich SEI. Benefiting from these merits, the as‐developed SEI shows fast Na+ transfer at the interphases and enhanced structural stability, thus preventing SEI rupture and reformation, and ultimately leading to a comprehensive improvement in sodium storage performance.

Achieving High Rate and Long Cycle Performance of Na2FePO4F Cathode Through Co-Modification of Ti Doping and Carbon Coating.

Layered Na2FePO4F (NFPF) cathode material has received widespread attention due to its green nontoxicity, abundant raw materials, and low cost. However, its poor inherent electronic conductivity and sluggish sodium ion transportation seriously impede its capacity delivery and cycling stability. In this work, NFPF by Ti doping and conformal carbon layer coating via solid-state reaction is modified. The results of experimental study and density functional theory calculations reveal that Ti doping enhances intrinsic conductivity, accelerates Na-ion transport, and generates more Na-ion storage sites, and pyrolytic carbon from polyvinylpyrrolidone (PVP) uniformly coated on the NFPF surface improves the surface/interface conductivity and suppresses the side reactions. Under the combined effect of Ti doping and carbon coating, the optimized NFPF (marked as 5T-NF@C) exhibits excellent electrochemical performance, with a high capacity of 108.4mAhg-1 at 0.2C, a considerable capacity of 80.0mAhg-1 even at high current density of 10C, and a high capacity retention rate of 81.8% after 2000 cycles at 10C. When assembled into a full cell with a hard carbon anode, 5T-NF@C also show good applicability. This work indicates that co-modification of Ti doping and carbon coating makes NFPF achieve high rate and long cycle performance for sodium-ion batteries.

Comparison and optimization of biomass-derived hard carbon as anode materials for sodium-ion batteries

Hard carbon made from biomass-based precursors has many advantages as anode for sodium-ion batteries such as low cost and sustainability. In this work, three different hard carbon materials derived from bamboo, wood and coconut shell with the same particle size are screened, combining acid etching and carbonization at 1200 °C, to compare the sodium ion storage performances. The anode material originated from bamboo shows the highest specific capacity among them. Subsequently, the hard carbon from bamboo is optimized by the same process, but changing the carbonization temperature ranging from 1000 °C to 1400 °C. Among the hard carbon materials, the bamboo-derived one prepared at 1300 ℃ exhibits excellent electrochemical performances at a current density of 30 mA g−1, with a high reversible specific capacity of 303.8 mAh/g and an initial coulombic efficiency of 83.7 %. After 150 cycles, a capacity retention of 94.7 % is achieved at a current density of 300 mA g−1. This work provides a potential hard carbon anode for sodium-ion batteries to realize large-scale energy storage due to the cheap sources of bamboo.

Electrospun Na3MnTi(PO4)3/C film: A multielectron-reaction and free-standing cathode for sodium-ion batteries

With the continuous advancement of renewable energy sources, sodium-ion batteries are currently regarded as highly promising technologies for large-scale electric energy storage. The compound Na3MnTi(PO4)3 has garnered significant attention owing to its exceptional theoretical capacity, robust structural stability, and abundant availability of resources. Herein, hierarchical carbon-decorated Na3MnTi(PO4)3 nanofibers are synthesized via a feasible electrospinning technique followed by pyrolysis, effectively addressing the issue of poor electronic conductivity in phosphate cathodes. The free-standing Na3MnTi(PO4)3/C electrode serves as a cathode for sodium-ion batteries, exhibiting exceptional electronic conductivity and superior Na+ transport capability. Moreover, it demonstrates an impressive reversible capacity of 171.4 mA h g−1 at 0.2C and exhibits outstanding cyclic stability with a capacity retention of 63.7 % after 6300 cycles at 1C. The full cell, assembled with independent Na3MnTi(PO4)3/C cathode and hard carbon anode, exhibits a reversible capacity of 153.7 mA h g−1 at a current density of 10 mA g−1. The in-situ synthesis of nanomaterial particles within interconnected porous nanocarbon fibers can effectively enhance the materials' poor electronic conductivity, thereby further improving their cyclic stability and Na+ transport kinetics.

