Enhanced Lithium Storage Capability Research Articles

Enhanced lithium storage capability of Ni-rich LiNi0.9CoxMn0.1−xO2(0 ≤ x ≤ 0.1) cathode by co-operation of Al-doping and V-coating

The Nickel-rich layer materials LiNixCoyMn1−x−yO2 (x ≥ 0.9) are usually accompanied by structural instability and inevitable capacity loss due to surface degradation during long cycles. The Al-V dual-modification is used in this research to enhance the stability of the structure and the electrochemical capacity of LiNi0.9Co0.05Mn0.05O2 (NCM). First, Al source was added during the co-precipitation synthesis of the precursors. Then, the Al-doped precursors were treated at 720 ℃ for 10 h with slight excess lithium to prevent volatilization of lithium during the sintering process. Finally, Al-doped LiNi0.9Co0.04Mn0.03Al0.03O2 (NCMA) materials were treated with V2O5 at 450 ℃ for 4 h. During calcination, Li3VO4-coated LiNi0.9Co0.04Mn0.03Al0.03O2 materials (NCMAV) were generated by employing residual lithium. Meantime, the Al-V dual-modification helps reduce the mingling degree of Ni2+/Li+ and promotes the diffusion of Li+. Hence, the Al-V dual-modified NCMAV displays a superior rate capability of 162.2 mAh g−1 at 5 C, remaining predominant capability retention of 90.5% after 100 cycles at 4.3 V. Compared with NCMAV, the discharge capability of pure NCM is 140.3 mAh g−1 and its capability retention is 81.6% at 5 C. This dual-modification strategy provides a facile and scalable method to achieve massive application of NCM LIBs with high density and excellent cycling stability.

Atomically dispersed Sn incorporated into carbon matrix for stable electrochemical lithium storage

Although possessing a high specific capacity, the practical implementation of SnO2 nanoparticles as a promising anode for lithium-ion batteries (LIBs) is hampered by their poor cyclability. This work demonstrates that incorporating single atomic Sn (SASn) species into a carbon matrix can address this issue effectively. The SASn/C composite was synthesized via polymerization of formaldehyde and 3-aminophenol in the presence of Tin(II) chloride, followed by pyrolysis. The SASn atoms were homogeneously dispersed in the carbon matrix. Each Sn atom coordinated with two O and two C atoms, forming the Sn-O-C and Sn-C bonds, providing channels for fast electron/ion transfer and boosting electrochemical kinetics. The SASn/C anode exhibited unique lithium storage behaviors, enhanced lithium storage capability, and excellent cyclic stability with a capacity fading rate of 0.0031% per cycle at 1000 mA g−1 after 7000 cycles. Density functional theory calculations reveal that one SASn atom can adsorb three Li+ ions at the fully discharged state during the discharging process. Subsequently, the Li+ ions are directly desorbed from the SASn atom, which is different from the traditional multi-step de-alloying process. This facile strategy represents a significant advancement in developing high-performance Sn-based anode materials for 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.

Enhanced Lithium Storage Capability of Sb2se3 by Phenolic Resin-Derived Carbon

Enhanced Lithium Storage Capability of Sb2se3 by Phenolic Resin-Derived Carbon

In Situ Synthesis of a Si/CNTs/C Composite by Directly Reacting Magnesium Silicide with Lithium Carbonate for Enhanced Lithium Storage Capability

