Weight Of Active Materials Research Articles

Current dependence of output voltage and discharge capacity of a tertiary battery

Tertiary batteries (TBs), which can be charged by a temperature change (ΔT), are prospective energy-harvesting devices. In this work, we investigated the variations in the output voltage (VTB) and discharge capacity (QTB) with current (I) of NaxCo[Fe(CN)6]0.87/NaxNi[Fe(CN)6]0.94 TBs (ΔT of 30 K) per unit weight of total active materials at 45 °C. Reflecting the battery resistance R, VTB(I) decreases with increasing I as VTBIRI=VTB0−MRI, where M is the total weight of the active material. We found that QTB(I) had values that were slightly smaller than those obtained by incorporating only the voltage-drop effect, QTBIRI=QTB(0)×VTBIR(I)VTB(0). The deviation between the observed QTB(I) and QTBIR(I) can be accurately explained in terms of the I-induced deformation of the discharge curve.

Exploring Carbonization Temperature to Create Closed Pores for Hard Carbon as High-Performance Sodium-Ion Battery Anodes.

Biomass-derived porous carbon materials are meaningful to employ as a hard carbon precursor for anode materials of sodium-ion batteries (SIBs) from a sustainability perspective. Here, a straightforward approach is proposed to develop rich closed pores in pinenut-derived carbon, with the aim of improving Na+ plateau storage by adjusting the pyrolysis temperature. The optimized sample, namely the pinenut-derived carbon at 1300 °C, demonstrates remarkable reversible specific capacity of 278 mAh g-1, along with a high initial Coulomb efficiency of 85% and robust cycling stability (with a capacity retention of 89% after 800 cycles at 0.2 A g-1). In situ and ex situ analyses unveil that the developed closed pores play a significant role in enhancing the plateau capacity, providing compelling evidence for the "adsorption-filling" mechanism. Moreover, the corresponding full-cell achieves a high energy density of 245.7Wh kg-1 (based on the total weight of both electrode active materials) and exhibits outstanding rate capability (191.4 mAh g-1 at 3 A g-1).

Design Improvement of Permanent Magnet Motor Using Single- and Multi-Objective Approaches

Abstract Optimisation, or optimal design, has become a fundamental aspect of engineering across various domains, including power devices, power systems, and industrial systems. Engineers and academics have been actively involved in optimising these systems to achieve better performance, efficiency, and cost-effectiveness. Optimising electrical machines, including permanent magnet motors, is a complex task. It often involves solving intricate problems with various parameters and constraints. Engineers use different optimisation methods to tackle these challenges. Depending on the specific requirements and goals of a design project, engineers may employ either single-objective or multi-objective optimisation approaches. Single-objective optimisation focuses on optimising a single objective, while multi-objective optimisation considers multiple conflicting objectives. In optimisation, objective functions are mathematical representations of what needs to be optimised. In this case, optimising the efficiency of the motor, reducing cogging torque, and minimising the total weight of active materials are defined as possible objective functions. Genetic algorithms are nature based algorithms that are commonly used in engineering to find optimal solutions to complex problems, including those with multiple objectives. In this paper, after conducting optimisations using different objective functions and methods, a comparative analysis of the results is performed. This helps in understanding the trade-offs and benefits of different design choices. Finite element analysis (FEA) is a computational method used to analyse the physical properties and behaviours of complex structures and systems. In this case, FEA is used to validate and analyse selected optimisation solutions to ensure they meet the desired characteristics and parameters. Overall, this work demonstrates the interdisciplinary nature of engineering, where mathematics, computer science (for optimisation algorithms), and physics (for FEA) converge to improve the performance and efficiency of electrical machines. It also underscores the importance of considering multiple objectives in design processes to find optimal solutions that strike a balance between competing goals.

Investigating the Superior Performance of Hard Carbon Anodes in Sodium-Ion Compared With Lithium- and Potassium-Ion Batteries.

Emerging sodium-ion batteries (NIBs) and potassium-ion batteries (KIBs) show promise in complementing lithium-ion battery (LIB) technology and diversifying the battery market. Hard carbon is a potential anode candidate for LIBs, NIBs, and KIBs due to its high capacity, sustainability, wide availability, and stable physicochemical properties. Herein, a series of hard carbons is synthesized by hydrothermal carbonization and subsequent pyrolysis at different temperatures to finely tune their structural properties. When tested as anodes, the hard carbons exhibit differing ion-storage trends for Li, Na, and K, with NIBs achieving the highest reversible capacity. Extensive materials and electrochemical characterizations are carried out to study the correlation of structural features with electrochemical performance and to explain the specific mechanisms of alkali-ion storage in hard carbons. In addition, the best-performing hard carbon is tested against a sodium cathode Na3 V2 (PO4 )3 in a Na-ion pouch cell, displaying a high power density of 2172W kg-1 at an energy density of 181.5Wh kg-1 (based on the total weight of active materials in both anode and cathode). The Na-ion pouch cell also shows stable ultralong-term cycling (9000 h or 5142 cycles) and demonstrates the promising potential of such materials as sustainable, scalable anodes for beyond Li-batteries.

