Enhanced Lithium Storage Performance Research Articles

Three-dimensional porous structure CoP/N-doped carbon nanospheres as anode for enhanced lithium storage performance

Transition metal phosphides (TMPs) with high theoretical capacities and safe operating voltage are recognized as prospective anode materials for lithium-ion batteries (LIBs). While, the huge volume expansion and low conductivity of TMPs still restrict their applications. Engineering nanostructured composites consisting of TMPs and conductive carbon-based materials is of great importance to improve electrochemical performance. Herein, a novel and facile pyrolysis-oxidation-phosphidation approach is designed to fabricate porous nanospheres composing of CoP nanoparticles and N-doped carbon substrate. The abundant pores in CoP/N-C provide ample active sites for lithium storage and facilitate Li+ transport. The introduction of N-doped carbon substrate enhances the electrical conductivity, allowing CoP to maintain its structure during cycling. The CoP/N-C anode achieves remarkable cycle performance, maintaining an extremely stable cycle life over 2000 cycles at 5 A g−1. More importantly, the full cell consisting of CoP/N-C and LiFePO4 also exhibits a prominent cycling durability with a capacity retention of 96.5 % at 0.1 A g−1 after 150 cycles. This work proposes a simple and feasible structural engineering strategy, which can provide a new way for optimizing the electrochemical performance of conversion-type anode materials.

Fabrication of NiO-CuO/RGO Composite for Lithium Storage Property

The lithium storage performance of binary transition metal oxide/graphene composites as anode materials has been attracting more interest from researchers, based on the fact that binary transition metal oxides and graphene are expected to create a synergistic effect and exhibit improved lithium storage characteristics. In this work, a NiO-CuO/reduced graphene oxide composite (NiO-CuO/RGO) was prepared by an ultrasonic agitation process. When the NiO-CuO/RGO is applied to the anode material for lithium-ion batteries (LIBs), the batteries display high discharge capacities (at 730 mA h/g after 100 cycles at 100 mA/g), high-rate performance (311 mA h/g with 5000 mA/g), and excellent stable cyclability (375 mA h/g within 2000 mA/g after 400 cycles). Such results indicate that the combination of NiO-CuO and RGO leads to enhanced lithium storage performance, for the RGO sheets inhibit the large volume change of binary NiO-CuO and enhance the fast transport of both lithium ions and electrons during the repeated lithium cycling processes.

Enhanced lithium storage performance of MoS2/C3N4 composites based on the structure design by controlling the amount of C3N4

In this paper, MoS2/C3N4 composites are prepared using a simple hydrothermal method, with alterations made to the weight of the g-C3N4 precursor, to explore the influence of C3N4 amount on lithium storage ability and other properties such as morphological/structural change. The support of C3N4 enhances the electronic conductivity of MoS2 and reduces the volume change of MoS2 as it undergoes continuous charging and discharging. Besides, the good formation of MoS2/C3N4 heterostructure, which is generated by the appropriate addition of the precursors, supplies more active sites for Li+ and leads to faster ionic diffusion rate and electronic transfer speed. Profiting from the above advantages, the MCN-100 could retain excellent reversible capacity of 533.2 mAh/g even under ultrahigh current of 5 A/g after 100 cycles and exhibited superior rate performance of 1414.4 mAh/g at 1 A/g.

Synthesis of nanosheet-like α-Ni(OH)2/g-C3N4 hybrid anode material with enhanced lithium storage performance

