Capacity Retention Rate Research Articles

Effective improvement of lithium-ion battery anode performance of Ti3C2 by alkali metal ion treatment strategy

MXene has emerged as a promising electrochemical energy storage material due to modifiable layered structure and good electrical conductivity. However, its lamellar stacking has severely limited the electrochemical performance during charging and discharging. Herein, the Li-treated Ti3C2 and Na-treated Ti3C2 nanocomposites are prepared by hydrothermal treatment. Li-treated Ti3C2 exhibits the largest discharge specific capacity, with an initial capacity of 551.5 mA h/g at a rate of 0.1 A/g, which is 81.3 mA h/g higher than Na-treated Ti3C2. After 200 cycles, the Li-Ti3C2 possesses a final capacity of 321.1 mA h/g, better than Na-Ti3C2 (151.7 mA h/g) and Ti3C2 (119.3 mA h/g). The Li-Ti3C2 shows superior cycling performance at a high rate of 2 A/g and a capacity retention rate of 84 % after 1000 cycles. During hydrothermal treatment, the in situ generated TiO2 plays a crucial role in the targeted introduction of metal ions. Density functional theory (DFT) calculations verify that LiTiO2 phase in Li-treated Ti3C2 possesses low band gap and lowest Li migration barrier. The synergy of these factors leads to the improved electrochemical performance of Li-treated Ti3C2. This work provides novel design strategies for developing MXene materials as high performance lithium-ion batteries.

The high-rate cycling stability of the LiFe0.6Mn0.4PO4/C cathode material is enhanced through in-situ Nb-doping

LiFe0.6Mn0.4PO4/C, due to its low cost and safety advantages, is gradually becoming a safe and reliable commercial lithium battery storage material. However, its lower capacity at high rates and poor cycle performance limit its further industrial application. To address this, this work used a one-step solvothermal method to prepare Li(Fe0.6Mn0.4)1‑xNbxPO4 (x = 0, 0.01, 0.02, 0.03) cathode materials to improve electrochemical performance. Characterization of the samples indicates that Nb doping promoted the growth of the material's [001] crystal orientation, thus enhancing the lithium ion diffusion rate, effectively reducing electrode polarization and charge transfer resistance, which helps to explain its excellent rate performance. More importantly, Nb doping increases the M-O bond energy, making the LMFP/C metal-oxygen framework more stable, and enhancing the stability of the crystal structure of lithium ions intercalating and deintercalating during cycling. The electrochemical test results further indicate that the LFMP/CNb0.02 cathode exhibits excellent electrochemical performance. It has remarkable capacities of 156.9 mAh·g‑1 at 0.2 C and 135.9 mAh·g‑1 at 1 C, particularly showing an initial discharge specific capacity of 121.4 mAh·g‑1 at a high rate of 5 C. After 500 cycles, it still maintains a capacity of 114.3 mAh·g‑1, with a capacity retention rate of 94.15 %, significantly outperforming the original LMFP/C (initial discharge specific capacity of 109.8 mAh·g‑1) which only retains 61.47 % of its capacity after 300 cycles.

The advanced copper oxide coating separator enhances the electrochemical performance of high-rate lithium-ion batteries

The performance and cycle life of Lithium-ion batteries (LIBs) are significantly influenced by the separator, a critical component. Traditional polyolefin separators can no longer meet the growing demand for energy storage. Coating conventional polyolefin separators with electrochemically inert ceramic materials can enhance stability but often increases weight and reduces battery capacity. This study introduces a novel separator coated with copper oxide (CuO), developed through a simple and efficient method. The CuO coating polypropylene (CuO@PP) separator demonstrates superior thermal resistance, enhanced electrolyte absorption, and increased porosity compared to conventional polypropylene (PP) separators. Additionally, the active participation of the CuO coating in electrochemical reactions during the charge-discharge process increases battery capacity. Results indicate that the CuO@PP separator provides an additional capacity of approximately 10 mAh g−1. The battery using the CuO@PP separator exhibited exceptional electrochemical properties in contrast to the traditional PP separator, with a first discharge capacity of 129.8 mAh g−1 at 10 C and a capacity retention rate of 92.4 % over 400 cycles at 10 C. Thus, enhancing the reliability and performance of LIBs by modifying the PP separator with a CuO coating presents a promising approach, offering novel perspectives for designing and manufacturing advanced battery separators.

