Output Energy Density Research Articles

Importance of Nuclear Energy to Accomplish Net Zero Carbon

The world is entangled with the urgent need for existing energy modes transition to clean energy for mitigating global warming and climate change. It ultimately demands to set stringent goals for achieving net zero carbon for each country. In this direction different approaches are being stipulated and one of the important options emerges as nuclear power, a compelling option for sustainable development. Unlike renewable energy sources such as solar, wind and nuclear energy which provides a continuous and reliable supply of electricity with minimal greenhouse gas emissions. On the other hand nuclear power plants operate with high capacity factor compared to variable renewable sources that depend on weather conditions and its reliability makes nuclear energy a strong candidate for baseload power. Moreover, nuclear energy's low carbon footprint and high energy density output makes it an attractive alternative to fossil fuels. Although, it is crucial to acknowledge the challenges associated with nuclear energy, including the safe management of nuclear waste, the risk of nuclear accidents, and the high upfront costs of building nuclear power plants. Hence, a balanced perspective on the future of nuclear energy and its potential to contribute to a sustainable future is to be adopted carefully. However, a periodic advancements in technology and stringent safety measures, modern Nuclear reactors are designed to minimize environmental impact and enhance safety.

Enhancing electromechanical conversion and motion-monitoring application of pore-oriented cellulose nanocrystal/agarose aerogel modified with flexible heterojunction structures

Oriented-porous cellulose nanocrystal (CNC)-based aerogels excel in directional energy conversion but face reduced toughness, and triboelectric performance bottlenecks owing to the absence of electron acceptors. In this work, we crosslinked quaternary ammonium CNC with another flexible carboxymethyl agarose (AG-), via borate dynamic bonds, exploiting the electron-accepting traits of boron and electrophilic modifications to boost the mechanical and triboelectric performance of aerogels. These results demonstrate that the compressive resilience and modulus of CNC/AG aerogel are improved up to 70.79 % (after 10-cycle 20 % strain) and 18.77 kPa attributing to the borate cross-linking network and oriented structure. Furthermore, the electromechanical response sensitivity and output energy density of the CNC/AG aerogel increased by 6.06 times (to 7.51 V/Hz) and 28.3 times (to 1.87 W/m2), respectively. The structure characteristics of the CNC/AG aerogel reveal that the oriented structure and heterojunction of the CNC/AG aerogel with electron transfer pathways reduce dielectric losses. The COMSOL simulation also show that oriented pores increase the polarization and charge density of the CNC/AG aerogel, thereby improving the electromechanical conversion efficiency. This work offers a synergistic approach for toughening aerogels and generating heterojunctions via flexible modification, presenting significant potential for smart devices with energy-collection ability.

Near-surface reconstruction strategy stabilizing high-voltage redox reactions in single crystal Li-rich Mn-based oxides

Li-rich Mn-based oxides (LRMO) greatly increase its output energy density due to its additional oxygen redox activity. However, the inherent oxygen loss and irreversible phase transition induce low initial coulombic efficiency and serious voltage decay, further seriously impeding its industrial application. Herein, a near-surface in-situ reconstruction strategy has been proposed, which constructs the oxygen vacancies and spinel phase coating on the surface of single-crystal Li-rich Mn-based oxide (SC-LRMO) concurrently to improve Li+ storage performance via the oxalic acid induction method. Intensive exploration based on structure characterizations demonstrates that such a near-surface in-situ reconstruction strategy not only accelerates the transmission of Li+, but also stabilizes high-voltage redox reactions by trapping the escaping On− within the newly formed spinel phase coating. Impressively, the modified sample exhibit 91.1% capacity retention ratio after 300 cycles, superior to the SC-LRMO (74.5% capacity retention ratio after 300 cycles). Additionally, even at a high cut-off voltage of 5 V, the acid etched sample exhibits significantly enhanced cycling stability, delivering 200 mAh g−1 with a 94% capacity retention ratio after 300 cycles. This surface self-reconstruction strategy provides profound insights into regulating the surface structure of LRMO for high-energy-density lithium-ion batteries.

