ABSTRACT
We unveil the fundamental insights of electrochemical kinetics of LFP cathode material and the passivation layer formation in the SO2-based non-flammable inorganic liquid electrolyte (IE). The influence of temperature and electrochemical potential cutoff in the electrochemical activity of LFP cathode and IE is disclosed. Furthermore, the materials compatibility, structural and chemical stability of LFP in IE is demonstrated using very slow galvanostatic cycling in combination with LiFePO4||Li0.9FePO4 symmetric cells. The lithium storage performance of LFP half-cell using inorganic electrolyte is presented with the optimum voltage window. LFP half-cells exhibit discharge capacities of 147, 111, and 75 mAh/g at 1, 4, 8C rates, respectively, with coulombic efficiencies of ~99.98%. The electrochemical behavior and mechanism of LFP||Graphite cell in IE is investigated while concurrently tracking the electrochemical potentials of LFP and Graphite half-cell.
ABSTRACT
Tremendous efforts are put forward to develop novel high-performance electrodes for Na-ion batteries (SIBs) in order to replace commercial Li-ion batteries (LIBs). Graphite, the most versatile anode for LIBs, fails to accommodate Na+ions owing to the poor thermodynamic stability of the binary graphite intercalation compound. This study aims to exfoliate the layers of graphite through a simple mechanical process at different time intervals (1, 5, 10, 20, 40, and 80 h) and examine the potential candidate for Na-storage in the presence of carbonate-based electrolytes. This study reports that ball milling plays a vital role in the performance of the graphite in Na-storage. The graphite exfoliated for 80 h (EG-80h) rendered an excellent reversible capacity of 209 mAh g-1 with coulombic efficiency of >99% after 100 cycles in EC-based electrolyte. In situ impedance analysis is performed to validate the charge storage mechanism and Na-ion kinetics. The performance of EG-80h in a full-cell assembly is evaluated with a carbon-coated Na3V2(PO4)3 cathode, which exhibited an initial capacity of ≈75 mAh g-1 and energy density of 201 Wh kg-1. In addition, the adaptability of the NVPC/EG-80h cell at different temperatures is examined from -10 to 50 °C, displaying excellent performance in both high and low-temperature conditions.
ABSTRACT
Compensating for the irreversible loss of limited active sodium (Na) is crucial for enhancing the energy density of practical sodium-ion batteries (SIBs) full-cell, especially when employing hard carbon anode with initially lower coulombic efficiency. Introducing sacrificial cathode presodiation agents, particularly those that own potential anionic oxidation activity with a high theoretical capacity, can provide additional sodium sources for compensating Na loss. Herein, Ni atoms are precisely implanted at the Na sites within Na2O framework, obtaining a (Na0.89Ni0.05â¡0.06)2O (Ni-Na2O) presodiation agent. The synergistic interaction between Na vacancies and Ni catalyst effectively tunes the band structure, forming moderate Ni-O covalent bonds, activating the oxidation activity of oxygen anion, reducing the decomposition overpotential to 2.8 V (vs Na/Na+), and achieving a high presodiation capacity of 710 mAh/g≈Na2O (Na2O decomposition rate >80%). Incorporating currently-modified presodiation agent with Na3V2(PO4)3 and Na2/3Ni2/3Mn1/3O2 cathodes, the energy density of corresponding Na-ion full-cells presents an essential improvement of 23.9% and 19.3%, respectively. Further, not limited to Ni-Na2O, the structure-function relationship between the anionic oxidation mechanism and electrode-electrolyte interface fabrication is revealed as a paradigm for the development of sacrificial cathode presodiation agent.