NaFe0.5Mn0.5PO4–Ge electrochemical system for sodium-ion batteries

A new electrochemical system for sodium-ion batteries, sodium iron-manganese phosphate–germanium nanowires, has been developed and tested. The laboratory batteries possessed an average discharge voltage of ∼2.0 V and an energy density based on the weight of active materials to 210 Wh kg–1.

Scalable synthesized high-performance TiO2-Si-C hybrid anode for lithium batteries

At present, developing a simple strategy to effectively solve the shackles of volume expansion, poor conductivity and interface compatibility faced by Si-C anode in lithium batteries (LIBs) is the key to its commercialization. Here, low-cost nano-Si powders were prepared from Si-waste of solar-cells by sanding treatment, which can effectively reduce the commercialization cost for Si-C anode. Furthermore, micro-nano structured Gr@Si/C/TiO2 anode materials with graphite (Gr) as the inner core, TiO2-doped and carbon-coated Si as the outer coating-layer, were synthesized at kilogram-scale per milling batch. Comprehensive characterization results indicate that TiO2-doped carbon layer can improve the interface compatibility with the electrolyte, further promote the reduction of electrode polarization, and finally enhance the battery performance for the Gr@Si/C/TiO2 anodes. Accordingly, Gr@Si/C/TiO2 composites can output excellent LIB performance, especially with high initial coulombic efficiency (ICE) of 82.51% and large average reversible capacity of ∼ 810 mA h g−1 at 0.8 A g−1 after 1000 cycles. Moreover, Gr@Si/C/TiO2||NCM811 pouch full cells deliver impressive performance especially with high energy density of ∼ 489.3 W h kg−1 based on the total weight of active materials, suggesting its promising application in the high performance LIBs.

(Keynote, Digital Presentation) Prussian Blue Analogues as Electrode Material of Batteries

Prussian blue analogues (PBA), which composed of cyano-bridged jungle-gym type framework and alkali metal ions, are promising material for electrode of batteries, because its framework is robust against electrochemical intercalation/deintercalation of alkali metal ions. In addition, the material consists of ubiquitous elements and is easily synthesized from aqueous solution. Thus, PBAs are promising electrode material for sodium ion secondary battery (SIB). We will introduce the overall features of PBAs as SIB electrode. Furthermore, PBAs are promising material for energy harvesting. We proposed a new type of battery (tertiary battery) that can be charged by the environmental heat using the difference in the thermal coefficient (α= dV/dT) of the redox potential (V) between the anode (αanode) and cathode (αcathode) materials. The tertiary battery can convert the environmental heat energy into electric energy during the thermal cycle, i.e., (i) heating to TH, (ii) discharge at TH, (iii) cooling to TL, and (iv) discharge at TL. In the (i) heating process, the V values of the anode and cathode change by αanodeΔTand αcathodeΔT, respectively. We expect a thermally induced change in the cell voltage (V cell) as large as (αcathode - αanode)ΔT. The stored electric energy can be extracted by the (ii) discharge process at TH. We fabricated several tertiary batteries made of PBA electrodes with different a and evaluated the thermal voltage (Vcell) and discharge capacity (Qcell). For example, NaxCo[Fe(CN)6]0.87/NaxNi[Fe(CN)6]0.94 tertiary battery exhibits Vcell = 24 mV and Qcell = 2.4 mAh/g per unit weight of total active material contains in the cathode and anode. We will correlate the observed Qcell values with the electrode parameters of the tertiary batteries. Y. Shimaura, T. Shibata, and Y. Moritomo, "Interrelation between discharge capacity and charge coefficient of redox potential in tertiary batteries made of transition metal hexacyanoferrate", Jpn. J. Appl. Phys. 61, 044004 (2022)I. Nagai, Y. Shimaura, T. Shibata, and Y. Moritomo, "Performance of tertiary battery made of Prussian blue analogues", Appl, Phys. Express. 14, 094004 (2021).Y. Moritomo, Y. Yoshida, D. Inoue, H. Iwaizumi, S. Kobayashi, S. Kawaguchi, and T. Shibata "Origin of the material dependence of the temperature coefficient of the redox potential in coordination polymers", J. Phys. Soc. Jpn. 90, 063801 (2021).T. Shibata, H. Iwaizumi, Y. Fukuzumi, and Y. Moritomo, "Energy harvesting thermocell with use of phase transition” Sci. Res., 10 1813 (2020)I. Takahara, T. Shibata, Y. Fukuzumi, and Y. Moritomo, " Improved thermal cyclability of tertiary battery made of Prussian blue analogues ", Chem. Select 4, 8558-8563 (2019)Y. Fukuzumi, K. Amaha, W. Kobayashi, H. Niwa, and Y. Moritomo, “Prussian blue analogues as promising thermal power generation materials”, Energy Technology, 6 (2018) 1 – 7.T. Shibata, Y. Fukuzumi, W. Kobayashi, and Y. Moritomo, “Thermal efficiency of a thermocell made of Prussian blue analogues”, Sci. Reps. Appl. Phys. Express. 8 (2018) 14784.T. Shibata, Y. Fukuzumi, W. Kobayashi, and Y. Moritomo, Thermal power generation during heat cycle near room temperature, Appl. Phys. Express. 11, 018101 (2018).M. Takachi, T. Matsuda, and Y. Moritomo, “Cobalt hexacyanoferrate as cathode material of Na+ secondary battery”, Appl. Phys. Express 6, 025802 (2013).M. Takachi, T. Matsuda, and Y. Moritomo, “Redox reaction in Prussian blue analogues with fast Na+ intercalation”, Jpn. J. Appl. Phys. 52, 092202 (2013).

