Long-life Lithium-ion Batteries Research Articles

Phthalocyanine-based solid-state electrolyte for high-capacity and long-life lithium-ion batteries

Phthalocyanine-based solid-state electrolyte for high-capacity and long-life lithium-ion batteries

Aging mechanism of Ni-rich cathode-based lithium-ion batteries: Focusing on upper cut-off voltages

Ni-rich cathode-based lithium-ion batteries are subject to certain limitations in electric vehicle applications due to their cycle life. Therefore, this study aims to investigate the aging mechanism of Ni-rich cathode-based lithium-ion batteries with different upper cut-off voltages, providing ideas for improving their cycle life. The change in the cathode lattice during the charging and discharging process obtained by in-situ XRD shows that the H2-H3 phase transition exacerbates the battery capacity degradation. In addition, the capacity degradation caused by lattice strain induced by the rapid release of anisotropic stress accumulation (ASA) in the H2 region cannot be ignored as well. After lowering the upper cut-off voltage, the surplus lithium in the cathode plays a pivotal role in avoiding the above rapid battery degradation, driven by the advantages of its ability to stabilize lattice structure and reduce the degree of Li/Ni cation mixing. Meanwhile, the low upper cut-off voltage effectively avoids side reactions such as electrolyte decomposition and transition metal dissolution. The above results would contribute to slowing down battery degradation, which would provide strong support for the design of high energy density and long-life lithium-ion batteries.

Monofluorinated Phosphate with Unique P-F Bond for Nonflammable and Long-Life Lithium-Ion Batteries.

Lithium-ion batteries (LIBs) with conventional carbonate-based electrolytes suffer from safety concerns in large-scale applications. Phosphates feature high flame retardancy but are incompatible with graphite anode due to their inability to form a passivated solid electrolyte interphase (SEI). Herein, we report a monofluorinated co-solvent, diethyl fluoridophosphate (DEFP), featuring a unique P-F bond that allows a trade-off between safety and electrochemical performance in LIBs. The P-F bond in DEFP weakens ion-dipole interactions with Li+ ions, lowering the desolvation barrier, and simultaneously reduces the lowest unoccupied molecular orbital (LUMO) of DEFP, promoting the formation of a robust and inorganic-rich SEI. Additionally, DEFP exhibits improved thermal stability due to both robust SEI and the inherent flame-retardant properties of the P-F bond. Consequently, the optimized DEFP-based electrolyte exhibits improved cyclability and rate capacity in LiNi0.8Co0.1Mn0.1O2 || graphite full cells compared with triethyl phosphate-based electrolytes and commercial carbonate electrolytes. Even at a low E/C ratio of 3.45 g Ah-1, the 1.16 Ah NCM811||Gr pouch cells achieve a high capacity retention of 94.2% after 200 cycles. This work provides a promising approach to decouple phosphate safety and graphite compatibility, paving the way for safer and high-performance lithium-ion batteries.

Regulating structural units and morphology of SiOC anode for enhanced high-rate storage and long-life lithium ion batteries

The widespread use of silicon oxycarbide (SiOC) anodes in industry has been hampered by their limited reversible capacity, subpar rate performance, and complex manufacturing methods. In this research, a novel strategy is proposed to in situ construct SiOC with oxygen-rich structural units and flake morphology via one-pot synthesis, which integratively facilitates the reversible capacity and enhances the transport capability of Li+. Benefiting from these structural and compositional merits, the produced SiOC electrode showcases an impressive reversible capacity of 906 mAh g−1 at 0.1 A g−1, a remarkable rate capability of 591 mAh g−1 and cycling stability of 98 % capacity retention rate at 2.0 A g−1 after 1200 cycles. Characterization results prove that the SiOC with a higher content of oxygen-rich structural units and flakes is helpful in forming the stable solid-electrolyte interface film and buffering volume expansion. Furthermore, it is demonstrated that the SiOC anodes containing LixSiOy compounds reduce the irreversible use of Li-ions during the initial reaction. Our findings present an effective method to simultaneously manipulate the structural units and morphology of SiOC compounds, paving the way for superior electrochemical performance.