ABSTRACT
This study demonstrates the enhanced performance in high-voltage sodium full cells using a novel electrolyte composition featuring a highly fluorinated borate ester anion (1 M Na[B(hfip)4].3DME) in a binary carbonate mixture (EC:EMC), compared to a conventional electrolyte (1 M Na[PF6] EC:EMC). The prolonged cycling performance of sodium metal battery employing high voltage cathodes (NVPF@C@CNT and NFMO) is attributed to uniform and dense sodium deposition along with the formation of fluorine and boron-rich solid electrolyte interphase (SEI) on the sodium metal anode. Simultaneously, a robust cathode electrolyte interphase (CEI) is formed on the cathode side due to the improved electrochemical stability window and superior aluminum passivation of the novel electrolyte. The CEIs on high-voltage cathodes are discovered to be abundant in C-F, B-O, and B-F components, which contributes to long-term cycling stability by effectively suppressing undesirable side reactions and mitigating electrolyte decomposition. The participation of DME in the primary solvation shell coupled with the comparatively weaker interaction between Na+ and [B(hfip)4]- in the secondary solvation shell, provides additional confirmation of labile desolvation. This, in turn, supports the active participation of the anion in the formation of fluorine and boron-rich interphases on both the anode and cathode.
ABSTRACT
Sodium ion batteries (SIBs) are considered as the ideal candidates for the next generation of electrochemical energy storage devices. The major challenges of anode lie in poor cycling stability and the sluggish kinetics attributed to the inherent large Na+ size. In this work, Bi nanosphere encapsulated in N-doped carbon nanowires (Bi@N-C) is assembled by facile electrospinning and carbonization. N-doped carbon mitigates the structure stress/strain during alloying/dealloying, optimizes the ionic/electronic diffusion, and provides fast electron transfer and structural stability. Due to the excellent structure, Bi@N-C shows excellent Na storage performance in SIBs in terms of good cycling stability and rate capacity in half cells and full cells. The fundamental mechanism of the outstanding electrochemical performance of Bi@N-C has been demonstrated through synchrotron in-situ XRD, atomic force microscopy, ex-situ scanning electron microscopy (SEM) and density functional theory (DFT) calculation. Importantly, a deeper understanding of the underlying reasons of the performance improvement is elucidated, which is vital for providing the theoretical basis for application of SIBs.
ABSTRACT
In this study, a flexible, free-standing Fe-doped CoP nanoarrays electrode for superior lithium-ion storage has been successfully fabricated. The electrode combines the advantages of a Fe-doping and a flexible carbon cloth (CC) support, resulting in a high specific capacity (1356 mAh/g at 0.2 A/g) and excellent cycling stability (1138 mAh/g after 100 cycles). The cyclic voltammetry (CV) curves at different scan rates investigate the outstanding lithium storage behavior of Fe-CoP-NAs/CC which indicates a combined influence of diffusion behavior and capacitance behavior on the electrochemical process. The galvanostatic intermittent titration technique (GITT) analyzes the diffusion kinetics of Li+ which indicates the fast diffusion kinetics in the Fe-CoP/NAs/CC anode. The assembled Fe-CoP-NAs/CC//LiFePO4 battery exhibits a remarkable capacity of 325.2 mAh/g even at 5 A/g. And the battery also has good cycle stability, and still provides 498.1 mAh/g specific capacity after 200 cycles. Moreover, the Fe-CoP-NAs/CC//LiFePO4 soft-pack battery can continuously power the LEDs when it is bent at various angles which demonstrates its potential for use in wearable devices.