Modelling and Validation of High-Energy Density 30µm Thin-Film Solid-State LiCoO2 Cell: 1D Cahn-Hilliard Phase Separation Model

LiCoO2 (LCO) dominates the industry of high energy density Li-batteries cathodes, with almost 20% of market share. Since its introduction in 1980, scientific community produced a rich literature; in particular, several studies suggest maximizing the loaded weight of active material as an interesting route for energy density increase: over the whole weight of the cell, the impact of electrolyte, current collectors, and anode decreases, determining an increase in volumetric and gravimetric energy density. Notwithstanding, unclear correlation between electrode thickness and delivered capacity, altogether with an extremely short cycle-life and poor rate-capability, reported for cathode thicker than 10µm [1], are now halting the development of cells with thick electrodes for both solid-state deposited (PVD, pulse laser, electroplating) and tape-casted cathode.We focused our work on unveiling the causal link between thickness and available capacity in LCO cathode, providing a simple formula to relate the latter with cathode dimension, discharge current, and temperature. We propose solid-state thin-film configuration in a lithium-free battery as a test vehicle to study pure LCO cathode. This configuration introduces no additional dynamic limitation like grain-to-grain diffusion.We exploited both model and experimental results to delve into the understanding of interfacial lithium accumulation during discharge and we linked the related capacity loss to phase separation occurring around 75% of intercalated lithium [2-3]. In order to interpret both dynamic and static results we have implemented a 1D model based on Cahn-Hilliard equation [4] and solved it using COMSOL. We will provide results to foster a division of LCO cathode into two domain: from 50% to 75% of lithium intercalation, a high-rate zone, which capacity can be delivered at high C-rate without any limitation for any considered LCO thickness; from 75% to 100%, a low-rate zone, which can provide capacity only at very low C-rate.We validated the model realizing 5, 10, 20 and 30µm thick LCO cathode in a thin-film all-solid-state configuration, with LIPON as solid electrolyte, tested for discharge current density from 0.2 to 2 mAcm-2. We also present the 30µm thick LCO cathode with the highest capacity reported for thin-film configuration so far (>1mAhcm-2) and provide strong evidences of linear correlation between delivered capacity and cathode thickness. The results obtained for all-solid-state thin-film cells, can be extended to all LCO cathode, whatever the deposition technique used, as long as the particle size is the same order of the present work and the main limiting factor from the dynamic point of view is the solid diffusion in the cathode.

Multifunctional Conformal Polymer Coating by Oxidative Chemical Vapor Deposition for High Specific Energy Ni-Rich Cathode

