Reversible Lithium Storage Capacity Research Articles

Pyrolysis combined with KOH activation to turn waste apple pruning branches into high performance electrode materials with multiple energy storage functions

In this paper, porous activated carbon is successfully prepared from waste apple pruning branches (PGZ), which demonstrates an ultra-high specific capacity of 505 F g −1 at a current density of 1 A g −1 with excellent rate performance (215 F g −1 at 50 A g−1). The assembled supercapacitor also exhibits excellent specific capacitance of 320 F g −1 (at 0.5 A g−1) and 160 F g −1 (at 20 A g−1), with a high energy density of 12.03 Wh kg −1 at a power density of 250.45 W kg −1 in 6 M KOH. In 1 M Na2SO 4 and 1 M Et4 NBF4/AC electrolytes, high energy densities of 18.8 Wh kg −1 and 44.1 Wh kg −1 could be achieved. It also exhibits high reversible lithium storage capacity of 636.2 mAh g −1 at 0.2 C and retains 390 mAh g −1 after 1000 cycles. Even at 0.8 C, the storage capacity is still as high as 327 mAh g −1, with 282 mAh g −1 retained after 1000 cycles. These excellent electrochemical properties are attributed to the hierarchical porous structure of the sample prepared under the optimum conditions. The large pores in the hierarchical structure will lead to high-speed capacitive properties due to their low ion transport resistance while the small mesopore and micropore provide a large electrode and electrolyte interface, which can facilitate charge transfer reaction. These outstanding performances highlights the first example of using waste apple pruning branches as a sustainable source of raw materials for the preparation of high value-added porous carbon materials with multiple energy storage functions.

Surface N Sites Mediate the Formation of Li Metal Cluster@N-Enriched Hierarchically Porous Carbon for Ultrahigh-Capacity Lithium Storage.

Graphite is the popular anode material of current lithium-ion batteries (LIBs). However, its low specific capacity and poor lithium intercalation potential hinder its use for high-power and large-scale energy storage. To meet the demand for energy storage, novel anode materials with high capacity, fast chargeable capability, and long cycle life are of great interest. Herein, we demonstrate an advanced nitrogen-enriched hierarchical porous carbon serving as a lithiophilic anode material for ultrahigh capacity and long-life LIBs. NHPC-700 (under optimal synthetic conditions), featuring a high surface area, rich N-doping, high porosity, and partially graphitized nanosheet structures, is successfully fabricated from a Schiff-base copolymer via a template-incipient wetness impregnation method. NHPC-700 exhibits an ultrahigh reversible lithium storage capacity of 2796 mA h g-1 at 0.1 A g-1 while still maintaining a high capacity of 526 mA h g-1 at 10 A g-1 after 1000 cycles. Theoretical and experimental studies reveal that this remarkable Li storage performance can be attributed to the large number of N lithiophilic sites on the inner surface of the small mesoporous pores. These sites guide Li metal nucleation in the initial period and control well the volume variation during charge/discharge cycles, thus exhibiting excellent cycle stability and great potential for practical application.

CO2-derived nitrogen doped porous carbon as advanced anodes for lithium-ion capacitors

Porous carbon is considered one of the most promising anode materials for lithium-ion capacitors due to its high ionic and electronic conductivity, high lithium storage capacitance and high chemical stability. However, the green and low-carbon preparation is a great challenge for the current porous carbon, especially for heteroatoms doped porous carbon. Herein, we report a low-carbon and environmentally friendly method to prepare N-doped porous carbon by the novel reaction of greenhouse gas CO2 with 5LiH-LiNH2. N-doped porous carbon delivers a reversible lithium storage capacity of 904 mAh g−1 at 0.1 A g−1, When paired with commercial activated carbon, the as-assembled lithium-ion capacitors provide a high energy density of 112 Wh kg−1 at a power density of 198.6 W kg−1 with a capacitance retention of 72% at 1.0 A g−1 after 6000 cycles. This work provides a green and low-carbon strategy for converting greenhouse gas CO2 into N-doped porous carbon for high-performance lithium-ion capacitors.

Low-temperature de-alloying and unique self-filling interface optimization mechanism of layered silicon for enhanced lithium storage.