The collaborative effect of Ni3S2-NiO heterojunction and porous carbon network modified lithium-sulfur battery separator for effectively inhibiting polysulfides shuttle

As an important part of lithium-sulfur battery (LSB), separator not only provides ion transport channel but also plays a key role in ensuring battery safety. However, the aperture of the commercial separator polypropylene (PP) is relatively large, which cannot effectively inhibit the migration of polysulfides generated during the charging and discharging process between the positive and negative electrodes, resulting in a decrease in the cycle stability of LSB. In this work, a modified LSB separator Ni3S2-NiO@AC-4@PP is designed, which is anchored by Ni3S2-NiO heterojunction on volcanic rock-like three-dimensional porous carbon network (AC) as the functional interlayer. The AC possesses a large specific surface area and excellent electrical conductivity, creating sufficient space for the physical and chemical adsorption of insoluble polysulfides. The Ni3S2-NiO heterojunction is embedded and attached to the AC, which helps to hinder the diffusion of polysulfides and accelerate the redox reaction. It is also confirmed by density functional theory (DFT) calculation that Ni3S2-NiO heterojunction inhibited the shuttle of polysulfides through the adsorption capacity of NiO and the catalytic activity of Ni3S2. Thus, the Ni3S2-NiO@AC-4@PP battery exhibits an elevated initial specific capacity of 1027.8 mAh g−1 at 0.2C, maintaining long-term stability after 200 cycles with the capacity retention rate of 81.4 %. At the higher current density (2C), Ni3S2-NiO@AC@PP battery demonstrates durable cycle with the capacity retention rate of 91.3 %. This study proposes a new feasible strategy to obtain high-performance, low-cost modified separators by designing functional interlayers with excellent adsorption and catalytic properties.

Bimolecular Salt Strategy Enhances Heteroatom Doping and Porosity Optimization of Porous Carbon for Supercapacitors.

The incompatibility between electrolyte ions and electrode pore sizes, coupled with the extensive use of activators and dopants, significantly restricts the fabrication of porous carbon materials. Consequently, developing environmentally sustainable and efficient methodologies that exploit the intrinsic properties and pretreatment of materials to facilitate self-activation and self-doping becomes crucial. In this study, potassium histidine and magnesium histidine molecular salts were synthesized as precursors, enabling specific ion activation and bimetallic template-directed tunable porosity through a one-step carbonization process. Notably, the ratio of bimolecular salts significantly influenced the porous structure of carbon, the properties of heteroatoms, and the electrochemical performance. By optimizing the ratio, the porous carbon materials exhibited high accessibility to electrolyte ions and effective ion/electron transport channels. Consequently, the optimal sample (NOSPC-2) achieved a high specific capacitance of 318 F g-1 at 0.1 A g-1 and a good capacitance retention rate of 98.8% after 50,000 cycles at 5 A g-1. In addition, NOSPC-2 also boasted high energy density and power density, reaching 22 Wh kg-1 and 25 kW kg-1, respectively. This research represents a significant stride in advancing preparation technologies for small molecule derived porous carbon materials, providing valuable insights for the rational design of carbon electrode materials for capacitive energy storage.

Laser-Generated Au nanoparticles as lithophilic sites in self-supported film host for anode-free lithium metal battery

Anode-free lithium metal batteries (AFLMBs) are considered to have greater application potential than traditional LMBs because of their higher energy density and safety. Unfortunately, their poor cycling performances originated from the unsatisfactory reversibility of Li plating/stripping remains a big challenge. A rational designed host for lithium deposition is an effective solving strategy. Herein, pure Au nanoparticles (NPs) without any impurities are prepared by a liquid-phase laser irradiation technology to construct and develop a self-supported Au/reduced graphene oxide (Au/rGO) film as lithium deposition host for AFLMBs. The densely and uniformly distributed Au NPs provide abundant lithiophilic sites that significantly reduce the nucleation barrier of lithium. Attributed to the precise regulation of Au sites towards lithium nucleation/growth, dendrites-free anode and improved electrochemical performance are obtained by using the Au/rGO film host. It keeps stable for 30 min of lithiation at 6 mA cm−2 without dendrite formation. Additionally, the Li||Au/rGO half-cell shows an overpotential close to 0 mV and maintains a Coulombic efficiency exceeding 97 % after 500 cycles at 1 mA cm−2. Moreover, a symmetric Au/rGO-Li cell can operate for 700 h without short-circuit. When paired with LiFePO4 (LFP) to assemble a full battery, the Au/rGO-Li achieves 96 % capacity retention rate after 100 cycles. This work not only develops an efficient host for lithium, but also provides a unique strategy to the safety concerns associated with LMBs’ anodes.

