Generation Lithium-ion Batteries Research Articles

In Operando Neutron Scattering Multiple-Scale Studies of Lithium-Ion Batteries.

Real-time observation of the electrochemical mechanistic behavior at various scales offers new insightful information to improve the performance of lithium-ion batteries (LIBs). As complementary to the X-ray-based techniques and electron microscopy-based methodologies, neutron scattering provides additional and unique advantages in materials research, owing to the different interactions with atomic nuclei. The non-Z-dependent elemental contrast, in addition to the high penetration ability and weak interaction with matters, makes neutron scattering an advanced probing tool for the in operando mechanistic studies of LIBs. The neutron-based techniques, such as neutron powder diffraction, small-angle neutron scattering, neutron reflectometry, and neutron imaging, have their distinct functionalities and characteristics regimes. These result in their scopes of application distributed in different battery components and covering the full spectrum of all aspects of LIBs. The review surveys the state-of-the-art developments of real-time investigation of the dynamic evolutions of electrochemically active compounds at various scales using neutron techniques. The atomic-scale, the mesoscopic-scale, and at the macroscopic-scale within LIBs during electrochemical functioning provide insightful information to battery researchers. The authors envision that this review will popularize the applications of neutron-based techniques in LIB studies and furnish important inspirations to battery researchers for the rational design of the new generation of LIBs.

A simplified electrophoretic deposition route for sandwiched structure-based Mn3O4/G composite electrodes as high-capacity anodes for lithium-ion batteries

Based on characteristic multielectron conversion reactions, transition-metal oxides are regarded as potential anode candidates for the new generation of lithium-ion batteries (LIBs) because they are endowed with high specific capacity. Nevertheless, the inferior electronic conductivity and larger volume change lead to fast capacity decay during cycling. Herein, we propose a novel electrophoretic deposition strategy to prepare binder-free Mn3O4/graphene hybrid electrodes and overcome these two obstacles simultaneously. In the rationally designed structure, Mn3O4 nanoparticles are well encapsulated in the conductive network constructed by interconnected graphene sheets. In the process of cycling, thanks to the excellent flexibility of graphene and the rich voids in this sandwiched structure, not only the structural integrity but also the unobstructed conductive network can be ensured. In addition, it is verified that electrode kinetics is a fast process for surface-controlled lithium storage. From this perspective, in addition to high reversible specific capacity (880 mAh g−1 at 0.1 A g−1), the prepared Mn3O4/graphene hybrid electrode possesses outstanding rate capability (678 mAh g−1 at 5 A g−1) and remarkable cycling stability (neglectable capacity decay after 500 cycles at 1 A g−1).

Evaluation of Nb-Doping on performance of LiNiO2 in wide temperature range

Multi-elemental doping is one of the most efficient approaches to stabilize the structure and improve the performance of the nickel-rich layered metal oxides, the promising cathode materials for next generation of lithium ion batteries. Nevertheless, to fully understand the fundamental role of each doped elements would be the practically requirement for the design of the materials. Herein, LiNiO2 doped with single element Nb, a common dopant in various electrode materials, is synthesized to elucidate the functionality of Nb for the LiNiO2-based materials. It is found that the Nb-doping would enlarge the crystal lattice of LiNiO2, and reduce the volume change of the crystal lattice from expansion/contraction during the electrochemical processes. As a result, the cycling and rate performance of the doped materials can be greatly improved, due to preservation of the integrity of the secondary particles of the materials and enlargement of the pathway for the Li+ ion diffusion, in addition to the mitigation of the interfacial reactions of the electrolyte. Those ensure the doped materials with superior performance in a wide operating temperature region (55 °C to −10 °C). Nevertheless, the Li+/Ni2+ cation mixing induced by Nb-doping would have great impact on the performance of the materials. In particular, the Li+/Ni2+ cation mixing in the presence of excess doped Nb might impede the diffusion of the Li+ ions, resulting in deterioration of the rate performance. Based on the results, it is suggested that careful optimization of the amount of the doped Nb would be necessary to ensure the stability of the integrated structure and efficient diffusion of the Li+ ions of the LiNiO2-based materials.