Layered silicon (L-Si) anodes are celebrated for their high theoretical capacity but face significant challenges regarding safety and material purity during preparation. This study addresses these challenges by employing NH4Cl-CaSi2 as the raw material in a gas-solid de-alloying process, which enhances both safety and purity compared to traditional methods. The L-Si anodes produced demonstrate outstanding electrochemical performance, delivering a high reversible lithium storage capacity of 1497.7 mA h g-1 at a current density of 0.5 A g-1, and exhibiting stable performance over 1200 charge-discharge cycles. In situ and ex situ characterizations reveal that electrolyte decomposition products effectively fill the voids within the electrode, while the gradual disintegration of the L-Si structure contributes to the formation of a dense, conductive network. This process enhances lithium ion transport and exploits the capacitive storage benefits of layered silicon.

Crystallographic engineering to improve the reversible lithium storage capacity of Li2ZnTi3O8 in fast charging batteries

Improving the discharge capacities of anode materials for lithium-ion batteries without sacrificing their cycling stability and rate performance at high current densities is a big challenge due to the limited Li+ diffusion kinetics and electronic conductivity. Therefore, the introduction of dissimilar metal ions into the crystal to form doping defects can effectively improve the microstructure and ion transport kinetics, thus significantly increasing the specific capacity. As an example, a new metal ion-substituted Li2ZnTi3O8 anode material with low agglomeration and high diffusion coefficient performs a large specific capacity of 112.4 mAh g−1 at 7.0 A g−1 and good cycle stability, as well as outstanding rate performance. The obtained electrochemical performance enhancement can be attributed to guest ions changing the microscopic crystal structure, including the influence of dopant atoms on the surrounding bulk atoms and the creation of vacancies, as well as enlarged ion transport tunnels. This strategy provides an effective way to improve the eXtreme Fast Charging of the lithium-ion battery.

Hierarchical-Structured Fe2O3 Anode with Exposed (001) Facet for Enhanced Lithium Storage Performance.

The hierarchical structure is an ideal nanostructure for conversion-type anodes with drastic volume expansion. Here, we demonstrate a tin-doping strategy for constructing Fe2O3 brushes, in which nanowires with exposed (001) facets are stacked into the hierarchical structure. Thanks to the tin-doping, the conductivity of the Sn-doped Fe2O3 has been improved greatly. Moreover, the volume changes of the Sn-doped Fe2O3 anodes can be limited to ~4% vertical expansion and ~13% horizontal expansion, thus resulting in high-rate performance and long-life stability due to the exposed (001) facet and the unique hierarchical structure. As a result, it delivers a high reversible lithium storage capacity of 580 mAh/g at a current density of 0.2C (0.2 A/g), and excellent rate performance of above 400 mAh/g even at a high current density of 2C (2 A/g) over 500 cycles, which is much higher than most of the reported transition metal oxide anodes. This doping strategy and the unique hierarchical structures bring inspiration for nanostructure design of functional materials in energy storage.

Adsorption-Assisted Redox Center in Porous Organic Frameworks for Boosting Lithium Storage.

Due to the designable structure and capacity, organic materials are promising candidates for lithium-ion batteries. Herein, we report a novel type of porous organic frameworks (POFs) based on the coupling reaction of diazonium salt as the anodes for lithium ion storage. The active center containing an azo group and the adjacent lithium-philic adsorption site is constructed to investigate the electrochemical behaviors and reaction mechanism. As synthesized POF material (named as POF-AN) exhibits high reversible lithium storage capacities of 523 mAh g-1 at 0.5 A g-1 and 445 mAh g-1 at 2.0 A g-1 after 1500 cycles, showing excellent cycle stability and rate performance. The detailed characterizations reveal that the azo group can act as an electrochemical active site that reversibly bonds with Li-ions, and the adjacent oxygen atoms can electrostatically adsorb with Li-ions to promote the lithium storage reaction. This adsorption-assisted three-atom redox center is beneficial to synergistically enhance the adsorption and intercalation of lithium ions, which can further improve the capacity and cycle stability. By replacing the precursor, it is also facile to synthesize more similar structure types. The reversible redox chemistry of the adsorption-assisted three-atom active center provides new opportunities for the development of long lifespan and high-rate organic anodes.