Nickel hydroxide (Ni(OH)2) has been recognized as a promising anode material for lithium-ion batteries (LIBs) because of its high theoretical capacity, cost-effectiveness, and simple synthesis method. However, the application of Ni(OH)2 is hampered by its volume effect and poor electrical conductivity. To address these challenges, herein, a α-Ni(OH)2/g-C3N4 composite is prepared by a hydrothermal approach. The composite possesses a hierarchical nanosheet-like morphology with fibrous nanostructures on the surface. Due to the unique hybrid nanostructure and the synergistic effect of α-Ni(OH)2 and g-C3N4 components, the α-Ni(OH)2/g-C3N4 composite exhibits significantly enhanced lithium storage performance in terms of electrochemical activity, cyclability, and kinetics than the bare α-Ni(OH)2 counterpart. Specifically, the α-Ni(OH)2/g-C3N4 achieves a remarkable capacity of 696 mA h g−1 after 400 cycles at 0.5 A g−1, far larger than the corresponding value (96 mA h g−1) of pure α-Ni(OH)2. CV and GITT analysis demonstrate the α-Ni(OH)2/g-C3N4 composite has an obvious pseudocapacitance behavior and a much smaller polarization effect than the bare α-Ni(OH)2 during cycling. This work could provide clues for the structural design and performance improvement of nickel hydroxide-based anode materials for LIBs.

Triblock Polymer/Acetylene Black Dual‐Assisted Preparation of Ge/C Nanocomposites with Superior Lithium Storage Performance

AbstractAnode materials based on IV main group elements like Si, Ge, and Sn show great potential for lithium‐ion batteries (LIBs) due to their high specific capacity and low working potential. However, issues such as volume expansion and lattice pulverization hinder their practical usage. To address these issues for Ge, a novel F127 triblock polymer/acetylene black dual‐assisted strategy is proposed to achieve uniform dispersion of polycrystalline Ge, enabling the preparation of Ge@C nanocomposites via hydrogen reduction. The introduced F127 triblock polymer and acetylene black serves a dual purpose to enhance electrical conductivity and prevent Ge nanoparticles from agglomeration. When tested as anode material for LIBs, the Ge@C nanocomposites exhibit exceptional electrochemical performances, demonstrating a sustained specific discharge capacity of 780 mA h g−1 at 0.2 A g−1 after 100 cycles. Moreover, the capacity remains at 767 mA h g−1 even after 300 cycles at a higher current density of 0.5 A g−1. These enhanced lithium storage performances are attributed to the combined effects of well‐dispersed tiny Ge nanoparticles, uniform carbon coating, and an abundance of defects. These factors effectively mitigate the volume expansion and lattice pulverization of Ge nanoparticles and concurrently enhance their conductivity, leading to improved overall performance in LIBs.

Rational design of yolk-shell CoFe2O4 nanospheres towards enhanced lithium storage performance

Rational design of yolk-shell CoFe2O4 nanospheres towards enhanced lithium storage performance

Construction of N–doped carbon encapsulated Mn2O3/MnO heterojunction for enhanced lithium storage performance

Owing to high theoretical capacity, low cost and abundant availability, manganese oxides are widely viewed as promising anodes for lithium–ion batteries (LIBs). Nonetheless, their practical application is significantly hindered by poor electrical conductivity, sluggish reaction kinetics and substantial volume change. In this work, an ingenious polypyrrole encapsulation followed by pyrolysis strategy is proposed to produce N–doped carbon encapsulated Mn2O3/MnO heterojunction (Mn2O3/MnO@NC) by using mechanically ground Mn3O4/C3N4 mixture as the precursor. The results show that the selection of precursor plays a pivotal role in the successful preparation of Mn2O3/MnO@NC hybrid. It is revealed that the uniform encapsulation by N–doped carbon significantly enhances the conductivity and structural stability of the final product. Concurrently, the Mn2O3/MnO heterojunction within the resultant hybrid exhibits a unique quantum–dot size, which effectively shortens ion transport pathways and exposes the active sites for lithium storage. Additionally, experimental observations and theoretical calculations demonstrate that the built–in electric fields generated at the interfaces of Mn2O3/MnO heterojunction accelerate the charge transfer and ion diffusion, thereby enhancing the electrochemical reaction kinetics. As a result, the Mn2O3/MnO@NC hybrid displays much enhanced lithium storage performance. Evidently, our work offers a good guidance for the design and synthesis of advanced transition metal oxide/carbon anodes for LIBs.

