Conversion-type Anode Materials Research Articles

Realizing the enhanced cyclability of a cactus-like NiCo2O4 nanocrystal anode fabricated by molecular layer deposition.

Lithium-ion batteries with conversion-type anode electrodes have attracted increasing interest in providing higher energy storage density than those with commercial intercalation-type electrodes. However, conversion-type materials exhibit severe structural instability and capacity fade during cycling. In this work, a molecular layer deposition (MLD)-derived conductive Al2O3/carbon layer was employed to stabilize the structure of the cactus-like NiCo2O4 nanocrystal (NC) anode. The conductive Al2O3/carbon network and cactus-like NiCo2O4 NCs are beneficial for fast Li+/e- transport. Moreover, the Al2O3/carbon buffer-layer can prevent the NiCo2O4 NCs from agglomeration and form a steady solid electrolyte interphase (SEI), thus hampering the penetration of the electrolyte. Owing to these advantages, the assembled NiCo2O4@Al2O3/carbon half battery shows a high reversible capacity (931.2 mA h g-1 at 2 A g-1) and long-term stability of 290 mA h g-1 at 5 A g-1 over 500 cycles. Quantitative analyses further reveal the fast kinetics and the capacitance-battery dual model mechanism in the 3D core-shell structures. The design and introduction of MLD-derived hybrid coating may open a new way to conversion-type and alloy-type anode materials beyond NiCo2O4 to achieve high cyclability.

Tantalum pentoxide-reduced graphene oxide nanocomposite as a new conversion type anode material having extrinsic pseudocapacitance for electrochemical lithium storage

Ta2O5 nanoparticles could be an exemplary conversion type anode material for electrochemical lithium ion storage which possesses promising extrinsic pseudocapacitance property. Ionic liquid assisted hydrothermal method have been employed to synthesize Ta2O5 nanoparticles followed by hydrothermal method to synthesize Ta2O5–reduced graphene oxide (Ta2O5-rGO) nanocomposite. The Ta2O5–rGO nanocomposite delivered enhanced specific capacity of 175 mAh g−1 after 200 cycles at 0.1C current rate compared to the pure Ta2O5 nanoparticles. The outstanding electrochemical performance of Ta2O5–rGO nanocomposite could be offered by two-dimensional reduced graphene oxide possessing high surface area, better mechanical stability and high electrical conductivity enhances the electron and ion transfer rate and also avoiding agglomeration of Ta2O5 NPs. Finally, the present investigation urges contemporary researchers to design advance Ta2O5-rGO nanocomposites for lithium ion battery applications.

Tunable Surface Selenization on MoO2 -Based Carbon Substrate for Notably Enhanced Sodium-Ion Storage Properties.

Transition metal chalcogenides with high theoretical capacity are promising conversion-type anode materials for sodium ion batteries (SIBs), but often suffer from unsatisfied cycling stability (hundreds of cycles) caused by structural collapse and agglomerate. Herein, a rational strategy of tunable surface selenization on highly crystalline MoO2 -based carbon substrate is designed, where the sheet-like MoSe2 can be coated on the surface of bundle-like N-doped carbon/granular MoO2 substrate, realizing partial transformation from MoO2 to MoSe2 , and creating b-NC/g-MoO2 @s-MoSe2 -10 with robust hierarchical MoO2 @MoSe2 heterostructures and strong chemical couplings (MoC and MoN). Such well-designed architecture can provide signally improved reaction kinetics and reinforced structural integrity for fast and stable sodium-ion storage, as confirmed by the ex situ results and kinetic analyses as well as the density functional theory calculations. As expected, the b-NC/g-MoO2 @s-MoSe2 -10 delivers splendid rate capability and ultralong cycling stability (254.2mAh g-1 reversible capacity at 5.0 A g-1 after 6000 cycles with ≈89.0% capacity retention). Therefore, the tunable surface strategy can provide new insights for designing and constructing heterostructures of transition metal chalcogenides toward high-performance SIBs.