Silicon is considered as an ideal anode material for the next generation of lithium-ion batteries (LIBs) owing to its high specific capacity, low lithiation potential, and high natural abundance. However, its potential application is greatly restricted by poor electrical conductivity and large volume expansion during lithiation/delithiation processes. Herein, a novel solid-state reaction route is developed to synthesize a silicon/carbon nanotubes/carbon (Si/CNTs/C) composite by directly reacting magnesium silicide (Mg2Si) with lithium carbonate (Li2CO3). This method realizes synchronous formation of Si, CNTs, and amorphous carbon with a good interfacial configuration. Transmission electron microscopy (TEM) reveals that MgO may be responsible for the in situ growth of CNTs during the chemical reaction process. The crystalline Si particles are encapsulated by CNTs and the amorphous carbon matrix, which not only accommodates the volume expansion of Si but also enhances the integral electronic conductivity. Consequently, the Si/CNTs/C composite exhibits a high reversible capacity (702 mA h g–1 at 0.2 A g–1), excellent rate performance (420 mA h g–1 at 5 A g–1), and long cycling life (over 1500 cycles) when used as an anode for LIBs. Notably, this research might provide a new strategy for large-scale synthesis and utilization of Si/C composites in high-performance LIBs.

Synthesis of pomegranate-shaped micron ZnMn2O4 with enhanced lithium storage capability

As high capacity anode materials, spinel-type transition metal oxides have a bottleneck of poor cyclic stability. Nano structure and carbon loading are common modification approaches, while the high cost is unaffordable for industrial implementation. In this study, micron scale zinc manganate was synthesized by solvothermal plus calcination process. The pomegranate-shaped ZnMn2O4 (p-ZMO) was obtained using solvent of ethylene glycol, and the microsphere-shaped ZnMn2O4 (m-ZMO) was obtained using water. During electrochemical testing, the p-ZMO anode delivered larger charge capacity of 726 mAh g−1 at 0.2 A g−1 than 589 mAh g−1 of m-ZMO. Even over 1000 cycles at 1 A g−1, the p-ZMO still maintained a reversible capacity of 506 mAh g−1 (much higher than 372 mAh g−1 of graphite anode), with a superior retention of 84%. It indicates that this work develops an effective strategy to prepare high-performance transition metal oxides for anode materials of lithium-ion batteries.

A synergistic effect of lithium titanate/pristine graphene composite with enhanced lithium storage capability

A synergistic effect of lithium titanate/pristine graphene composite with enhanced lithium storage capability

Cobalt phthalocyanine derived bifunctional carbon decorated CoSe with enhanced lithium storage capability

Transition-metal chalcogenides (TMCs) have attracted much attention as their good electrical conductivity and high lithium storage capacity. In this work, a simple and scalable approach was employed to synthesize CoSe nanoparticles confined in bifunctional N-doped carbon framework/carbon layer (CoSe/NC/C). Specifically, pyrolysis of cobalt phthalocyanine (CoPc)/Selenium mixtures was accompanied by Ethanol Steam Reforming (ESR) simultaneously, which could bring in double carbon network and restrict the growth of CoSe grains effectively to achieve more stable structure and fast ion/electron transfer within CoSe electrode. As a result, CoSe/NC/C composite delivers a superior discharge capacity of 531 mA h g-1 after 400 cycles at 1 A g-1 at room temperature and a remarkable cycling stability (458 mA h g-1 after 100 cycles at 1 A g-1) at elevated temperature (55 ℃). This excellent electrochemical performance may be attributed to the following factors. (a) The bifunctional carbon architecture can not only endow the composites with superior conductivity and enhanced structure stability, but also facilitate the uniform distribution of nano-sized CoSe. (b) The effective catalytic activity is inspired by the synergistic effect between CoSe nanoparticles and bifunctional carbon, which is supposed to contribute significant capacity and manifest distinct pseudocapacitive behavior, especially at high current density.

Hybrid of Co-doped SnO2 and graphene sheets as anode material with enhanced lithium storage properties

For improving the electrochemical performance of SnO2-based anodes, a novel hybrid material of cobalt-doped SnO2 and graphene sheets (Co-SnO2@GS) was fabricated via a facile co-hydrolysis approach. In this hybrid, numerous fine Co-SnO2 nanoparticles (4–7 nm) are uniformly deposited on the GS. Furthermore, Co doping can strengthen the interface interaction between SnO2 and GS. Benefiting from the synergistic effects of graphene hybridization and Co doping, the Co-SnO2@GS hybrid shows significantly enhanced lithium storage capability compared with undoped SnO2@GS and bare SnO2. It delivers a stable discharge capacity of 1157.4 mAh g−1 over 90 cycles at 0.1 A g−1 and maintains 828.5 mAh g−1 at 0.5 A g−1 even after 200 cycles. In addition, this hybrid material also exhibits excellent rate performance with an admirable capacity of 674.7 mAh g−1 at 1 A g−1. Our study presents a realizable strategy toward boosting the Li-storage capability of SnO2 material for beyond lithium-ion batteries.