ABSTRACT
The development of Na3V2(PO4)3 (NVP) has been severely hindered by low conductivity and unstable crystal structure. A simultaneously optimized strategy of Na-rich and Sn substitution is proposed for the first time. SnX-NVP@CNTs with different doping gradients are successfully prepared by the facile sol-gel method. Notably, more hole carriers can be generated by introducing Sn2+, thus improving its electron transport efficiency. In addition, since Sn2+ ions have a larger ion radius; when replacing V3+ ions at pillar positions, the lattice spacing can be enlarged to improve the structural stability of electrode materials. Meanwhile, it is beneficial to the movement of deep-level Na+ ions and improves the utilization rate of electrode materials. Moreover, to achieve charge compensation, it is necessary to introduce excess Na+ to the Sn-doped NVP system, which will increase the number of Na+ involved in the deintercalation process and improve its reversible capacity. Furthermore, the dense coating of CNTs can form an efficient conductive network structure, which improves the electron transport rate and inhibits the accumulation of active grains to accelerate Na+ diffusion. Under the synergistic adjustment of Sn2+ doping and CNTs enwrapping, the prepared Sn0.07-NVP@CNTs exhibit a high reversible capacity of 115.1 mAh/g at 0.1C, and the capacity retention rate reaches 89.35 % after 2000 cycles at 10C. Even after 10,000 cycles at 60C, its reversible capacity dropped from the initial 75.9 to 51.3 mAh/g, with a capacity loss of only 0.003 % per cycle. Besides, the Sn0.07-NVP@CNTs//CHC full battery releases a capacity of 139.9 mAh/g, highlighting its great potential for actual applications.
ABSTRACT
Silicon (Si) is considered a promising anode material for lithium-ion batteries (LIBs) due to its high theoretical specific capacity of up to 4200 mAh/g. However, the poor cycling and rate performances of Si induced by the low intrinsic electronic conductivity and large volume expansion during the lithiation/delithiation process limit its practical application. Herein, a novel silicon/bismuth@nitrogen-doped carbon (Si/Bi@NC) composite with nanovoids was synthesized and investigated as an advanced anode material for LIBs. In such a structure, ultrafine bismuth nanoparticles coupled with an N-doped carbon layer were introduced to modify the surface of Si nanoparticles. Subsequently, the lithiated LixBi has excellent high ionic conductivity and acts as a fast transport bridge for lithium ions. The introduced carbon coating layer and nanovoids can buffer the volume expansion of Si during the lithiation/delithiation process, thus maintaining structural stability during the cycling process. As a result, the Si/Bi@NC composite exhibits excellent electrochemical performance, providing a relatively high capacity of 955.8 mAh/g at 0.5 A/g after 450 cycles and excellent rate performance with a high capacity of 477.8 mAh/g even at 10.0 A/g. Furthermore, the assembled full cell with LiFePO4 as cathode and pre-lithium Si/Bi@NC as anode can provide a high capacity of 138.8 mAh/g at 1C after 90 cycles, exhibiting outstanding cycling performance.
ABSTRACT
Compensating the irreversible loss of limited active lithium (Li) is essentially important for improving the energy-density and cycle-life of practical Li-ion battery full-cell, especially after employing high-capacity but low initial coulombic efficiency anode candidates. Introducing prelithiation agent can provide additional Li source for such compensation. Herein, we precisely implant trace Co (extracted from transition metal oxide) into the Li site of Li2 O, obtaining (Li0.66 Co0.11 â¡0.23 )2 O (CLO) cathode prelithiation agent. The synergistic formation of Li vacancies and Co-derived catalysis efficiently enhance the inherent conductivity and weaken the Li-O interaction of Li2 O, which facilitates its anionic oxidation to peroxo/superoxo species and gaseous O2 , achieving 1642.7â mAh/g~Li2O prelithiation capacity (≈980â mAh/g for prelithiation agent). Coupled 6.5â wt % CLO-based prelithiation agent with LiCoO2 cathode, substantial additional Li source stored within CLO is efficiently released to compensate the Li consumption on the SiO/C anode, achieving 270â Wh/kg pouch-type full-cell with 92 % capacity retention after 1000 cycles.
ABSTRACT
Graphite (Gr) has been considered as the most promising anode material for potassium-ion batteries (PIBs) commercialization due to its high theoretical specific capacity and low cost. However, Gr-based PIBs remain unfeasible at low temperature (LT), suffering from either poor kinetics based on conventional carbonate electrolytes or K+ -solvent co-intercalation issue based on typical ether electrolytes. Herein, a high-performance Gr-based LT rechargeable PIB is realized for the first time by electrolyte chemistry. Applying unidentate-ether-based molecule as the solvent dramatically weakens the K+ -solvent interactions and lowers corresponding K+ de-solvation kinetic barrier. Meanwhile, introduction of steric hindrance suppresses co-intercalation of K+ -solvent into Gr, greatly elevating operating voltage and cyclability of the full battery. Consequently, the as-prepared Gr||prepotassiated 3,4,9,10-perylene-tetracarboxylicacid-dianhydride (KPTCDA) full PIB can reversibly charge/discharge between -30 and 45 °C with a considerable energy density up to 197â Wh kgcathode -1 at -20 °C, hopefully facilitating the development of LT PIBs.