Bimetallic ions modified 2‐methylimidazolium functionalized polypyrrole/graphene oxide for the improved supercapacitor

AbstractThin films with two‐dimensional (2D) nanostructures possess good environmental stability, thinner thickness and large surface area, which are widely used as a promising modified electrode material in the field of energy storage, supercapacitors, electrochemical sensors and biosensors. Herein, unique bimetallic ions modified polypyrrole/graphene oxide (PPy/GO) nanosheets, including Co2+‐Zr4+/(2‐MeIm)x@PPy/GO and Co2+‐Run+/(2‐MeIm)x@PPy/GO (n = 0, 4), are prepared by using 2‐methylimidazolium (2‐MeIm) as the linkers between PPy/GO and metal ions. The obtained electrodes constructed by Co2+‐Run+/(2‐MeIm)x@PPy/GO (n = 0, 4) and Co2+‐Zr4+/(2‐MeIm)x@PPy/GO exhibit improved capacitor electrochemical properties due to the reversible redox reaction, the large specific surface area and the high theoretical specific capacitance value of the metal ions compared to the unmodified PPy/GO. Especially, the specific capacitance value of Co2+‐Run+/(2‐MeIm)x@PPy/GO (n = 0, 4) electrode reaches 321.78 F g−1 at a current density of 1 A g−1 and the capacitance retention rate is achieved to 100% in the long cycle charge/discharge test after 10 000 cycles (10 A g−1). It will provide a practical experience for the design and preparation of supercapacitors based on bimetallic ions modified PPy/GO.

One-step in situ doping of Sb achieves enhanced performance of [001]-oriented nano-LiFe0.6Mn0.4PO4/C cathode high-rate materials

The LiFe0.6Mn0.4PO4/C composite has become a cost-effective and reliable material for lithium battery storage in commercial applications, due to its significant safety benefits. However, its industrial application is limited by its suboptimal high-rate capacity and unsatisfactory cycling performance. To address this issue, Li(Fe0.6Mn0.4)1-xSbxPO4 (x = 0, 0.01, 0.03, 0.04, 0.05) materials were synthesized using a one-step solvothermal method in this study, aiming to modulate the microstructure and achieve Sb doping, thereby enhancing the electrochemical performance. The electrochemical test results indicate that LFMP/C doped with Sb (designated as LFMP/C-Sb0.04) displays exceptional electrochemical performance, with remarkable capacities of 166.6 mAh·g−1 and 146.8 mAh·g−1 at 0.2C and 1C, respectively. Notably, it achieves a capacity of 126.1 mAh·g−1 at a high rate (5C) and maintains an impressive capacity retention rate of 93.6 % after 300 cycles, outperforming the original LMFP/C (109.5 mAh·g−1), which retains only 61.5 % of its initial capacity. Further characterization of the samples reveals that in situ Sb doping promotes the growth of the [001] crystal orientation, enhancing the lithium-ion diffusion rate and effectively reducing electrode polarization and charge transfer resistance, thereby contributing to its exceptional rate performance. Moreover, Sb doping increases the M − O binding energy, strengthens the metal-oxygen framework, mitigates the Jahn-Teller effect caused by Mn3+ dissolution, and enhances its cycling stability.