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.

Pre-introducing Li4NiWO6 defect phase by tungsten modification enables highly stabilized Ni-rich cathode

Tungsten (W) has attracted considerable attention as a promising dopant capable of enhancing the structural stability of Ni-rich cathode materials. However, investigations into W modification remain highly debated due to the elusive mechanisms involved, particularly in determining whether W is doped into the lattice structure or exists as a distinct phase on the surface of the particles. In this work, we systematically observe the effects induced by the introduction of W into LiNi0.9Co0.05Mn0.05O2 (NCM). We discovered that during high-temperature solid-state reactions, W-containing substances tend to react preferentially with surface Li, creating a lithium-deficient state on the NCM surface, resulting in the generation of Li4NiWO6. Molecular dynamics simulations tracking Li, W, and Ni elemental changes at the interface confirm the initial creation of Li6WO6, succeeded by diffusion of Ni to replace Li, forming Li4NiWO6. The pre-introducing Li4NiWO6 defect phase can effectively absorb anisotropic lattice strain, preserving the mechanical integrity of the secondary particles. Furthermore, the Li4NiWO6 phase, combined with the amorphous LixWyOz coating layer, effectively acts as a guard against undesirable interfacial side reactions, ultimately imparting excellent electrochemical performance to NCM. Understanding the dynamic processes of interfacial reactions is crucial for tailoring surface properties of Ni-rich cathodes towards long-life lithium-ion batteries.

Elements gradient doping in Mn-based Li-rich layered oxides for long-life lithium-ion batteries

The cobalt-free Mn-based Li-rich layered oxide material has the advantages of low cost, high energy density, and good performance at low temperatures, and is the promising choice for energy storage batteries. However, the long-cycling stability of batteries needs to be improved. Herein, the Mn-based Li-rich cathode materials with small amounts of Li2MnO3 crystal domains and gradient doping of Al and Ti elements from the surface to the bulk have been developed to improve the structure and interface stability. Then the batteries with a high energy density of 600 Wh kg−1, excellent capacity retention of 99.7 % with low voltage decay of 0.03 mV cycle−1 after 800 cycles, and good rates performances can be achieved. Therefore, the structure and cycling stability of low voltage Mn-based Li-rich cathode materials can be significantly improved by the bulk structure design and interface regulation, and this work has paved the way for developing low-cost and high-energy Mn-based energy storage batteries with long lifetime.

Surface N Sites Mediate the Formation of Li Metal Cluster@N-Enriched Hierarchically Porous Carbon for Ultrahigh-Capacity Lithium Storage.

Graphite is the popular anode material of current lithium-ion batteries (LIBs). However, its low specific capacity and poor lithium intercalation potential hinder its use for high-power and large-scale energy storage. To meet the demand for energy storage, novel anode materials with high capacity, fast chargeable capability, and long cycle life are of great interest. Herein, we demonstrate an advanced nitrogen-enriched hierarchical porous carbon serving as a lithiophilic anode material for ultrahigh capacity and long-life LIBs. NHPC-700 (under optimal synthetic conditions), featuring a high surface area, rich N-doping, high porosity, and partially graphitized nanosheet structures, is successfully fabricated from a Schiff-base copolymer via a template-incipient wetness impregnation method. NHPC-700 exhibits an ultrahigh reversible lithium storage capacity of 2796 mA h g-1 at 0.1 A g-1 while still maintaining a high capacity of 526 mA h g-1 at 10 A g-1 after 1000 cycles. Theoretical and experimental studies reveal that this remarkable Li storage performance can be attributed to the large number of N lithiophilic sites on the inner surface of the small mesoporous pores. These sites guide Li metal nucleation in the initial period and control well the volume variation during charge/discharge cycles, thus exhibiting excellent cycle stability and great potential for practical application.

