High-energy Lithium-ion Batteries Research Articles

Monolithic Layered Silicon Composed of a Crystalline-Amorphous Network for Sustainable Lithium-Ion Battery Anodes.

While nanostructural engineering holds promise for improving the stability of high-capacity silicon (Si) anodes in lithium-ion batteries (LIBs), challenges like complex synthesis and the high cost of nano-Si impede its commercial application. In this study, we present a local reduction technique to synthesize micron-scale monolithic layered Si (10-20 μm) with a high tap density of 0.9-1.0 g cm-3 from cost-effective montmorillonite, a natural layered silicate mineral. The created mesoporous structure within each layer, combined with the void spaces between interlayers, effectively mitigates both lateral and vertical expansion throughout repeated lithiation/delithiation cycles. Furthermore, the remaining SiO2 network fortifies the layered structure, preventing it from collapsing during cycling. Half-cell tests reveal a capacity retention of 92% with a reversible capacity of 1130 mAh g-1 over 500 cycles. Moreover, the pouch cell integrated with this Si anode (with a mass loading of 3.0 mg cm-2) and a commercial NCM811 cathode delivers a high energy density of 655 Wh kg-1 (based on the total mass of the cathode and anode) and maintains 82% capacity after 200 cycles. This work demonstrates a cost-efficient and scalable strategy to manufacture high-performance micron Si anodes for the ever-growing demand for high-energy LIBs.

Lanthanum doping and surface Li3BO3 passivating layer enabling 4.8 V nickel-rich layered oxide cathodes toward high energy lithium-ion batteries

Single crystalline Ni-rich layered oxide cathodes show high energy density and low cost, have been regarded as one of the most promising candidates for next generation lithium-ion batteries (LIBs). Extending the cycling voltage window will significantly improve the energy density, however, suffers from bulk structural and interfacial chemistry degradation, leading to rapidly cycle performance deterioration. Here, we propose a dual-modification strategy to synthesize La doping and Li3BO3 (LBO) coating layers modified LiNi0.8Co0.1Mn0.1O2 (NCM811) by a facile one-step heating treatment processing. In-situ EIS and XRD, ex-situ XPS techniques are applied to demonstrate that the La diffused amorphous domains and Li3BO3 passivating layers dampen the lattice distortion, enhance the interfacial chemistry behavior as well as lithium ion transportation kinetics. Specifically, surface La doping amorphous domains successfully suppress the intense lattice stress and volume changes induced by the phase transitions during lithiation/delithiation, thus avoiding the intergranular crack and enhancing the mechanical stability of the material. Moreover, the LBO layer formed by the consumption of residual lithium prevents successive parasitic reactions at the interface as well as provides rapid Li-ion diffusion channels. Furthermore, the coating layer also diminishes the residual lithium compounds, increasing the atmosphere stability and safety of LIBs. Consequently, the La doping and LBO coating NCM811 exhibits an exceptional initial specific capacity (230.6 mAh/g) at 0.5C under a high cutoff voltage of 4.8 V, and a 73.8 % capacity retention following 100 cycles. In addition, a superior specific capacity of 133.8 mAh/g is provided even at a high current density (4C). Our work paves a promising road to tackle the integral structure deterioration and interfacial instability of Ni-rich cathodes.

A synergistic duo for enhanced cathode stability in high-voltage lithium-ion batteries

Lithium-ion batteries with high-nickel cathode materials are promising candidates for achieving significantly higher energy densities. However, when Ni-rich subjected to higher charging cutoff voltages accelerates both electrolyte decomposition and structural degradation, leading to compromised cycling stability and reduced lifespan. In this study, we have developed a dual-additive strategy using lithium difluoro bisoxalate phosphate (LiDFBOP), and 1,3-divinyl-1,1,3,3-tetramethyldisilazane (DTDS) to address these challenges and improve the battery's performance. Theoretical calculations and experimental results indicate that the LiDFBOP regulates Li⁺ solvation for robust CEI formation, while DTDS scavenges impurities and promotes the formation of an inorganic/organic interphase. The synergistic effect of these additives combination allows Li||NCM811 coin cell to retain a capacity retention 87.9 % at 4.6 V and Graphite||NCM811full cell achieved 90.5 % capacity retention at 4.5 V. Moreover, the 1Ah pouch full cells exhibit excellent cycling stability, with a capacity retention of 91.4 % after 610 cycles at a constant current of 500 mA and voltage of 4.5 V. This work offers guidance on designing multifunctional additives to achieve synergistic electrolyte engineering for high-energy lithium-ion batteries.