The successful commercialization of lithium-ion batteries (LIBs) leads to wide utilization in portable electronic devices such as cellphones and laptops because of their excellent cycle performance and moderate rate capability [1]. Technical challenges still remain to enhance specific energy of LIBs to be implemented in large-scale devices including hybrid electric vehicles (HEVs) and electric vehicles (EVs) [2]. Adopting high specific capacity electrode materials and decreasing the weight ratio of non-capacity materials in batteries are considered as two main methods for improving the overall specific energy for LIBs.Ni-rich layer oxides as one of the mainstream cathode materials have drawn much attention due to their high theoretical specific capacity. However, the surface and bulk degradation of Ni-rich materials during circulation may trigger capacity loss and generate serious safety issues, which limits its application in LIBs [3]. Coating inert inorganic compounds has been suggested to enhance the stability of Ni-rich materials. However, it is also reported that the coating layer was delaminated from the cathode bulk particles due to the anisotropic volume change during lithiation and delithiation as well as the stiff nature of inorganic coating materials [4].On the other hand, reducing non-capacity materials such as conductive carbon led to the lower electronic conductivity, which may cause polarization and increase the resistance of the battery. Meanwhile, a traditional binder is electronically insulating, limiting electron transportation. In addition, less binder in electrodes could result in separation of the active materials from the electrode, causing battery capacity loss [5].In order to accommodate the volume variation during circulation, polymers with resilience possibly protect the Ni-rich particles during cycle life. Further, binders and conductive carbonaceous are preferred to construct conductive networks for electrodes for enhancing the overall conductivity of the battery. As thus the polymer with electronic conductivity is supposed to be uniformly coated on Ni-rich particles and sufficiently distributed in the electrode.Poly(3,4-ethylenedioxythiophene) (PEDOT) is a promising polymer due to its high electrical conductivity and the demonstrated protection ability for Ni-rich materials in LIBs [6]. Meanwhile, as an emerging technique, oxidative chemical vapor deposition (oCVD) is a deposition process that generates uniform and conformal polymers via gas phase reaction with a vaporized source monomer (in this case EDOT) and an oxidizer (in this case FeCl3). PEDOT deposited on the electrode through the oCVD method is homogeneous on the surface of Ni-rich particles. And the high electronic conductivity of the polymer would enhance the battery performance as well as the adhesive ability of the polymer own.In this study, Ni-rich cathode with 99% active materials weight ratio was prepared from as-synthesized LiNi0.8Co0.1Mn0.1O2 (NCM811) particles and oxidative chemical vapor deposition method was employed to generate a controllable PEDOT layer with 55 nm thickness. Moreover, the PEDOT layer was found between the secondary particles, indicating excellent conformal coating capability of the oCVD technique. Further characterization X-ray photoelectron spectroscopy (XPS) and Density functional theory calculation (DFT) revealed that sulfide in PEDOT is preferentially bonded with transition metal (Ni, Co and Mn) in NCM811, which prolonged the service life of the PEDOT layer. Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) and XPS was employed which unveiled the formed PEDOT layer restricted the parasite reaction during the charge/discharge process and diminished the transition metal dissolving, and endowed the battery with improved stability (81.6% after 300 cycles under 1C, 1C = 200 mA g-1) Cyclic voltammetry (CV) showed less difference value for modification sample (△E=0.14 V) compared with pristine sample (△E=0.25 V). Furthermore, the battery even showed 171.5 mAh g-1 under 7C and high reversibility after a high rate, which provides a potential for the fast-charge. The trifunctional PEDOT layer is verified to serve as the protection layer, binder and electronic conductivity network for the cathode materials. The results of this study demonstrate significant promises of employing the high active material weight ratio with high cycle life and a pathway for various kinds of cathode materials for reaching higher specific energy as well.Reference:[1]. Goodenough, J. B.; Park, K. S., J Am Chem Soc 2013, 135 (4), 1167-76.[2]. Lee, W.; Yoon, W.-S., Advanced Energy Materials 2018, 8 (4), 1701788.[3]. Sun, Y. K.; Myung, S. T.; Park, B. C.; Prakash, J.; Belharouak, I.; Amine, K., Nat Mater 2009, 8 (4), 320-4.[4]. Liu, J.; Manthiram, A., Journal of The Electrochemical Society 2009, 156 (1).[5]. Jeong S.S., Journal of Power Source 2012, 199 (1).[6]. Xu G.-L.; Chen G., Nature Energy 2019, 4. Figure 1

Dielectric Barrier Discharge Plasma Jet (DBDjet) Processed Reduced Graphene Oxide/Polypyrrole/Chitosan Nanocomposite Supercapacitors.

Reduced graphene oxide (rGO) and/or polypyrrole (PPy) are mixed with chitosan (CS) binder materials for screen-printing supercapacitors (SCs) on arc atmospheric-pressure plasma jet (APPJ)-treated carbon cloth. The performance of gel-electrolyte rGO/CS, PPy/CS, and rGO/PPy/CS SCs processed by a dielectric barrier discharge plasma jet (DBDjet) was assessed and compared. DBDjet processing improved the hydrophilicity of these three nanocomposite electrode materials. Electrochemical measurements including electrical impedance spectroscopy (EIS), cyclic voltammetry (CV), and galvanostatic charging-discharging (GCD) were used to evaluate the performance of the three types of SCs. The Trasatti method was used to evaluate the electric-double layer capacitance (EDLC) and pseudocapacitance (PC) of the capacitance. The energy and power density of the three types of SCs were illustrated and compared using Ragone plots. Our experiments verify that, with the same weight of active materials, the combined use of rGO and PPy in SCs can significantly increase the capacitance and improve the operation stability.