Composite Membrane of Poly(vinylidene fluoride) and 2D Ni(OH)2 Nanosheets for High-Performance Lithium-Ion Battery

For the first time, we explored the possibility of utilizing 2D nickel hydroxide nanosheets (NHNs) to prepare NHN/poly(vinylidene fluoride) composite membranes for battery separator applications. The effect of these ultrathin 2D nanosheets on the morphology, crystallization behaviors, porosity, electrolyte uptake ratio, ionic conductivity, and thermal stability of the composite membranes were systematically investigated. A low filler content of only 3 wt % NHNs into PVDF membranes not only promoted superior thermal stability (1.9% shrinkage at 130 °C for 0.5 h) but also led to a significant increase of β-phase content (85.0%), electrolyte affinity (327.6% uptake ratio), and ionic conductivity (1.5 mS cm–1). Strong interfacial interactions between 2D NHNs and polymer molecular chains are responsible for significant α to β crystalline phase conversion, benefiting to high ionic conductivity and electrochemical performance of cells. Moreover, in order to gain more insights for battery applications, this membrane was assembled and evaluated in Li/LiFePO4 half-cells, showing a good cycling performance and rate capability, with a capacity retention of 95.9% after 100 cycles at 2 C and a high specific capacity of 129.1 mAhg–1 at 2 C. Thus, this NHN/PVDF composite membrane could be a promising separator for next generation lithium-ion batteries requiring high safety and ultrafast rechargeability.

Black glasses grafted micron silicon: a resilient anode material for high-performance lithium-ion batteries

Effective methodology for designing a resilient micron silicon-based anode material for stable and reversible storage of lithium ions and its practical application in next generation lithium-ion batteries.

A porous silicon anode prepared by dealloying a Sr-modified Al-Si eutectic alloy for lithium ion batteries.

Silicon has been considered to be one of the most promising anode materials for next generation lithium ion batteries due to its high theoretical specific capacity. However, its huge volume expansion during the lithiation/delithiation process that can result in rapid capacity fading and low conductivity present significant challenges for application. In this study, the morphology of Si in an Al–Si eutectic alloy was modified by Sr, and porous Si was then produced by dealloying the precursor. Profiting from the unique structure, the Si anode exhibits an excellent reversible capacity of 405 mA h g−1 at 0.5 A g−1 after 100 cycles and a fantastic first cycle coulombic efficiency of 83.74%. Furthermore, the porous silicon modified by Sr delivers a stable capacity of 594.8 mA h g−1 even at a high current density of 2 A g−1 after 50 cycles, suggesting a good rate capability.

An Environmental Sustainability Analysis Tool for Next Generation Lithium Ion Batteries of Electric Vehicles

Lithium-ion batteries (LIBs) are widely used in portable electronics and electric vehicles, but are limited in capacity and energy density. Tremendous efforts have been devoted to the research and development of next-generation LIBs with a high capacity and energy density, particularly through adoption of novel nano-structured materials in the LIB electrodes. The synthesis of nanomaterials, however, involves heavy use of toxic chemicals and nanoparticle emissions, which induce grave concerns on the environmental sustainability of next-generation LIBs. Silicon, with a high theoretical specific capacity, has been recognized as one of the most promising anode materials for next-generation LIBs. In this study, a comprehensive analysis tool is developed to evaluate the environmental sustainability of silicon-based LIBs for EVs by incorporating previously published data, and two nanostructured silicon materials, i.e., silicon nanowires (SiNWs) and silicon nanotubes (SiNTs) are chosen as examples. The purpose is to provide decision support for sustainable design of next-generation LIB technologies by providing overall environmental impact results and feedback to next-generation LIB designers to identify the tradeoffs between technical specifications and sustainability performance. Specifically, this tool based on an Excel spreadsheet comprises six modules, i.e., Dashboard, Material Consumptions, Gas and Aqueous Emissions, Nano Particle Emissions, Energy Consumption, and Life Cycle Impacts. The specifications of the battery packs are inputted in the Dashboard and the environmental impact assessment is conducted through the rest modules utilizing the inputted data to compute each modular results using the embedded formula from our previously published work. The conventional emissions and energy consumption data are characterized with the life cycle impact assessment method for design feedback, while the nanoparticle emission data are experimentally measured and directly used. This analysis tool provides insights into material consumptions and environmental impacts of SiNW-and SiNT-based LIBs and can be expanded for future analyses of other nanostructured next-generation LIB technologies for electric vehicles.