Effects of sealing and prior shot peening treatments on fatigue behavior of sulphuric acid anodic oxidation coated 6082-T6 aluminium alloy

In this study, the effects of sealing and prior shot peening treatments on the fatigue behavior of the sulphuric acid anodic oxidation coated 6082-T6 aluminium alloy were investigated. Experimental results indicate that the preferential fracture of anodic oxidation coatings due to its higher brittleness and lower fracture toughness as well as the stress concentration of near-interface substrate caused by the interface cyclic dislocation accumulation could cause the fatigue failure of anodic oxidation coated specimens. Consequently, the fatigue property of anodic oxidation coated specimens notably decreases compared to as-machined specimens, with a decrease of 26.7 % in the fatigue limit corresponding to 2 × 107 fatigue cycles. Additionally, the sealing treatment introduces numerous cracks that penetrate the coating entirely, diminishing the coating's resistance to cracking under fatigue loading; this alteration changes the fatigue failure mechanism of anodic oxidation coated specimens, ultimately resulting in a decrease of 15.5 % in the fatigue limit of anodic oxidation coated specimens. Despite exacerbating the surface integrity and increasing the surface roughness of anodic oxidation coated specimens, the prior shot peening treatment increases the fatigue limit of anodic oxidation coated specimens by 82.8 % since the affecting layer beneath the interface plays a crucial role in inhibiting the further propagation of coating cracks into the substrate as well as the crack propagation in the substrate beneath the interface.

Improve the Insulation Performance of Anodic Coating by Plasma Discharge Treatment

Since the plasma discharge treatment has been applied for the insulation enhancement of anodic coatings, we explored how the current density impacted the coating insulation performance. SEM, XRD and electrochemical workstation were utilized for identifying the coating crystallinity, compactness and impedance. As demonstrated by results, the anodic coating is transformable into compact crystalline alumina at a 30-mA/cm2 current density, whose impedance is twice that of original anodic coating.

Nitrogen/fluorine dual-doped resin-based hard carbon anode with high capacity retention for lithium storage

Nitrogen/fluorine dual-doped resin-based hard carbon anode with high capacity retention for lithium storage

Formation of a black anodic coating on alloy AA5052 by using anodizing in a tri-acid environmentally friendly electrolyte

For the first time, an organic electrolyte has been created, which allowed the formation of black anodized aluminum (Al) by direct anodizing of alloy AA5052. The electrolyte consists of a mixture of three environmentally friendly acids. The structural and optical properties of black anodic coatings were determined before and after thermal treatment. Total reflection tests of black anodized Al have shown that AA5052 samples have a total reflectance value of 5–7% in the visible (VIS) range. The study of specular reflectance on the angle of incidence of the light at a wavelength of 600 nm has shown that sample AA5052 has the highest angular intensity compared to that of AA1050. Thermal treatment reduced the porosity of alloy AA5052 about 2.5 times, but did not affect its optical properties. Black anodized alloy AA5052 has excellent thermal stability both at 100 °C and 200 °C temperatures, i.e. the total reflectance value did not change by more than 5% in the VIS range. Hence, the developed black anodized coatings are suitable for solar water heating systems.

Hybrid hard carbon framework derived from polystyrene bearing distinct molecular crosslinking for enhanced sodium storage

AbstractExploiting high‐performance yet low‐cost hard carbon anodes is crucial to advancing the state‐of‐the‐art sodium‐ion batteries. However, the achievement of superior initial Coulombic efficiency (ICE) and high Na‐storage capacity via low‐temperature carbonization remains challenging due to the presence of tremendous defects with few closed pores. Here, a facile hybrid carbon framework design is proposed from the polystyrene precursor bearing distinct molecular bridges at a low pyrolysis temperature of 800°C via in situ fusion and embedding strategy. This is realized by integrating triazine‐ and carbonyl‐crosslinked polystyrene nanospheres during carbonization. The triazine crosslinking allows in situ fusion of spheres into layered carbon with low defects and abundant closed pores, which serves as a matrix for embedding the well‐retained carbon spheres with nanopores/defects derived from carbonyl crosslinking. Therefore, the hybrid hard carbon with intimate interface showcases synergistic Na ions storage behavior, showing an ICE of 70.2%, a high capacity of 279.3 mAh g−1, and long‐term 500 cycles, superior to carbons from the respective precursor and other reported carbons fabricated under the low carbonization temperature. The present protocol opens new avenues toward low‐cost hard carbon anode materials for high‐performance sodium‐ion batteries.

Electrolyte Chemistry toward Ultrawide-Temperature (-25 to 75 °C) Sodium-Ion Batteries Achieved by Phosphorus/Silicon-Synergistic Interphase Manipulation.

All-weather operation is considered an ultimate pursuit of the practical development of sodium-ion batteries (SIBs), however, blocked by a lack of suitable electrolytes at present. Herein, by introducing synergistic manipulation mechanisms driven by phosphorus/silicon involvement, the compact electrode/electrolyte interphases are endowed with improved interfacial Na-ion transport kinetics and desirable structural/thermal stability. Therefore, the modified carbonate-based electrolyte successfully enables all-weather adaptability for long-term operation over a wide temperature range. As a verification, the half-cells using the designed electrolyte operate stably over a temperature range of -25 to 75 °C, accompanied by a capacity retention rate exceeding 70% even after 1700 cycles at 60 °C. More importantly, the full cells assembled with Na3V2(PO4)2O2F cathode and hard carbon anode also have excellent cycling stability, exceeding 500 and 1000 cycles at -25 to 50 °C and superb temperature adaptability during all-weather dynamic testing with continuous temperature change. In short, this work proposes an advanced interfacial regulation strategy targeted at the all-climate SIB operation, which is of good practicability and reference significance.