New insights on ultrafast Na[solv]+ coinserted graphite driven by an electric field

Sodium ions (Na+) and ether electrolyte co-inserted graphite possesses a considerable volume expansion effect. However, the mechanism fails to clearly explain its stability. In response to this deficiency, the co-inserted reaction is proposed, which is affected by the Lorentz force of the applied electric field under the high-current condition. The Na+ ions are separated out, while the ethylene glycol dimethyl ether molecules remain between the graphite layers. This insight provides a reasonable explanation for the extraordinary stability of this material. In situ X-ray diffraction and density functional theory calculations confirm the separation and release of Na+. On the basis of this result, unmodified commercial graphite was stably cycled 6400 times at a current density of up to 10 A g−1, and the capacity retention rate was as high as 97.2%. The full battery assembled in the laboratory has a maximum output power of 14,846 W kg−1 and an output energy density of 103 W h kg−1 (relative to the weight of anodic and cathodic active materials). The new mechanism provides innovative ideas for the design of large-scale energy storage devices.

Electromagnetic reducers in electromechanical systems


 
 
 
 
 
 
 
 
 
 
 Currently, due to the rising cost of electricity, low-power wind turbines (1-5 kW) are often used to supply consumers with electricity. In this case, wind turbines are used with both horizontal and vertical axes of rotation, the speed of which at an average wind speed V = 5 ÷ 10 m / s and is quite low, and is approximately n = 100 - 300 rpm. A low-speed electric generator for a wind generator with such a speed of rotation with a direct connection of the wind rotor shaft and the electric generator has a large number of poles and reaches a fairly large size. Therefore, magnifying gears (multiplexers) are often used and can increase the speed of the electric generator several times and, thus, reduce the mass of its active part, because the electromagnetic moment is proportional to the volume of the electric machine. However, manual transmissions are a source of additional noise, require frequent maintenance and reduce the durability of the wind turbine. This article will use permanent magnet reducers for wind turbines, which, unlike mechanical reducers, do not create additional noise, do not require lubrication, their durability is higher, operating costs are also significantly reduced, while the magnetic reducer can be integrated with an electric generator. at a wind rotor power P = 4 kW and speed n = 100-300 rpm, high-speed electric generator and magnetic reducer have approximately 2 times less total weight of magnets and 1.7 times less total weight of active materials (magnetic reducer + electric generator) than a low-speed multipole external generator. The aim of the study is to develop and implement an electromagnetic reducer in electromechanical systems. The basis of such systems are high-coercive magnets.
 To achieve this goal, the following tasks are set:
 - literary-patent search on the research topic;
 - selection of a prototype of a magnetic reducer and calculation of its main parameters;
 - development of graphical and numerical models to evaluate the effectiveness of the developed prototype;
 - optimization of the design of the magnetic reducer;
 - development of a system for converting mechanical energy with low potential into electricity;
 - prototyping and experimental studies of the system of conversion of mechanical energy with low potential into electrical energy

Si Nanoparticles inside a Carbon Matrix As an Anode for Next Generation LIB

1. Introduction Lithium-ion batteries (LIB) are used in many applications such as cellular phones, mobile computers and electrical vehicles since they have high capacity and long cycle life. There is a continuing demand for advanced LIBs with higher energy density. However, graphite, conventional anode materials for commercial LIBs, are approaching their theoretical capacity limits. In this context, Si anodes have attracted much attention for the alternatives of graphite anodes because of their high capacity, low cost and environmental benignity. However, Si anodes suffer from drastic volume change and huge stress generation during the lithiation and delithiation process, which causes fracture of Si and deformation of the electrode. Such unfavorable phenomena arising from the severe volume change results in the poor cycle ability of Si anodes. These crucial problems hamper the direct utilization of Si anodes for next-generation LIBs.Amorphous SiO x (x<2) anodes have shown the cycle performance improvement since the amorphous structure and SiO2 phase serve as the buffer layer which suppresses the volume expansion during the lithiation delithiation process. However, the irreversible capacity of the first cycle is large due to the formation of inactive Li-Si-O phase from SiO2 phase. [1-2]Much research on composite anodes containing Si and graphite has been investigated, and improvement of the cycle performance of composite electrodes have been demonstrated. However, the amount of Si in the composite electrode is limited since there is a strong trade-off relationship between the capacity and the cycle performance in the composite electrode. [3-4]Recently, we have successfully synthesized Si nanoparticles inside a Carbon Matrix (SCM). Here, we show the electrochemical Li storage performance of SCM. 2. Experimental Synthesis of Si nanoparticles with Voids inside a Carbon Matrix (SCM) We synthesized SCM through chemical techniques. The cross-sectional SEM image of SCM is shown in Fig. 1. Si nanoparticles with voids inside the carbon matrix are observed. Electrode preparation SCM powder as active material, carbon powder as conductive additive and polyacrylate as binder at a mass ratio of 92:1:7 were mixed in water to form slurry. The slurry was coated onto Cu foil (10μm thickness) and dried at 90 ºC for 5 min, and then heated in vacuum at 100 ºC overnight. The electrode was punched into discs typically with a diameter of 13.8 mm. The weight of active material in the electrode is ranged from 3.0 to 4.0 mg. CR2032 cell preparation Coin type cell (CR2032) was assembled in the Ar-filled glove box. Li metal (Honjyou metal) was used as the counter electrode. Polypropylene was used as the separator. The liquid electrolyte used was 1.2 M LiPF6 in ethylene carbonate (EC)/diethyl carbonate (DEC) (1:1 vol %) with fluoroethylene carbonate (FEC) (2 vol %). 3. Results First charge –discharge curves of the SCM electrode with current rate of 0.1 C is shown in Fig. 2. During the first cycle, the electrode exhibited a reversible capacity of 680 mAhg-1 with an efficiency of 75.6 %. Cycle performance of the SCM electrode and shape of the SCM particle after cycling will be reported and discussed. 4. Reference [1] J. Yang et al. SiOx-based anodes for secondary lithium batteries. Solid State Ionics 152-153, 125-129 (2002).[2] M. N. Obrovac et al. Alloy Negative Electrodes for Li-Ion Batteries. Chem. Rev. 114, 11444−11502 (2014).[3] Y. liu et al. Silicon/carbon composites as anode materials for Li-ion batteries. Electrochem. Solid State Lett. 7 (10), A369-372 (2004).[4] U. Kasavajjula et al. Nano- and bulk-silicon-based insertion anodes for lithium-ion secondary cells. J. Power Sources 163, 1003-1039 (2007) Figure 1