Synchronous construction of oxygen vacancies with suitable concentrations and carbon coating on the surface of Li-rich layered oxide cathode materials by spray drying for Li-ion batteries

Lithium-rich layered oxide materials with high reversible capacities (over 250 mAh g−1) are considered as one of the most promising cathode materials for the next generation of lithium-ion batteries. However, some challenges including low initial Coulombic efficiency, voltage decay and poor cycling restrict their commercial application. Herrin, Li-rich layered oxide materials Li1.2Ni0.2Co0.08Mn0.52O2 co-modified by constructing oxygen vacancies with suitable concentration and C coating layer have been synthesized via a facile spray drying process. The oxygen vacancies with suitable concentration can not only suppress the release of O2 and improve the stability of the layered structure, but also facilitate Li diffusion. Moreover, C coating layer acts as a physical barrier to protect the materials from electrolyte, and reduce the interface impedance. The co-modified material shows excellent electrochemical properties: a high initial Coulombic efficiency of 83.1%, a small voltage decay rate of 0.306 mV, and a capacity retention of 78.3% after 1000 cycles at 5 C. And it provides a simple and feasible way to improve the properties of lithium-rich layered oxide materials.

Coaxial Electrospinning Construction Si@C Core-Shell Nanofibers for Advanced Flexible Lithium-Ion Batteries.

Silicon (Si) is expected to be a high-energy anode for the next generation of lithium-ion batteries (LIBs). However, the large volume change along with the severe capacity degradation during the cycling process is still a barrier for its practical application. Herein, we successfully construct flexible silicon/carbon nanofibers with a core–shell structure via a facile coaxial electrospinning technique. The resultant Si@C nanofibers (Si@C NFs) are composed of a hard carbon shell and the Si-embedded amorphous carbon core framework demonstrates an initial reversible capacity of 1162.8 mAh g−1 at 0.1 A g−1 with a retained capacity of 762.0 mAh g−1 after 100 cycles. In addition, flexible LIBs assembled with Si@C NFs were hardly impacted under an extreme bending state, illustrating excellent electrochemical performance. The impressive performances are attributed to the high electric conductivity and structural stability of the porous carbon fibers with a hierarchical porous structure, indicating that the novel Si@C NFs fabricated using this electrospinning technique have great potential for advanced flexible energy storage.

Three-dimensional flexible molybdenum oxynitride thin film as a high capacity anode for Li-ion batteries

With the fast development of flexible wearable electronics, mobile electronic equipment, electric tool and electric vehicles, high specific capacity, superior cycle stability and excellent fast-charge performance are required for lithium-ion batteries (LIBs). Nevertheless, commercial graphite with the limited theoretical capacity (372 mAh g−1) and short lifespan is difficult to satisfy the requirements of the new generation of LIBs. In this work, the three-dimensional flexible molybdenum oxynitride (MNO) thin films with non-binder were prepared by magnetron sputtering approach. The charge transfer resistance and Li-ion diffusion coefficient were measured by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV), and the results show that molybdenum nitride is helpful to increase the diffusion and electron transfer of Li-ion. The MNO thin film annealed at 300 °C with irregular aggregate matrix structure shows a discharge capacity of 413 mAh g−1 after 180 cycles at 1 A g−1. The outstanding rate performance and cycle stability suggest that these binder-free thin film electrodes, especially nitrides, offer great opportunity for energy storage systems with fast-charge capabilities.