Multilayer Electrode Strategy Shorten Thermal Charging Time and Boost Energy Output in Gelatin‐Based i‐TE Cells

AbstractGel‐based ionic thermoelectric (i‐TE) cells provide alternative thermal energy harvesting from the environment, showing obvious advantages in voltage matching for self‐powered Internet‐of‐Things (IoT) sensors. However, the gel‐based i‐TE cells always suffer a long thermal charging time and poor output power performance. Herein, a multilayer electrode engineering strategy is proposed from the device‐design level, aiming to decrease the ions' diffusion distance, increase the electrode surface area, and facilitate the ions' reaction and recovery process. The thermal charging time is shortened from 27 to 8 min as the electrode layers increase from 2 to 8. An ultrahigh instantaneous power density of 15.8 mW m−2 K−2 and 2 h output energy density (E2h) of 403 J m−2 are achieved in an 8‐layer electrode i‐TE cell. Finally, A flexible and wearable i‐TE device with 20 units is demonstrated to generate a remarkable voltage of 3.8 V and output power of 282 µW by harvesting the human body heat. This work provides a feasible and effective route to design the i‐TE device, hopefully promoting its practical power generation application.

Precisely Tunable Instantaneous Carbon Rearrangement Enables Low-Working-Potential Hard Carbon Toward Sodium-Ion Batteries with Enhanced Energy Density.

As the preferred anode material for sodium-ion batteries, hard carbon (HC) confronts significant obstacles in providing a long and dominant low-voltage plateau to boost the output energy density of full batteries. The critical challenge lies in precisely enhancing the local graphitization degree to minimize Na+ ad-/chemisorption, while effectively controlling the growth of internal closed nanopores to maximize Na+ filling. Unfortunately, traditional high-temperature preparation methods struggle to achieve both objectives simultaneously. Herein, a transient sintering-involved kinetically-controlled synthesis strategy is proposed that enables the creation of metastable HCs with precisely tunable carbon phases and low discharge/charge voltage plateaus. By optimizing the temperature and width of thermal pulses, the high-throughput screened HCs are characterized by short-range ordered graphitic micro-domains that possess accurate crystallite width and height, as well as appropriately-sized closed nanopores. This advancement realizes HC anodes with significantly prolonged low-voltage plateaus below 0.1V, with the best sample exhibiting a high plateau capacity of up to 325mAhg-1. The energy density of the HC||Na3V2(PO4)3 full battery can therefore be increased by 20.7%. Machine learning study explicitly unveils the "carbon phase evolution-electrochemistry" relationship. This work promises disruptive changes to the synthesis, optimization, and commercialization of HC anodes for high-energy-density sodium-ion batteries.

Manipulating Interfacial Renovation via In Situ Formed Metal Fluoride Heterogeneous Protective Layer toward Exceptional Durable Sodium Metal Anodes

AbstractSodium metal is regarded as an optimal anode material for high‐energy‐density sodium‐ion batteries (SIBs). However, during the processes of sodium deposition and stripping, the failure of the solid electrolyte interphase (SEI) film leads to the continuous accumulation of inactive sodium, thereby compromising the cycling reversibility of the battery. Here, a novel metal fluoride heterointerface layer is generated and constructed through in situ manipulation of the continuous reaction between TiF4 and metal Na. The reconstructed NaF/TiF3 interface layer, which tightly anchors the sodium metal, effectively suppresses the formation of sodium dendrites during the charge‐discharge process. The highly sodium‐philic TiF3 component exhibits strong binding with Na ions, while NaF reduces the Na+ diffusion energy barrier, significantly enhancing the reaction kinetics. Due to the successful artificial construction of this interface layer, the Na/TiF4 composite electrode demonstrates an exceptional ultra‐long cycling stability of 2370 h in symmetric cells (0.5 mAh cm−2). Density functional theory (DFT) calculations further validate the functionality of each component in the Na/TiF4 protective layer. When paired with NaNi1/3Fe1/3Mn1/3O2 cathode in a pouch cell, it exhibits stability up to 2000 cycles at current densities of 2 C and 4 C, with a maximum energy density output of 483.1 Wh kg−1 (power density: 320.8 W kg−1).