Fabrication of GeO2 microspheres /hierarchical porous N-doped carbon with superior cyclic stability for Li-ion batteries

GeO2 microspheres/N-doped hierarchical porous carbon (NHPC) composites are solvothermally prepared and subsequent calcinated employing ginger as biotemplate. The SEM and TEM images demonstrate the GeO2 microspheres are uniformly dispersed or embedded in NHPC matrix. Evaluating the performances of GeO2/NHPC composites as Li-ion battery electrodes, they deliver a specific capacities of 2261.4 ​mA ​h ​g−1 at 200 ​mA ​g−1, after 100 cycles it remains a high reversible capacity of 1014.3 ​mA ​h ​g−1 and close to 100% coulomb efficiency. The enhanced lithium storage capability is chalked up to high specific surface area and properly hierarchical porous structure of GeO2/NHPC. The synthetic technique is a feasible and successful paradigm for other large capacity materials with large change in volume and poor electroconductivity.

ZnMn2O4/milk-derived Carbon hybrids with enhanced Lithium storage capability

One of the effective ways to improve the conductivity and structural stability of binary metal oxide nanostructures is to tightly composite them with nano-carbon materials with excellent conductivity. However, the introduction of low density carbon materials also reduces the energy density of batteries. Therefore, we provides a new idea to enhance the lithium storage performance of carbon/binary transition metal oxide anode materials by multi-element co-doping carbon. ZnMn2O4 provides high lithium storage capacity; non-metallic heteroatoms in milk-derived carbon greatly improve the conductivity of carbon materials; metal heteroatoms in milk-derived carbon increase the density of carbon materials. Multicomponent co-doping carbon can build up the mass specific capacity, ratio performance, cyclic life and mechanical properties of binary metal oxides/porous carbon nanocomposites. As the anode materials of lithium-ion batteries, the ZnMn2O4/MC (milk-derived carbon) hybrids deliver a high reversible capacity of 1352 mAh g−1 after 400 cycles at 0.1 A g−1, and a remarkable long-term cyclability with 635 mAh g−1 after 300 cycles at 1.0 A g−1.

Scalable preparation of porous nano‑silicon/TiN@carbon anode for lithium-ion batteries

A novel porous nano‑silicon/TiN@carbon anode with superior cycling stability and long-term durability has been proposed by the facile strategy of mechanical ball-milling/low-temperature calcination. This porous architecture can contain enough void spaces to stabilize the severe volume expansion, and provide sufficient migration channels for lithium ions. Meanwhile, the TiN sheets can efficiently facilitate the charge transfer and mitigate the massive silicon swelling. This anode develops the enhanced lithium storage capability with 1614.6 mAh g−1 at 100 mA g−1 for 110 cycles, and achieves better long-cycling life with 852.8 mAh g−1 at 500 mA g−1 after 800 cycles. Furthermore, the anode can also grab a good wide-temperature performance from 5 to 50 °C.

Ethylene glycol solvent induced expansion of interplanar spacing and 2H-1T phase transformation of molybdenum disulfide nanocomposites for enhanced lithium storage capability

Molybdenum disulfide (MoS2), has aroused people's much research interest as an anode candidate for next generation of Li-ion batteries because of special layered structure and high theoretical capacity. However, MoS2 suffers from a poor cycling stability and an inferior rate capability upon charge/discharge processes. So we have successfully synthesized a more stable expanded nanocomposite with superior electrical conductivity by intercalating moderate amorphous carbon between two adjacent S–Mo–S interlayer via a simple method which exhibits excellent lithium storage performance with high capacity (858.9 mA h g−1 at 1 A g−1 for 1000 cycles), and superior rate capability (518 mA h g−1 at 4 A g−1). This superior electrochemical performance is attributed to the special structure (few layers, 2H phase, expanded interlayer spacing, amorphous carbon between S–Mo–S layers, C–O–Mo bond in the layer), small size and evenly distributed MoS2 nanosheets. Besides, we study the 2H-1T phase transformation mechanism by controlling the ratio of ethylene glycol to water and O–CO bond plays an important role in promoting 2H-1T phase transformation.