Decoding of Oxygen Network Distortion in a Layered High-Rate Anode by In Situ Investigation of a Single Microelectrode.

Sluggish conversion reactions severely impair the rate capability for lithium storage, which is the main disadvantage of the conversion-type anode materials. Here, the microplatform based on a single microelectrode is designed and utilized for the fundamental understanding of the conversion reaction. The kinetic-favorable layered structure of the anode material is on-site synthesized in the microplatform. The in situ characterization reveals that introducing an oxygen network distortion in the layered oxide anode effectively circumvents the severe passivation of the electrode material by lithium oxide, thus leading to highly reversible conversion reactions. As a result, the high-rate capability of the conversion-type anode materials is realized. The on-site synthesis strategy is further applied in the large-scale synthesis of nanomaterials for lithium-ion batteries. As such, oxide nanorods with the layered structure are synthesized by a facile chemical strategy, showing high rate performance (574 mAh g-1 at 10 A g-1). This work unveils the beneficial effect of oxygen network distortion in the layered anode for conversion reactions over cycling, thus providing an alternative strategy to enhance the rate capability of conversion-type anodes for lithium storage.

Highly durable Li-ion battery anode from Fe3O4 nanoparticles embedded in nitrogen-doped porous carbon with improved rate capabilities

For next generation, lithium-ion batteries (LIBs) developing high capacity anode materials are crucial with increasing demand of large-scale application. Conversion-type anode materials are promising if stable cycling behavior could be achieved. In this work, a nitrogen-doped porous carbon-Fe3O4 (NPC-Fe3O4) nanocomposite is synthesized via a simple and scalable approach. Composite is prepared by pyrolysis of polymer silica hybrid PolyHIPE (high internal phase emulsion) into NPC, and Fe3O4 nanoparticles (NPs) are anchored on its surface via hydrothermal synthesis. As-prepared NPC-Fe3O4 nanocomposite delivers high reversible capacity of around 1001 mAhg−1 at 0.1 Ag−1 current density and rate capabilities and displays excellent cycling stability as high as 95% capacity retention even after 400 cycles. Superior electrochemical performance of NPC-Fe3O4 is attributed to the hierarchical porous structure and nitrogen doping of carbon which shorten the diffusion path of Li+ and provide ample space to prevent aggregation of Fe3O4 nanoparticles.

Achieving Fast and Durable Lithium Storage through Amorphous FeP Nanoparticles Encapsulated in Ultrathin 3D P-Doped Porous Carbon Nanosheets.

Conversion-type transition-metal phosphide anode materials with high theoretical capacity usually suffer from low-rate capability and severe capacity decay, which are mainly caused by their inferior electronic conductivities and large volumetric variations together with the poor reversibility of discharge product (Li3P), impeding their practical applications. Herein, guided by density functional theory calculations, these obstacles are simultaneously mitigated by confining amorphous FeP nanoparticles into ultrathin 3D interconnected P-doped porous carbon nanosheets (denoted as FeP@CNs) via a facile approach, forming an intriguing 3D flake-CNs-like configuration. As an anode for lithium-ion batteries (LIBs), the resulting FeP@CNs electrode not only reaches a high reversible capacity (837 mA h g-1 after 300 cycles at 0.2 A g-1) and an exceptional rate capability (403 mA h g-1 at 16 A g-1) but also exhibits extraordinary durability (2500 cycles, 563 mA h g-1 at 4 A g-1, 98% capacity retention). By combining DFT calculations, in situ transmission electron microscopy, and a suite of ex situ microscopic and spectroscopic techniques, we show that the superior performances of FeP@CNs anode originate from its prominent structural and compositional merits, which render fast electron/ion-transport kinetics and abundant active sites (amorphous FeP nanoparticles and structural defects in P-doped CNs) for charge storage, promote the reversibility of conversion reactions, and buffer the volume variations while preventing pulverization/aggregation of FeP during cycling, thus enabling a high rate and highly durable lithium storage. Furthermore, a full cell composed of the prelithiated FeP@CNs anode and commercial LiFePO4 cathode exhibits impressive rate performance while maintaining superior cycling stability. This work fundamentally and experimentally presents a facile and effective structural engineering strategy for markedly improving the performance of conversion-type anodes for advanced LIBs.