Interface regulation strategy in constructing ZnS@MoS2 heterostructure with enhanced surface reaction dynamics for robust lithium-ion storage

Heterostructure construction is an effective method used to synthesize lithium-ion battery anode materials with high electrochemical performance. In this study, an interface regulated ZnS@MoS2 heterostructure was achieved through a designed solvothermal strategy. The designed strategy introduces interface regulation in the heterostructure, increasing active sites for lithium adsorption and improving the overall dynamics of lithium-ion storage. The build-in electric field is introduced at the interfaces enhancing electron transfer and lithium migration. Ex-situ analyses confirmed the enhanced lithium storage performance in the heterostructure is derived from the stepwise reaction mechanism and the stepwise reactions contribute to cycling stability. DFT calculations revealed electron redistribution at the interfaces in the heterostructure boosting the lithium-ion migration and electron transfer. The interface regulated ZnS@MoS2 heterostructure exhibits outstanding lithium-ion storage performances in both half and full cells. Specifically, the high capacity of 996.0 mAh g−1 is achieved at 5 A g−1 after 1000 rounds, demonstrating remarkable lithium storage performance. This research presents a promising approach to enhance heterostructure electrochemical performance through interface regulation strategies.

Disorder/order-heterophase VO2 for enhanced lithium storage performance in lithium-ion capacitors

Interfacial engineering has proved to be an effective strategy for improving the performance of electrode materials in many applications. Herein, we report the disorder-order engineering of VO2 nanorods, and construct a crystal core and a surface-amorphized shell heterostructure (denoted as A-VO2) by simple hydrothermal method and reduction reaction, as a promising anode of lithium ion capacitor (LIC). The tunable amorphous layer introduces a large number of oxygen vacancy, which can efficiently improve electronic conductivity and enhance Li ion storage capacity. The crystalline-amorphous heterointerface generated in A-VO2 can significantly reduce the surface energy of VO2 and Li+ diffusion barrier, as well as increase the charge storage sites. The crystalline-amorphous heterogeneous phases work synergistically to facilitate ion and electron transport and maintain structural stability in discharge/charge process. The A-VO2-2 nanorods electrode possesses high capacity of 309 mAh g−1 at 0.1 A g−1 after 300 cycles, obviously larger than the crystalline VO2 electrode. In addition, the LIC, assembled with A-VO2-2 nanorods as anode and commercial active carbon (AC) as cathode, exhibit great energy density of 76.75 and 22.05 W h kg−1 at power density of 195 and 9360 W kg−1. It can remain 38.9 % of the initial capacity after 5000 cycles, demonstrating an instructive paradigm for disorder-order engineering in LIC electrode materials.

General Synthesis of Graphene/Metal Oxide Heterostructures for Enhanced Lithium Storage Performance

AbstractGraphene/metal oxide (rGO/MOx) heterostructures hold great promise for energy storage, yet a full understanding of their synthesis remains elusive. Herein, a general, efficient, and scalable synthesis strategy is designed for the preparation of various rGO/MOx heterostructure materials featuring robust interfacial interactions. The heterogeneous nucleation growth mechanism of metal oxides on graphene is elucidated through ex situ characterization and theoretical simulation. The surface of graphene oxide (GO) is enriched with reactive oxygen‐containing functional groups, serving as potent nucleation sites that facilitate the rapid and heterogeneous nucleation of MOx grains. Simultaneously, a stable interface (C−O−M bond) is in situ formed between graphene and adsorbed metal ions during heat treatment, producing rGO/MOx heterostructure materials. Notably, the resultant rGO/CoO heterostructure material is employed as an anode and LiCoO2 as a cathode to assemble a soft packaging quasi‐solid‐state battery, which has demonstrated an impressive energy density of 341.4 Wh kg−1 and maintains outstanding capacity retention at 93.4% after 300 cycles at a 1C current. These findings provide valuable insights into the preparation and potential applications of rGO/MOx heterostructure materials for energy storage.