Carbon polyhedra encapsulated Si derived from Co-Mo bimetal MOFs as anode materials for lithium-ion batteries

Silicon (Si) holds promise as an anode material for lithium-ion batteries (LIBs) as it is widely available and characterized by high specific capacity and suitable working potential. However, the relatively low electrical conductivity of Si and the significantly high extent of volume expansion realized during lithiation hinder its practical application. We prepared N-doped carbon polyhedral micro cage encapsulated Si nanoparticles derived from Co-Mo bimetal metal-organic framework (MOFs) (denoted as Si/CoMo@NCP) and explored their lithium storage performance as anode materials to address these problems. The Si/CoMo@NCP anode exhibited a high reversible lithium storage capacity (1013 mAh g−1 at 0.5 A g−1 after 100 cycles), stable cycle performance (745 mAh g−1 at 1 A g−1 after 400 cycles), and excellent rate performance (723 mAh g−1 at 2 A g−1). Also, the constructed the full-cell NCM811//Si/CoMo@NCP exhibited well reversible capacity. The excellent electrochemical performances of Si/CoMo@NCP were attributed to two unique properties. The encapsulation of NCP with doped nitrogen and porous structural carbon improves the electrical conductivity and cycling stability of the molecules. The introductions of metallic cobalt and its oxides help to improve the rate capability and lithiation capacity of the materials following multi-electron reaction mechanisms.

Deciphering Structural Origins of Highly Reversible Lithium Storage in High Entropy Oxides with In Situ Transmission Electron Microscopy.

Configurational entropy-stabilized single-phase high-entropy oxides (HEOs) have been considered revolutionary electrode materials with both reversible lithium storage and high specific capacity that are difficult to fulfill simultaneously by conventional electrodes. However, precise understanding of lithium storage mechanisms in such HEOs remains controversial due to complex multi-cationic oxide systems. Here, distinct reaction dynamics and structural evolutions in rocksalt-type HEOs upon cycling are carefully studied by in situ transmission electron microscopy (TEM) including imaging, electron diffraction, and electron energy loss spectroscopy at atomic scale. The mechanisms of composition-dependent conversion/alloying reaction kinetics along with spatiotemporal variations of valence states upon lithiation are revealed, characterized by disappearance of the original rocksalt phase. Unexpectedly, it is found from the first visualization evidence that the post-lithiation polyphase state can be recovered to the original rocksalt-structured HEOs via reversible and symmetrical delithiation reactions, which is unavailable for monometallic oxide systems. Rigorous electrochemical tests coupled with postmortem ex situ TEM and bulk-level phase analyses further validate the crucial role of structural recovery capability in ensuring the reversible high-capacity Li-storage in HEOs. These findings can provide valuable guidelines to design compositionally engineer HEOs for almighty electrodes of next-generation long-life energy storage devices.

Graphene cladded cobalt phosphide nanoparticles with a sandwich structure by plasma for lithium and sodium storage.

Graphene cladded cobalt phosphide nanoparticles with a sandwich structure are synthesized using Ar-H2-P plasma. In situ phosphorization and graphene reduction are achieved at the same time. Benefitting from the sandwich structure and heterointerface between CoP and RGO, the electrode delivered a high reversible capacity and durable lifespan for both lithium and sodium storage.

Overall Carbon-neutral Electrochemical Reduction of CO2 in Molten Salts using a Liquid Metal Sn Cathode.

An overall carbon-neutral CO2 electroreduction requires enhanced conversion efficiency and intensified functionality of CO2-derived products to balance the carbon footprint from CO2 electroreduction against fixed CO2. A liquid Sn cathode is herein introduced into electrochemical reduction of CO2 in molten salts to fabricate core-shell Sn-C spheres (Sn@C). An in-situ generated Li2SnO3/C directs a self-template formation of Sn@C. Benefitting from the accelerated reaction kinetics from the liquid Sn cathode and the core-shell structure of Sn@C, a CO2-fixation current efficiency higher than 84% and a high reversible lithium-storage capacity of Sn@C are achieved. The versatility of this strategy is demonstrated by other low melting point metals, such as Zn and Bi. This process integrates energy-efficient CO2 conversion and template-free fabrication of value-added metal-carbon, achieving an overall carbon-neutral electrochemical reduction of CO2.