Significant performance enhancement of Zn-ion hybrid supercapacitors based on microwave-assisted pyrolyzed active carbon via synergistic effect of NaHCO3 activation and CNT networks

Zinc-ion hybrid supercapacitors (ZIHSCs) represents a promising technological approach for large-scale energy storage with the combined advantages of supercapacitors and zinc-ion batteries. Unfortunately, it is still challengeable to quickly fabricate low-cost, high-performance carbonaceous cathode materials at relatively low temperature. To address such issues, herein, taking waste Eucommia ulmoides Oliver (EUO) wood as an example, we present a novel microwave-assisted carbonization (MWC) approach at relatively low temperature to quickly prepare active carbon, and we present a synergistic strategy to significantly enhance the electrochemical performance by introducing sodium bicarbonate activation (SA) and constructing conductive carbon nanotubes (CNT) networks. The MWC-SA@CNT hybrid exhibits outstanding specific capacitance of 344.2 F/g at 0.2 A/g within three-electrode system, much better than conventional high-temperature pyrolyzed AC, MWC carbon, and MWC-SA carbon. The superior performance of MWC-SA@CNT can be attributed to the synergistic effect of its large specific surface area of 1102.7 m2/g, high mesoporous percentage of 53.5%, and rich –OH and CO groups due to microwave-assisted carbonization and sodium bicarbonate activation, and rich electron transport paths due to the presence of CNT networks. Furthermore, ZIHSCs assembled by MWC-SA@CNT cathode could delivers impressive performance with excellent capacity (194.37 mA h/g at current density of 1 A/g), energy density (142.30 Wh/kg), and durability (capacitance retention rate of 97.65% after 5000 cycles). This work offers a rapid and low-temperature method for preparing wood-based active carbon with rich nanopores and strong conductivity to improve performance of Zinc ion storage.

The impact of processing voltage of wire electric discharge machining on the performance of Mo doped V-VO0.2 based Archimedean micro-supercapacitors.

Vanadium oxide-based electrode materials have attracted increasing attention owing to their extraordinary capacitance and prolonged lifespan, excellent conductivity and outstanding electrochemical reversibility. However, the development of vanadium oxide-based integrated electrodes with outstanding capacitive performance is an enduring challenge. This research reports a facile method for structuring 3D Archimedean micro-supercapacitors (AMSCs) composed of Mo doped V-VO0.2 (Mo@V-VO0.2) based integrated electrodes with designable geometric shape, using computer-aided wire electric discharge machining (WEDM). The performance of Mo@V-VO0.2 based AMSCs manufactured by different processing voltages of 60 V, 80 V and 100 V were evaluated. It was found that 80 V is the optimal processing voltage for manufacturing Mo@V-VO0.2 based AMSCs with the best electrochemical performance. This device demonstrates superior capacitive behavior even at an ultra-high scan rate of 50, 000 mV s-1, and achieves a good capacitance retention rate of 94.4% after 2000 cycles. Additionally, the characteristics of electric field distribution were also simulated for optimizing the geometric structure of the microdevices. This WEDM fabrication technique, which is easy, secure, patternable, efficient, economical, eco-friendly, and does not require binders or conductive additives, enables the development of high-capacity 3D pseudocapacitive micro-supercapacitors and demonstrates the great potential for metal oxide synthesis and microdevice manufacturing.

In Situ Self‐Polymerization of Thioctic Acid Enabled Interphase Engineering Towards High‐Performance Lithium–Sulfur Battery

AbstractLithium–sulfur (Li–S) batteries possess high theoretical energy density, whereas the shuttle effect of polysulfides and the uncontrollable lithium (Li) dendrites seriously reduce the reversible capacity and cycling lifespan. Constructing an interphase to address the issues in both the cathode and anode simultaneously is significant but still challenging. In this study, a strategy of functionalizing commercial polypropylene (PP) separators is proposed by in situ poly(thioctic acid) (PTA) polymerization. Compared with the conventional separator modifications, the ring‐opening polymerization methodology initiated by heat is more facile and environment‐friendly without changing the nanostructures among the porous separators. On the cathode side, the PTA‐coated separator (PTA‐PP) blocks the shuttle of polysulfides through the electrostatic interaction. On the anode side, the PTA‐coated generates a lithium fluoride (LiF)‐rich solid electrolyte interface (SEI), identified by cryo‐transmission electron microscopy (cryo‐TEM), to accelerate the Li+ diffusion and inhibit the growth of Li dendrites. Due to the interphases constructed by the PTA‐PP separator, the Li–S cells exhibit excellent long‐term cycling in which the capacity retention rate is more than 76% after 700 cycles at 0.5 C. The in situ elaborate modification strategy may provide insights into the high‐performance separator design to promote the potentially large‐scale applications of Li–S batteries.