The high-fluorinated bi-molecular combination enables high-energy lithium batteries under challenging environment

The drawbacks of temperature sensitivity, high voltage intolerance, and flammability of lithium batteries are gradually brought to light in conventional carbonate electrolytes. To solve these problems, a localized high concentration electrolyte (LHCE) employing highly fluorinated ethyl trifluoroacetate (TFAE) and 2,2,3,3-tetrafluoro-1-(1,1,2,2-tetrafluoroethoxy) propane (TFEP) is designed. When applied in high-energy lithium batteries, the discharge specific capacity of Li||NMC811 battery can maintain 143.6 mAh/g after 500 cycles at 4.6 V and 1C, and the capacity retention of Li||LNMO battery retains as high as 89.99 % after 500 cycles at 5 V. In addition, this LHCE also possesses the ability to operate the battery under challenging conditions including low temperature, fast charge, safety risks, etc. The LHCE based on TFAE and TFEP has unique solvated structures to generate a moderate LiF-rich interfacial layer, ensuring the fast Li+ migration. This work will provide strong guidance for future electrolyte industrial design of high-energy lithium battery.

Precycling Strategy in Suitable Voltage to Improve the Stability of Interfacial Film and Suppress the Decline of LiNi0.6Mn0.2Co0.2O2 Cathode at Elevated Temperatures.

Layered ternary oxide LiNixMnyCo1-x-yO2 is a promising cathode candidate for high-energy lithium-ion batteries (LIBs). However, the capacity of LIBs is significantly restricted by several factors, including the repeated dissolution-regeneration of the interfacial film at high temperatures, the dissolution of transition metals, and the increase of impedance. Herein, a new precycling strategy in suitable voltage scope at room temperature is proposed to construct a uniform, thermally stable, and insoluble cathode-electrolyte interface (CEI), which helps to maintain stable cycling performances at high temperatures. Specifically, after 5 precycles in the range of 3.85-4.3 V at room temperature, a CEI layer containing numerous inorganic components and oligomers is formed on the surface of LiNi0.6Mn0.2Co0.2O2. Subsequently, the harmful side reactions are effectively suppressed, endowing the cell with an excellent capacity retention of 84.67% after 50 cycles at 0.5C and 55 °C, much higher than that of 65.61% under the conventional film-forming process conditions. This work emphasizes the crucial role of the precycling strategy in regulating the characteristics of CEI layer on the surface of cathode electrode, opening up a new avenue for the high-temperature application of positive electrodes of LIBs.

Mathematical Model for a Lithium-Ion Battery with a SiO/Graphite Blended Electrode Based on a Reduced Order Model Derived Using Perturbation Theory

Silicon oxide (SiO) is a promising anode material for high-energy lithium-ion batteries, as it is made from low-cost precursors, has a potential close to that of Li, and has high theoretical specific capacity. However, the applications of SiO are limited by the intrinsic low electrical conductivity, large volume change, and low coulombic efficiency, which often lead to poor cycling performance. A common strategy to address these shortcomings is to blend SiO with graphite active materials to form a composite anode for better capacity retention. In this work, we derive a reduced order model (ROM1) using perturbation theory. We employ the multi-site, multi-reaction (MSMR) framework of a composite porous electrode blend consisting of two lithium-host materials, SiO and graphite. The ROM1 model employs a single-particle model (SPM) approach as the leading-order solution and involves the numerical analysis of a single, nonlinear partial differential equation for each host material that describes diffusion by means of irreversible thermodynamics, wherein chemical-potential gradients are the driving forces for the diffusion. The first-order correction treats losses other than that of the SPM.