Improving the energy density and flexibility of PMN-0.3PT based piezoelectric generator by composite designing

Ceramics based piezoelectric generators are known for their high energy density and poor flexibility. In this work, 0.7Pb(Mg1/3Nb2/3O3)-0.3PbTiO3 (PMN-0.3PT) and polydimethylsiloxane (PDMS) based 2–2 composite with optimum PMN-0.3PT content (vr) was designed that demonstrated enhanced output energy density and superior mechanical flexibility under dynamic mechanical excitation. vr-PMN-0.3PT/PDMS 2–2 composite with different PMN-PT reinforcement content (vr) and two different reinforcement configurations were fabricated and characterized for effective electro-elastic properties and energy harvesting response. Parallelly, using the finite element method and analytical models, effective electromechanical properties were calculated. Composites with parallel connectivity of the reinforcement phase demonstrated enhanced piezoelectric charge coefficient (d33c) even with low PMN-0.3PT content whereas the relative permittivity (κ33c) and elastic modulus (E33c) exhibited a linearly increasing trend with reinforcement volume fraction. At a compressive load of 50 N and 5 Hz frequency, a piezoelectric generator (PG) based on a vr = 0.2, vr- PMN-0.3PT/PDMS 2–2 composite with parallel connectivity produced a maximum short-circuit current density of 69 nA/cm2 and an open-circuit electric field of 189 V/cm, translating to a maximum output power density of ∼13 μW/cm3 higher than that of pristine PMN-0.3 PT based piezoelectric generator. Estimated mechanical flexibility was found to be ∼53 % higher than that of pristine PMN-0.3PT.

Organic Anodes with Nearly 100% Initial Coulombic Efficiency Enabled by Wet‐Chemically Constructed Artificial Solid‐Electrolyte Interphase Film toward High‐Energy‐Density Organic Full Batteries

AbstractLithium‐ion batteries (LIBs) built on inorganic anodes have achieved great commercial success. By contrast, the practical application of organic anode materials encounters key bottlenecks including electronic insulation, high solubility, and poor initial coulombic efficiency (ICE). Among them, improving ICEs (normally 30–60%) faces enormous challenges in both theory and technology, and there has been no substantial breakthrough yet. Herein, a wet chemical pretreatment technology to increase the ICE of maleic acid (MA)‐based anodes from 43.2% to nearly 100% is proposed for the first time, and this strategy demonstrates universal applicability. Typically, the wet chemical pretreatment involves reacting with lithium‐biphenyl to form LixMA intermediates (x = 4–6) and further forming a compact artificial solid‐electrolyte interphase (SEI) film through the spontaneous reaction between active LixMA and battery organic electrolytes. This wet chemically‐constructed artificial SEI layer can almost completely suppress lithium loss in the initial cycle of the MA electrode and significantly boost the actual output energy density, rate capability, and cycling durability of MA anode‐based full batteries. Significantly, the study further demonstrated that a series of organic anode materials with high ICEs can be achieved through similar wet chemical pretreatment. This work will open up the true application of high‐ICE organic anodes in LIBs.

Performance improvement of Li-rich Mn-based materials with the submicron-sized single-crystal morphology and cationic doping

Lithium-rich manganese-based cathode materials (LRMCs) can be regarded as one of the most potential cathode materials for the next-generation high-energy Li-ion batteries due to the extra oxygen redox, which can greatly increase the actual output energy density of LRMCs. Nevertheless, the structure degradation and inevitable loss of oxygen will be triggered by the irreversible oxygen redox, which will cause a significant decline in cyclic performance and limited initial Coulombic efficiency, thus restricting their industrial applicability. Herein, the LRMCs with the submicron-sized single-crystal morphology and sodium doping are prepared by molten salt treatment with NaCl. On one hand, the submicron-sized single-crystal cathode effectively reduces the diffusion path for Li+ due to the smaller particle dimensions. On the other hand, Na+ doping expands the Li slab spacing, promoting the transport of Li+. The results show that the as-prepared material can purposefully alleviate oxygen release, improve structure stability, and increase the Li+ diffusion rate for the pristine LRMCs. Moreover, the as-prepared material in this study exhibits a higher reversible capacity of 282.8 mAh g−1 at 0.1 C and displays good cyclic performance, retaining a capacity rate of 80.9% after 200 cycles at 1 C. Therefore, this study offers a potential exploration for designing LRMCs with high energy density and excellent cyclic performance, which are achieved through building submicron-sized single-crystal morphology and introducing cationic doping.

