Enhanced Energy Density Research Articles

Synthesis of MnMoO4/α-MoO3 composite materials for supercapacitor

In the quest for developing supercapacitors with enhanced energy density, we have successfully synthesized MnMoO4/MoO3 composite materials tailored for supercapacitor applications. The synthesis process utilized (NH4)6Mo7O24·4H2O and MnCl2·4H2O as precursors. The resulting composite materials were thoroughly characterized using a suite of analytical techniques, including scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction analysis, Brunauer-Emmett-Teller surface area measurements, thermogravimetric analysis, and differential scanning calorimetry. Furthermore, the supercapacitive performance of the MnMoO4/α-MoO3 composite materials was evaluated using cyclic voltammetry and constant current charge–discharge methods. The synthesis yielded an ideal composite material, with low-resistance MnMoO4 seamlessly integrated with high ion-conductive MoO3. At a current density of 3 A/g, the specific capacitance was measured at 1878.7 F/g, achieving an energy density of 260.9 Wh kg−1 and a power density of 1.448 kW kg−1. The composite materials demonstrated significant potential for the production of high-density supercapacitors.

Dynamic characteristics of pumped thermal-liquid air energy storage system: Modeling, analysis, and optimization

Pumped thermal-liquid air energy storage (PTLAES) is a novel energy storage technology that combines pumped thermal- and liquid air energy storage and eliminates the need for cold storage. However, existing studies on this system are all based on steady-state assumption, lacking dynamic analysis and optimization to better understand the system’s performance under cyclic operation. To fill this gap, the mainbody-linearized cyclic dynamic model of the PTLAES system with packed bed thermal energy storage (TES) was first developed. Then, the dynamic characteristics of the baseline system were investigated. Sensitivity analyses were carried out on TES parameters. Minimal values of levelized cost of storage (LCOS) were observed for all parameters in the range of interest. Subsequently, the TES circuit was optimized, and a triple improvement of efficiency and energy density enhancement, discharge stabilization, and cost reduction was achieved. The optimized system's round-trip efficiency and energy density increased from 61.7% to 63.1% and from 141.9 kWh/m³ to 159.2 kWh/m³, and the LCOS decreased from 163.2 $/MWh to 159.4 $/MWh. A power offset ratio lower than 3% was reached, which is the lowest value ever reported in the literature. This study provides reference for future design and operation of the PTLAES system.

Thermal hazard comparison and assessment of Li-ion battery and Na-ion battery

Na-ion batteries are considered a promising next-generation battery alternative to Li-ion batteries, due to the abundant Na resources and low cost. Most efforts focus on developing new materials to enhance energy density and electrochemical performance to enable it comparable to Li-ion batteries, without considering thermal hazard of Na-ion batteries and comparison with Li-ion batteries. To address this issue, our work comprehensively compares commercial prismatic lithium iron phosphate (LFP) battery, lithium nickel cobalt manganese oxide (NCM523) battery and Na-ion battery of the same size from thermal hazard perspective using Accelerating Rate Calorimeter. The thermal hazard of the three cells is then qualitatively assessed from thermal stability, early warning and thermal runaway severity perspectives by integrating eight characteristic parameters. The Na-ion cell displays comparable thermal stability with LFP while LFP exhibits the lowest thermal runaway hazard and severity. However, the Na-ion cell displays the lowest safety venting temperature and the longest time interval between safety venting and thermal runaway, allowing the generated gas to be released as early as possible and detected in a timely manner, providing sufficient time for early warning. Finally, a database of thermal runaway characteristic temperature for Li-ion and Na-ion cells is collected and processed to delineate four thermal hazard levels for quantitative assessment. Overall, LFP cells exhibit the lowest thermal hazard, followed by the Na-ion cells and NCM523 cells. This work clarifies the thermal hazard discrepancy between the Na-ion cell and prevalent Li-ion cells, providing crucial guidance for development and application of Na-ion cell.