Flexible bidirectional pulse charging regulation achieving long-life lithium-ion batteries

Typical application scenarios, such as vehicle to grid (V2G) and frequency regulation, have imposed significant long-life demands on lithium-ion batteries. Herein, we propose an advanced battery life-extension method employing bidirectional pulse charging (BPC) strategy. Unlike traditional constant current charging methods, BPC strategy not only achieves comparable charging speeds but also facilitates V2G frequency regulation simultaneously. It significantly enhances battery cycle ampere-hour throughput and demonstrates remarkable life extension capabilities. For this interesting conclusion, adopting model identification and postmortem characterization to reveal the life regulation mechanism of BPC: it mitigates battery capacity loss attributed to loss of lithium-ion inventory (LLI) in graphite anodes by intermittently regulating the overall battery voltage and anode potential using a negative charging current. Then, from the perspective of internal side reaction, the life extension mechanism is further revealed as inhibition of solid electrolyte interphase (SEI) and lithium dendrite growth by regulating voltage with a bidirectional pulse current, and a semi-empirical life degradation model combining SEI and lithium dendrite growth is developed for BPC scenarios health management, the model parameters are identified by genetic algorithm with the life simulation exhibiting an accuracy exceeding 99%. This finding indicates that under typical rate conditions, adaptable BPC strategies can extend the service life of LFP battery by approximately 123%. Consequently, the developed advanced BPC strategy offers innovative perspectives and insights for the development of long-life battery applications in the future.

Interface Engineering of MOF-Derived Co3O4@CNT and CoS2@CNT Anodes with Long Cycle Life and High-Rate Properties in Lithium/Sodium-Ion Batteries.

Metal-organic framework materials can be converted into carbon-based nanoporous materials by pyrolysis, which have a wide range of applications in energy storage. Here, we design special interface engineering to combine the carbon skeleton and nitrogen-doped carbon nanotubes (CNTs) with the transition metal compounds (TMCs) well, which mitigates the bulk effect of the TMCs and improves the conductivity of the electrodes. Zeolitic imidazolate framework-67 is used as a precursor to form a carbon skeleton and a large number of nitrogen-doped CNTs by pyrolysis followed by the in situ formation of Co3O4 and CoS2, and finally, Co3O4@CNTs and CoS2@CNTs are synthesized. The obtained anode electrodes exhibit a long cycle life and high-rate properties. In lithium-ion batteries (LIBs), Co3O4@CNTs have a high capacity of 581 mAh g-1 at a high current of 5 A g-1, and their reversible capacity is still 1037.6 mAh g-1 after 200 cycles at 1 A g-1. In sodium-ion batteries (SIBs), CoS2@CNTs have a capacity of 859.9 mAh g-1 at 0.1 A g-1 and can be retained at 801.2 mAh g-1 after 50 cycles. The unique interface engineering and excellent electrochemical properties make them ideal anode materials for high-rate, long-life LIBs and SIBs.

SnO2-MoO2 nanoparticles coated on graphene oxide as a high-capacity, high-speed, long-life lithium-ion battery anode

Ternary SnO2-MoO2-GO (SMGO) nanocomposites were synthesized by hydrothermal method, modified Hummers method, and ball milling method. SMGO nanocomposites have the following advantages, including mitigating volume expansion during cycling, enhancing conductivity, and reducing the transmission path length for both electrons and Li+. Consequently, the SMGO composite material demonstrates a capacity of 1215.2 mAh/g after 200 cycles at 0.2 Ag−1, and a capacity of 1032.9 mAh/g after 1000 cycles at 1.0 Ag−1. Moreover, subsequent SEM analysis of the electrode material reveals the absence of accumulation or notable cracks, underscoring the remarkable cycling stability of the SMGO composite material.