Superior initial Coulombic efficiency and areal capacity of hard carbon anode enabled by graphite-assisted carbonization for sodium-ion battery

Hard carbons are perceived as promising anode materials in sodium-ion batteries, while their practical implementation is largely impeded by the insufficient initial Coulombic efficiency (ICE). Hard carbons with self-supporting architecture are intriguing to enhance ICE owing to the omission of binder and conductive agent; whereas elaborate architecture and microstructure design are still required to further raise the ICE to the level of commercial graphite in lithium-ion batteries, especially under high areal capacity. Herein, we propose a graphite-assisted pressurization strategy during carbonization to achieve remarkable ICE and high areal capacity in resulting self-supporting cellulose tissue derived hard carbon anode. The intimate contact of graphite plate enables suitable local ordering of pseudo-graphitic nanodomains with low intrinsic defects, responsible for enhanced ICE. While the pressure-reinforced dense yet self-interwoven fibrous networks render high areal capacity. Consequently, the as-prepared self-supporting hard carbon anode displays remarkable ICE to 95% and areal capacity of 2.4 mAh cm−2, far exceeding the reported value of less than 0.8 mAh cm−2. Meanwhile, the rate and durability are not scarified under such superior ICE due to the well-manipulated pseudo-graphitic nanodomains and porous fibrous networks. The practicality is further demonstrated in coin-type and pouch-type full cells delivering high capacity and long-term stability. Our finding offers an impetus for the development of high ICE and areal capacity for sodium-ion battery anode.

Fluoride Doping Na3Al2/3V4/3(PO4)3 Microspheres As Cathode Materials for Sodium-Ion Batteries with Multielectron Redox.

Sodium-ion batteries (SIBs) are potential candidates for large energy storage usage because of the natural abundance and cheap sodium. Nevertheless, improving the energy density and cycling steadiness of SIB cathodes remains a challenge. In this work, F-doping Na3Al2/3V4/3(PO4)3(NAVP) microspheres (Na3Al2/3V4/3(PO4)2.9F0.3(NAVPF)) are synthesized via spray drying and investigated as SIB cathodes. XRD and Rietveld refinement reveal expanded lattice parameters for NAVPF compared to the undoped sample, and the successful cation doping into the Na superionic conductor (NASICON) framework improves Na+ diffusion channels. The NAVPF delivers an ultrahigh capacity of 148 mAh g-1 at 100mA g-1 with 90.8% retention after 200 cycles, enabled by the activation of V2+/V5+ multielectron reaction. Notably, NAVPF delivers an ultrahigh rate performance, with a discharge capacity of 83.6 mAh g-1 at 5000mA g-1. In situ XRD demonstrates solid-solution reactions occurred during charge-discharge of NAVPF without two-phase reactions, indicating enhanced structural stability after F-doped. The full cell with NAVPF cathode and Na+ preintercalated hard carbon anode shows a large discharge capacity of 100 mAh g-1 at 100mA g-1 with 80.2% retention after 100 cycles. This anion doping strategy creates a promising SIB cathode candidate for future high-energy-density energy storage applications.

Effect of Zirconia Thickness, Cement Color, and Titanium Implant Abutment Surface Treatment Type on the Esthetic Outcomes of High-Translucency Monolithic Zirconia.

To investigate the esthetic outcomes based on the color differences in zirconia (Zr) of varying thickness, resin cement color, and types of titanium (Ti) implant surface treatments. Overall, 28 high-translucency monolithic zirconia (HTMZ) specimens were arranged into four groups based on Zr thickness: 1.0, 1.5, 2.0, and 2.5 mm (n &#61; 7 per thickness). Each group was tested using two resin cement colors (clear and opaque) in combination with six surface-treated Ti groups (n &#61; 7), including untreated titanium (UT), anodization (AN), 50-μm alumina airborne-particle abrasion followed by AN (SBAN), AN followed by 50-μm alumina airborne-particle abrasion (ANSB), 9.5% hydrofluoric acid followed by AN (HFAN), and AN followed by 9.5% hydrofluoric acid (ANHF). This created a total of 48 experimental groups, including the use of composite resin (n &#61; 7, shade A2D) for four control groups. All specimens were measured using a spectrophotometer and subsequently compared with composite resin (control) with the corresponding Zr thickness to establish color differences. A color difference of < 2.7 was considered clinically acceptable. The data obtained were statistically analyzed using ANOVA and post hoc test (P &#61; .05). Zr thickness, resin cement color, and type of Ti implant surface treatment significantly affected the observed color differences (P < .05). When using 2.5-mm HTMZ with clear resin cement on AN, UT, SBAN, HFAN, and ANSB, the mean color differences were below the clinically acceptable values, and the 95% CIs of color differences were below the clinically acceptable values for AN, UT, and SBAN groups. HTMZ with a minimum thickness of 2.5 mm and clear resin cement on AN, UT, and SBAN groups potentially result in acceptable color matching with 95% CIs.

