Petroleum pitch, composed of polynuclear aromatic hydrocarbons, is a promising carbon precursor for advanced functional materials. In this study, a synergistic strategy combining high-temperature carbonization and in situ nitrogen doping is proposed to produce highly conductive carbon materials with enhanced crystallinity and electron delocalization. Systematic conductivity screening identifies 1300 degrees C as the optimal carbonization temperature, achieving a conductivity of 12.7 S cm-1. Introducing nitrogen during carbonization further increases the conductivity to 24.7 S cm-1, which is attributed to improved graphitic ordering and incorporation of graphitic nitrogen that enhances carrier density and electron transport. The obtained material is milled to nanoscale particles to improve dispersion within composite electrodes. When applied as a conductive agent in silicon oxide-based lithium-ion battery anodes, the nitrogen-doped pitch based conductive material delivers electrochemical performance comparable to that of commercial carbon black. The enhanced electrochemical performance is associated with its high intrinsic conductivity and stable conductive network formation within the electrode. These results demonstrate an effective approach to designing high-conductivity pitch-derived carbon materials for practical energy storage applications.

Developing high-energy lithium batteries inevitably involves separators that suppress uncontrolled ion transport and parasitic reactions over repeated cycling. Here, we introduce a dual-functional active separator comprising a uniformly dip-coated double-bond-containing poly(vinylidene fluoride) (DPVDF) layer with covalently cross-linked branched polyethyleneimine (BPEI) robust framework interfaces. The amine-enriched DPVDF-BPEI-modified separator (PDB) electrostatically regulates PF6 - anions, as evidenced by spectroscopic, computational, and electrochemical studies. PF6 - regulation suppresses significantly hydrofluoric acid (HF)-forming fragmentation and facilitates selective Li+ diffusion, leading to ca. twice higher Li+ transference numbers (polypropylene (PP): 0.49 and PDB: 0.80) and ca. 3 times higher Li+ diffusion coefficient (PP: 0.46 & times; 10-6 and PDB: 1.29 & times; 10-6 cm2 s-1) than PP. In addition, it thereby results in the formation of ultrathin, compositionally uniform electrode-electrolyte interphases (SEI/CEI). Those unique effects of the PDB enable long-term stability, ca. 1,000 cycles in Li||LFP and ca. 400 cycles in Li||NCM811 half-cells. The Si||LFP full-cell exhibits stable cycling for more than 400 cycles at 3.0 C. The PDB supports dendrite-free operation for 1,000 h in Li||Li symmetric cells, demonstrating uniform Li deposition. This work establishes a scalable separator design strategy that integrates structural durability with targeted anion regulation and efficient ion-diffusion control, providing a practical pathway toward stable, high-energy lithium-based batteries.

Ar-mediated autogenic pressure pyrolysis upcycles polyurethane into heteroatom-doped carbon with optimized structure and enhanced lithium storage performance.

Grid-scale energy storage has emerged as a critical component for modern power systems, so batteries are at the forefront of this technological revolution. This trend delves into the long-duration, higher energy and safer energy storage system. All-solid-state lithium-ion battery system is one of the promising candidates for addressing this challenges, and high-Ni material is notable cathode due to its high energy density and high technical maturity for practical applications. However, their performances in solid electrolyte system still cannot achieve the performance levels that are attained in the conventional liquid electrolyte system with severe reaction inhomogenity. Therefore, for the effective utilization and prolonged lifespan of high-Ni cathode materials in all-solid-state lithium-ion batteries, careful design of particles in both nano-scale and micro-scale is necessary. In this work, we designed three different LiNi0.8Co0.1Mn0.1O2 (Polycrystalline, single-crystal, cluster with twin boundaries) by tuning the nanostructure and microstructure and revealed how these particles are utilized in all-solid-state lithium-ion battery system. We found that the intentionally synthesized defects at particle surface can enhance Li-ion diffusivity, and single crystal structure greatly improves reaction homogeneity. We also demonstrate comparative studies of these high-Ni particles in both liquid and solid electrolyte system. These results provide opportunities for gaining insights into how to design high-Ni materials for the future all-solidstate lithium-ion battery system.

Impurities of sulfate ions inside the NCA precursor adversely affect the cathode materials. This issue is mitigated by removing impurities through ion exchange.

As demand for lithium-ion batteries increases, the supply of materials is increasingly constrained by their geographical concentration. This has spurred significant research into recycling spent batteries to enhance resource circulation. Currently, commercially applied recycling methods (such as pyrometallurgy and hydrometallurgy) face environmental and economic challenges, including waste acid and gas generation, high-temperature heat treatment, and operational complexity. A promising alternative is the carbothermic reduction process, which operates at lower temperatures, minimizing costs and environmental emissions. However, this method still requires large quantities of external reducing agents. Therefore, this study aims to introduce a simplified direct carbothermic reduction (SDCR) process. The SDCR process leveraged carbon conductive materials and organic binders within the electrode as reducing agents. Additionally, the high compaction state created a conducive environment for reducing gases, promoting efficient reduction and material recovery. This approach reduces the reliance on external reducing agents and streamlines the re-upcycling process, making it commercially viable.