Quenching-Induced Ultrathin LiF-Rich Interphases on LiNi0.8Co0.1Mn0.1O2 Cathode

Nickel-rich layered oxides (NCM) are a promising contender material for the cathode electrode of high-energy lithium-ion batteries (LIBs) due to their large reversible capacity and high operating voltage. However, the poor surface/interfacial stability and the dissolution of transition metal ions hinder the commercial application of NCM. To create an artificial cathode electrolyte interphase (CEI) with LiF-rich inorganic phase on the NCM surface, a practical and efficient way of quenching the NCM powder from high temperature in 1,1,2,2-Tetrafluoroethyl 2,2,2-trifluoroethyl ether (HFE) was devised. With this artificial CEI film, the side reactions between NCM and electrolytes are inhibited, and the dissolution of TM ions is retarded. The quenched-NCM achieved fantastic cycling performance and suppressed voltage decay. Our research offers an efficient and worthy approach for improving the surface/interfacial stabilization of nickel-rich cathode materials for high-energy-density LIBs.

Remarkably improved cycling stability of commercial micron-sized silicon enabled by a novel organic/inorganic hybrid binder

Silicon (Si) anode with ultra-high capacity and low cost are highly desirable for next-generation high-energy lithium-ion batteries, whereas suffers from severe volume change that causes rapid capacity decay upon lithiation/delithiation. The development of high-performance binders to alleviate volumetric expansion and maintain integrity of Si particles remains a significant challenge. Here, reported is a novel organic/inorganic hybrid binder composed of partial neutralized polyacrylic acid (PAAS) and sodium metaborate tetrahydrate (SMTH), which achieves in-situ crosslinking upon drying wafer electrodes. The robust crosslinked network structure with borate ester bonds is successfully attained, and can be modulated by changing the content of sodium metaborate. The strong covalent bond network endows the hybrid binder system with superior mechanical properties and powerful adhesion, which improve the contact and integrity of wafer silicon electrode by suppressing volume expansion and exfoliation, therefore facilitating Li-ion migration and enhancing electrochemical performance. The resulting commercial micro-silicon wafer electrode with PAAS/0.08SMTH binder remains a reversible specific capacity of 1670 mAh g−1 after 150 cycles at 300 mA g−1, largely superior to that prepared with the original PAAS binder because its reversible specific capacity was determined to be only 1046 mAh g−1 under identical conditions. The in-situ crosslinked 3D network structure provides a facile feasible way to improve the high-capacity anode materials for lithium-ion batteries.

Constructing adaptive silicon–carbon interconnected network for high-energy lithium-ion batteries

Nano-silicon (n-Si)/graphite anodes are highly desirable for high-energy lithium-ion batteries. Nevertheless, the high surface energy of n-Si grains is prone to causing serious agglomeration. In this work, the modified n-Si is evenly dispersed on the g-C3N4 carbon mesh that acquired through melamine heat treatment constructing an adaptive Si-carbon interconnection network structure (mSi50/g-C3N4). Ideally, the mSi50/g-C3N4 composite can be well dispersed and fill the gaps in graphite through traditional ball milling processes. The obtained mSi50/g-C3N4/Gr composite prevents the accumulation of Si grains which is beneficial for expediting ion transport, improving conductivity and structural stability. As a result, this anode provides a reversible capacity of 621 mAh⋅g−1 at 0.2 C, with high-capacity retention of 93.3 % after 300 cycles at 1 C and low volume expansion of only 28.6 %. Furthermore, it also maintains excellent cycling stability in full batteries with LiFePO4 cathode. Therefore, constructing the mSi50/g-C3N4 network is an effective strategy to achieve uniform dispersion of Si in graphite and promote larger scale industrialization of n-Si/graphite anode.

Rest in phase transition: Should charging habits in next generation EVs be adapted?

Nickel-rich cathode materials are a popular cathode for high energy lithium ion batteries in the current and next generation of electric vehicles. While nickel-rich cathodes offer high energy density, their cycle-life is compromised due to several factors directly related to their (de)lithiation behavior. At high state of charge the nickel-rich cathode experiences a hexagonal-hexagonal transition which is accompanied by drastic changes in the unit cell parameters. This phenomenon is detrimental for cycle-life of a battery cell. This work elucidates on the effect of storing LiNi0.8Mn0.1Co0.1O2‖Graphite cells at 95 % state of charge corresponding to the above-mentioned transition for 10 h every six cycles. The results are compared to cells cycled without a rest at high state of charge and cells cycled to 100 % state of charge. Analysis of the obtained cycling data shows that resting lithium ion cells based nickel-rich cathode based cells is detrimental leading to higher impedance growth and capacity decay than cycling to 100 % state of charge.