One‐step surface nitridation of CoO for high‐energy‐density lithium‐ion batteries

The surface of micrometer-sized CoO particles is finely tuned by a nitride produced through one-step process with various heat treatments with solid-state urea, which has been frequently used as a surfactant for the nanosynthesis of CoO in aqueous media. After conducting simple surface nitridation processes without a solvent using an autogenic reactor, it is found that the CoO surface is clearly modified by a cobalt-rich nitride (Co5.47N) by X-ray diffraction analyses. As the heat treatment temperature increases, the content of the cobalt nitride also grows. A temperature above 500°C for the surface modification causes an initial specific capacity loss because of the growth of the inert cobalt nitride; however, the surface-modified samples exhibit a more prolonged cycle life than the pristine CoO due to decreased kinetic barrier and enhanced surface stability. Additionally, the surface nitridation leads to a high rate capability, which can solve poor power density for conversion-type anode materials. It is found that the surface nitridation allows a high electrical conductivity and reduces the surface charge transfer resistance.

Macroporous Mn3O4 microspheres as a conversion-type anode material morphology for Li-ion batteries

Transition metal oxides can electrochemically react with Li+ to result in the formation of Li2O and metal nanoparticles, and thus are good candidates as high-capacity anode materials for Li-ion batteries (LIBs). Research on particle designs is required to overcome the large volume change that occurs during charging and discharging processes. Herein, we have assessed the applicability of the macroporous Mn3O4 microspheres as the anode material morphology for LIBs through a single-particle measurement technique and battery tests (using a conventional electrode mixed with conductive carbon and a binder). The intrinsic electrochemical performance of the macroporous Mn3O4 gradually degrades because of the particle fragmentation caused by the volume change. On a conventional electrode mixed with conductive carbon and a binder, the macroporous Mn3O4 microspheres can incorporate nearby carbon particles during the charging and discharging processes, and consequently, the electron conductive pathways are generated within the transformed aggregates, and they play a role in braking the capacity drop. The pores and microstructures within the particles serve as conductive pathways for Li+ and electrons, and they are a means for improving the electrochemical performance of the conversion reaction–based metal oxide anodes.

Ultrasmall SnS Quantum Dots Anchored onto Nitrogen-Enriched Carbon Nanospheres as an Advanced Anode Material for Sodium-Ion Batteries.

Structural pulverization of metal chalcogenides such as Sn-based compounds is a serious issue for development of high-performance anode materials and results in serious capacity fading during continuous charge and discharge cycles. In this work, we synthesize ultrasmall SnS quantum dots (QDs) anchored onto nitrogen-enriched carbon (NC) nanospheres through facile hydrothermal and carbonization processes to prepare a progressive anode material for sodium-ion batteries. The optimized SnS QDs@NC electrode delivered an initial discharge capacity of 281 mAh g-1 at 100 mA g-1 and exhibited excellent cycling stability with a capacity retention of 75% after 500 cycles at a high current density of 1000 mA g-1. Ex situ XRD, XPS, FE-SEM, TEM measurements, and kinetics study were performed to unveil the sodium storage mechanism of the SnS QDs@NC electrode. A sodium-ion full cell assembled with an SnS QDs@NC anode and a Na3V2(PO4)3 cathode exhibited high capacity and good cycling stability. Such a superior electrochemical performance of SnS QDs@NC can be attributed to the synergistic effects of NC and SnS QDs where NC serves as a conducting matrix to support SnS QDs and helps avoid structural degradation. This work provides a promising strategy to resolve the pulverization issue of alloying and conversion-type anode materials.