Enhancement of high-efficiency potassium ion hybrid supercapacitors utilizing oxygen-deficient Co2NiO4@nitrogen-doped carbon nanoflower

Transition metal oxides represent a promising category of pseudocapacitive materials for potassium-ion hybrid supercapacitors (PIHCs) characterized by high energy density. Nevertheless, their utility is hindered by intrinsic low conductivity, restricted electrochemical sites, and notable volume expansion, all of which directly contribute to the degradation of their electrochemical performance, thereby limiting their practical applicability in supercapacitor systems. In this study, we present a facile synthesis approach to fabricate nitrogen-doped carbon-supported oxygen vacancy-rich Co2NiO4 nanoflowers (Ov-Co2NiO4/NC NFs) featuring tunable surface layering and electron distribution. The nanoflower structure augments the contact area between the material and the electrolyte. Density functional theory (DFT) calculations reveal oxygen vacancies could bring an enhanced charge density across the entire Fermi level in Co2NiO4 and expand the interatomic distances between adjacent cobalt and nickel atoms to 3.370 Å. N-doped carbon carriers further accelerate charge transfer, increase the electrostatic energy storage and inhibit the structural collapse of Co2NiO4. These structural modifications serve to improve electrochemical reaction kinetics, augment the binding energy of K+ (−2.87 eV), and mitigate structural variations during K+ storage. In a 6 M KOH electrolyte, Ov-Co2NiO4/NC NF exhibits a specific capacitance of 1104 F g−1 at a current density of 0.5 A g−1, with a remarkable capacitance retention rate of 91.48 % after 6500 cycles. Furthermore, the assembled PIHCs demonstrate an energy density of 47.8 Wh kg−1 and an ultra-high power density of 376 W kg−1, alongside notable cycle stability, retaining 90.13 % of its capacitance after 8000 cycles in a 6 M KOH electrolyte.

Hydrothermal preparation of cotton-based rGO/N-doped porous carbon as electrode materials of supercapacitors

Porous carbon electrode materials are commonly used in supercapacitors due to their inexpensive raw materials, simple processing, and low pollution, aligning with the vision for green energy storage. Consequently, there is a current trend to discover porous carbon electrode materials with superior electrochemical properties. To enhance the pore volume ratio and electrochemical performance of porous carbon materials, this study proposes a hydrothermal method to pretreat the raw materials, facilitating the doping of nitrogen from urea. Moreover, graphene is introduced for its excellent conductivity, which can further improve the electrochemical properties of the material. We found a new one-step reduction Graphene Oxide (rGO)and the doping of nitrogen (N) elements were optimized by hydrothermal method, the wettability and pseudo-capacitance performance of the material are improved, and HTPC-700 shows a very excellent specific capacitance, its specific capacitance reaches 600 F g−1 at a current density of 0.5 A g−1, and it even reaches 260 F g−1 at a current density of 1 A g−1. Meanwhile the power density and energy density are respectively 74 W h kg−1 and 280 W kg−1. It also exhibits a remarkable capacitance retention rate of over 98.7 % after 5000 cycles at a current density of 1 A g−1. Additionally, it demonstrates a rich ant nest-like pore structure and good specific surface area of 2427 m2/g, and a large pore volume of 1.09 cm3/g after carbonization and KOH activation. This study offers a novel doping method and provides a unique perspective for the development of porous carbon electrodes.

VO2-C Cathode Material Prepared from Reduction of V2O5 by Citric Acid for Aqueous Zinc Ion Batteries

Designing and synthesizing cathode materials with high specific capacity and stability for aqueous zinc ion battery remains a significant challenge. In this study, citric acid was selected as the reducing agent for converting V2O5 to VO2 with a carbon matrix using the hydrothermal method. The introduction of citric acid not only created a distinct microstructure in V4+ materials but also provided carbon matrix, which resulted in a fast diffusion of zinc ion and a good conductivity. This carbon containing vanadium-oxide material exhibited excellent electrochemical performance as a cathode material for aqueous zinc ion batteries, showing a high specific capacity of 399.33 mAh g−1 at 1 A g−1, and a capacity retention rate up to 98.3% after cycling for 1000 cycles at a high current density of 5 A g−1.