Complex reaction mechanisms of electrolyte decomposition at large-scale Ni-rich Li-ion battery cells including electrode crosstalk effect

Ni-rich cathodes are essential for the advancement of high-energy lithium-ion batteries but encounter significant challenges at elevated voltages, including oxygen liberation and enhanced surface reactivity, which precipitate electrolyte decomposition. This study explores the intricate reaction mechanisms of electrolyte decomposition linked to the pronounced release of oxygen from the cathode lattice in large-scale 18650 cylindrical cells employing Ni-rich LiNi0.90Mn0.05Co0.05O2(NMC90)//graphite configurations, focusing on electrode crosstalk effects at high voltages. Notably, acetals such as methoxy methanol (49.93 %) and methane diol (50.07 %) were identified at 4.7 V, with their presence escalating at 4.9 V. Formaldehyde, present at 7.21 %, along with methanol (22.77 %), methane diol (36.35 %), and methoxy methanol (33.67 %), begins to manifest at 4.9 V. The dissolution of transition metals was analyzed using Inductively Coupled Plasma Atomic Emission Spectrometry, and changes in the double-layer capacitance were assessed through electrochemical impedance spectroscopy, further validating the link between these decomposition products and cathode failure associated with oxygen release. These insights reveal the complex relationship between electrolyte decomposition and cathode degradation due to oxygen release, highlighting a critical failure mechanism in large-scale cylindrical lithium-ion batteries.

Design of dual carbon encapsulated porous micron silicon composite with compact surface for enhanced reaction kinetics of lithium-ion battery anodes

Developing high-performance composites with fast charging and superior cycle life is paramount for lithium-ion batteries (LIBs). Herein, we synthesized a double-shell carbon-coated porous structure composite with a compact surface (P-Si@rGO@C) using low-cost commercial micron-sized silicon (Si) instead of nanoscale silicon. Results reveal that the unique P-Si@rGO@C features high adaptability to volume expansion, accelerates electron/ion transmission rate, and forms a stable solid electrolyte interphase (SEI) film. This phenomenon arises from the synergistic effect of abundant internal voids and an external double-layer carbon shell with a dense surface. Specifically, the P-Si@rGO@C anode exhibits a high initial coulombic efficiency (ICE) (88.0 %), impressive rate-capability (612.1 mAh/g at 2C), and exceptional long-term cyclability (972.2 mAh/g over 500 cycles at 0.5C). Further kinetic studies elucidate the diffusion-capacitance hybrid energy storage mechanism and reveal an improved Li+ diffusion coefficient (from 3.47 × 10-11 to 2.85 × 10-9 cm2 s-1). Ex-situ characterization confirms the crystal phase change of micron-sized Si and the formation of a stable LiF-rich SEI. Theoretical calculations support these findings by demonstrating an enhancement in the adsorption ability of Si to Li+ (from -0.89 to -0.97 eV) and a reduction in the energy migration barrier (from 0.35 to 0.18 eV). Additionally, practical LixSi powder is shown to increase the ICE of full cells from 67.4 % to 87.9 %. Furthermore, a pouch cell utilizing the prelithiated P-Si@rGO@C anode paired with LiNi1/3Co1/3Mn1/3O2 (NCM111) cathode delivers a high initial reversible capacity of 7.2 mAh and 76.8 % capacity retention after 100 cycles. This work provides insights into the application of commercial silicon-aluminum alloy powder in the anode of high-energy LIBs.

Dual-gate design enables intrinsic safety of high-energy batteries

The safety issue hampers the application of high-energy lithium-ion batteries in electric vehicles, grid energy storage, electric ships and aircrafts. The chemical cross-talk, which refers to the migration of energetic intermediates between cathode and anode, initiates battery self-heating and accelerates the intensive heat release during battery thermal failure. However, blocking the chemical cross-talk is extremely hard. Previously, we may expect a thermally stable separator can guard the gate between battery cathode and anode, however, large amount of hot gas breaks the defense mechanically not thermally. Draining the cross-talk gas is of equal importance with blocking it. Herein, a dual-gate design notion is proposed, using separator as “block gate” and vent valve as “removal gate” to regulate the spatial distribution of energetic species to reduce the major heat release during battery thermal runaway. The design is validated by more than 50 battery chemistries. Typically, the maximum temperature of NMC811||Gr pouch cell decreases from >800 °C to <300 °C, the highest temperature rising rate decreases from 761.0 °C/s to 0.013 °C/s. The morphology and crystalline change of cathode verify that the chemical cross-talk is successfully suppressed. Moreover, such design has little side effect on the electrochemical performance of batteries. The dual-gate design breaks the bottleneck for the safety design of high energy batteries, providing insight into the safe utilization of electrochemical energy storage materials.