Development of a High Energy Density, Long Cycle Life and Safety Enhanced Li-S Battery

Rechargeable lithium-sulfur (Li-S) batteries are widely considered the most promising “Beyond Li-ion” candidates, notably for their high theoretical energy density. The low and moderate atomic weight of Li and S, respectively, translates to a battery chemistry pairing that is lightweight. Since each S atom can ultimately host two lithium ions (Li+), compared with 0.5–0.7 Li+ per host atom in Li-ion batteries [1], the Li-S battery chemistry offers a much higher Li storage capacity potential. Assuming a complete redox couple reaction, S8 + 16Li+ + 16e- ↔ 8Li2S, the S cathode can have a high theoretical specific capacity of 1672 mAh/g with an average discharge voltage of ~2.1V (vs. Li/Li+), which leads to a theoretical specific energy of ~2500 Wh/kg based on the active material weight of a Li-S cell [2]. Other compelling attributes of Li-S batteries include high S natural abundance, low cost of S materials and safety characteristics owing to an intrinsic tolerance to overcharge [3]. In addition, the primary constituents of Li-S batteries are non-toxic and environmentally friendly [4].However, currently no commercial Li-S battery exists due to some significant technical challenges that have thus far prevented the realization of the tremendous energy density and performance potentials of Li-S batteries. These technical challenges include: low practical specific energy or energy density yield, significant capacity loss with cycling, high self-discharge rates, low Coulombic efficiency and safety concerns due to the use of Li metal anode [5].We will present our efforts in the development of a high energy density, long cycle life, safe and economically scalable Li-S battery technology via a holistic approach to nanoengineer/functionalize cell components including active components (i.e., S cathode, Li metal anode) and inactive components (e.g., separator, electrolyte), to address the Li-S battery cycle life degradation challenges and safety concerns. We will show that our comprehensive approaches afforded high discharge specific capacity, Coulombic efficiency (CE) and stable cycle life of the resultant Li-S cells (Figure 1).Our study demonstrates that the holistic approach of nanoengineering/functionalizing the active and inactive cell components represent a very promising strategy to develop a high energy density, long cycle life and safety enhanced Li-S battery technology. References Bullis, “Revisiting Lithium-Sulfur Batteries” MIT Review, May 22, 2009.Arumugam Manthiram, Yongzhu Fu, and Yu-Sheng Su, Acc. Chem. Res., 46 (5), pp 1125–1134 (2013)James R. Akridge, “Lithium Sulfur Rechargeable Battery Safety”, Battery Power Products & Technology, October 2001.Yongguang Zhang, Yan Zhao, Kyung Eun Sun and P. Chen, The Open Materials Science Journal, 5, 215-221 (2011).Monica Marinescu, Laura O’Neill, Teng Zhang, Sylwia Walus, Timothy E. Wilson, and Gregory J. Offer, J. Electrochem. Soc, 165 (1) A6107-A6118 (2018). Acknowledgement This material is based upon work supported by the C5ISR Center, Power and Integration Directorate (CP & I) under Contract No. W56KGU-18-C-0009. Figure 1