Encapsulating N-Doped Carbon Nanorod Bundles/MoO2 Nanoparticles via Surface Growth of Ultrathin MoS2 Nanosheets for Ultrafast and Ultralong Cycling Sodium Storage.

Conversion-type anode materials possess high theoretical capacity for sodium-ion batteries (SIBs), owing to multi-electron transmission (2-6 electrons). Mo-based chalcogenides are a class of great promise, high-capacity host materials, but their development still undergoes serious volume changes and low transport kinetics during the cycling process. Here, MoO2 nanoparticles anchored on N-doped carbon nanorod bundles (N-CNRBs/MoO2) are synthesized by a facile self-polymerized route and a following annealing. After hydrothermal sulfuration, N-CNRBs/MoO2 composites are encapsulated by surface growth of ultrathin MoS2 nanosheets, acquiring hierarchical N-CNRBs/MoO2@MoS2 composites. Serving as the SIB anode, the N-CNRBs/MoO2@MoS2 electrode exhibits significantly improved sodium-ion storage properties. The reversible capacity is up to 554.4 mA h g-1 at 0.05 A g-1 and maintains 249.3 mA h g-1 even at 10.0 A g-1. During 5000 cycles, no obvious capacity decay is observed and the reversible capacities retain 334.8 mA h g-1 at 3.0 A g-1 and 301.4 mA h g-1 at 5.0 A g-1. These properties could be ascribed to the vertical encapsulation of MoS2 nanosheets on high-crystalline N-CNRBs/MoO2 substrates. The hierarchical architecture and unique heterostructure between MoO2 and MoS2 synergistically facilitate sodium-ion diffusion, relieve volume changes, and boost pseudocapacitive charge storage of N-CNRBs/MoO2@MoS2 electrode. Therefore, the rational growth of nanosheets on complex substrates shows promising potential to construct anode materials for high-performance batteries.

Bimetal Synergistic Effect Induced High Reversibility of Conversion-Type Ni@NiCo2S4 as a Free-Standing Anode for Sodium Ion Batteries.

Conversion-type anode materials for sodium ion batteries have received extensive attention because of their relatively high theoretical capacity. However, multiple challenging obstacles stand in the way of their commercial application, especially their poor cycling stability resulting from the bad reversibility of the conversion reaction. Herein, Ni-Co bimetal sulfide was selected and investigated with the goal of improving the reversibility of the conversion reaction owing to the similarity of Ni and Co. As expected, when three-dimensional hierarchical Ni@NiCo2S4 (NiCo2S4 nanowires growing on the Ni foam) was applied as the free-standing anode for sodium ion batteries, it demonstrated high capacity and excellent cycling stability (90.65%, 100 cycles) compared with those of monometallic sulfides. Various characterization [in situ X-ray diffraction (XRD), ex situ XRD, ex situ X-ray photoelectron spectroscopy, FESEM mapping, and high-resolution transmission electron microscopy] tests confirmed that the Ni-Co alloy was formed during the discharge process and effectively prevented the crystalline grain growth of conversion reaction products, improving the reaction kinetics and reversibility.

Lithium ion storage in lithium titanium germanate

lithium titanium-based oxides have been demonstrated as good anode materials for lithium-ion batteries. These materials perform at safe operating potential of the electrolyte, but suffer from low energy density. Here, we reported a new type titanium-based anode material, Li2TiGeO5, for lithium-ion batteries, which delivers a reversible specific capacity of 691 mA h g−1 and 68% initial coulombic efficiency under a current density of 0.02 A g−1, with operational potential of 0.5 V vs. Li/Li+. The experiments, including in-situ X-ray diffraction, in-situ Raman spectra, synchrotron-based X-ray absorption spectroscopy, coupled with first-principles calculations, demonstrated multi-electron reaction during discharge/charge process. The lithiation products including electronic conducting TiO and Li–Ge alloy simultaneously with Li-ion conducting Li2O provide good electrochemical performances of Li2TiGeO5 anode in lithium-ion batteries. Those results indicate a conversion reaction mechanism of lithium-ion storage with a high initial coulombic efficiency comparable to that of most other conversion-type anode materials. Our work provides a new class of anode material with large capacity and high safety in lithium-ion batteries.