Ginkgo biloba-derived biogenic carbon quantum dots modified NiCo-LDH: significantly enhanced energy density and cycle stability

A significant development in the usage of hydroxides in energy storage applications is the creation of LDH materials with excellent electrical conductivity and structural stability. Due to their poor electrical conductivity, bimetallic layered double hydroxides have weak rate performance and limited cycling ability. To address these issues, carbon quantum dots derived from waste Ginkgo biloba and labeled as GBC were incorporated in the preparation of NiCo-LDH. With the many oxygen-containing functional groups on the surface, GBC increases the composite's wettability while maintaining the LDH lamellar structure. It can also create localized electron-rich regions, which give the material more space and channels for electron transport, improving electrical conductivity and rate performance. Furthermore, GBC is evenly dispersed throughout the LDH skeleton, giving the composites a homogenous surface state that can mitigate the structural collapse issue brought on by the volume change during cycling. The findings demonstrate that by modulating the amount of GBC, NiCo-LDH/GBC-20 performs better electrochemically than NiCo-LDH. The capacity was 276.1 mAh g-1 at 1 A g-1, an 84.1% improvement over NiCo-LDH. Finally, the energy density displayed by the NiCo-LDH/GBC-20//AC HSC device is 72.5 Wh kg-1 (at 798.7 W kg-1), and maintains 78.2% of its original capacity after 12,000 cycles.

3D-printed Bio-inspired porous electrode by bidirectional enhancement strategy with high mass loading and enhanced energy density for supercapacitors

The effective strategy for increasing areal capacity involves the use of 3D printed thick-electrode with high mass loading. However, thick-electrode still encounters challenges such as incomplete electrolyte penetration and slow ion transport. Here, we successfully prepared lignocellulosic nanofibrils (LCNFs) from abundant bamboo biomass and developed functional ink composed of LCNFs/ carbon nanotubes (CNTs) / polyaniline (PANI) / polyvinyl alcohol (PVA) for printing. An innovative 3D printing bidirectional enhancement strategy was proposed to increase the mass loading of active materials in the vertical direction and construct ion transport channels in the transverse direction. The biomimetic porous N-doped electrode obtained after annealing treatment exhibits a more continuous conductive network, larger surface area, higher utilization of active materials, and smoother ion transport pathways compared to thick-electrode. Therefore, the Triangles biomimetic electrode exhibits an enhanced areal/specific capacitance compared to thick-electrode, reaching 5.30F·cm−2 (184.03F·g−1) and 4.40F·cm−2 (122.22F·g−1) at 2 mA·cm−2, respectively. The symmetric device demonstrates an areal capacitance of 1.34F·cm−2 at 1 mA·cm−2 and achieves an energy density of 0.186 mWh·cm−2 at a power density of 0.49 mW·cm−2. The work provides valuable insights into the design of electrode structures for high-performance supercapacitors.

Pushing the Energy-Lifetime Frontier of Li-Ion Batteries: Study of Ni-Rich, Co-Free NMAW Cathode Material

Abstract Dopants and coatings have been widely used to improve the performance of Ni-rich positive electrode active materials. Previous studies have aimed to elucidate the mechanism by which Al and W improve lithium metal oxides, providing valuable insight on the design of enhanced electrode materials for Li-ion batteries. In this work, Al and W are compared as individual dopants as well as co-dopants in order to design an optimal Ni-rich, Co-free material. This involved studying the effect of synthesis temperature in the presence of Al and/or W as well as the effect that these metals have on the morphology of the resultant polycrystalline materials. In addition, structural analysis by X-ray diffraction, electrochemical analysis, and characterization of the mechanical strength of the materials were also conducted. The change in performance with the addition of Al and W depends greatly on particle size and chemical composition. Small sized Ni-rich polycrystalline particles (Ni content of 94%) with low contents of Al (3%) and W (1%) showed the greatest enhancement in energy density with good cycle life.