ABSTRACT
The recycling of spent graphite from waste lithium-ion batteries (LIBs) holds great importance in terms of environmental protection and conservation of natural resources. In this study, a simple two-step method involving heat treatment and solution washing was employed to recycle spent graphite. Subsequently, the recycled graphite was milled with red phosphorus to create a carbon/red phosphorus composite that served as an anode material for the new LIBs, aiming to address the low capacity issue. In a half-cell configuration, the carbon/red phosphorus composite exhibited remarkable cycling stability, maintaining a capacity of 721.7 mAh g-1 after 500 cycles at 0.2 A g-1, and demonstrated an excellent rate performance with a capacity of 276.2 mAh g-1 at 3 A g-1. The improved performance can be attributed to the structure of the composite, where the red phosphorus particles are covered by the carbon layer. This composite outperformed pure recycled graphite, highlighting its potential in enhancing the electrochemical properties of LIBs. Furthermore, when the carbon/red phosphorus composite was assembled into a full-cell configuration with LiCoO2 as the cathode material, it displayed a stable electrochemical performance, further validating its practical applicability. This work presents a promising and green strategy for recycling spent graphite and using it in the production of new batteries. The findings offer a high potential for commercialization, contributing to the advancement of sustainable and ecofriendly energy storage technologies.
ABSTRACT
Heterogeneous composite ZnS/SnS2 is designed to meet various requirements for alkali metal-ion batteries. The composite is prepared using an electrostatic spinning method and encapsulated in N-doped carbon fibers after high-temperature vulcanization. The special structure of the composite provides a dependable interconnection and fast conductive network for alkali metal ions. The conductive carbon network shortens the diffusion path and greatly improves the migration efficiency of the alkali metal ions in the electrode. As expected, when the current density is 0.1 A g-1, the ZnS/SnS2@NCNFs maintain a high discharge capacity of more than 1437.5, 1321.2, and 861.6 mA h g-1 for lithium-ion, sodium-ion, and potassium-ion batteries, respectively. What is more, a full cell using a prelithiated composite anode and a LiFePO4 cathode is tested and shows excellent electrochemical performance. This work provides new perspectives for the development of novel anodes that can efficiently store alkali metal ions, as well as for the fine-structure design of materials.
ABSTRACT
Lithium-ion batteries are at the core of the democratisation of electric transportation and portative electronic devices. However, fast and/or low temperature charge induce performance loss, mainly through lithium plating, a degrading mechanism. In this report, 7Li operando Nuclear Magnetic Resonance spectroscopy is used to detect the onset of metastable lithium deposits in an NMC622/graphite cell at 0 °C and fast charge. An operando setup, compatible with low temperatures, was developed with special attention to the pressure applied on the electrodes/separator stack and noise reduction to enable early detection and good time-resolution. Direct detection of metallic lithium enables drawing correlations between lithium plating and electrochemical data.