Design and Synthesis of D‐A Polymer as Cathode Material for Na‐Based Dual‐Ion Batteries with Excellent Cycling Performance

AbstractOrganic bipolar electrodes can undergo both n‐type and p‐type reactions for energy storage due to numerous active sites, which can usually deliver a high theoretical specific capacity. Herein, a new bipolar polymer cathode material PQPZ is designed and synthesized. The electron‐donating phenazine group undergoes a two‐electron redox reaction which can store anions, the electron‐withdrawing phenanthraquinone can store sodium‐ions through a two‐electron redox reaction. Notably, as a bipolar cathode material for sodium‐ion batteries, PQPZ exhibits a reversible specific capacity of up to 270 mAh g−1 in the voltage range of 1.0–4.0 V (vs. Na+/Na) and achieves a high energy density of 696 Wh kg−1 in a half‐cell. A capacity retention rate of 90% is obtained after 300 cycles at a current density of 0.5C. More excitingly, even after being cycled for 10000 cycles at 10C, the PQPZ electrode shows an average decay rate as low as 0.0036% per cycle, manifesting a very stable cycling performance. In addition, PQPZ also shows excellent performances when tested at −10 °C, making it promising in practical applications. Considering the bipolar character of PQPZ, symmetric batteries are also successfully constructed, fulfilling the “ready‐to‐charge” property without a pre‐activation process. The results reveal the potential application of PQPZ in practical use.

High Capacitance Performance N, O Codoped Carbon Foams Synthesized via an All-In-One Step Carbonization of Molecular Salt Strategy.

The preparation of porous carbon is constrained by the extensive use and detrimental impact of activators and dopants. Therefore, developing green and efficient strategies that leverage the intrinsic properties and pretreatment of the materials to achieve self-activation and self-doping is particularly crucial for porous carbon materials. Herein, potassium histidine was utilized as the molecular salt precursor, attaining the efficient and streamlined preparation of porous carbon through a one-step carbonization process that enables self-activation, self-doping, and self-templating. More interestingly, the carbonization temperature significantly impacts the porous structure of the molecular salt precursors, the properties of the heteroatoms, and electrochemical performance. The designed electrodes exhibit high accessibility to electrolyte ions and effective ion-electron transport channels. Therefore, the optimal carbon material (KHis800) has an excellent mass-specific capacitance of 305.2 F g-1 at 0.2 A g-1, and a high capacitance retention rate of 115.6% (50,000 cycles at 5 A g-1). Notably, KHis800 also shows a maximum energy density of 19.6 Wh kg-1. This research is dedicated to exploring a more efficient preparation method for porous carbon material via molecular salts, offering insights for the sustainable development of carbon materials.

The phosphorus doping modification of Ti3C2Tx MXene films assisted by tripolyphosphate-crosslinking for flexible supercapacitors

MXenes is a new two-dimensional material with good electrical conductivity and high theoretical pseudocapacitance, which is widely used in various energy storage devices. Heterogeneous atom doping is one of the effective strategies to adjust the properties of MXenes and improve its electrochemical performance. In this work, a facile and cost-effective KTPP (potassium tripolyphosphate, phosphorus source) assistance strategy is demonstrated to dope Ti3C2Tx MXene with phosphorus atoms by heat treatment. The results show that the phosphorus doping level reached 1.25 at.%. As expected, the specific capacitance of the phosphate-doped Ti3C2Tx electrode is 365.1 F g−1 at the scanning rate of 10 mV s−1, which is twice that of the pristine Ti3C2Tx (183.1 F g−1). Besides, the flexible supercapacitor device assembled with Ti3C2Tx-P-300°C-3h sample has a high energy density of 10.76 Wh kg−1 at 483.03 W kg−1 power density and the capacitance retention rate is 84.51 % after 5000 cycles at the current density of 1 A g−1. With bent at different angles (0°, 60°, 90°, 120°), the specific capacitance values of flexible supercapacitor devices have not changed significantly, and the capacitance retention rate reached 90.09 %. The reason for the enhanced electrochemical performance is that the phosphorus doping can increase the active sites of Ti3C2Tx, bring PO bonds that enhance activity, optimize the redox reaction process, and accelerate the ion transport rate. Therefore, a simple and effective method to improve the electrochemical performance of Ti3C2Tx MXene is proposed in this work.