Innovations in Biodegradable Batteries: A Sustainable Future

The increasing demand for batteries in several industries such as medical and electric car (EV) Industry has led to significant environmental challenges due to the production and disposal of traditional batteries, which are nonbiodegradable and pose risks to ecosystems. This report investigates the potential of biodegradable batteries as a sustainable alternative to traditional batteries, aiming to minimize environmental impact. This study analyzing and comparing the fiber batteries, zinc-molybdenum batteries, plant-based batteries (Flower battery), crab shell battery as well as algal biopolymers battery. It also highlights the key materials, methods for manufacture, and performance characteristics (biodegradability, energy capacity, degradation time) of each type of biodegradable batteries. The findings suggest that biodegradable batteries offer promising solutions for specific applications, such as in biomedical devices, wearable electronics, and precision agriculture, where their biocompatibility and environmental safety are crucial. Future development should focus on enhancing energy density, optimizing degradation timelines, and reducing costs to make these batteries more competitive with traditional options.

Single‐Crystalline LiMg Alloy Anode for Deep Cycling All Solid State Lithium Metal Batteries

AbstractAll solid state lithium metal batteries (ASSLMBs) with enhanced energy density has driven the exploration of Li‐alloy anodes such as Li‐Mg alloy owing to its solid‐solution structure and high theoretical specific capacity. But the Li atom diffusion limitation on Li‐Mg electrode surface further leads to sluggish atoms transport dynamics. Herein, single‐crystalline (110)‐oriented Li0.9Mg0.1 (denoted as LiMg(110)) anode is obtained by a tailored melt‐annealing procedure to tackle the above issues. Theoretical analyses and experimental results demonstrate that the crystallographic structural (110) orientation of LiMg anode can facilitate Li atom diffusion and guarantee the electrode stability during deep cycling. As a result, the LiMg(110) electrode exhibits longer cycle life with lower overpotential than polycrystalline LiMg at high current densities and areal capacities in symmetric cells. A critical current density (CCD) at the forefront of 2.5 mA cm−2 is achieved in Li3InCl6 (LIC) solid‐state system. The ASSLMB with high areal capacity (3.8 mAh cm−2), high current density (0.76 mA cm−2), and low negative/positive capacity N/P ratio (2.14) achieves exceptional cyclability over 160 cycles. The outcomes highlight a promising crystallographic regulation strategy toward practical applications of high‐performance lithium metal batteries.

Separator‐Supported Electrode Configuration for Ultra‐High Energy Density Lithium Secondary Battery

AbstractSignificant efforts are being made to develop high‐performance battery materials, particularly active materials. However, material‐dependent strategies for increasing energy density face challenges such as raw material costs and supply limitations, reducing their versatility to some extent. In this regard, the development of efficient battery designs can be a universal approach to increasing the energy density of lithium‐ion batteries with relatively low dependence on material properties. Herein, a novel configuration of an electrode‐separator assembly is presented, where the electrode layer is directly coated on the separator, to realize lightweight lithium‐ion batteries by removing heavy current collectors. Even on the hydrophobic separator, a poly(vinyl alcohol) binder enables uniform and scalable coating of aqueous electrode slurries through molecular interactions with the separator surface. Moreover, carbon nanotubes are utilized to reinforce the electronic conduction of the electrode, providing consistent electronic pathways regardless of SEI formation. Furthermore, owing to the superior permeability of liquid electrolytes through this electrode‐separator assembly, a multilayered electrode‐separator assembly can be suggested to further increase energy density when combined with a lithium metal anode. This lithium metal battery can achieve an areal capacity of ≈30 mAh cm−2 and an enhanced energy density of over 20% compared to conventional battery configurations.

