High-performance Lithium-ion Batteries Research Articles

Fully sp2 Carbon-conjugated Covalent Organic Frameworks with Multiple Active Sites for Advanced Lithium-ion Battery Cathodes.

Covalent organic frameworks (COFs) hold great promise for rechargeable batteries. However, the synthesis of COFs with abundant active sites, excellent stability, and increased conductivity remains a challenge. Here, chemically stable fully sp2 carbon-conjugated COFs (sp2c-COFs) with multiple active sites are designed by the polymerization of benzo[1,2-b:3,4-b':5,6-b'']trithiophene-2,5,8-tricarbaldehyde) (BTT) and s-indacene-1,3,5,7(2H,6H)-tetrone (ICTO) (denoted as BTT-ICTO). The morphology and structure of the COF are precisely regulated from "butterfly-shaped" to "cable-like" through an in-situ controllable growth strategy, significantly promoting the exposure and utilization of active sites. When the unique "cable-like" BTT-ICTO@CNT is employed as lithium-ion batteries (LIBs) cathode, it exhibits exceptional capacity (396 mAh g-1 at 0.1 A g-1 with 97.9% active sites utilization rate), superb rate capacity (227 mAh g-1 at 5.0 A g-1), and excellent cycling performance (184 mAh g-1 over 8000 cycles at 2.0 A g-1 with 0.00365% decay rate per cycle). The lithium storage mechanism of BTT-ICTO is exhaustively revealed by in-situ Fourier transform infrared, in-situ Raman, and density functional theory calculations. This work provides in-depth insights into fully sp2c-COFs with multiple active sites for high-performance LIBs.

In-situ Formation of a LiF-rich Interphase for Graphite Anode Operated at Low Temperatures.

Inorganic LiF is generally a desirable component in solid electrolyte interface (SEI) for graphite anode due to its electronic insulation, low Li+ diffusion barrier, high modulus and good chemical stability. Herein, fluorinated carbon (CFx) was incorporated into graphite material, which exhibited a high discharge potential prior to electrolyte decomposition and in-situ formed a crystalline LiF-based SEI with improved Li+ diffusion rate. The optimized graphite anode therefore demonstrated a fast-charging capability with 124 mAh g-1 at high rate of 8 C and a remarkable capacity retention of 83.8% at the low temperature of -30 oC compared to that at 25 oC. Furthermore, the optimized graphite|LiFePO4 full cell exhibited a significantly high discharge capacity of 109 mAh g-1 at -30 oC, corresponding to a notable 77.3% room-temperature capacity retention. These findings highlight a facile strategy to attain a LiF-rich SEI for high-performance lithium-ion batteries.

Interfacial engineering in SnO2-embedded graphene anode materials for high performance lithium-ion batteries

Tin dioxide is regarded as an alternative anode material rather than graphite due to its high theoretical specific capacity. Modification with carbon is a typical strategy to mitigate the volume expansion effect of SnO2 during the charge process. Strengthening the interface bonding is crucial for improving the electrochemical performance of SnO2/C composites. Here, SnO2-embedded reduced graphene oxide (rGO) composite with a low graphene content of approximately 5 wt.% was in situ synthesized via a cetyltrimethylammonium bromide (CTAB)-assisted hydrothermal method. The structural integrity of the SnO2/rGO composite is significantly improved by optimizing the Sn–O–C electronic structure with CTAB, resulting a reversible capacity of 598 mAh g−1 after 200 cycles at a current density of 1 A g−1. CTAB-assisted synthesis enhances the rate performance and cyclic stability of tin dioxide/graphene composites, and boosts their application as the anode materials for the next-generation lithium-ion batteries.

Tailoring Alkalized and Oxidized V2CTx as Anode Materials for High-Performance Lithium Ion Batteries

V2CTx MXenes have gained considerable attention in lithium ion batteries (LIBs) owing to their special two-dimensional (2D) construction with large lithium storage capability. However, engineering high-capacity V2CTx MXenes is still a great challenge due to the limited interlayer space and poor surface terminations. In view of this, alkalized and oxidized V2CTx MXenes (OA-V2C) are envisaged. SEM characterization confirms the accordion-like layered morphology of OA-V2C. The XPS technique illustrates that undergoing alkalized and oxidized treatment, V2CTX MXene replaces -F and -OH with -O groups, which are more conducive to pseudocapacitive properties as well as Na ion diffusion, providing more active sites for ion storage in OA-V2C. Accordingly, the electrochemical performance of OA-V2C as anode materials for LIBs is evaluated in this work, showing excellent performance with high reversible capacity (601 mAh g−1 at 0.2 A g−1 over 500 cycles), competitive rate performance (222.2 mAh g−1 and 152.8 mAh g−1 at 2 A g−1 and 5 A g−1), as well as durable long-term cycling property (252 mAh g−1 at 5 A g−1 undergoing 5000 cycles). It is noted that the intercalation of Na+ ions and oxidation co-modification greatly reduces F surface termination and concurrently increases interlayer spacing in OA-V2C, significantly expediting ion/electron transportation and providing an efficient way to maximize the performance of MXenes in LIBs. This innovative refinement methodology paves the way for building high-performance V2CTx MXenes anode materials in LIBs.