Mechanism Study of Carbon Coating Effects on Conversion-Type Anode Materials in Lithium-Ion Batteries: Case Study of ZnMn2O4 and ZnO-MnO Composites.

The carbon coating strategy is intensively used in the modification of conversion-type anode materials to improve their cycling stability and rate capability. Thus, it is necessary to elucidate the modification mechanism induced by carbon coating. For this purpose, bare ZnMn2O4, carbon-derivative-coated ZnMn2O4, and carbon-coated ZnO-MnO composite materials have been synthesized and investigated in-depth. Herein, high-temperature synchrotron radiation diffraction is used to monitor the phase transition from ZnMn2O4 to ZnO-MnO composite during the carbonization process. The electrochemical performance has been evaluated by cyclic voltammetry, galvanostatic cycling, and electrochemical impedance spectroscopy. The carbon- and carbon-derivative-coated samples display well-improved cycling stability in terms of suppressed electrode polarization, a moderate increase in resistance, and slight capacity variation. The influence of carbon coating on the intrinsic conversion process is investigated by ex situ X-ray absorption spectroscopy, which reveals the evolution of Zn and Mn oxidation states. This result confirms that the strong capacity variation of the bare ZnMn2O4 is induced not only by the reversible charge storage in the solid electrolyte interphase but also by the phase evolution of active materials. Carbon coating is an effective method to prevent the additional oxidation of MnO to Mn3O4, which leads to a stabilization of the main conversion reaction.

Carbon coated transition metal borates as anode materials for Na-ion batteries

Development of anode materials with high performance is crucial for the successful application of Na-ion batteries. In this study, we provide a novel type of conversion-type anode materials, transition metal borates, as promising candidates for Na-ion storage. The transition metal borates (Fe3BO5 and Ni3(BO3)2) are successfully fabricated by a facile sol-gel route. When they are firstly evaluated for Na-ion storage, they deliver remarkably better Na-ion insertion kinetics and high reversible capacity than transition metal oxides. It’s notable that the conversion reaction can be thoroughly realized for transition metal borates during sodiation/desodiation process accompanying with the change of B-O coordination. First-principles calculation indicates that Na insertion into transition metal borate are energetically much more favorable compared with transition metal oxides. Furthermore, carbon coated borates are designed and firstly prepared, which exhibit good rate capability and excellent cycling stability. Moreover, the Fe3BO5/Na2V3(PO4)2F3 full cell exhibits a high energy density of 180.3 Wh kg−1 at a high power density of 150.1 W kg−1. This study demonstrates a class of new promising conversion-type anodes and also verifies the practical application in Na-ion batteries with high energy/power density.

High performance columnar-like Fe2O3@carbon composite anode via yolk@shell structural design

Abstract Conversion-type reaction anode materials with high specific capacity are attractive candidates to improve lithium ion batteries (LIBs), yet the rapid capacity fading and poor rate capability caused by drastic volume change and low electronic conductivity greatly hinder their practical applications. To circumvent these issues, the successful design of yolk@shell Fe2O3@C hybrid composed of a columnar-like Fe2O3 core within a hollow cavity completely surrounded by a thin, self-supported carbon (C) shell is presented as an anode for high-performance LIBs. This yolk@shell structure allows each Fe2O3 core to swell upon lithiation without deforming the carbon shell. This preserves the structural and electrical integrity against pulverization, as revealed by in situ transmission electron microscopy (TEM) measurement. Benefiting from these structural advantages, the resulting electrode exhibits a high reversible capacity (1013 mAh g−1 after 80 cycles at 0.2 A g−1), outstanding rate capability (710 mAh g−1 at 8 A g−1) and superior cycling stability (800 mAh g−1 after 300 cycles at 4 A g−1). A Li-ion full cell using prelithiated yolk@shell Fe2O3@C hybrid as the anode and commercial LiCoO2 (LCO) as the cathode demonstrates impressive cycling stability with a capacity retention of 84.5% after 100 cycles at 1 C rate, holding great promise for future practical applications.