Si nanoparticles seeded in carbon-coated Sn nanowires as an anode for high-energy and high-rate lithium-ion batteries

Abstract High-capacity and high-rate anode materials are desperately desired for applications in the next generation lithium-ion batteries. Here, we report preparation of an anode showing a structure of Si nanoparticles wrapped inside Sn nanowires. This anode inherits the advantages of both Si and Sn, endowing lithiation/delithiation of Si nanoparticles inside the conducting networks of Sn nanowires. It demonstrates a high and reversible capacity of ∼1500 mAh g−1 over 300 cycles at 0.2 °C and a good rate capability (0.2 °C–5 °C) equivalent to Sn. The excellent cycling performance is attributed to the novel structure of the anode as well as the strong mechanical strength of the nanowires which is directly confirmed by in-situ lithiation and bending experiments.

Mechanistic insights into the reversible lithium storage in an open porous carbon via metal cluster formation in all solid-state batteries

Porous carbons are promising anode materials for next generation lithium batteries due to their large lithium storage capacities. However, their highsloping capacity during lithiation and delithiation as well as capacity fading due to intense formation of solid electrolyte interphase (SEI) limit their gravimetric and volumetric energy densities. Herein we compare a microporous carbide-derived carbon material (MPC) as promising future anode for all solid-state batteries with a commercial high-performance hard carbon anode. The MPC obtains high and reversible lithiation capacities of 1000 mAh g−1carbon in half-cells exhibiting an extended plateau region near 0 V vs. Li/Li+ preferable for full-cell application. The well-defined microporosity of the MPC with a specific surface area of >1500 m2 g−1 combines well with the argyrodite-type electrolyte (Li6PS5Cl) suppressing extensive SEI formation to deliver high coulombic efficiencies. Preliminary full-cell measurements vs. nickel-rich NMC-cathodes (LiNi0.9Co0.05Mn0.05O2) provide a considerably improved average potential of 3.76 V leading to a projected energy density as high as 449 Wh kg−1 and reversible cycling for more than 60 cycles. 7Li Nuclear Magnetic Resonance spectroscopy was combined with ex-situ Small Angle X-ray Scattering to elucidate the storage mechanism of lithium inside the carbon matrix. The formation of extended quasi-metallic lithium clusters after electrochemical lithiation was revealed.

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.

The polyethylene glycol@MoO3/canbon nanotubes/S composite fixing polysulfides for lithium-sulfur batteries

Lithium-sulfur batteries are the extremely promising next generation lithium-ion batteries, but solving the shuttle effect of polysulfide is challenging. Here, the polyethylene glycol@MoO3/carbon nanotubes/S composite（PEG@MoO3/CNTs/S）is prepared in this paper. PEG can trap polysulfides and suppress the shuttle effect. Meanwhile, the polar MoO3 can effectively limit the transfer of polysulfides by chemisorption. Furthermore, the CNTs with the excellent electrical conductivity and mechanical properties is used as the substrate in lithium-sulfur batteries. The 2.5-PEG@MoO3/CNTs/S (2.5 refers to percentage of PEG coated) cathode exhibits a high initial discharge capacity (1327.4 ​mAh g−1 at 0.1C), an outstanding cycling stability (capacity fading rate of 0.067% per cycle at 0.5C over 800 cycles) and an excellent rate performance (899.1 ​mAh g−1 at 1C).

Advanced Electrode Materials for Lithium-ion Battery: Silicon-based Anodes and Co-less-Ni-rich Cathodes

The development of higher-performance rechargeable lithium-ion batteries (LIBs) is critical to the substantial development of electric vehicles and portable electronic devices. The cost of lithium-ion batteries needs to be decreased more and the specific energy as well as recycling degradation rate needs to be enhanced further. Silicon anodes and cobalt-free nickel-rich cathodes are widely regarded as promising materials for the next generation of lithium-ion batteries. This review discusses the current state of research on silicon anode nanomaterials and nickel-rich cathode materials without cobalt.