An all-organic aqueous potassium dual-ion battery

An all-organic aqueous potassium dual-ion full battery was assembled with polytriphenylamine cathode, 21 M Potassium bis(fluoroslufonyl)imide water-in-salt electrolyte and 3,4,9,10-perylenetetracarboxylic diimide anode for the first time. • The advanced all organic aqueous potassium dual-ion full battery (APIB) is assembled. • The reaction mechanism of APIB is verified by X-ray spectroscopy and scanning electron microscopy. • The solvation structures of different concentration electrolytes are investigated. Benefiting from the environmental friendliness of organic electrodes and the high security of aqueous electrolyte, an all-organic aqueous potassium dual-ion full battery (APDIB) was assembled with 21 M potassium bis(fluoroslufonyl)imide (KFSI) water-in-salt as the electrolyte. The APDIB could deliver a reversible capacity of around 50 mAh g −1 at 200 mA g −1 (based on the weight of total active materials), a long cycle stability over 900 cycles at 500 mA g −1 and a high coulombic efficiency of 98.5%. The reaction mechanism of APDIB during the charge/discharge processes is verified: the FSI − could associate/disassociate with the nitrogen atom in the polytriphenylamine (PTPAn) cathode, while the K + could react with C O bonds in the 3,4,9,10-perylenetetracarboxylic diimide (PTCDI) anode reversibly. Our work contributes toward the understanding the nature of water-into-salt electrolyte and successfully constructed all-organic APDIB.

Improvement of the Battery Performance of Indigo, an Organic Electrode Material, Using PEDOT/PSS with d-Sorbitol.

Rare-metal-free and high-performance secondary batteries are necessary for improving the efficiency of renewable energy systems. Organic compounds are attractive candidates for the active material of such batteries. Many studies have reported organic active materials that show high energy density per active material weight. However, organic active materials, most of which exhibit low conductivity and low specific density, typically require a large amount of a conductive additive (>50 wt %) to obtain a high utilization rate. Therefore, organic active materials rarely display high energy density per electrode weight. High energy densities per electrode weight can be obtained using high weight fractions of active materials and low weight fractions of conductive additives. Herein, we report that a low-conductivity organic active material, indigo, showed improved net discharge capacity density when even a small amount of a conductive polymer composite, poly(3,4-ethylenedioxythiophene)/polystyrene sulfonic acid (PEDOT/PSS) with d-sorbitol, was used as both a binder and conductive additive. The cycle life was also improved by coating one side of the separator with the composite, which probably hindered the dissolution of the active material. A discharge capacity of 96% of the theoretical capacity of indigo and an improved cycle life were achieved with an electrode containing 80 wt % indigo and with a PEDOT/PSS-coated separator. The optimal fraction of the conductive binder was examined, and the mechanism of conductivity enhancement was discussed. The present scheme allows us to replace the dispersion solvent of the slurry, N-methylpyrrolidone, with water, which can reduce the environmental load during battery manufacturing processes.

Preparation of high surface area nitrogen doped graphene for the assessment of morphologic properties and nitrogen content impacts on supercapacitors

Supercapacitors have been caught great attention owing to their high power density and fast charge/discharge ability with superior capacitance retention which originates from the formation of an electrical double layer on high surface area electrodes. In this study, Two-step organic sol-gel procedure is applied to graphene oxide to produce high surface area nitrogen doped graphene samples varying in surface area and nitrogen content. The higher impacts of specific surface area and porosity on capacitative performance of graphene than nitrogen content are observed in different electrolytes. All the samples give superior capacitative performance than those of graphene oxide and blank sample, but higher in acidic electrolyte than the alkaline yielding a volumetric specific capacitance of ~118 F·cm−3 with Coulombic efficiency of >99% and capacitance retention >80% after 10,000 successive cycle. Based on the weight of active material, the maximum gravimetric energy density is as high as 39 Wh·kg−1 in acidic electrolyte at 0.1 A·g−1, which is almost 2.6 times of graphene oxide used in this study.

Development of a High Energy Density, Long Cycle Life and Safety Enhanced Li-S Battery

Rechargeable lithium-sulfur (Li-S) batteries are widely considered the most promising “Beyond Li-ion” candidates, notably for their high theoretical energy density. The low and moderate atomic weight of Li and S, respectively, translates to a battery chemistry pairing that is lightweight. Since each S atom can ultimately host two lithium ions (Li+), compared with 0.5–0.7 Li+ per host atom in Li-ion batteries [1], the Li-S battery chemistry offers a much higher Li storage capacity potential. Assuming a complete redox couple reaction, S8 + 16Li+ + 16e- ↔ 8Li2S, the S cathode can have a high theoretical specific capacity of 1672 mAh/g with an average discharge voltage of ~2.1V (vs. Li/Li+), which leads to a theoretical specific energy of ~2500 Wh/kg based on the active material weight of a Li-S cell [2]. Other compelling attributes of Li-S batteries include high S natural abundance, low cost of S materials and safety characteristics owing to an intrinsic tolerance to overcharge [3]. In addition, the primary constituents of Li-S batteries are non-toxic and environmentally friendly [4].However, currently no commercial Li-S battery exists due to some significant technical challenges that have thus far prevented the realization of the tremendous energy density and performance potentials of Li-S batteries. These technical challenges include: low practical specific energy or energy density yield, significant capacity loss with cycling, high self-discharge rates, low Coulombic efficiency and safety concerns due to the use of Li metal anode [5].We will present our efforts in the development of a high energy density, long cycle life, safe and economically scalable Li-S battery technology via a holistic approach to nanoengineer/functionalize cell components including active components (i.e., S cathode, Li metal anode) and inactive components (e.g., separator, electrolyte), to address the Li-S battery cycle life degradation challenges and safety concerns. We will show that our comprehensive approaches afforded high discharge specific capacity, Coulombic efficiency (CE) and stable cycle life of the resultant Li-S cells (Figure 1).Our study demonstrates that the holistic approach of nanoengineering/functionalizing the active and inactive cell components represent a very promising strategy to develop a high energy density, long cycle life and safety enhanced Li-S battery technology.