Enhanced storage performance of a low-cost hard carbon derived from biomass

Hard Carbon is the most widely used negative electrode material for sodium-ion batteries today. Achieving high storage capacity and increasing the plateau capacity, as opposed to the sloping profile, are crucial for enhancing energy density of the full cells. While several publications address the synthesis of hard carbon, the economic viability for commercial scale-up hinges on the choice of precursors. In this study, we report the electrochemical properties of hard carbon derived from two biomass precursors, sugarcane waste (bagasse) and corn waste, and compare their performances with commercially available hard carbon. The hard carbon derived from bagasse delivers a capacity of 307 mAh/g at C/10 rate and retains approximately 234 mAh/g at 3C discharge rate. We integrate surface area, pore size distribution, Raman spectroscopy, small-angle X-ray and neutron scattering data to elucidate the sodium storage mechanism in these hard carbon samples. Correlated graphitic domains with hexagonal ordering along with fractal like agglomeration of the nanosheets are quantified. The high plateau capacity of the bagasse-derived hard carbon is attributed to the characteristic morphology and size distribution of the nanosheets and their nature of agglomeration.

Electrolyte‐free solid‐state batteries demonstrated with bifunctional Li2VCl4

All‐solid‐state batteries have attracted much attention because of the expected high energy density and inherent safety stemming from their nonflammable property. While improving the energy density of the cathode poses a significant challenge, here we introduce a novel battery design strategy to enhance energy density by employing bifunctional cathode material, allowing the weight ratio of the active material to be increased without using an electrolyte for the cathode. By employing lithium‐containing vanadium halide Li2VCl4, serving as both active material and electrolyte, the all‐solid‐state battery cell with no electrolyte for the cathode with a capacity approaching the theoretical limit is demonstrated. In addition, we present a guideline for improving capacity retention from the perspective of interfacial stability. Notably, thermodynamic analysis revealed interfacial instability between Li2VCl4 and sulfide material. A double‐layer separator, incorporating halide materials for the cathode side, was implemented to enhance the interfacial stability and mitigate the capacity degradation. Furthermore, it was found that the rate capability depends on the lithium content in synthesized Li2‐xVCl4 and does not change with the state of charge significantly. This study will contribute to designing the bifunctional cathode material for an all‐solid‐state battery and describe its unique properties.

Crucial role of polymeric binders in enhancing energy density of supercapacitors

Crucial role of polymeric binders in enhancing energy density of supercapacitors

A bottom-up framework to investigate environmental and techno-economic aspects of lithium-ion batteries: A case study of conventional vs. pre-lithiated lithium-ion battery cells

As per-lithiation emerges as a promising technology for the next generation of lithium-ion battery cells, aimed at enhancing energy density and cycle life, it is crucial to evaluate its technological, production cost, and environmental impacts on an industrial scale. In this study, we developed a cradle-to-gate process-based model framework using LiNi0.8Mn0.1Co0.1O2 (NMC811)/Graphite as a reference cell to propose industrial-scale roll-to-roll direct contact pre-lithiation method for NMC811/Prelithiated-Graphite (prGr) and NMC811/Prelithiated-Graphite-Silicon (prGrSi) cells. Our findings indicate that pre-lithiated cells exhibit a gravimetric energy density increase of approximately 11%–27% compared to the baseline of 288 Wh.kg−1. This improvement could offset or even reduce the environmental impacts associated with the additional lithium foil component inserted into the cell during production. Economically, our analysis underscores the significant influence of lithium foil unit price, which is a critical factor in the overall cost of this technology, and a stable material market is crucial for its success. Overall, the investigation into environmental and economic aspects suggests that the prospects for industrialization and adoption are more promising than challenging in the near term.

Enhanced Energy Density and Charge–Discharge Efficiency of the Bilayer Film over a Broad Temperature Range

Enhanced Energy Density and Charge–Discharge Efficiency of the Bilayer Film over a Broad Temperature Range

Selective Methylation of Cyclic Ether Towards Highly Elastic Solid Electrolyte Interphase for Silicon-based Anodes.