Toward Cost-Effective High-Energy Lithium-Ion Battery Cathodes: Covalent Bond Formation Empowers Solid-State Oxygen Redox in Antifluorite-Type Lithium-Rich Iron Oxide

Toward Cost-Effective High-Energy Lithium-Ion Battery Cathodes: Covalent Bond Formation Empowers Solid-State Oxygen Redox in Antifluorite-Type Lithium-Rich Iron Oxide

Advanced Micro/Nanostructure Silicon-Based Anode Materials for High-Energy Lithium-Ion Batteries: From Liquid- to Solid-State Batteries

Advanced Micro/Nanostructure Silicon-Based Anode Materials for High-Energy Lithium-Ion Batteries: From Liquid- to Solid-State Batteries

Reduced Volume Expansion of Micron-Sized SiOx via Closed-Nanopore Structure Constructed by Mg-Induced Elemental Segregation.

The inherently huge volume expansion during Li uptake has hindered the use of Si-based anodes in high-energy lithium-ion batteries. While some pore-forming and nano-architecting strategies show promises to effectively buffer the volume change, other parameters essential for practical electrode fabrication, such as compaction density, are often compromised. Here we propose a new in situ Mg doping strategy to form closed-nanopore structure into a micron-sized SiOx particle at a high bulk density. The doped Mg atoms promote the segregation of O, so that high-density magnesium silicates form to generate closed nanopores. By altering the mass content of Mg dopant, the average radii (ranged from 5.4 to 9.7 nm) and porosities (ranged from 1.4 % to 15.9 %) of the closed pores are precisely adjustable, which accounts for volume expansion of SiOx from 77.8 % to 22.2 % at the minimum. Benefited from the small volume variation, the Mg-doped micron-SiOx anode demonstrates improved Li storage performance towards realization of a 700-(dis)charge-cycle, 11-Ah-pouch-type cell at a capacity retention of >80 %. This work offers insights into reasonable design of the internal structure of micron-sized SiOx and other materials that undergo conversion or alloying reactions with drastic volume change, to enable high-energy batteries with stable electrochemistry.

Double-Shelled Fe-Fe3C Nanoparticles Embedded on a Porous Carbon Framework for Superior Lithium-Ion Half/Full Batteries.

Cost-effective and environmentally friendly Fe-based active materials offer exceptionally high energy capacity in lithium-ion batteries (LIBs) due to their multiple electron redox reactions. However, challenges, such as morphology degradation during cycling, cell pulverization, and electrochemical stability, have hindered their widespread use. Herein, we demonstrated a simple salt-assisted freeze-drying method to design a double-shelled Fe/Fe3C core tightly anchored on a porous carbon framework (FEC). The shell consists of a thin Fe3O4 layer (≈2 nm) and a carbon layer (≈10 nm) on the outermost part. Benefiting from the complex nanostructuring (porous carbon support, core-shell nanoparticles, and Fe3C incorporation), the FEC anode delivered a high discharge capacity of 947 mAh g-1 at 50 mA g-1 and a fast-rate capability of 305 mAh g-1 at 10 A g-1. Notably, the FEC cell still showed 86% reversible capacity retention (794 mAh g-1 at 50 mA g-1) at a high cycling temperature of 80 °C, indicating superior structural integrity during cycling at extreme temperatures. Furthermore, we conducted a simple solid-state fluorination technique using the as-prepared FEC sample and excess NH4F to prepare iron fluoride-carbon composites (FeF2/C) as the positive electrode. The full cell configuration, consisting of the FEC anode and FeF2/C cathode, reached a remarkable capacity of 200 mAh g-1 at a 20 mA g-1 rate or an energy density of approximately 530 Wh kg-1. Thus, the straightforward and simple experimental design holds great potential as a revolutionary Fe-based cathodic-anodic pair candidate for high-energy LIBs.