Fabricating a high-performance anode by coating a carbon layer on a yolk-shell bimetallic selenide microsphere for enhanced lithium storage.

The rational synthesis of an electrode material with a highly active and stable architecture is very critical to achieving high-performance electrochemical energy storage. Herein, N-doped carbon restricting yolk-shell CoSe2/Ni3Se4 (CoSe2/Ni3Se4@NC) flower-like microspheres were successfully synthesized from solid CoNi-glycerate microspheres using a coating technology as an anode material for lithium-ion batteries (LIBs). The unique yolk-shell CoSe2/Ni3Se4@NC microspheres with hierarchical pores can increase the contact area with the electrolyte and provide enough transfer channels for the diffusion of Li+. The carbon layer on the surface of CoSe2/Ni3Se4@NC can not only improve the conductivity of the electrode but also provide the protective effect of active nanosheets during the process of synthesis, avoiding the overall structure collapse during the charge/discharge process of LIBs. Benefiting from the high conductivity, hollow structure, and elastic NC shell bestowed by the unique architecture, the yolk-shell CoSe2/Ni3Se4@NC anode shows excellent lithium storage performances, such as an excellent reversible specific capacity of 319 mA h g-1 at a current density of 1000 mA g-1 after 500 cycles and excellent cycling stability. This synthesis strategy provides a new way to optimize the lithium storage performance of transition metal compound electrode materials, which is helpful to the design of the next generation of high-performance LIBs.

In-situ synthesis of Fe3O4@Fe3C nanoparticles with heterostructures embedded in the N-doped porous carbon for high-performance lithium ion batteries

Metal oxides (Fe3O4) have attracted immense attention as high-capacity anode materials for high-performance electrochemical energy storage systems. However, the large structural change and sluggish reaction kinetics in the lithiation and delithiation reactions critically limit their practical development. Here, we design a novel composite consisting of Fe3O4@Fe3C nanoparticles embedded in N-doped porous carbon (Fe3O4@Fe3C-NPC) for lithium ion batteries. Benefiting from the synergistic effect of heterostructures, the Fe3O4@Fe3C-NPC delivers high reversible capacities (911.9 mAh g−1 at 0.2 A g−1, 319.6 mAh g−1 at 5.0 A g−1). The formed heterointerfaces can build an internal electric field, which help to improve reaction kinetics with fast ion diffusion kinetics and low charge transfer resistance. Furthermore, the Fe3O4@Fe3C-NPC//LiFePO4 full cell also displays great performance. The structural design concept and efficient synthesis method in the work can be extended to construct metal oxide/carbide heterostructures for anode materials.

NiCo Nanoparticles Encapsulated in Nitrogen-Doped Carbon Tubes as Anode Materials for High-Performance Lithium-Ion Batteries

NiCo Nanoparticles Encapsulated in Nitrogen-Doped Carbon Tubes as Anode Materials for High-Performance Lithium-Ion Batteries

CALiSol-23: Experimental electrolyte conductivity data for various Li-salts and solvent combinations

Ion transport in non-aqueous electrolytes is crucial for high performance lithium-ion battery (LIB) development. The design of superior electrolytes requires extensive experimentation across the compositional space. To support data driven accelerated electrolyte discovery efforts, we curated and analyzed a large dataset covering a wide range of experimentally recorded ionic conductivities for various combinations of lithium salts, solvents, concentrations, and temperatures. The dataset is named as ’Conductivity Atlas for Lithium salts and Solvents’ (CALiSol-23). Comprehensive datasets are lacking but are critical to building chemistry agnostic machine learning models for conductivity as well as data driven electrolyte optimization tasks. CALiSol-23 was derived from an exhaustive review of literature concerning experimental non-aqueous electrolyte conductivity measurement. The final dataset consists of 13,825 individual data points from 27 different experimental articles, in total covering 38 solvents, a broad temperature range, and 14 lithium salts. CALiSol-23 can help expedite machine learning model development that can help in understanding the complexities of ion transport and streamlining the optimization of non-aqueous electrolyte mixtures.