Facile Synthesis of 2D SiOx-3D Si Hybrid Anode Materials by Ca Modification Effect for Enhanced Lithium Storage Performance.

Al-Si dealloying method is widely used to prepare Si anode for alleviating the issues caused by a drastic volume change of Si-based anode. However, this method suffers from the problems of low Si powder yield (<20wt.% Si) and complicated cooling equipment due to the hindrance of large-size primary Si particles. Here, a new modification strategy to convert primary Si to 2D SiOx nanosheets by introducing a Ca modifier into Al-Si alloy melt is presented. The thermodynamics calculation shows that the primary Si is preferentially converted to CaAl2Si2 intermetallic compound in Al-Si-Ca alloy system. After the dealloying process, the CaAl2Si2 is further converted to 2D SiOx nanosheets, and eutectic Si is converted to 3D Si, thus obtaining the 2D SiOx-3D Si hybrid Si-based materials (HSiBM). Benefiting from the modification effect, the HSiBM anode shows a significantly improved electrochemical performance, which delivers a capacity retention of over 90% after 100 cycles and keeps 98.94% capacity after the rate test. This work exhibits an innovative approach to produce stable Si-based anode through Al-Si dealloying method with a high Si yield and without complicated rapid cooling techniques, which has a certain significance for the scalable production of Si-based anodes.

Enhanced lithium storage performance of anodes for lithium-ion batteries with biscuit-shaped LaNiO3-NiO/g-C3N4 composites

The significance of lithium-ion batteries in our daily lives cannot be overstated, and the advancement of anode materials is instrumental in achieving battery systems with remarkable energy and power density. Perovskite-type oxides with high theoretical capacity and environmental friendliness have received attention, their poor conductivity and bulk effect urgently need to be improved. With graphene-like layered structure, the rich nitrogen content of g-C3N4 can improve the wettability of the electrode and electrolyte, thus improving the lithium charge transfer process. Therefore, we demonstrated that LaNiO3 is the major phase in the LaNiO3-NiO composites with 80.57% and NiO is the sub-phase with 19.43% using Rietveld XRD refinement treatment. The theoretical capacity of the composites was calculated to be 666.8 mAh g−1 combining the respective theoretical capacities of the two phases. Subsequently, the Biscuit-shaped LaNiO3-NiO/g-C3N4 composite was prepared, which showed excellent electrochemical performance when used as an anode material for lithium-ion batteries. The LaNiO3-NiO/g-C3N4 electrodes exhibit excellent rate performance (with 154.5 mAh g−1 at 10 A g−1) and cycling stability (with 502.5 mAh g−1 for 900 cycles at 1.0 A g−1). This work is believed to provide new ideas for the design and synthesis of perovskite oxide materials in the future.

Enhanced lithium storage performance derived from Fe2Ti1-xNixO5 (0 ≤ x ≤ 0.1) as a fast charging anode

Using iron titanate (Fe2TiO5) as an electrode provides high theoretical capacity and good cycling stability because of its multiple redox couples and unique crystal structure. The synthesis of the material is successfully carried out using the conventional ceramic method. The effect of Ni2+ substitution on the overall electrochemical performance of Fe2Ti1-xNixO5 anode material is explored. When Ni2+ replaces Ti4+ in the pseudobrookite Fe2TiO5 unit cell, the volume increases smoothly with the amount of nickel and the electrical conductivity is enhanced because of the higher Ti3+/Ti4+ ratio. With pore sizes of around 10 nm and specific surface areas of 330.81 m2 g−1, Fe2Ti1-xNixO5 can provide large contact areas between the electrode and electrolyte and shorten the lithium-ion diffusion distance. With discharge capacities of 368.6 mAh g−1 at the 100th cycle, Fe2Ti1-xNixO5 negative electrode exhibits outstanding electrochemical performance. Furthermore, it demonstrates excellent rate stability, with a discharge capacity of 310.6 mAh g−1 at a current rate of 5000 mA g−1. Over another 45 cycles, a high discharge capacity of 367.1 mAh g−1 was maintained at a current density of 100 mA g−1 even after the rate performance test. The Ni2+ doping results in faster Li+ insertion/extraction kinetics due to reduced Li+ diffusion paths, which leads to performance improvement.