Elucidating the Energy Storage Performance of 2D Metallic Vanadium Ditelluride/Carbon Nanotube for Next‐Generation Asymmetric Supercapacitors Using Emerging MoSSe/Carbon Nanotube

Recently, vanadium ditelluride (VTe2) a member of the transition metal ditellurdies family has emerged as a functional material for energy storage applications owing to its exotic intrinsic properties. Similar to most of the nanostructured materials, a hybrid structure of VTe2 is expected to provide enhanced energy storage capability. Herein, two hybrid structures of VTe2 are engineered using well‐explored nanocarbons such as RGO and carbon nanotube (CNT) to create a compelling supercapacitor electrode material. Both the hybrid structures show improved electrochemical activity, but VTe2/CNT fared better in the charge storage efficiency. The enhanced active sites, short ionic/electronic pathways provided by the CNT network, and the large electric double‐layer contribution have synergized for the inflated capacitance of VTe2/CNT. Further, a high‐performance asymmetric supercapacitor (ASC) of VTe2/CNT//MoSSe/CNT is constructed in a typical Swagelok cell, and the ASC delivered an energy density output of 36.28 Wh kg−1 at a power density of 463.16 W kg−1 with a remarkable 80.26% capacitance retention. The results of this work suggest that VTe2/CNT is a promising contender in the pantheon of functional materials for energy storage applications in the near future.

Unraveling Flow Effect on Capacitive Energy Extraction from Salinity Gradients.

The harvesting of salinity gradient energy through a capacitive double-layer expansion (CDLE) technique is directly associated with ion adsorption and desorption in electrodes. Herein, we show that energy extraction can be modulated by regulating ion adsorption/desorption through water flow. The flow effects on the output energy, capacitance, and energy density under practical conditions are systematically investigated from a theoretical perspective, upon which the optimal operating condition is identified for energy extraction. We demonstrate that the net charge accumulation displays a negative correlation with the water flow velocity and so does the surface charge density, and this causes a nontrivial variation in the magnitude of output energy when water flows are introduced. When high water flows are introduced in both the charging and discharging processes, the energy extraction can be significantly reduced by 47.69-49.32%. However, when a high flow is solely exerted in the discharging process, the energy extraction can be enhanced by 12.94-14.49% even at low operation voltages. This study not only offers a comprehensive understanding of the microscopic mechanisms of surface-engineered energy extraction with water flows but also provides a novel direction for energy extraction enhancement.

Enabling Wasted A4 Papers as a Promising Carbon Source to Construct Partially Graphitic Hierarchical Porous Carbon for High-Performance Aqueous Zn-Ion Storage.

Considering the superiorities of abundance, easy collection, low cost, and nearly constant composition, the wasted A4 papers are deemed as a recyclable and scalable carbon source to fabricate functional carbon materials for Zn-ion hybrid supercapacitors (ZIHSCs), which integrate the supercapacitors' high-power output and batteries' high energy density. Herein, the wasted A4 papers are efficiently converted into an advanced carbon material owning a hierarchical porous structure with a high surface area and interconnected multiscale channels, a graphitic structure, and a good level of N/O codoping. By taking advantage of these features, an express electron/ion transfer pathway, a large accessible surface interface, and a robust architecture are achieved for swift kinetics, numerous active sites, and excellent steadiness to afford a charming Zn2+ storage capability for the aqueous coin-type ZIHSC device (a high capacity of 244 mAh g-1 at 0.1 A g-1 with a capacity conservation of 116.4 mAh g-1 even amplifying the current density by 200 times, a supreme energy density of 190.4 Wh kg-1, a supreme power output of 18 kW kg-1, and an eminent durability of 93.8% over 10,000 cycles at 10 A g-1). Excitingly, the quasi-solid ZIHSC device also bespeaks an enjoyable capacity of 211.7 mAh g-1, a high energy density of 159.3 Wh kg-1, good mechanical flexibility, and a low self-discharge rate. This work puts forward a simple and scalable strategy to enable the wasted A4 paper as a competitive carbon source to construct advanced cathode material for Zn2+ storage.

Zn-based batteries for sustainable energy storage: strategies and mechanisms.