Three-dimensional interwoven CoS2/reduced graphene oxide/carbon nanotubes composite as anode materials for high-performance lithium-ion batteries

CoS2 exhibits abundant redox reactions, high theoretical capacity, excellent, mechanical properties, and is regarded as a prospective electrode material. However, rational design of CoS2 composites with high capacity and ultra-long cycle life remains a major challenge. In this work, we formed CoS2/rGO/CNT electrode materials by compositing reduced graphene oxide (rGO), carbon nanotubes (CNT) and CoS2 with a three-dimensional interwoven network. The elemental composition and three-dimensional network morphology were described using SEM, TEM, XRD, Raman, BET, TGA and XPS. The large loading area provided by the three-dimensional network for Li+ facilitates the effective diffusion of Li+ during the cycling process. In addition, the three-dimensional network acts as an adhesion substrate for CoS2 nanoparticles, mitigating the bulk change and reducing the aggregation of CoS2 nanoparticles. On the other hand, the tight bonding of CNT with CoS2/rGO facilitates fast transfer of electron in CoS2/rGO/CNT. The electrochemical measurement results show that after 1000 cycles, the capacity is 615.8 mAh/g at 2000 mA/g and can still reach 233.7 mAh/g at 5000 mA/g after 2000 cycles. The favorable electrochemical properties prove that CoS2/rGO/CNT is an excellent anode material for long-life lithium-ion batteries.

Long-Life Lithium-Ion Sulfur Pouch Battery Enabled by Regulating Solvent Molecules and Using Lithiated Graphite Anode.

The development of lithium-sulfur (Li-S) batteries is severely limited by the shuttle effect and instability of Li-metal anode. Constructing Li-ion S batteries (LISBs), by using more stable commercial graphite (Gr) anode instead of Li-metal, is an effective way to realize long-cycle-life Li-S batteries. However, Gr electrode is usually incompatible with the ether-based electrolytes commonly used for Li-S batteries due to the Li+ -ether complex co-intercalation into Gr interlayers. Herein, a solvent molecule structure regulation strategy is provided to weaken the Li+ -solvent binding by increasing steric hindrance and electronegativity, to accelerate Li+ de-solvation process and prevent Li+ -ether complex co-intercalation into Gr anode. Meanwhile, the weakly solvating power of solvent can suppress the shuttle effect of lithium polysulfides and makes more anions participate in Li+ solvation structure to generate a stable anion-derived solid electrolyte interface on Gr surface. Therefore, a LISB coin-cell consisting of lithiated graphite anode and S@C cathode displays a stable capacity of ≈770 mAh g-1 within 200 cycles. Furthermore, an unprecedented practical LISB pouch-cell with a high Gr loading (≈10.5mg cm-2 ) also delivers a high initial capacity of 802.3 mAh g-1 and releases a stable capacity of 499.1 mAh g-1 with a high Coulombic efficiency (≈95.9%) after 120 cycles.

Atomic pins bridging integrated surface to assist high-rate stability for Co-free Li-rich cathode

Li- and Mn-rich oxides (LMR) have emerged as promising cathode materials for next-generation Li-ion batteries due to their cost effectiveness, impressive capacity, and high energy density. However, the poor electrochemical kinetics and structural instability in hostile interface environments have result in continuous voltage/capacity decay and undesirable rate performance, impeding the large-scale commercial application of LMR materials. In this study, we introduce an atomic pins-assisted integrated surface reconstruction (AISR) strategy to address the interfacial degradation and instability issues. Utilizing the bidirectional diffusion effect of the aluminum-containing intermediate layer during the heat treatment process, we employ aluminum atoms as bridging centers to in situ construct a composite interface structure. This approach capitalizes on the element diffusion reaction and anchoring effect to achieve multifunctional modification through the Al-based ionic conductor network constructing and near-surface Al doping for LMR material. Intriguingly multiple kinetic investigations and calculations reveal that the epitaxial ionic conductor layer suppresses interfacial side reactions, enhances ionic conductivity, and improves electronic conductivity by regulating cationic/anionic redox activity through Al surface doping.Impressively, the modified electrodes exhibited an increased reversible capacity at both 0.1C/5C rates (0.1C, 2 ∼ 4.8 V, from 264.2 mAh∙g−1 to 274 mAh∙g−1; 5C, 2 ∼ 4.6 V, from 145.5 mAh∙g−1 to 197.9 mAh∙g−1) and improved capacity retention after 250 cycles at 1C/5C rates (2 ∼ 4.6 V: 1C, from 69.46% to 81.92%; 5C from 57.73% to 81.35%). We systematically summarized the rate-dependent failure mechanism and the corresponding integrated interface reconstruction principle. These key findings offer valuable insights for the development of high-energy–density and long-life lithium-ion batteries in commercial applications.