Cage-like MnSe@PPyC/rGO as superior dual anode materials in Li/Na-ions storage

Along with high reversible capacity, superior cycling and rate performances, transition metal-based materials have been considered as promising dual anode materials for lithium/sodium ion storage. However, one of the greatest challenges during the selenization process is that the as-prepared transition metal selenides with designed morphology could retain the original morphology of transition metal oxides well. To address this key issue, in this work, a cage-like MnSe@PPyC/rGO composite is successfully developed by one-step selenization/carbonization treatment with in-situ formed polypyrrole coated MnO2 nanorods and graphene oxide as precursors, which effectively preserve the original rod-like morphology and endow a conductive network. The morphology control process, composition and microstructural change have been systematically characterized with SEM, EDS, TEM, TGA, BET, XRD, and XPS. Benefited from the above composition and structure, cage-like MnSe@PPyC/rGO exhibits good rate performance (310.3 mAh/g at 3.2 A/g) and high reversible lithium storage capacity (776.9 mAh/g at 0.1 A/g after rate testing). As anode materials for SIBs, the composite demonstrates high capacity of 546.6 mAh/g at 0.2 A/g as well as outstanding rate capability and cycle stability (294.4 mAh/g after 455 cycles at 2 A/g and 194.5 mAh/g after 2000 cycles at 10 A/g). The finding provides a new avenue for the study of transition metal/carbon composites with special morphology as dual anode materials for Li/Na-ions storage.

Mns@N/S-C Anode Electrode with High Lithium Storage Property By Simple Polyol Refluxing Method

Transition-metal sulfides are of significant interest as rechargeable battery anodes owing to their low cost, wide availability, eco-friendliness, and high theoretical capacities. However, the structural change due to the volume change during the electrochemical reaction and the capacity decrease due to the dissolution of polysulfide remain as problems. Herein, a simple one-pot polyol refluxing method is used for fabricating a manganese sulfide (MnS) electrode composited with nitrogen and sulfur co-doped carbon (MnS@NS-C) for high-power lithium-ion batteries. This composite electrode is a carbon-coated nanostructure, exhibits unique spherical particle morphology with optimized average partical size (300 < x < 500nm) and porous features. Owing to its nanostructure, porous nature, and an electrically conducting carbon coating network co-doped with heteroatoms, the composite electrode overcomes the strong structural variations and polysulfide dissolution to afford high practical storage capacities, long-term cycle stability, and outstanding rate capability. The MnS@NS-C electrode demonstrated high reversible lithium storage capacities of 999 mAh g-1 at 0.1 A g-1, the highest reversible capacity of 761 mAh g-1 at 2 A g-1 for over 300 cycles, and average rate capacities of 453 mAh g-1 at 10 A g-1. In-situ X-ray diffraction investigations indicated a uniquely combined intercalation-cum-conversion reaction mechanism leading to β-Li2(1-x)MnS, Li2S, and Mn discharge products. The results of this study can provide deep insights into understanding reaction mechanism and motivate further study of transition-metal sulfides for prospective high-energy battery applications. References N. Nitta, F. Wu, J. T. Lee and G. Yushin, Mater. Today, 2015, 18, 252–264. V. Etacheri, R. Marom, R. Elazari, G. Salitra and D. Aurbach, Energy Environ. Sci., 2011, 4, 3243–3262. Y. Hao, C. Chen, X. Yang, G. Xiao, B. Zou, J. Yang and C. Wang, J. Power Sources, 2017, 338, 9–16. Y. Ye, C. Jo, I. Jeong and J. Lee, Nanoscale, 2013, 5, 4584–4605. L. Zhang, L. Zhou, H. Bin Wu, R. Xu and X. W. Lou, Angew. Chemie - Int. Ed., 2012, 51, 7267–7270.

Boosting lithium storage performance of diatomite derived Si/SiOx micronplates via rationally regulating the composition, morphology and crystalline structure

Nano- and micro-sized silicon and its low valence oxide show as one of the potentially promising anode materials for lithium-ion batteries (LIBs) with high energy density. Even so, the high price of nanosized silicon and poor tolerance against mechanical stress of microsized silicon limit their practical applications as silicon anode materials. Herein, using diatomite, a naturally occurring siliceous sedimentary rock, as a precursor, a series of porous Si/SiOx micronplates are synthesized through magnesiothermic reduction followed by an acid etching process. When evaluated as LIB anodes, the Si/SiOx micronplates exhibit significant improvement of cycle stability compared to commercial silicon anodes. Moreover, etched Si/SiOx micronplates achieve a highly reversible lithium storage capacity of 980 mAh g-1 at 100 mA g-1 after 100 cycles, which is over two times as high as unetched Si/SiOx anodes. The boosting lithium storage performance is attributed to the rational regulations of composition, morphology, and crystalline structures of microsized Si/SiOx, which demonstrate that the as-prepared Si/SiOx micronplates should be a series of promising anode materials for high energy density LIBs.