In-situ rooting biconical-nanorods-like Co-doped FeP @carbon architectures toward enhanced lithium storage performance

With desirable high capacity, theoretical work voltage and abundant resources, iron phosphide (FeP) has been garnered much consideration as a hopeful anode material for lithium-ion batteries (LIBs). Nevertheless, structural stability and low electronic conductivity restrict its application. Herein, metal organic frameworks (MOFs)-derived biconical-nanorods-like Co-doped FeP confined by phosphorus-doped carbon (Co-doped FeP@P-C) is successfully prepared. The unique biconical-nanorods-like structure, MOFs in-situ derived carbon coating and Co-doping can accelerate the ion and electron transport efficiency, supply abundant reaction active sites and moderate the volume expansion of FeP material. Benefiting from these merits, the as-prepared Co-doped FeP@P-C anode manifests a high Li+ storage capacity (784 mAh/g at 0.2 A g−1) and long-term stability (555.6 mAh/g at 1 A g−1 after 700 cycles). The experimental studies coupled with density functional theory (DFT) theoretical calculations uncover the effect of Co-doping on boosting charge transfer and enriching the reaction active sites in FeP@P-C anode. Furthermore, the electrochemical kinetic analysis revealed the underlying mechanism of lithium storage in detail, ex-situ X-ray diffraction and X-ray photoelectron spectroscopy analysis. LiCoO2//Co-doped FeP@P-C full-cells are successfully assembled and exhibit relatively high reversible capacity. The present work can provide a rational design and promising cation doping strategy for other metal phosphide anode materials for LIBs.

Glucose promoted synthesis of homogeneously embedded black phosphorus carbon composite with enhanced lithium storage performance

Black phosphorus (BP) has attracted extensive attention in high-rate lithium-ion batteries due to its high theoretical capacity and moderate lithiation potential. However, the large volume expansion and the low conductivity of BP nanostructures in the electrochemical cycle have inhibited the rate performance and long-term cycle stability. In this paper, by combining the glucose-assisted ball-milling and carbonization method, a black-phosphorus/carbon (BP@C) composite anodic material is developed, in which the nano-sized BP nanoparticles are homogeneously embedded in the amorphous carbon matrix. Both the phosphorus-oxygen-carbon bonds and the phosphorus-carbon bonds improve the cross-link between BP and the surface-coated carbon matrix. The unique well-embedded structure promotes the cycling stability and the rate performance of BP@C. The composite shows a high discharge specific capacity of about 1881 mAh g−1 at 0.1 A g−1, the specific capacity at 4 A g−1 is about 63% of the low current capacity, and the discharge specific capacity retains 1130 mAh g−1 after 300 charge-discharge cycles at 0.5 A g−1. Moreover, the significant role of the active unsaturated groups for building the well-embedded composite is further revealed. These results indicate that dual regulation of surface coating and structure optimization offers great potential for further optimizing phosphorus-based anode materials.

Atomic layer deposition of aluminum-doped zinc oxide onto MoO3 nanorods toward enhanced lithium storage performance

An atomic layer deposition (ALD) of aluminum-doped zinc oxide (AZO) onto MoO3 nanorods (denoted as MoO3@AZO) was developed to enhance the lithium storage performance of MoO3 anode. Thanks to the highly conductive and robust AZO layer, the MoO3@AZO electrode demonstrated high pseudocapacitive contribution (76.2 % at 1.0 mV s−1), enhanced electron/ion transferability, outstanding rate performance (708 mAh g−1 at 2 A g−1) and excellent cycling stability (973 mAh g−1 after 100 cycles at 0.2 A g−1 with a high capacity retention of 92.8 %) when applied as an anode for lithium-ion batteries. Ex-situ transmission electron microscopy analysis revealed that the rod feature of MoO3@AZO was well retained with the protection of the AZO layer even after 100 cycles. Moreover, the ALD-AZO coating may also be commonly used for other metal oxides to enhance their electron conductivity and structural stability.