Although polypropylene (PP) is frequently used as a typical separator materials of Li-ion batteries (LIBs), it encounters several obstacles, including inadequate mechanical strength, weak electrolyte affinity, and limited thermal stability. Many excellent studies have explored coating strategies to enhance the properties of PP-based separators (PPSs). Building on this foundation, our study aims to further explore the functional role of tailored and optimized coating layers. In this work, we demonstrate a surface engineering of coating layers to identify an optimum point at which coating layers enhance the mechanical and thermal properties of PP-based separators (PPSs) without compromising electrochemical performance due to their excessive thickness. PPSs were coated with the double-bond contained PVDF terpolymer (DPVDF) via simple dip-coating with different concentrations (1, 3, 5, and 7 wt%, designated as PVX1, PVX3, PVX5, and PVX7), followed by a crosslinking process. When tested in LiFePO4 (LFP) half-cells at 1C, the LFP half-cell with PVX3 separator exhibited a high capacity of 118.83 mAh g-1 over 300 cycles, maintaining an excellent capacity retention of 89.46 %. The PVX3 cell also demonstrated stable cycling at different active materials and current density conditions. Notably, at high loading content of LFP, it exhibits superior practical applicability relative to PP separators, with a capacity of 128.33 mAh g-1 and a capacity retention of 92.50 % over 200 cycles, representing increases of 15.57 % and 15.58 %, respectively, compared to PP separators. We believe that our study introduces appropriate criteria for coating and modification processes toward reinforced separators.

Graphite-Silicon (G-Si) blended anodes are promising candidates for replacing commercial graphite anodes in lithium-ion batteries owing to the high gravimetric capacity of silicon and industrial feasibility due to the structural stability of graphite. However, the optimized electrode conditions for G-Si blended anodes have not been fully elucidated. In this study, we investigate the physical limitations of G-Si blended anodes and the influence of Si content on electrode manufacturing. Our results indicate that the achievable physical limit of mass loading decreases as the silicon content increases. At loading levels below 10 mg cm- 2, the electrode density is increased with increasing Si loading. However, at loading levels above 10 mg cm- 2, the electrode density remains nearly unchanged with further increases in Si loading. These results indicate that each material has its unique maximum achievable electrode density. Electrochemical measurements indicate that increasing the Si ratio leads to lower cyclability and higher resistance. However, the rate performance of the G-Si blended electrodes is superior to that of the graphite electrode. We anticipate that this study will contribute to the optimization of electrode conditions for newly developed electrode materials.

Although ultra-high nickel layered cathode materials (LiNixCoyMn1_ x_ yO2, x >= 0.9, NCM90) offer advantages of high energy density and cost-effectiveness, the deterioration of cycle characteristics remains a challenge due to electrolyte decomposition reactions and irreversible phase transitions. In this study, we explored the morphology-controlled Al oxide coatings to mitigate cycle degradation in NCM90. The coating layer was applied in an island-shaped morphology, forming a relatively thick layer compared to fully passivated film-shaped coatings. This morphology effectively suppresses increasing impedance, reduces electrolyte decomposition reactions, and limits the dissolution of transition metals during the electrochemical cycling. It also provides high stability across both normal (3.0-4.3 V) and high (3.0-4.5 V) voltage ranges due to the maintenance of coating integrity against HF attacks. This study underscores the importance of a strategically engineered coating layer, demonstrating that an island-shaped morphology can significantly enhance the cycle performance of NCM90.

The extremely fast charging (XFC) of Li-ion cells is an urgent milestone in promoting the widespread adoption of electric vehicles. However, EV-targeted cell designs with thicker electrodes compromise the XFC capability when conventional electrolytes are used, leading to hazardous Li plating and a considerable loss in Li inventory. This study presents noncarbonate solvents for superionic conductive, low-viscosity high-concentration electrolytes (HCEs). A methyl acetate (MA)-based HCE with a solid-electrolyte interphase (SEI)-stabilizing additive (3MF) was comparatively examined using a dimethyl carbonate (DMC) solvent, which has an extra oxygen atom in the molecule, across all aspects, including solvation structures, interfacial kinetics, and bulk Li+ transport. The 3MF electrolyte demonstrated outstanding XFC performance in a pouch cell (1.2 Ah) format and outperformed DMC-based HCE, showcasing improved cycling performance at low temperatures (-20 °C), 10 C-rate (6-min charging), and with a thick electrode (6.0 mAh cm-2). By satisfying the energy barrier thresholds for Li+ desolvation and Li+ migration across the SEI, MA can guide smaller solvation clusters and serve as a molecular lubricant along the Li+ percolation pathway in the HCE framework, which is crucial for boosting XFC capabilities.