Ceramic coating on Mg alloy for enhanced degradation resistance as implant material

Magnesium (Mg) alloys display very appealing characteristics, including biocompatibility, bioactivity, biodegradability, lightweightness, and a similar density to cortical bone tissue, but they have some constraints, such as inappropriate corrosion and degradation resistance, which lead to failing early mechanical strength. Therefore, calcium phosphate (CaP)-based ceramic coating like hydroxyapatite (HA) coating is fabricated on the anodization-induced surfaces of pure Mg and ZK41 Mg alloy specimens to overcome those constraints in medical applications. In mechanical integrity like microhardness, adhesion strength tests demonstrated that HA coated ZK41 and Mg specimens significantly increased Vickers' hardness number (about 2 times) compared to unmodified substrates and had greater adhesion strength in comparison with the anodization-induced layer, respectively. In the in vitro immersion test, the HA-coated samples showed plate-like and needle-like crystal formations. This provided more surface area, which improved the corrosion and degradation resistance characteristics. As a consequence, the least amount of weight loss has occurred.Additionally, the anodized (AN) Mg, HA coated Mg, untreated ZK41, and anodized ZK41 samples all have higher corrosion rates than the HA coated ZK41 (0.018 mm/year). Cell viability of HA coated Mg and its alloy ZK41 was comparatively high, which ensures biocompatibility as an implant material. Therefore, HA coatings for Mg and ZK41 alloys for clinical applications could be more promising. In this study, ZK41 Mg alloy has been used as an inventive substrate for HA coating in place of the prior Mg alloys, with the intention of addressing the earlier drawbacks.

Friction Behavior of Anodic Oxide Layer Coating on 2017A T4 Aluminum Alloy under Severe Friction Solicitation: The Effect of Anodizing Parameters

This article aims to highlight the wear mechanisms and friction behavior of the 2017A T4 anodized aluminum alloy used for automotive and aerospace applications. The effect of the processing parameters on the durability of the anodized layer under high friction is studied. Scratch tests were carried out to study the level of the friction coefficient with the increase in the thickness of the oxide layer formed on the Al 2017 A (AU4G) substrate. The results of the scratch tests show that the variation in the anodization duration, which influences the thickness of the oxide layer, induces an increase in the coefficient of friction. Besides, the variations in friction coefficient with sliding distance are influenced by the changes in wear morphology and degree of oxidation. Treated surfaces with a thickness of 50 μm have the lowest friction coefficients and wear rates. Their improved wear resistance may be related to the increased bond strength compared to other anodized surfaces. The tribological damage was characterized by the detachment of debris, which increases with the increase of the duration of anodization. Upon sliding, its detachment leads to delamination of the underlying anodic aluminum oxides and subsequent abrasion of the aluminum substrate.

Wear resistance of hard anodic coatings fabricated on 5005 and 6061 aluminum alloys

Wear resistance of hard anodic coatings fabricated on 5005 and 6061 aluminum alloys

Optimizing Synthesis Temperature for Lignin-Derived Hard Carbon Anode for High Cycling Capacity in Sodium-Ion Batteries

This comprehensive study sheds light on the promising potential of lignin-derived carbonaceous materials as sustainable and cost-effective anode materials for sodium-ion batteries, contributing to the development of eco-friendly energy storage technologies. Lignin, a complex and abundant biopolymer, undergoes a facile pyrolysis process to produce carbonaceous materials. The unique microstructure of lignin-derived carbon, characterized by a relatively high surface area and interconnected porous network, facilitates efficient sodium ion diffusion and accommodates volume changes during cycling. The effects of pre-treatment methods, carbonization conditions, and structural modifications of lignin on the electrochemical performance are systematically investigated. Furthermore, the electrochemical mechanisms underlying the sodiation/desodiation processes in lignin-derived carbon (LDC) based anodes are elucidated through advanced characterization techniques, including in situ spectroscopy and microscopy. Among the different hard carbon materials, pre-pyrolyzed lignin-derived carbon LDC-300–1400 (300 shows which pre-treatment pyrolysis temperature was used and 1400 is the post-pyrolysis temperature in °C) shows the most favourable outcomes, demonstrating a reversible capacity of 359 mAh g−1, 1st cycle coulombic efficiency of 81%, and good rate capabilities. Hydrothermally pre-treated LDCs show a slightly lower specific capacity value reaching up to 337 mAh g−1.