Batteries play a pivotal role in various electrochemical energy storage systems, functioning as essential components to enhance energy utilization efficiency and expedite the realization of energy and environmental sustainability. Zn-based batteries have attracted increasing attention as a promising alternative to lithium-ion batteries owing to their cost effectiveness, enhanced intrinsic safety, and favorable electrochemical performance. In this context, substantial endeavors have been dedicated to crafting and advancing high-performance Zn-based batteries. However, some challenges, including limited discharging capacity, low operating voltage, low energy density, short cycle life, and complicated energy storage mechanism, need to be addressed in order to render large-scale practical applications. In this review, we comprehensively present recent advances in designing high-performance Zn-based batteries and in elucidating energy storage mechanisms. First, various redox mechanisms in Zn-based batteries are systematically summarized, including insertion-type, conversion-type, coordination-type, and catalysis-type mechanisms. Subsequently, the design strategies aiming at enhancing the electrochemical performance of Zn-based batteries are underscored, focusing on several aspects, including output voltage, capacity, energy density, and cycle life. Finally, challenges and future prospects of Zn-based batteries are discussed.

Boosting the maximized output energy density of triboelectric nanogenerators

A comprehensive strategy including charge excitation, interface insulation, and material screening was employed to achieve a record-high output energy density of 4.3 × 105 J m−3 for a triboelectric nanogenerator.

Ultrahigh output energy density of explosive-energy-conversion devices assembled from multilayer ferroelectric films

A multilayer PMN–PZT + 2Li film stack with a volume of 0.9 cm3 could generate a current of 3156 A, exceeding that of existing ferroelectric ceramics by 2 orders of magnitude.

Energy Density in Ionic Thermoelectric Generators by Prussian Blue Electrodes

Solid-state ionic thermoelectric generators have emerged as promising solutions for efficient harvesting of low-grade waste heat. However, the main challenge in achieving continuous power supply is the low efficiency of thermoelectric conversion. In this work, substantial achievements have been made in improving the thermoelectric conversion characteristics by introducing redox pairs on the electrode surfaces. This approach takes advantage of the synergistic effect of thermal diffusion and thermoelectric effects to maximize the conversion efficiency. To improve the thermoelectric storage and output power performance, Prussian blue was attached to a carbon woven fabric and used as an electrode. The incorporation of Prussian blue/carbon woven fabric electrodes results in an increase in current density output and an instantaneous power density of 3.7 mW/m 2 ·K 2 . Furthermore, under a temperature gradient of 10 K, the output energy density for 2 h is 194 J/m 2 , and the Carnot relative efficiency is as high as 0.12% at a hot side temperature ( T H ) of 30 °C and a cold side temperature ( T C ) of 20 °C. Our findings validate the efficacy of integrating thermal diffusion and redox reactions in ionic thermoelectric generators, paving the way for the progress of thermocharged devices and their potential commercial applications.

Sustainable conversion of agricultural biomass waste into electrode materials with enhanced energy density for aqueous zinc-ion hybrid capacitors

Herein, we demonstrate the facile, economic and highly scalable conversion of (N, O and Fe)-self-doped heteroatom Solanum melongena (SM) biomass into highly electro-active carbon material for symmetric supercapacitor and zinc-ion hybrid capacitor (ZIHC) applications. The SM is ubiquous agri-bio-waste that inherently possess electro-active constituents and upon conversion resulted in high surface area, self-doped heteroatoms (N, O and Fe) through one step pyrolysis. A synergetic combination of N, O and Fe co-doping and relatively high-surface-area features that offers widespread interfacial active sites for charge storage and fast kinetics of electrochemical reactions in both supercapacitor and battery-type capacitor to maximize energy and power output. The symmetric supercapacitor is fabricated using 6 M KOH, delivering high specific capacitance of 154.64 F/g at 0.1 A/g current density. Long cycling performance of device exhibits 99 % retention over 50,000 charge and discharge cycles at 10 A/g. While SM carbon as the cathode in zinc ion hybrid capacitor (ZIHC) endows excellent Zn2+ ion storage capacity with 2 M ZnSO4·7H2O as electrolyte. The ZIHC delivered an excellent specific capacitance of 313.08 F/g, a substantial energy density output of 141.35 W h/kg and a power density of 6935.38 W/kg. In addition, ZIHC exhibited better cyclic stability with 1.92 % loss over 20,000 charge and discharge cycles at 4 A/g. The ZIHC device delivered excellent output in wearable devices and in lightning the LED (25.04 min). This study provides ubiquitous agri-waste-derived carbon that can be outstanding electrode material in energy storage devices owing to their hierarchal pore configuration, graphitization degree and self-doping of heteroatoms.