ABSTRACT
Zinc ion hybrid supercapacitors (ZIHSCs) are truly promising as next-generation high-performance energy storage systems because they could offer high energy density like batteries while exhibiting high power output and long cycle life traits of supercapacitors. The key point of constructing a high-performance ZIHSC is to couple the Zn anode with an appropriate cathode material, which has high theoretical capacity, cost-effectiveness, and intrinsic safety features. In this work, we have demonstrated the potentiality of S, N co-doped porous carbon nanocubes (S, N-CNCs) as a cathode material for devising a ZIHSC with excellent energy density and cycle life. The S, N-CNCs are prepared from a zeolitic imidazolate framework (ZIF)-8 precursor via a simultaneous pyrolyzing-doping strategy in an inert atmosphere. Resultant CNCs are monodisperse with an average size of around 65 nm and porous in nature, with uniform N and S doping throughout the structure. Benefitted from such hierarchical porous architecture and the presence of abundant heteroatoms, the assembled ZIHSC with S, N-CNC as the cathode and Zn-foil as the anode in a ZnSO4 aqueous electrolyte could reach a specific capacity as high as 165.5 mA h g-1 (331 F g-1) at 1 A g-1, which corresponds to a satisfactory energy density of 148.9 W h kg-1 at the power density of 900 W kg-1. The ZIHSC has displayed a good cycle stability with more than 70% capacity retention after 10,000 charge-discharge cycles. Furthermore, to verify the practical feasibility of such a cathode material, an aqueous 3D Zn@Cu//S, N-CNC full-cell device is fabricated, which has demonstrated a satisfactory specific capacity (49.6 mAh g-1 at 0.25 A g-1) and an impressive energy density (42.2 Wh kg-1 with 212.2 W kg-1). Full ZIHSC devices are also found to be efficient in powering light-emitting diodes, further substantiating their feasibility in next-generation energy storage applications.
ABSTRACT
The initial Na loss limits the theoretical specific capacity of cathodes in Na-ion full cell applications, especially for Na-deficient P2-type cathodes. In this study, we propose a presodiation strategy for cathodes to compensate for the initial Na loss in Na-ion full cells, resulting in a higher specific capacity and a higher energy density. By employing an electrochemical presodiation approach, we inject 0.32 excess active Na into P2-type Na0.67Li0.1Fe0.37Mn0.53O2 (NLFMO), aiming to compensate for the initial Na loss in hard carbon (HC) and the inherent Na deficiency of NLFMO. The structure of the NLFMO cathode converts from P2 to P'2 upon active Na injection, without affecting subsequent cycles. As a result, the HC||NLFMOpreNa full cell exhibits a specific capacity of 125 mAh/g, surpassing the value of 61 mAh/g of the HC||NLFMO full cell without presodiation due to the injected active Na. Moreover, the presodiation effect can be achieved through other engineering approaches (e.g., Na-metal contact), suggesting the scalability of this methodology.
ABSTRACT
Lithium-sulfur (Li-S) batteries using Li2S and Li-free anodes have emerged as a potential high-energy and safe battery technology. Although the operation of Li-S full batteries based on Li2S has been demonstrated at room temperature, their effective use at a subzero temperature has not been realized due to the low electrochemical utilization of Li2S. Here, ammonium nitrate (NH4NO3) is introduced as a functional additive that allows Li-S full batteries to operate at -10 °C. The polar N-H bonds in the additive alter the activation pathway of Li2S by inducing the dissolution of the Li2S surface. Then, Li2S with an amorphized surface layer undergoes the modified activation process, which consists of the disproportionation and direct conversion reaction, through which Li2S is efficiently converted into S8. The Li-S full battery using NH4NO3 delivers a reversible capacity and cycling stability over 400 cycles at -10 °C.
ABSTRACT
Research and development of flexible electrodes with high performance are crucial to largely determine the performance of flexible lithium-ion batteries (FLIBs) to a large extent. In this work, a flexible anode (TiO2 NRs-MoS2 NSFs/CC) is rationally designed and successfully constructed, in which TiO2 nanorods arrays (NRs) vertically grown on CC as a supporting backbone for MoS2 nanosheets flowers (NSFs) to form a TiO2 NRs-MoS2 NSFs heterostructure. The backbone can not only serve as a mechanical support MoS2 and improve its electronic conductivity, but also limit the dissolution of polysulfides issue during cycling. The density functional theory (DFT) analysis manifests that the obvious interaction between O and S at the interface for the TiO2 NRs-MoS2 NSFs heterostructure changes the electronic structure and reduces the band gap of TiO2 NRs-MoS2 NSFs. The small band gap and high electron state at the Fermi level are both beneficial to the transport of electrons, enhancing the kinetics, and giving the long cycling stability at high density and excellent rate capacity. Furthermore, the assembled TiO2 NRs-MoS2 NSFs/CC//NCM622 full cell delivers superior rate capacity and good cycling stability. Meanwhile, the soft-packed cell shows good mechanical flexibility, which can be lighted up successfully and keep brightness when folding with different angles. This result illustrates that it is a highly potential strategy for constructing flexible electrodes with the controlled electronic structure through band engineering to not only improve the electrochemical performance, but also possibly meet the requirements of high-performance FLIBs.