Ultra-high nickel cathode materials (LiNi0.9Co0.05Mn0.05O2) offer a promising pathway toward high energy density and cost-effective lithium-ion batteries. While the high nickel content enables increased specific capacity, intrinsic structural instability and the excess lithium consumed during synthesis make the material prone to degradation when it encounters ambient H2O and CO2. This degradation promotes the excessive formation of residual lithium compounds (RLCs) and induces a phase transition to a rock-salt structure, resulting in poor electrochemical performance. In this study, we present a facile heat treatment strategy incorporating Na doping to rejuvenate the degraded Ni-rich cathode. This process effectively reincorporates RLCs into the bulk lattice with Na doping targeted to the region of degradation. Owing to the enhanced structural stability, the rejuvenated cathode exhibits improved cycling stability over both the normal (3.0-4.3 V) and extended high-voltage (2.7-4.5 V) ranges. Moreover, Na doping expands the Li slab spacing, enabling the rejuvenated cathode to achieve superior rate performance. This rejuvenation approach not only offers a practical route for restoring the collapsed lattice but also mitigates the structural vulnerability associated with high-Ni content cathodes.

Essential, but not too much-Roles of electrolyte additive (FEC) in Li+ solvation structures and interfacial reactions are revealed in a high-concentration electrolyte. While excessive FEC addition can intervene in original Li+ solvation, compromising interfacial kinetics, minimal FEC is essential in fast-charging applications to seamlessly facilitate Li+ desolvation while reinforcing interfacial stability.

Ni-rich layered transition metal oxides have been regarded as the most feasible way for achieving high energy density of lithium-ion batteries. Conventional Ni-rich cathodes are composed of spherical secondary particles, consisting of numerous primary particles. Unfortunately, the grain boundaries in the polycrystalline structure are vulnerable to the pulverization, leading to microcracks during cycling. The newly exposed surface from the microcrack can induce undesirable side reactions with the electrolyte, which severely deteriorates the battery performance. On the other hand, single-crystalline Ni-rich cathodes have gained significant attention for industrial applications due to their robust mechanical strength, resulting from the elimination of grain boundaries. The improved mechanical properties of single-crystalline cathodes effectively mitigate the interfacial side reactions, thereby attaining superior structural, thermal, and electrochemical performance. Herein, we have introduced various synthetic methods of the single-crystalline cathode, encompassing not only high-temperature sintering and the molten-salt method for the Ni-rich cathode but also the other strategies for different single-crystalline cathode materials. This review aims to provide a comprehensive understanding of single-crystalline cathode synthesis, with implications for the development of high-performance cathode materials.

Dry electrode technology is a next-generation method for manufacturing lithium-ion batteries because it is useful for fabricating thick electrodes without solvents, facilitating high energy densities and cutting down on the battery manufacturing costs. However, the commonly used polytetrafluoroethylene (PTFE) binder in dry electrode technology undergoes severe decomposition in dry-processed anodes during the first lithiation process due to its low lowest unoccupied molecular orbital level. This phenomenon seriously aggravates battery performance, such as in terms of the initial coulombic efficiency and cycle life. Thus, a strategy to suppress this irreversible reaction of PTFE should be established for dry-processed anodes to increase the energy density of LIBs without adverse effects on battery performance. To address this challenge, in this work, fluoroethylene carbonate (FEC) as an electrolyte additive has been introduced to form a preemptive and stable FEC-derived solid electrolyte interface (SEI) to protect a graphite and the PTFE binder. This SEI considerably alleviates the irreversible reaction of PTFE, thereby securing the reversible capacity and maintaining the structure of the electrode through the great binding properties. These results provide guidance for increasing the electrochemical stability in dry-processed anode systems, which gets closer the innovative dry anode technology for cost-effectiveness and high energy density.

Lithium hexafluorophosphate (LiPF6)-based carbonate electrolytes are widely used in commercial lithium -ion batteries (LIBs), but their thermal instability limits the cycle life and safety of LIBs at elevated temperatures. Few studies have yielded insight into the initial PF6- decomposition reaction that promotes thermal instability of LiPF6- based electrolytes. Here, we find that lithium -ion hopping assisted by the overall reorientational motion of propylene carbonate molecules facilitates PF6- decomposition at elevated temperatures in 1 M LiPF6/propylene carbonate electrolyte. Further, we demonstrate that urea additives, by preventing lithium -ion hopping, suppress the initial LiPF6 decomposition reaction and enhance the thermal stability of the electrolyte. LIB cell tests with LiNi0.6Mn0.2Co0.2O2||Li4Ti5O12 show improved LIB performance at elevated temperatures with the thermally stabilized electrolyte. This study provides key insights into the design of thermally stable LiPF6-based carbonate electrolytes for improving the cycle life, calendar life, and safety of LIBs in elevated -temperature applications.