Mitigating voltage decay of Li-Rich layer oxide cathode material via an ultrathin “lithium ion pump” heteroepitaxial surface modification

Lithium-rich layered oxides are widely considered as the most promising candidate for high energy density cathode in lithium-ion batteries (LIBs) due to their extraordinary capacity. However, cycle instability, poor rate capability and voltage decay impede their practical applications, which are caused by oxygen release and phase transformation during cycling. In this work, an ultrathin spinel Li4Ti5O12 (LTO) coating acting alike a “lithium ion pump” is built on the surface of lithium-rich layered oxides Li1.2Ni0.2Mn0.6O2 (LLNMO) through solvothermal method. It is identified that spinel LTO and layered LLNMO phases display heteroepitaxial structure resulting in reduction of oxygen loss, phase transformation, capacity decline and voltage fading. The cathode with heteroepitaxial structure demonstrates an acceptable initial coulombic efficiency up to 87.7% (only 79.8% for LLNMO), highly competitive cycling stability (97.9% capacity retention at 0.1C after 100 cycles), minimal voltage decay of 1.22 mV cycle−1 and excellent rate capability (171.5 mAh g−1 at 10C). The supreme electrochemical performances suggest that epitaxial spinel LTO coating can effectively stabilize oxygen framework and the layered structure on the surface of lithium-rich layered oxides for modification of high-capacity cathode in next generation LIBs.

Research Progress on Coating Structure of Silicon Anode Materials for Lithium-Ion Batteries.

Silicon, which has been widely studied by virtue of its extremely high theoretical capacity and abundance, is recognized as one of the most promising anode materials for the next generation of lithium-ion batteries. However, silicon undergoes tremendous volume change during cycling, which leads to the destruction of the electrode structure and irreversible capacity loss, so the promotion of silicon materials in commercial applications is greatly hampered. In recent years, many strategies have been proposed to address these shortcomings of silicon. This Review focused on different coatings materials (e. g., carbon-based materials, metals, oxides, conducting polymers, etc.) for silicon materials. The role of different types of materials in the modification of silicon-based material encapsulation structure was reviewed to confirm the feasibility of the protective layer strategy. Finally, the future research direction of the silicon-based material coating structure design for the next-generation lithium-ion battery was summarized.

Lithium sulfide nanocrystals as cathode materials for advanced batteries

The ever-increasing need for sustainable development requires advanced battery techniques beyond the current generation of lithium ion batteries. Among all candidates being explored, lithium-sulfur batteries are a very promising system to be commercialized in the near future. Towards this end, the development of lithium sulfide (Li2S) nanocrystal-based cathodes has received tremendous effort and witnessed multiple reviews. Differentiated from the focus on performance improvement in previous reviews, this review summarizes the research progress in line with the approaches of materials synthesis and electrode fabrication. The key chemistry, operation procedure, materials characterizations and performance assessments are all given a balanced description. Moreover, all approaches are collectively analyzed along the lines of six criteria towards practical applications, i.e., electrode performance, materials quality, resources sustainability, production cost, operation procedure, and consumed energy. Finally, some perspective viewpoints on the future research directions are offered.

Understanding the formation of antiphase boundaries in layered oxide cathode materials and their evolution upon electrochemical cycling

Understanding the formation of antiphase boundaries in layered oxide cathode materials and their evolution upon electrochemical cycling

Electrolyte Oxidation and the Role of Acidic Fluorophosphates in Capacity Loss for Lithium Ion Batteries

Cycling lithiated metal oxides to high potential (>4.5 V vs Li) is of significant interest for the next generation of lithium ion batteries. Cathodes cycled to high potential suffer from rapid capacity fade due to a combination of thickening of the anode solid electrolyte interphase (SEI) and impedance growth on the cathode. While transition metal catalyzed degradation of the anode SEI has been widely proposed as a primary source of capacity loss, we propose a related acid induced degradation of the anode SEI. A systematic investigation of LiMn2O4, LiNi0.5Mn1.5O4, LiNi0.6Mn0.2Co0.2O2, and LiNi0.8Mn0.1Co0.1O2 cathodes will be presented. The role of potential on the generation of soluble acidic fluorophosphates crossover species and the impact of these species on the structure and stability of the SEI will be presented.