A highly Meso@Microporous carbon-supported Antimony sulfide nanoparticles coated by conductive polymer for high-performance lithium and sodium ion batteries

A novel multi-step method that combines solvothermal, sulfidation and polymerization process was utilized to synthesize Antimony Sulfide/Meso@Microporous Carbon nanofibers@polypyrrole (Sb2S3/MMCN@ppy) composite. As the host, the MMCN is full of microporous and mesoporous naturally, which can prevent the aggregation during the sulfidation process and accelerate the transfer of electron inside the whole composite. Meanwhile, the effective coverage of ppy layer can accommodate the volume changes during cycling and fast the electron transfer on the surface of the composite. Combining those merits, the dual physical barrier composed of MMCN and conductive ppy layer guarantees the ultrastable structure for superior electrochemical performance. When used as an anode for lithium-ion batteries, Sb2S3/MMCN@ppy composite demonstrates the stable electrochemical performance with an enhanced lithium-storage capability. Impressively, even at the high current density of 1000 mA g−1, a specific reversible capacity about 556 mA h g−1 can be delivered after 300 long cycles. In addition, Sb2S3/MMCN@ppy composite also displays the outstanding stability sodium-storage property in sodium-ion batteries (269 mAh g−1 at 1000 mA g−1 after 300 long cycles). The results show that this product may be considered as a promising anode material for advanced LIBs and SIBs.

Hollow mesoporous hetero-ZnO/ZnMnO3 microspheres: template-free formation process and enhanced lithium storage capability towards Li-ion batteries as a competitive anode

Hierarchical hollow mesoporous ZnO/ZnMnO3 microspheres were fabricated and exhibited outstanding Li-storage behaviors as competitive anode for Li-ion batteries.

Enhanced lithium storage capability of FeF3·0.33H2O single crystal with active insertion site exposed

Iron fluoride cathode for lithium batteries intrigues researchers for decades due to high capacity and low cost, but suffers from poor electronic and ionic conductivity. Hierarchical micro/nano construction with preferred orientation growth can shorten ion diffusion pathway and facilitate electron transportation without inducing side reactions. Here, FeF3·0.33H2O hierarchical microspheres self-assembled by octagonal single crystal slices are prepared. Benefiting from the artful structure, SAED and XRD characterizations confirm that the octagonal single crystal slices provides more lithium ions intercalation positions (4c sites). Electrochemical tests demonstrate that the well designed FeF3·0.33H2O single crystal (FFH-S) delivers 30 mAh g−1 higher capacity (172 mAh g−1 at 0.1C) than the common FeF3·0.33H2O polycrystal (FFH-P). In-situ XRD combined with theoretic calculation elucidate the difference in lithium storage capacity. Instructive argument that single crystal octagon slices with [110] oriented growth provide more active sites for lithium ions intercalation contributes to the preparation of high performance iron fluoride cathode materials for rechargeable battery.