Fe2O3/C-modified Si nanoparticles as anode material for high-performance lithium-ion batteries

Silicon is widely investigated as an advanced conversion-type anode material for lithium ion batteries due to the high theoretical capacity and natural abundance. However, the practical application is limited by the intrinsic poor conductivity and serious volume change. To promote the reaction kinetics and reversibility of Si electrode, core-shell structured Si@Fe2O3/C nanoparticles are fabricated employing metal-organic-frameworks as sacrificed template of Fe2O3-embedded carbon coating layer. The carbon layer not only boosts the conductivity of Si and Fe2O3 nanoparticles but also accommodates their volume expansion during repeat lithiation/delithiation process. The metallic Fe(0) resulted from the lithiation process helps to improve the conductivity. As anode material for lithium ion batteries, Si@Fe2O3/C delivers high specific capacity (2941.8 mAh g−1 at 100 mA g−1), good cycling stability (680.7 mAh g−1 after 300 cycles at 1 A g−1) and good rate capability (423 mAh g−1 at 10 A g−1).

Electrochemical Properties of Amorphous Silica As an Anode Material for Li-Ion Batteries

After conquering the scene of portable electronics (i.e. mobile phones and laptop computers) since their introduction to the marketplace in 1991, lithium ion batteries (LIBs) are set to further enable wide-scale deployment of electric vehicles (EVs) and hybrid electric vehicles (HEVs). However, a series of challenges still remain with respect to a number of important factors, such as the operational safety of LIBs, raw material supply, cost, recycling and environmental aspects. In order to fulfill future demands for large-scale applications, significant improvements and deeper understanding are required in these areas. As of today, graphite is the anode (negative electrode) material primarily used in commercial LIBs, mainly due to its charge-discharge capacity retention capability and an attractively low, flat operational voltage as well as a manageable voltage hysteresis upon (de)intercalation which altogether maximizes both the energy density and energy efficiency of the cell in which it is employed. However, recent projections regarding the future cost and availability of graphite have prompted researchers to explore alternatives in the context of cheap and sustainable materials for electrochemical energy storage. Silica (SiO2) is currently being explored as a possible alternative candidate material in this context. SiO2 was long disregarded as a potential electrode material due to its apparent electrochemical inactivity. However, studies in recent years have sparked renewed interest in SiO2 after it was demonstrated that modified nano-SiO2 may indeed be electrochemically active. SiO2 is a conversion-type anode material which irreverisbly produces various silicates (e.g. Li4SiO4 and Li2Si2O5) as well as elemental Si during electrochemical lithiation. Although the precise reaction mechanism is still a topic for debate, it is believed that the by-products formed in-situ during electrochemical cycling can mechanically buffer the stress and strain associated with continued (de)lithiation of Si and thereby extending the cycle life of the electrode material. The present study systematically investigates the electrochemical properties of amorphous SiO2 as a negative electrode material for Li-ion batteries. The SiO2 materials in question include spherical nano-particulate SiO2 recovered as an industrial by-product or naturally nano-sized 3D-architectured SiO2 extracted from a renewable resource of biological origin – the main motivation here clearly being the study of dirt-cheap, highly abundant materials and the possible prospect of their implementation in electrochemical storage devices. By virtue of its electronically insulating properties, SiO2 needs to be carefully engineered in order to activate the material. Important factors in this regard include control of particle morphology, surface area and porosity as well as enhancement of electronic conductivity. Consequently, various carbon sources (i.e. glucose, sucrose, starch) have been utilized in varying amounts in order to achieve a conductive carbon coating on the SiO2 particles via high-temperature pyrolysis (i.e. carbonization), ultimately yielding SiO2/C composites with improved electrochemical properties in relation to bare SiO2. Here, these variations in carbon precursor, carbon content and coating thickness etc. are directly related to the electrochemical activity of the different SiO2 materials. These aspects are additionally highlighted by means of a series of advanced characterization techniques. The influence of particle size and morphology is further made possible by the direct comparison of spherical SiO2 nanoparticles to the intricate 3D-architecture of the SiO2 derived from harvested biomass. Preliminary results indicate it appears possible to electrochemically activate (i.e. displace Si followed by its electrochemical lithiation at low voltages vs. Li+/Li) the latter via careful considerations in terms of electrode design and electrochemical testing procedures which results in gravimetric capacities of >1000 mAh g-1 at an average (de)lithiation voltage in the range of 0.2-0.4 V vs. Li+/Li. By comparison, the spherical nanoparticles exhibit significantly lower electrochemical activity, i.e. a reversible gravimetric capacity of 300-400 mAhg-1 with highly sloping voltage profiles in an electrochemical cycling windowof ~0-2 V vs. Li+/Li.