CALiSol-23: Experimental electrolyte conductivity data for various Li-salts and solvent combinations

Ion transport in non-aqueous electrolytes is crucial for high performance lithium-ion battery (LIB) development. The design of superior electrolytes requires extensive experimentation across the compositional space. To support data driven accelerated electrolyte discovery efforts, we curated and analyzed a large dataset covering a wide range of experimentally recorded ionic conductivities for various combinations of lithium salts, solvents, concentrations, and temperatures. The dataset is named as ’Conductivity Atlas for Lithium salts and Solvents’ (CALiSol-23). Comprehensive datasets are lacking but are critical to building chemistry agnostic machine learning models for conductivity as well as data driven electrolyte optimization tasks. CALiSol-23 was derived from an exhaustive review of literature concerning experimental non-aqueous electrolyte conductivity measurement. The final dataset consists of 13,825 individual data points from 27 different experimental articles, in total covering 38 solvents, a broad temperature range, and 14 lithium salts. CALiSol-23 can help expedite machine learning model development that can help in understanding the complexities of ion transport and streamlining the optimization of non-aqueous electrolyte mixtures.

In Situ Polymerized Zwitterionic Copolymer Ionic Gel Electrolytes with High Performance for Lithium-Ion Batteries.

Gel electrolytes are a promising research direction due to their high safety. However, its poor room temperature conductivity along with complex preparation process hinder its practical application. In this article, a type of zwitterionic gel electrolyte is prepared by in situ polymerization. The introduction of charged but nonmigrating zwitterionic copolymer in the polymer chain is beneficial to the dissociation of the lithium salt, improving the ion transport of the electrolyte on this account. At room temperature, the conductivity of lithium ion reaches 9.1 × 10-4 S cm-1, which contributes to achieve excellent electrochemical performance at high rates. The assembled Li|LiFePO4 cell also shows a capacity retention rate of 90.5% after 150 cycles at 0.5 C at room temperature as well as remarkable cycle stability at 1 C. These offer a novel tactic for the efficient and safe commercial application of lithium-ion batteries.

Electronic structure and delithiation mechanism of vanadium and nickel doped Li2MnPO4F cathode material for lithium-ion batteries

This study calculates the energy band structure and density of states of Lithium manganese fluorophosphate (Li2MnPO4F, a lithium transition metal phosphate compounds) using the first-principles plane-wave pseudopotential approach within the density-functional theory. The model of Li2M0.5Mn0.5PO4F (M = V, Ni) with transition metal doped Mn sites is constructed by using the CASTEP module. The calculation findings indicate that the transition metal doping can regulate the energy band structure of the intrinsic system, and Li2MnPO4F makes the band gap decrease, and the volume increase with the Li ions of being deintercalated, and the electrons can be readily stimulated from the valence band to the conduction band. The findings indicate that Li2MnPO4F is a favorable cathode material for high-voltage lithium ion batteries (LIBs). The introduction of vanadium (V) and nickel (Ni) doping reduces the band gap, facilitating an easier excitation of electrons from the valence band to the conduction band. This study provides a theoretical study of new cathode materials for high performance LIBs.

Enhanced mechanical and surface chemical stability in cobalt-free, high-nickel cathode materials for lithium-ion batteries

Cobalt-free, high-nickel cathode materials are essential for the sustainable evolution of energy storage technologies, reducing the dependence on resources with significant environmental and social implications and simultaneously improving the efficiency and cost effectiveness of batteries. This paper introduces a cobalt-free, high-nickel cathode material called 0.01B-LiNi0.98Mg0.01Zr0.01O2 (NMZB) developed using a novel blend of elements to enhance mechanical and surface chemical stability. Detailed evaluations confirmed the successful integration of Mg, Zr, and B into the particles, with Mg and Zr primarily located within the particle interior and B predominantly on the surface. This unique elemental configuration significantly improves the stability of the bulk phase and surface structure of the material. In addition, the refinement of primary particles within NMZB further enhances its mechanical stability. As a result, NMZB exhibits exceptional electrochemical stability, achieving 90.5 % capacity retention after 200 cycles at a 1C rate. This compositional strategy incorporates a high nickel content into layered materials while eliminating cobalt, which is crucial for advancing the development of cost effective and high-performance lithium-ion battery technology.