Facile synthesis of cobalt ferrite nanoparticles (CFO-NPs) as anode material with enhanced lithium storage capability

In this work, CoFe2O4 spinel phase nanoparticles (CFO-NPs) with an average diameter of 80 nm were synthesized through facile urea combustion method, which can be extended for the large scale fabrication of nanoparticles. The obtained product is characterized by X-ray diffraction (XRD), Transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, Brunauer Emmett and Teller (BET) and X-ray photoelectron spectroscopy (XPS). When CFO-NPs are used as an anode material for Li-ion battery, it show excellent electrochemical performance due to its typical nano-sized particles, which results excellent diffusion of electrolyte ions and ensured the fast electron transportation. As a result, CFO-NPs show excellent initial charge and discharge capacities of 1506 and 1524 mA h g−1, respectively. After fifty cycles, the discharge capacity still remains at 896 mA h g−1 at a current density of 100 mA g−1, and excellent rate capability. Given their excellent electrochemical performance, the CFO-NPs considered as a promising anode material for Li-ion batteries.

Enhanced lithium storage capability enabled by metal nickel dotted NiO–graphene composites

The electrochemical performance of Li-ion batteries, which is limited by large volume changes and low intrinsic conductivity, can be improved by using a NiO–graphene composite as an electrode. Herein, we constructed metallic Ni-dotted NiO flakes on folded graphene and evaluated the electrochemical performance of the resulting composites. Introduction of graphene produced an excellent 2D structure that led to the homogeneous growth of Ni–NiO particles and improved the structural stability and conductivity of the final material. After 50 cycles, the reversible discharge capacity of Ni–NiO/G-2 reached 660.7 mAh g−1 at a current density of 100 mAh g−1 and approximately 75.0% of the capacity was maintained relative to the initial discharge capacity. The Ni–NiO/G-4 electrode displayed excellent high-rating performance, and the metallic Ni particles effectively improved the reversibility of solid electrolyte interface (SEI) films. Test results showed that the decomposition/regeneration of SEI films influenced the charge/discharge capacities of the electrodes during cycling.

One-pot hydrothermal fabrication and enhanced lithium storage capability of SnO2 nanorods intertangled with carbon nanotubes and graphene nanosheets

A three-dimensional (3D) nanoarchitectured ternary composite of SnO2 nanorods intertangled with multiwalled carbon nanotubes and graphene nanosheets (SnO2/CNTs/Gr) was synthesized via one-pot template-free hydrothermal method and investigated as anode for lithium-ion batteries. Compared to bare SnO2 and corresponding binary composites including SnO2/CNTs and SnO2/Gr, SnO2/CNTs/Gr shows significantly improved cycling stability and rate performance. The initial discharge specific capacity of SnO2/CNTs/Gr is 1391 mAh g−1 and remains 522 mAh g−1 after 50 cycles at a current density of 100 mA g−1. Meanwhile, the composite shows excellent rate reversibility. For example, 120 mAh g−1 can be retained at a high current density of up to 1600 mA g−1, and 582 mAh g−1 can still be retrieved once the current density is switched back to 50 mA g−1. The carbon nanotubes and graphene nanosheets in the composites play different enhancing effect. The significantly improved energy storage capability of SnO2/CNTs/Gr can be attributed to a synergistic effect of the intertangled CNTs and graphene nanosheets.

Carbon and few-layer MoS2 nanosheets co-modified TiO2 nanosheets with enhanced electrochemical properties for lithium storage

Carbon and few-layer MoS2 nanosheets co-modified TiO2 nanocomposites (defined as MoS2-C@TiO2) were prepared through a facile one-step pyrolysis reaction technique. In this unique nanostructure, the TiO2 nanosheets with stable structure serve as the backbones, and carbon coating and few-layer MoS2 tightly adhere onto the surface of the TiO2. It needs to be pointed out that the carbon coating improves the overall electronic conductivity and the few-layer MoS2 facilitates the diffusion of lithium ions and offers more active sites for lithium-ion storage. As a result, when evaluated as lithium-ion battery anodes, the MoS2-C@TiO2 nanocomposites exhibit markedly enhanced lithium storage capability compared with pure TiO2. A high specific capacity of 180 mA·h·g−1 has been achieved during the preliminary cycles, and the specific capacity can maintain 160 mA·h·g−1 at a high current density of 1C (1C=167 mA·g−1) even after 300 discharge/charge cycles, indicating the great potential of the MoS2-C@TiO2 on energy storage.