Long-life lithium-ion batteries realized by low-Ni, Co-free cathode chemistry

Long-life lithium-ion batteries realized by low-Ni, Co-free cathode chemistry

Research on the utilization of ultra-long carbon nanotubes in lithium-ion batteries based on an environment-friendly society.

To build an environment-friendly society, clean transportation systems, and renewable energy sources play essential roles. It is critical to improve the lifetime mileage of electric vehicles' batteries for reducing the cycle life cost and carbon footprint in green transportation. In this paper, a long-life lithium-ion battery is achieved by using ultra-long carbon nanotubes (UCNTs) as a conductive agent with relatively low content (up to 0.2% wt.%) in the electrode. Ultra-long CNT could realize longer conductive path crossing active material bulks in the electrode. Meanwhile, the low content of UCNTs can help to minimize conductive agent content in electrodes and obtain higher energy density. The film resistance and electrochemical impedance spectroscopy (EIS) confirmed that the use of UCNTs could markedly enhance electronic conductivity in the battery. The battery's life and life mileage can be prolonged by almost half due to the superior electronic conductivity of UCNTs. The life cycle cost and carbon footprint are also significantly reduced, which could markedly increase economic and environmental performance.

Fabrication of a LiNi0.5Mn0.4Ti0.03Mg0.03Nb0.01Mo0.03O2 cathode for low-cost long-life lithium-ion batteries.

The high price of Co and Ni restricts the development of the lithium-ion battery industry. Reducing the Ni content and eliminating Co is an effective way to lower the cost. In this work, we eliminate the Co in NCM523 cathodes by using a complex concentrated doping strategy. LiNi0.5Mn0.4Ti0.03Mg0.03Nb0.01Mo0.03O2 shows an unparalleled cost advantage with relatively high specific energy (>720 W h kg-1) and significantly improved overall performance (96% capacity retained after 1000 cycles). This report offers an important pathway to fabricate cathode materials for low-cost and long-life LIBs.

Suppressing the Mn dissolution in LiMn2O4 positive materials toward long-life lithium ion battery through Gd2O3 surface modification

Suppressing the Mn dissolution in LiMn2O4 positive materials toward long-life lithium ion battery through Gd2O3 surface modification

Integrated Modification Strategy Enables Remarkable Cyclability and Thermal Stability of Ni-Rich Cathode Materials for Lithium-Ion Batteries

Structural degradation and surface chemical instability are dominant issues of Ni-rich layered cathodes, which trigger capacity fading and safety concerns, hindering the extensive application of Ni-rich cathodes toward high-energy, long-life lithium-ion batteries. Here, by combining trace Ta doping and an ultrathin Zr-Y mixed oxide coating, an integrated modification strategy significantly improves the cycling and thermal stability of Ni-rich LiNi0.88Co0.10Al0.02O2 (NCA) cathodes. The integrated modified Ni-rich cathode provides an unprecedented comprehensive performance with a high discharge capacity of 212.2 mA h g-1 at 0.1 C, an 88.6% cycling retention after 500 cycles at 1 C, and a high exothermic peak temperature of 261 °C compared with the pristine NCA cathode (67.4% capacity retention for 500 cycles and 221 °C for the exothermic peak). Further mechanism studies illustrate that a dual-structural surface constructed of a rock salt surface induced by Ta doping and ultrathin Zr-Y mixed oxide coating jointly suppresses surface side reactions between cathodes and electrolytes. Moreover, trace Ta doping in the bulk stabilizes the bulk structure and prevents mechanical cracks. This study highlights the importance of comprehensive modification of the bulk and surface for improving the electrochemical performance and provides a potential optimizing strategy for the commercialization of high-capacity Ni-rich cathode materials.

Bio-template synthesis of LiVO3 anode material for high-rate and long-life lithium-ion batteries

Bio-template synthesis of LiVO3 anode material for high-rate and long-life lithium-ion batteries