Ultrahigh rate and cycling properties of Li2CuTi3O8 anode derived from HKUST-1 copper source for high-performance lithium-ion batteries

Rational design and preparation of titanium-based anode materials with superior fast charge and discharge are a key focuses of the lithium-ion batteries research. Herein, a novel and facile synthesis of uniformly carbon-coated Li2CuTi3O8 (LCuTO) nanoparticles with excellent high-rate lithium storage properties is presented using HKUST-1 with pore structure and active metal sites as a copper source. The well-designed LCuTO@HKUST with carbon bridges between the particles and the carbon layer on the outer surface offers high electronic conductivity for fast charge and discharge. The LCuTO@HKUST exhibits extraordinary lithium storage performance: high capacity (251.8 mAh/g after 1000 cycles at a current density of 1.0 A/g), a superior high-rate capability (160.3 mAh/g after 500 cycles at 3.0 A/g and 138.1 mAh/g after 500 cycles at 5.0 A/g), and excellent cycle reversibility and cycle stability under various current densities. In addition, the lower Li+ migration barrier in LCuTO@HKUST demonstrated by density functional theory (DFT) calculations is beneficial to the long-cycle stability and high-rate performance. The proposed preparation method and the strategy of using the MOF as a metal source for lithium-ion battery anode materials provide a new approach for advanced fast charge–discharge energy storage applications.

Multilayer Ti3C2Tx-loaded CoOHF composite structures for high-performance lithium-ion batteries

Research into new composites to enhance the performance of lithium-ion battery electrode materials has become a trendy area of study. Cobalt-based composites are particularly prominent due to their exceptional electrochemical performance and unique physicochemical properties. Additionally, Ti3C2Tx MXenes materials are anticipated to replace graphene and other carbonaceous materials since they possess an open structure and low lithium-ion diffusion barrier. In this work, we employed simple hydrothermal method to combine layered Ti3C2Tx with needle-shaped CoOHF. The resulting nanosheets showed an even dispersion of CoOHF in the surface, leading to a remarkable increase in specific capacity. Furthermore, Ti3C2Tx provided a higher number of lithium-ion active sites and improved the lithium-ion migration rate, while also ensuring the structure and stability of CoOHF. This composite material enables stable cycling for 1000 cycles at high current densities of 2 A g−1 and ultimately shows a large capacity of 802.4 mAh g−1 stably. Additionally, CoOHF/MXene composites display exceptional performance rate and cycling stability. This study highlights new feasible strategies for using multilayer Ti3C2Tx in lithium-ion batteries, along with metal hydroxyfluorides in new, highly efficient lithium-ion battery anode materials.

A novel embedded KVO3/NC anode for high-performance lithium-ion batteries

Vanadium-based metallic salts, characterized by intrinsic low electronic conductivity, are impeded their advancement as anode materials in the realm of lithium-ion battery technology. This study presents a novel embedded anode material KVO3/NC(KVO/NC) synthesized via a sol–gel method, with KVO3(KVO) particles in situ growing on N-doped carbon, thereby ameliorating conductivity and electrochemical performance. The findings reveal that KVO/NC composite has three lithium-ion storage sites, ultra-high cycling stability (289 mA h/g@5000 cycles@10C@100 %), and superior rate performance (249 mA h/g@15C; 221 mA h/g@20C). Coupled with LiFePO4 cathode, it achieves a competitive energy density (391 W h kg−1@0.1C; 1–3.9 V). This work reveals the practical potential of KVO/NC as a new type of lithium-ion battery anode material with high energy density and long cycle life through a series of ex situ/in situ characterizations.

Fabrication of single-ion conductive quasi-solid-state electrolyte membrane for high-performance lithium-ion batteries

The aim of this work is to develop new quasi-solid-state electrolyte materials for lithium-ion batteries (LIBs) to improve their safety and comprehensive electrochemical performance. Herein, helical mesoporous silica nanofibers were synthesized by a sol–gel method. After grafting lithium salt onto their surfaces, a single-ion conductor (SL) was obtained. Then, using poly(vinylidene fluoride-co-hexafluoropropylene) as the polymer matrix, SL as the filler, a porous composite film was prepared by solution casting method. After soaking organic electrolyte with low concentration Li salt till saturation, one quasi-solid-state electrolyte membrane (PSLE) was achieved. It showed high electrolyte adsorption rate of 660 % and good thermal stability. A high lithium-ion transfer number of 0.85 indicated typical single-ion conductivity. Moreover, a high electrochemical stability window of up to 5.5 V and an ionic conductivity of 2.5 × 10−3 S·cm−1 at 25 °C were gained. The assembled LFP|PSLE|Li battery exhibited excellent rate performance and cycle stability, indicating that the PSLE has great application prospect in solid-state LIBs.