Valence state of V combined with D-tartaric acid and heat treatment affect sodium storage performance of NASICON-type multiphase composite

The polyanionic compound Na3V2(PO4)3 (NVP) and Na3V2(PO4)2F3 (NVPF) are promising cathode materials for sodium-ion batteries, but their poor electronic conductivity affects the electrochemical performance and the output energy density. The easy interconversion between V4+ and V5+ in the solution appears due to the weak bonds of D-tartaric acid, which lowers the energy barrier for further transition to V3+ and results in an excess V3+ in the product. A small amount of NVPF/C is converted to NVP/C due to the volatility of fluorine after heat treatment. D-tartaric acid as a carbon source forms a 3D network structure after calcination, thresholds the growth of NVP or NVPF and hinders the volume expansion during sodium storage. The initial discharge specific capacity of NVPF/C-650 is 85 mAh g−1 at 5C, and remains 59.2 mAh g−1 after 1000 cycles, which is related to the low charge transfer resistance, rapid Na+ ion diffusion and the pseudocapacitance effect. The binding of V and the carbon source in the solution affects the content of V3+/V4+ content, and the annealing temperature affects the formation and composition of the conducting carbon, both of which influence the electrochemical performance. This result provides a concept for possible screening of the carbon source for sodium storage materials with excellent performance.

Thermoelectric coupling effect in BNT-BZT-xGaN pyroelectric ceramics for low-grade temperature-driven energy harvesting

Pyroelectric energy harvesting has received increasing attention due to its ability to convert low-grade waste heat into electricity. However, the low output energy density driven by low-grade temperature limits its practical applications. Here, we show a high-performance hybrid BNT-BZT-xGaN thermal energy harvesting system with environmentally friendly lead-free BNT-BZT pyroelectric matrix and high thermal conductivity GaN as dopant. The theoretical analysis of BNT-BZT and BNT-BZT-xGaN with x = 0.1 wt% suggests that the introduction of GaN facilitates the resonance vibration between Ga and Ti, O atoms, which not only contributes to the enhancement of the lattice heat conduction, but also improves the vibration of TiO6 octahedra, resulting in simultaneous improvement of thermal conductivity and pyroelectric coefficient. Therefore, a thermoelectric coupling enhanced energy harvesting density of 80 μJ cm−3 has been achieved in BNT-BZT-xGaN ceramics with x = 0.1 wt% driven by a temperature variation of 2 oC, at the optical load resistance of 600 MΩ.

Gigantic effect due to redox electrodes on thermoelectric properties of ionic thermoelectric devices

Breakthroughs in thermoelectric converters based on ionic conductive materials have opened up new possibilities in low-grade waste heat harvesting and wearable electronic applications. In order to increase energy output of thermoelectric devices, electrodes with higher specific capacitance are required to increase the energy density and power density of thermoelectric devices. In this work, Prussian blue graphite (PB-G) electrode sheets are prepared by electrodepositing Prussian blue onto graphite electrodes to obtain highly efficient flexible electrode materials for thermoelectric devices. The PB-G electrode was assembled with ion-conductive hydrogel to form a thermoelectric device. The specific capacitance of the PB-G electrode calculated by a galvanostatic charge-discharge was 1254.6 F·m−2, which was 710.3 F·m−2 higher than that of the graphite electrode (544.3 F·m−2). A significant enhancement was made in the instantaneous power density (∆T=30 K, 1145.45 mW·m−2) of the PB-G based thermoelectric devices by 14.71 times and a high output energy density foy 1.5 h (23.12 J·m−2) by 53 times than graphite electrode based thermoelectric devices. This work presents a new solution for increasing the output power of thermoelectric devices which could lead to a new vista for the application of low thermal energy acquisition in tunable ion thermoelectric (i-TE) devices.