In situ visualization of sodium transport and conversion reactions of FeS2 nanotubes made by morphology engineering

Iron disulfide (FeS2), existing in nature as pyrite, holds great promise as a conversion-type anode material for sodium-ion batteries (SIBs), owing to its low cost and high theoretical capacity. However, the large volume expansion and the sluggish electrode reaction kinetics during conversion reactions impede its large-scale practical application in SIBs. Here, we demonstrate the utilization of morphological engineering to achieve poly-crystalline FeS2 nanotubes (NTs) consisting of tiny FeS2 crystallites. In situ transmission electron microscopy observations reveal that 1D shape can afford straight pathways for Na transport to expedite reaction kinetics, and poly-crystalline structure can buffer large volume expansion and structural strain. Furthermore, high-resolution imaging and electron diffraction were utilized to track phase evolution associated with conversion reactions in real time. We have identified an intercalation-conversion reaction mechanism from the FeS2 phase to the Na2S + Fe phases via the intermediate NaFeS2 phase upon initial sodiation. Impressively, a reversible and symmetric conversion reaction between NaFeS2 phase and Na2S + Fe phases is established during subsequent sodiation−desodiation cycles. Notably, this is the first report of FeS2 NTs investigated for secondary battery electrode material. This work not only provides valuable insights into sodium storage mechanism of FeS2 material, but also corroborates the pivotal role of morphology engineering in optimizing the microstructure of electrode materials for advanced SIBs.

Closed-loop hydrometallurgical treatment of end-of-life lithium ion batteries: Towards zero-waste process and metal recycling in advanced batteries

Abstract This work presents an enhanced hydrometallurgical process for recycling lithium ion batteries. First, end-of-life batteries were processed in a physical pre-treatment plant to obtain a representative electrode material. The resulting leachate was purified forth by iron-precipitation, liquid–liquid extractions, and an innovative Li–Na separation, in order to obtain valuable products. These products include high-grade graphite, cobalt oxide (Co3O4, purity 83%), cobalt oxalate (CoC2O4, purity 96%), nickel oxide (NiO, purity 89%), and lithium carbonate (Li2CO3, purity 99.8%). The recovery rate was quantitative for graphite, between 80% and 85% for cobalt depending on the nature of the recovery method, 90% for nickel, and 72% for lithium. Secondary streams were also valorized to obtain sodium sulfate (Na2SO4, purity 96%), and MnCoFe2O4 magnetic nano-sorbents according to the zero-waste concept. In order to close the loop, recycled Co3O4 and NiO were used as conversion-type anode materials for advanced lithium ion batteries showing promising performances.

Rational Combination of an Alabandite MnS Laminated Pyrrhotite Fe1–xS Nanocomposite as a Superior Anode Material for High Performance Sodium-Ion Battery

Conversion-based transition metal sulfide compounds have been considered as a promising anode material for sodium-ion batteries (SIBs). The major obstacle of these conversion-type anode materials i...