Dramatic improvement enabled by incorporating thermal conductive TiN into Si-based anodes for lithium ion batteries

Building stable SEI film is highly desirable for high-performance Si-based anode materials used in high energy-density lithium ion batteries (LIBs), which is strongly related with the generated-heat distribution in the electrode. Herein, Si/graphene@carbon embedding with TiN nanoparticles (Si/G@C/TiN) are prepared via a facile ultrasonic spraying method. The Si/G@C/TiN delivers a reversible discharge capacity of 660 ​mAh▪g−1 ​at 10 A▪g−1 and 776.5 ​mAh▪g−1 ​at 5 A▪g−1 after 400 cycles. High electronical conductivity of TiN embedding in the porous carbon framework can not only facilitate electrons transfer in the electrode, but also improve Li-ion kenetic diffusion. High thermal conductivity of TiN would be helpful to faster heat-dissipation and uniform heat-distribution in the electrode during the charging/discharging process, resulting in balanced growth of stable SEI film and excellent cycling stability especially at elevated temperature. Moreover, Si/G@C/TiN pouch cells using LiNi0.5Co0.2Mn0.3O2 as cathode, deliver impressive energy density of ~476 ​Wh▪kg-1 based on the total weight of active materials, suggesting its promising application in the high energy-density LIBs.

Nanoengineered Separators for a High Energy Density, Long Cycle Life Li-S Battery

Rechargeable lithium-sulfur (Li-S) batteries are widely considered the most promising “Beyond Li-ion” candidates, notably for their high theoretical energy density. The low and moderate atomic weight of Li and S, respectively, translates to a battery chemistry pairing that is lightweight. Since each S atom can ultimately host two lithium ions (Li+), compared with 0.5–0.7 Li+ per host atom in Li-ion batteries [1], the Li-S battery chemistry offers a much higher Li storage capacity potential. Assuming a complete redox couple reaction, S8 + 16Li+ + 16e- ↔ 8Li2S, the S cathode can have a high theoretical specific capacity of 1672 mAh/g with an average discharge voltage of ~2.1V (vs. Li/Li+), which leads to a theoretical specific energy of ~2500 Wh/kg based on the active material weight of a Li-S cell [2]. Other compelling attributes of Li-S batteries include high S natural abundance, low cost of S materials and safety characteristics owing to an intrinsic tolerance to overcharge [3]. In addition, the primary constituents of Li-S batteries are non-toxic and environmentally friendly [4]. However, currently no commercial Li-S battery exists due to some significant technical challenges that have thus far prevented the realization of the tremendous energy density and performance potentials of Li-S batteries. These technical challenges include: low practical specific energy or energy density yield, significant capacity loss with cycling, high self-discharge rates, low Coulombic efficiency and safety concerns due to the use of Li metal anode [5]. We will present our efforts in the development of a high energy density and long cycle life Li-S battery technology via nanoengineered battery separators. We will show that our atomic and/or molecular level, functional material coated separators exhibit much improved physical properties including tensile strength, thermal shrinkage, and electrolyte wettability (Figure 1). When used in Li-S cells, the nanoengineered separators (coated) afforded a significant increase in specific capacity compared with the control (uncoated) separator, as illustrated in Figure 2. The enhanced Li-S cell performance suggests polysulfide blockage from the nanoscale functional material coated separators used in the resultant Li-S cells. Our study demonstrates that the nanoengineered separator approach represents a very promising strategy to develop a high energy density, long cycle life, safe and economically scalable Li-S battery technology. References Bullis, “Revisiting Lithium-Sulfur Batteries” MIT Review, May 22, 2009.Arumugam Manthiram, Yongzhu Fu, and Yu-Sheng Su, Acc. Chem. Res., 46 (5), pp 1125–1134 (2013)James R. Akridge, “Lithium Sulfur Rechargeable Battery Safety”, Battery Power Products & Technology, October 2001.Yongguang Zhang, Yan Zhao, Kyung Eun Sun and P. Chen, The Open Materials Science Journal, 5, 215-221 (2011).Monica Marinescu, Laura O’Neill, Teng Zhang, Sylwia Walus, Timothy E. Wilson, and Gregory J. Offer, J. Electrochem. Soc, 165 (1) A6107-A6118 (2018). Figure 1