Metal alkoxides: A new type of reversible anode materials for stable and high-rate lithium-ion batteries

Metal-organic compounds have attracted significant attention for lithium-ion battery (LIB) anodes. However, their practical application is severely hindered by the poor structural stability and sluggish Li+ reaction kinetics. Herein, we proposed a new type of metal–organic compound, metal alkoxides, for high-performance LIBs. A series of metal-alkoxide/graphene composites with different transition metal centers and alkoxide anions are prepared to investigate the structural stability, Li-storage ability, and Li+ diffusion kinetics. The results reveal that the metal centers and alkoxide anions have significant influence on the structural stability, molar mass, and electronic structures, which are highly related to the Li-storage performance. Among them, Co-EG/rGO (EG represents the ethylene glycol anion) delivers the best performance involving high specific capacity (975 mAh g−1 at 0.2 A g−1), excellent rate capability (400.8 mAh g−1 at 10 A g−1), and stable cycling performance (86.8 % capacity retention after 600 cycles) due to its stable structure, smaller molar mass, and favorable electronic structure. Moreover, the Li-storage mechanism and solid electrolyte interphase (SEI) evolution of the Co-EG/rGO electrode are studied in detail through multiple ex-situ/in-situ characterizations. This work provides a new type of metal alkoxide anode material for high-rate and long-life LIBs toward practical energy applications.

Interface Engineering via Manipulating Solvation Chemistry for Liquid Lithium-Ion Batteries Operated ≥ 100 °C.

High-performance and temperature-resistant lithium-ion batteries (LIBs), which are able to operate at elevated temperatures (i.e., >60 °C) are highly demanded in various fields, especially in military or aerospace exploration. However, their applications were impeded by the poor electrochemical performance and unsatisfying safety issues, which was induced by the severe side reactions between electrolytes and electrodes at high temperatures. Herein, with the synergetic effects of solvation chemistry and functional additive in the elaborately designed weakly solvating electrolyte, a unique robust organic/inorganic hetero-interphase, composed of gradient F, B-rich inorganic components and homogeneously distributed Si-rich organic components, was successfully constructed on both cathodes and anodes, which would effectively inhibit the constant decomposition of electrolytes and dissolution of transition metal ions. As a result, both cathodes and anodes, without compromising their low-temperature performance,operate at temperatures ≥100 ℃, with excellent capacity retentions of 96.1 % after 500 cycles and 93.5% after ≥200 cycles, respectively, at 80 ℃. Ah-level LiCoO2||graphite full cells with a cut-off voltage of 4.3 V also exhibited superior temperature-resistance with a capacity retention of 89.9% at temperature as high as 120 ℃. Moreover, the fully charged pouch cells exhibited highly enhanced safety, demonstrating their potentials in practical applications at ultrahigh temperatures.

Design of two-dimensional coordination polymer with multiple redox-active sites for high-performance lithium-ion batteries anode material

Design of two-dimensional coordination polymer with multiple redox-active sites for high-performance lithium-ion batteries anode material

Application of Li6.4La3Zr1.45Ta0.5Mo0.05O12/PEO Composite Solid Electrolyte in High-Performance Lithium Batteries.

Replacing the flammable liquid electrolytes with solid ones has been considered to be the most effective way to improve the safety of the lithium batteries. However, the solid electrolytes often suffer from low ionic conductivity and poor rate capability due to their relatively stable molecular/atomic architectures. In this study, we report a composite solid electrolyte, in which polyethylene oxide (PEO) is the matrix and Li6.4La3Zr1.45Ta0.5Mo0.05O12 (LLZTMO) and Li6.4La3Zr1.4Ta0.6O12 (LLZTO) are the fillers. Ta/Mo co-doping can further promote the ion transport capacity in the electrolyte. The synthesized composite electrolytes exhibit high thermal stability (up to 413 °C) and good ionic conductivity (LLZTMO-PEO 2.00 × 10-4 S·cm-1, LLZTO-PEO 1.53 × 10-4 S·cm-1) at 35 °C. Compared with a pure PEO electrolyte, whose ionic conductivity is in the range of 10-7~10-6 S·cm-1, the ionic conductivity of composite solid electrolytes is greatly improved. The full cell assembled with LiFePO4 as the positive electrode exhibits excellent rate performance and good cycling stability, indicating that prepared solid electrolytes have great potential applications in lithium batteries.