ABSTRACT
Lithium sulfide (Li2 S) is considered as a promising cathode material for sulfur-based batteries. However, its activation remains to be one of the key challenges against its commercialization. The extraction of Li+ from bulk Li2 S has a high activation energy (Ea ) barrier, which is fundamentally responsible for the initial large overpotential. Herein, a systematic investigation of accelerated bulk Li2 S oxidation reaction kinetics was studied by using organochalcogenide-based redox mediators, in which phenyl ditelluride (PDTe) can significantly reduce the Ea of Li2 S and lower the initial charge potential. Simultaneously, it can alleviate the polysulfides shuttling effect by covalently anchoring the soluble polysulfides and converting them into insoluble lithium phenyl tellusulfides (PhTe-Sx Li, x>1). This alters the redox pathway and accelerates the reaction kinetics of Li2 S cathode. Consequently, the Li||Li2 S-PDTe cell shows excellent rate capability and enhanced cycling stability. The Si||Li2 S-PDTe full cell delivers a considerable capacity of 953.5â mAh g-1 at 0.2â C.
ABSTRACT
Potassium-ion batteries (PIBs) are promising for cryogenic energy storage. However, current researches on low-temperature PIBs are limited to half cells utilizing potassium metal as an anode, and realizing rechargeable full cells is challenged by lacking viable anode materials and compatible electrolytes. Herein, a hard carbon (HC)-based low-temperature potassium-ion full cell is successfully fabricated for the first time. Experimental evidence and theoretical analysis revealed that potassium storage behaviors of HC anodes in the matched low-temperature electrolyte involve defect adsorption, interlayer co-intercalation, and nanopore filling. Notably, these unique potassiation processes exhibited low interfacial resistances and small reaction activation energies, enabling an excellent cycling performance of HC with a capacity of 175â mAh g-1 at -40 °C (68 % of its room-temperature capacity). Consequently, the HC-based full cells demonstrated impressive rechargeability and high energy density above 100â Wh kg-1 cathode at -40 °C, representing a significant advancement in the development of PIBs.
ABSTRACT
2D transition metal dichalcogenides (TMDCs) and single-atom catalysts (SACs) are promising electrodes for energy conversion/storage because of the layered structure and maximum atom utilization efficiency. However, the integration of such two type materials and the relevant sodium storage applications remain daunting challenges. Here, an ingenious diatomite-templated synthetic strategy is designed to fabricate single-atom cobalt-doped MoS2 /carbon (SA Co-MoS2 /C) composites toward the high-performance sodium storage. Benefiting from the unique hierarchical structure, high electron/sodium-ion conductivity, and abundant active sites, the obtained SA Co-MoS2 /C reveals remarkable specific capacity (≈604.0 mAh g-1 at 0.1 A g-1 ), high rate performance, and outstanding long cyclic stability. Particularly, the sodium-ion full cell composed of SA Co-MoS2 /C anode and Na3 V2 (PO4 )3 cathode demonstrates unexpected stability with the cycle number exceeded 1200. The internal sodium storage mechanism is clarified with the aid of density functional theory calculations and in situ experimental characterizations. This work not only represents a substantial leap in terms of synthesizing SACs on 2D TMDCs but also provides a crucial step toward the practical sodium-ion battery applications.