Finite phosphorene derived partial reduction of metal organic framework nanofoams for enhanced lithium storage capability

As a new class of crystalline porous materials, metal organic frameworks (MOFs) are promising in lithium-ion batteries (LIBs). However, the electrical conductivity and stability of conventional MOFs cannot meet the demand by next-generation high-rate LIBs. Herein, a partially-reduced MOF nanofoam (NiCo-MOF(P) NF) is synthesized by adding a small amount of phosphorene during the sol-gel self-assembly process. Since the amount of surface metallic species is increased, the carrier concentration and electrical conductivity are improved. Moreover, the structural stability is enhanced by phosphorus-oxygen and phosphorus-metal bonds generated during partial reduction. Although the phosphorus concentration is quite low (<2 wt%), the NiCo-MOF(P) NFs exhibit three times higher reversible lithium storage capacity (1230.3 mA h g−1 at 0.2 A g−1) compared to the stock NiCo-MOF after 250 cycles. At a higher current density (2.0 A g−1), the NiCo-MOF(P) NFs maintain the high capability (550 mA h g−1) after 700 cycles. These results demonstrate that the novel process of phosphorene-induced mild reduction improves the lithium storage capability of mixed-valence MOFs. The surface functionalization strategy and unique in situ molecular interactions have large potential in the development of advanced functional materials.

One-pot synthesis of nanosized MnO incorporated into N-doped carbon nanosheets for high performance lithium storage

As potential anode materials for lithium-ion batteries, transition metal oxides have been extensively investigated due to their high theoretical capacity. Nevertheless, how to address rapid capacity degradation and improve rate capability is still a big challenge. Herein, nanosized MnO incorporated into N-doped carbon nanosheets (MnO/NCN) was rationally designed by a facile one-pot salt-templated synthesis method. The nanosized MnO particles (around 20 nm) were powerfully anchored on the ultrathin N-doped carbon nanosheets to build a high-efficiency electrons/ions hybrid conductive framework. In addition, based on the stable interfacial interaction between MnO and N-doped carbon nanosheets, the MnO/NCN hybrid exhibits great structural stability, thus delivering high reversible lithium storage capacity (719 mA h g−1 at 0.1 A g−1) and superior stability (497 mA h g−1 at 1 A g−1 over 1000 cycles). Besides, the assembled lithium-ion capacitor with MnO/NCN anode exhibits excellent energy-power characteristics (142 W h kg−1 at 412 W kg−1). Such impressive lithium storage performance demonstrates that the MnO/NCN electrode is promising for large-scale energy storage devices.

Interfacial covalent bonding enables transition metal phosphide superior lithium storage performance

High theoretical capacity and moderate redox potential enable transition metal phosphide (TMP) sparkle under a spotlight as viable anode materials for lithium-ion batteries (LIBs). However, TMP suffers from severe voltage hysteresis and poor reversibility due to the breaking and formation of TM-P and Li-P bonds during lithiation/delithiation processes, resulting in significant energy dissipation and rapid capacity decay. Besides, traditional thermal phosphorization involves generation of toxic PH3, which contradicts green chemistry concept. Herein, Ni2P@C composite is successfully achieved under plasma activation with Ni MOF-74 and red phosphide as the starting materials. The monodispersed Ni2P nanoparticles are uniformly anchored within carbon matrix through covalent chemical bonding of C-O-Ni and C-P. Systematic experimental analysis and theoretical calculation indicates that such efficient interfacial chemical linkage could weaken TM-P bonds and bridge the gap between Ni2P nanoparticles and carbon matrix, thus promoting the conversion reversibility during charge/discharge reactions. Benefited from the unique structure, voltage hysteresis of Ni2P@C is significantly suppressed, the reversible lithium storage capacity and cycling stability is greatly enhanced. By employing Ni2P@C and commercial LiFePO4 as anode and cathode, the full LIBs delivers a high reversible capacity of 0.6 mAh cm−2 after 300 cycles at 1.7 mA cm−2. This strategy is expected to shed more light on interfacial chemical linkage towards rational design of advanced materials for LIBs.