Silicon (Si)-based anodes offer high theoretical capacity for lithium-ion batteries but suffer from severe volume changes and continuous solid electrolyte interphase (SEI) degradation. Here, we address these challenges by selective methylation of 1,3-dioxolane (DOL), thus shifting the unstable bulk polymerization to controlled interfacial reactions and resulting in a highly elastic SEI. Comparative studies of 2-methyl-1,3-dioxolane (2MDOL) and 4-methyl-1,3-dioxolane (4MDOL) reveal that 4MDOL, with its larger ring strain and more stable radical intermediates due to hyperconjugation effect, promotes the formation of high-molecular-weight polymeric species at the electrode-electrolyte interface. This elastic, polymer-rich SEI effectively accommodates volume changes of Si and inhibits continuous side reactions. Our designed electrolyte enables Si-based anode to achieve 85.4% capacity retention after 400 cycles at 0.5 C without additives, significantly outperforming conventional carbonate-based electrolytes. Full cells also demonstrate stable long-term cycling. This work provides new insights into molecular-level electrolyte design for high-performance Si anodes, offering a promising pathway toward next-generation lithium-ion batteries with enhanced energy density and longevity.

Selective Methylation of Cyclic Ether Towards Highly Elastic Solid Electrolyte Interphase for Silicon‐based Anodes

Silicon (Si)‐based anodes offer high theoretical capacity for lithium‐ion batteries but suffer from severe volume changes and continuous solid electrolyte interphase (SEI) degradation. Here, we address these challenges by selective methylation of 1,3‐dioxolane (DOL), thus shifting the unstable bulk polymerization to controlled interfacial reactions and resulting in a highly elastic SEI. Comparative studies of 2‐methyl‐1,3‐dioxolane (2MDOL) and 4‐methyl‐1,3‐dioxolane (4MDOL) reveal that 4MDOL, with its larger ring strain and more stable radical intermediates due to hyperconjugation effect, promotes the formation of high‐molecular‐weight polymeric species at the electrode‐electrolyte interface. This elastic, polymer‐rich SEI effectively accommodates volume changes of Si and inhibits continuous side reactions. Our designed electrolyte enables Si‐based anode to achieve 85.4% capacity retention after 400 cycles at 0.5 C without additives, significantly outperforming conventional carbonate‐based electrolytes. Full cells also demonstrate stable long‐term cycling. This work provides new insights into molecular‐level electrolyte design for high‐performance Si anodes, offering a promising pathway toward next‐generation lithium‐ion batteries with enhanced energy density and longevity.

Bulk/Interfacial Structure Design of Li-Rich Mn-Based Cathodes for All-Solid-State Lithium Batteries.

Li-rich Mn-based cathode materials (LRMO) are promising for enhancing energy density of all-solid-state batteries (ASSBs). Nonetheless, the development of efficient Li+/e- pathways is hindered by the poor electrical conductivity of LRMO cathodes and their incompatible interfaces with solid electrolytes (SEs). Herein, we propose a strategy of in-situ bulk/interfacial structure design to construct fast and stable Li+/e- pathways by introducing Li2WO4, which reduces the energy barrier for Li+ migration and enhances the stability of the surface oxygen structure. The reversibility of oxygen redox was improved, and the voltage decay of the LRMO cathode was addressed significantly. As a result, the bulk structure of the LRMO cathodes and the high-voltage solid-solid interfacial stability are improved. Therefore, the ASSBs achieve a high areal capacity (∼3.15 mAh/cm2) and outstanding cycle stability of ≥1200 cycles with 84.1% capacity retention at 1 C at 25 °C. This study offers new insights into LRMO cathode design strategies for ASSBs, focusing on ultrastable high-voltage interfaces and high-loading composite electrodes.