Flexible and High-Strength Porous Graphene/Polyurea Composite Film for Multifunctional Applications

Porous composites possess distinctive structural features and performance advantages, making them promising for applications in various domains such as sensing, energy storage, and acoustics. A simple, efficient, and environmentally friendly method was employed to prepare porous polyurea materials, which were then modified with graphene nanosheets. The resulting graphene/polyurea porous composites demonstrated enhanced mechanical properties, with a 35.04% increase in tensile strength at a graphene content of 5 wt%. These composites exhibited exceptional multifunctionality, achieving a specific capacitance of 35.74 F/g when used as capacitor electrodes. Additionally, they displayed high sensitivity to resistance and capacitance changes under various mechanical loads, such as tensile, torsional, and bending stresses, with a resistance change rate of 57.72% under 180-degree torsion, highlighting their potential as resistive and capacitive sensors. Compared to traditional materials, the multifunctional composites maintained a resistance change rate below 40% and a capacitance retention rate above 95.07% after 10,000 cycles, underscoring their durability and reliability. Moreover, the developed graphene/polyurea porous composites exhibited good corrosion resistance and an impressive sound absorption rate of 30.68% for high-decibel noise, reducing environmental limitations for their applications. These properties position the composite as a durable, high-sensitivity, multifunctional material with significant potential in sensing, energy storage, and noise reduction applications.

Researching the electrochemical performance by Mn2+ substituted Na3+xV2-xMnx(PO4)3/rGO cathode materials for aqueous zinc-ion batteries

Aqueous zinc-ion batteries (AZIBs) are gaining rising popularity as potential energy storage solutions for large-scale renewable energy, attributed to their affordable pricing and inherent safety features. The reversible capacity of AZIBs, which is crucial for their cycle performance, is significantly influenced by the choice of cathode material, with Na3V2(PO4)3 standing out as promising candidates for their large 3D transport channels and rapid kinetics. However, they suffer from rapid degradation caused by low structural stability during the charge-discharge process. In this work, we researched the electrochemical performance of cathode materials by employing a sol-gel preparation for Mn-doped Na3-xV2-xMnx(PO4)3/rGO (x = 0, 0.05, 0.1), in which graphene oxides (rGO) were introduced as carbon sources. It is identified that the Mn doping exerts a beneficial influence to enhance stability of the structure. The Mn0.05-NVP/rGO material, optimized for performance, exhibits a specific capacity of 106.3 mAh·g−1 with a discharge plateau at 1.3 V at a current density of 100 mA·g−1, which corresponds to an energy density of 134.7 Wh·kg−1. Particularly, the addition of Mn enhances cycling performance, leading to a remarkable capacity retention rate of 75.3 % even after 100 cycles. This work confirms the feasibility using NASICON-type cathodes and offers valuable perceptions into the advancement of cathode materials in AZIBs.

Efficient Co-ZrO2 electrocatalyst achieves high-performance solid-state lithium-sulfur batteries

Abstract Li-S batteries are recognized as a promising secondary battery system because of their high energy density, low cost, and environmental friendliness. However, the development of Li-S batteries is mainly limited by issues such as electrode volume expansion, lithium polysulfide (LiPSs) shuttle, and slow redox reaction kinetics of sulfur. Here, a kind of solid-state Li-S battery with in situ solidified solid-state electrolytes (SSEs) is reported, which dramatically reduces the electrode/electrolyte interfacial impedance. In addition, electrospinning is used to fabricate a macroporous carbon nanofibers film (MP-CNFs) loaded with dispersed Co-ZrO2 nanodot electrocatalyst as the cathode host. The in-situ gel electrolyte can be easily infiltrated into the porous carbon nanofibers and contact the Co-ZrO2 catalyst, thus fully exerting its catalytic and conversion effects on LiPSs. The results indicate that solid-state Li-S batteries exhibit a high initial capacity of 795.5 mA h·g−1 and a capacity retention rate of ∼100% after 200 cycles at 1 C.