ZnMn2O4/ZnMnO3/ZnO composite with novel bilayer heterojunction structure for enhanced lithium storage performance

Innovative anode materials with high capacity and good cyclic stability play a vital role on pursuing the high-performance lithium-ion batteries (LIBs). Herein, ZnMn2O4/ZnMnO3/ZnO composite with a unique bilayer heterojunction structure is successfully synthesized by sintering of ZIF-8 coated Zn1/3Mn2/3CO3. The crystal phase, microstructure and chemical composition of ZnMn2O4/ZnMnO3/ZnO composite are characterized to analyze the heterostructure in detail. When used as anode materials for LIBs, the rich heterostructure interface of the composite can adsorb more e- and Li+, improving the lithium storage behavior of material. Meanwhile, the build-in electric field generated by the heterojunction is conducive to accelerating the migration speed of e- and Li+, thus improving the conductivity of the material. As a result, after long-term cycles of 320 times, the specific capacity of ZnMn2O4/ZnMnO3/ZnO composite is up to 857.5 mAh g−1, and it still keeps a high specific capacity of 201.4 mAh g−1 at the high current of 5 C. These results indicate that ZnMn2O4/ZnMnO3/ZnO composite has great potential in the field of LIBs.

Simple ball milling-assisted method enabling N-doped carbon embedded Si for high performance lithium-ion battery anode

Si has been regarded as a hopeful advanced anode of lithium-ion batteries due to its features such as ultrahigh theoretical specific capacity and high natural abundance. But, it suffers from electrochemical irreversibility because of large volumetric change and poor conductivity during cycle. In spite of obtaining enhanced lithium storage performance after compositing with carbon materials, most of the reported Si/C composite anodes lack a simple preparation process. For the new anode materials, the simple preparation process is as important as showing high performance. Herein, an efficient simple method is developed to prepare a composite of N-doped carbon embedding Si nanoparticles (Si@C) to response to the above Si faced challenges. Its preparation process just consists of very simple ball milling and pyrolysis carbonization, showing great simplicity. The findings confirm that the combination of the ball-milling mixing and the use of PVP carbon precursor enables the optimal Si@C-2 composite to have a N-doped carbon embedding structure and a robust interface Si-O-C chemical bond bonding, hence obtaining enhanced conductivity, high electrochemical kinetics and superb structure stability during cycling process. Therefore, the Si@C-2 anode exhibits excellent performance, with 1542 and 794.7 mA h g−1 after 100 and 1000 cycles at 100 and 1000 mA g−1, respectively, superior to many reported Si/C composites. The simple, scalable preparation method and superb performances offer Si@C-2 great promising in advanced LIB anode applications.

Metal-organic framework derived CdSe wrapped with rGO for enhanced lithium storage performance.

Considering the advantages of MOF-based, CdSe-based, and rGO-based materials, CdSe nanoparticles encapsulated with rGO (CdSe@rGO) were synthesized by a metal-organic framework derived method. CdSe nanoparticles encapsulated with rGO can effectively tolerate volume expansion and improve electrical conductivity, leading to excellent cycling stability (396 mAh g-1 at 0.3 A g-1 after 200 cycles, 311 mAh g-1 at 0.5 A g-1 after 500 cycles), and rate performance (562 mAh g-1 at 0.1 A g-1 and 122.2 mAh g-1 at 4 A g-1) for lithium-ion storage. This strategy for preparing metal selenides protected by carbon layers can be extended to the design of other high-performance materials.

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.