SnO2/SnxMo1−xO3−x solid solution nanocomposites: Demonstration of enhanced lithium storage behavior with general synergistic effects

SnO2/SnxMo1−xO3−x solid solution-based nanocomposites have been prepared via a two-step hydrothermal and following annealing processes. At a Sn/Mo molar ratio of 1:2 (the Sn/Mo = 1:2), a single-phase SnxMo1−xO3−x with ionic flake-like structure can be obtained; while, a SnO2/SnxMo1−xO3−x solid solution nanocomposite can be obtained at a Sn/Mo molar ratio of 1:1 (the Sn/Mo = 1:1), which combines with iconic sphere and flake-like structure. Then, electrochemical properties are systematically studied with pure SnO2 and pure MoO3 comparisons as anodes for LIBs. The after cycled Sn/Mo = 1:1 electrode could contain three phases of metallic Sn, MoO2 and an amorphous Sn-Mo oxides, which provide a general synergistic effect to enhance the surface charge contribution, reduce the charge transfer resistance and increase the reaction kinetics. Specifically, the Sn/Mo = 1:1 electrode exhibits a high initial coulombic efficiency of 73.5% with an excellent reversible lithium storage capacity of 735 mAh g−1 at a current density of 0.4 A g−1 after 500 cycles, and a high-rate performance with a specific capacity of 337 mAh g−1 can be obtained at current density of 4 A g−1. This work could provide some inspirations to design solid solution-based nanocomposite with a general synergistic effect to enhance the electrochemical performance for lithium storage application.

Hierarchical core/shell titanium dioxide/molybdenum disulfide nanosheets coupled with carbon architecture for superior lithium/sodium ion storage

The peculiar core/shell structure with abundant interfaces is favorable for Li+/Na+ storage, which can elevate the efficiency of energy storage and conversion. Herein, a unique core/shell structure composite with diverse interfaces was successfully designed and fabricated via a facile coordination reaction combined with thermal treatment. Specially, well-crystallized TiO2 nanoparticles were encapsulated and embedded in carbon nanospheres wrapped with MoS2 nanosheets, leading to abundant interfacial structure and boundaries. Benefitting from the synergistic effect between numerous interfaces and distinctive hierarchal core/shell structure, such a hybrid material possesses fascinating features including ultrafast ion diffusion, plentiful storage active sites and prominent electric conductivity. As a proof of concept, as-prepared samples demonstrated superior reversible lithium storage capacity and hybrid lithium-ion capacitor. What is more, when the material was acted as anode material for SIBs, the discharge capacity maintained at a high capacity of 267.2 mA h g−1 after 1000 cycles at 2.0 A g−1. This work highlights a convenient strategy to synthesize other hybrid materials for electrode materials of energy storage and conversion applications.

Dual‐Ligand Zn‐Based Metal–Organic Framework as Reversible and Stable Anode Material for Next Generation Lithium‐Ion Batteries

Metal–organic frameworks (MOFs) have received intensive scientific attention as electrode materials for lithium‐ion batteries because of their tailorable physical and chemical properties by incorporating different organic ligands. Herein, a zinc‐based MOF (Zn‐MOF) with a special dual‐ligand system, tris(4‐(1H‐1,2,4‐triazol‐1‐yl)phenyl)amine and dihydroxylterepthate, as anode material for lithium‐ion batteries is successfully fabricated. The activated Zn‐MOF based battery delivered a reversible and efficient lithium storage capacity of ≈200 mA h g−1 at 0.5 A g−1 with a 99% Coulombic efficiency over 1000 cycles. The sweep rate cyclic voltammetry and ex situ Fourier transform infrared spectroscopy on the electrode materials at different charging/discharging states reveal that lithium insertion in the organic moiety with a diffusion‐controlled process plays a critical role in the storage mechanism of the Zn‐MOF anode. Further spectroscopic analysis reveals the excellent material stability of dual‐ligand Zn‐MOFs with limited solid–electrolyte interface growth under long‐term charge–discharge operation, which is beneficial for next‐generation battery anodes.