Copper-Based Para-Phthalic Acid Metal-Organic Framework: An Efficient Anodic material for Super-capattery Hybrid Systems

The battery-supercapacitor hybrid, an asymmetric energy storage system, has garnered considerable attention due to its outstanding energy storage capabilities. Anodic materials have become a central focus, driven by the quest for enhanced energy density, power density, cycle life, and overall performance. In this study, we have synthesized copper-based para-phthalic acid (PTA) metal-organic frameworks (MOFs) via a facile hydrothermal method to be employed as the positive electrode material in a battery-supercapacitor hybrid matrix. The initial testing indicates the battery-type nature of the prepared electrode along with maximum specific capacity of 260.5 C g-1 at 0.7 A g-1. Subjection of Cu-PTA MOF electrode to real device configuration (Super-capattery device) results in considerable specific capacity of 152.2 C g-1 along with specific energy and power of 35.9 Wh kg-1 and 5950 W kg-1, respectively at 0.3 A g-1. The device also demonstrated a stability potential of 92.15% when tested for 5000 continuous charge-discharge cycles. The present study presents Cu-PTA MOF an exciting addition for advancing current state of research in the field of energy storage technology.

Spray combustion characteristics of boron slurry fuel in high particle loading conditions

Enhancing the energy density of hydrocarbon fuels is indeed crucial, especially in the context of addressing energy needs. Incorporating energetic particles as additives into conventional liquid fuels garners increased attention due to its potential to enhance energy density. Due to its high energy potential, boron is the most promising additive in several energetic particles. However, the study focusing on the boron-loaded slurry fuels are limited. Therefore, the present work focuses on the effect of boron loading on the spray combustion of boron-loaded slurry fuel, especially at higher loadings (10%, 20% & 30% boron + Jet A-1 fuel) using a swirl-stabilized spray combustor. The research scrutinizes the feed and exhaust particles' surface morphology, chemical composition and active boron content through diverse particle characterization techniques. Furthermore, the study investigates the influence of boron loading on the combustion characteristics of slurry fuel using methods such as colour flame imaging, spectroscopy, and BO2* Chemiluminescence imaging. The impact of boron loading on the positive thermal contribution of the slurry was examined by analyzing temperature measurements at various locations within the combustor. The BO2* chemiluminescence imaging and spectroscopy results indicate that the intensity of BO2 emission increases with a rise in particle loading. The temperature results reveal an increase in temperature compared to pure Jet A-1 for all the boron-loaded cases. In particular, JB10 and JB20 achieved nearly 90% and 85% of the theoretical temperature increase. The diffractogram and thermogravimetric results of the burnt particles collected show that the particles were burnt thoroughly for the boron-loaded cases.

Introducing phosphoric acid to fluorinated polyimide towards high performance laser induced graphene electrodes for high energy micro-supercapacitors

Micro-supercapacitors (MSCs) have wide application prospects in microelectronic fields such as wearable electronics due to merits of stable performance, high safety and easy integration. However, the relatively low energy density of MSCs limits their practical application. In this context, phosphorus and fluorine co-doped laser-induced graphene (FP-LIG) microelectrodes were fabricated from fluorinated polyimide containing phosphoric acid by laser direct writing (LDW) method. The introduced phosphoric acid slows down the decomposition of –CF3 during the LDW process, resulting in much more ordered and stable pores; meanwhile, phosphorus entered the graphene lattice to replace some carbon atoms, forming a C3PO structure, which not only stabilizes the interface between the electrode and the electrolyte and therefore achieves an enlarged working potential of 1.4 V, but also increases the wettability of the electrode. Using FP-3-LIG microelectrodes and PVA/H2SO4 as the gel electrolyte, the assembled FP-3-MSC demonstrates significantly enhanced energy density, delivering an energy density of 10.40 μWh cm−2 (@0.09 mA cm−2), 2.7 times that of F-MSC and 346.7 times that of MSC. FP-3-MSC has excellent cyclic stability, displaying an areal capacitance retention rate of above 90 % after 10,000 long cycles. In addition, FP-3-MSC demonstrates excellent flexibility, indicating promising potential in the field of flexible wearable electronics.