SiO Enabled by ZSM‐5 and Graphene as Long‐Cycle and High‐Rate Anodes for Lithium‐Ion Batteries

AbstractSilicon oxides (SiO, SiO2) with high theoretical capacity and low cost are viewed as promising anodes for the next‐generation lithium‐ion batteries (LIBs) but suffer from inferior rate capability and coulombic efficiency (CE) owing to the sluggish charge transfer kinetics. Herein, the study proposes a multichannel modulation strategy induced by ZSM‐5 and SiO as well as electron‐rich graphene to effectively solve the above issue. Specially, the ZSM‐5, which can not only provide a certain Li+ reserve capacity as an anode material, but also serve as a bridge to connect the isolated SiO nanoparticles, providing Li+ transport channel and adjusting the transfer kinetic, making it to achieve two things at one stroke, so that the as‐obtained SiO@ZSM@Gra composite shows improved rate performance and CE compared to that of single silicon oxides. Combing with the CV and EIS fitting analysis, it is demonstrated that the constructed composites own higher Li+ diffusion coefficient and more charge conduction capability. Furthermore, the fabricated full cell with LiNi0.8Co0.1Mn0.1O2 exhibits good electro‐chemical properties. The proposed strategy for intrinsic accelerating charge transfer can be conductive to electrode design for the next‐generation low cost and high energy LIBs.

A simple and effective approach to relieve stress and enhance cyclability of Si-based materials toward high-energy lithium-ion batteries

Silicon-based materials are promising anodes to keep up with the demands for next-generation lithium-ion batteries in the coming decades owing to their ultrahigh theoretical capacities. However, the severe volume changes and mechanical fractures during cycling greatly hinder their way to commercialization. So far, it still remains a great challenge to develop advanced Si-based electrodes with high mechanical stability and remarkable electrochemical properties. In this work, we propose a simple and effective strategy to encapsulate Si@SiOx particles into B, N co-doped carbon nanotubes (BNCNTs) to develop Si@SiOx@BNCNT electrode for enhanced lithium storage. The SiOx layer upon Si particle is designed to mitigate the volume expansion of Si and maintain the particle integrity. Finite element analysis demonstrates that BNCNTs with high mechanical strength can further relieve the internal stress induced by Si expansion upon lithiation. The double restraint effect from SiOx layers and BNCNTs on the Si particles contributes to excellent resistance to structural degradation, enabling high stability and desirable electrochemical performance of Si@SiOx@BNCNT electrode. This strategy provides great opportunities for the practical application of Si-based anodes in high-energy lithium-ion batteries.

Precise modulation of surface lattice to reinforce structural stability of high-nickel layered oxide cathode by hafnium gradient doping

The quest for high-energy lithium-ion batteries has intensified interest in high-nickel layered oxide cathode materials, while the rise in nickel content adversely impacts structural stability and cycling performance. Herein, Hafnium (Hf) anchored at nickel (Ni) site precisely modulates the surface crystal lattice of high-nickel cathode (LiNi0.9Co0.05Mn0.05O2, NCM90) that is confirmed by Rietveld refinement of neutron powder diffraction. Notably, the strengthened structural stability thanks to Hf gradient doping is firmly substantiated by in-situ X-ray diffraction and in-situ X-ray adsorption spectroscopy. This enhancement can be ascribed to the substantial atomic mass of Hf and large radius of Hf4+, facilitating the minimization of potential alterations of interlayer or intralayer. The intensified Hf-O bond significantly increases the formation energy of oxygen vacancies and efficiently restrains the detrimental Li+/Ni2+ disorder, thereby mitigating lattice oxygen loss and enhancing both cycling and thermal stability of high-nickel cathode. Consequently, the 0.3 % Hf-doping cathode exhibits considerable improvement in electrochemical performance, delivering superior capacity retention of 95.0% after 100 cycles at 1C (1 C = 200 mA g−1) and 83.9 % after 500 cycles at 1C/5C in the voltage range of 3.0∼4.3 V. This work highlights the benefits of precise modulation strategy for high-nickel cathodes, offering a viable approach to enhance structural stability and electrochemical performance of high-nickel cathodes.