Search Results (522)

Given the confining effect of porous carbon and strong surface polarity of transition metal phosphides, their composite would be a promising cathode candidate to solve the problems of lithium–sulfur batteries including volume expansion and the shuttling effect of polysulfides. Herein, cobalt phosphide (CoP)-loaded phosphorous (P)-containing carbonized bamboo (CoP/PCBs) composites were fabricated via the co-pyrolysis of phytic acid, waste bamboo and Co(NO₃)₂·6H₂O via Joule heating at 600–1200 °C. Hydrogen radicals released from phytic acid enabled CoP/PCBs with developed porosity (438.1–812.4 m²/g). CoP nanoparticles coated with graphitic carbon were distributed uniformly on a porous matrix of PCBs. CoP/PCBs presented obviously enhanced adsorption capabilities for Li₂S₆, and 57.8–80.4 wt.% of sulfur was confined in CoP/PCBs/S cathodes. CoP/PCB heated at 1200 °C exhibited a high reversible capacity of 477.5 mAh/g after 500 cycles at a current density of 1 C with an average capacity decay rate of 0.045%. The specific capacity remained at 453.3 mAh/g after 300 cycles even under a high sulfur load of 4.0 mg/cm². Conversion of sulfur/polysulfides during the electrochemical process could be promoted via the physical confinement of sulfur and chemical confinement of Li₂S₆. This work provided a valuable reference for the facile fabrication of lithium–sulfur cathodes and utilization of metal phosphides in advanced lithium–sulfur battery systems. Full article

The accuracy of lithium-ion battery thermal-runaway early warning is strongly affected by the State of Charge (SOC). To improve the adaptability of fixed-threshold strategies, this study investigated SOC-dependent temperature and gas responses of 18650 LiNi₁/₃Co₁/₃Mn₁/₃O₂/graphite cells under thermal abuse at 50%, 75%, and 100% SOC, representing limited and complete thermal-runaway scenarios respectively, using a sealed pressure-resistant chamber. Temperature and chamber concentrations of characteristic gases, including CO₂, CO, C₂H₄, and CH₄, were monitored. The results show that higher SOC lowers the critical temperature for rapid self-heating, advances characteristic gas appearance, and increases the measured chamber gas concentrations by approximately 2.1–2.8 orders of magnitude. Reaction-kinetics analysis indicates that stronger electrolyte reduction by highly lithiated graphite at high SOC is the main reason for the different gas-evolution patterns. Based on these findings, an SOC-adaptive dual-parameter threshold model combining temperature and CO₂ concentration was established and retrospectively evaluated. The model provides earlier and more balanced warnings than fixed-threshold strategies, while the limitations associated with discrete GC-MS sampling and practical BMS implementation are discussed. Full article

Battery use in trolleybuses improves energy efficiency and enables driving outside routes with overhead contact lines. This paper analyses the ageing process of lithium-ion batteries by determining the State of Heath (SOH) curve based on real-world data collected during six and a half years of trolleybus operation. The battery, manufactured using NMC technology (lithium-nickel-manganese-cobalt LiNiMnCoO₂), was used as an onboard energy storage unit. The battery pack powers the trolleybus on the non-electrified route segments and improves its energy efficiency. In this paper, the ageing process of the lithium-ion battery in such a vehicle was investigated, using recorded data for each day of operation between 2016 and 2023. The SOH of the battery was estimated on the basis of three criteria: specific SOC range, specific battery voltage range and specific battery pack temperature range. Under these circumstances, the values of electric charge and energy flow into the battery were analysed, allowing the obtainment of the battery SOH value. Empirical distributions of random variables related to the minimum and maximum battery temperature and battery discharge current were presented. Based on these empirical distributions, statistical descriptors representing health indicators were calculated. The environmental factors (temperature, SOC, discharge and charge currents) that had a significant impact on the ageing process of the battery under test were analysed as well. Full article

Fluorinated carboxylate ester solvents are promising electrolyte components for lithium metal batteries because they can improve oxidative stability and promote LiF-rich solid electrolyte interphase (SEI) formation. However, how fluorination position and degree regulate their intrinsic decomposition behavior on lithium metal remains unclear. Herein, density functional theory (DFT) calculations and ab initio molecular dynamics (AIMD) simulations were employed to systematically investigate six pure fluorinated ethyl acetate solvents on the Li(001) surface, including α-fluorinated ethyl fluoroacetate (EFA), ethyl difluoroacetate (EDFA), and ethyl trifluoroacetate (ETFA), as well as β-fluorinated 2-fluoroethyl acetate (FEA), 2,2-difluoroethyl acetate (DFEA), and 2,2,2-trifluoroethyl acetate (TFEA). Electronic-structure analysis shows that although the lowest unoccupied molecular orbitals (LUMOs) of all six solvents are mainly distributed around the carbonyl and adjacent regions, the dominant electron-accepting center strongly depends on the fluorination position. In α-fluorinated solvents, the LUMO is highly localized on the α-C atom directly bonded to fluorine, whereas in β-fluorinated solvents, it remains concentrated around the carbonyl C atom. Real-time Bader charge and bond-evolution analyses reveal that fluorination position is the primary factor governing the initial decomposition pathway. The α-fluorinated series preferentially undergoes C-F bond cleavage, and increasing fluorination degree induces deeper cascade decomposition; fully fluorinated ETFA even exhibits C=O double bond cleavage. In contrast, β-fluorinated solvents preferentially undergo carbonyl-side C-O bond cleavage, while C-F bond cleavage occurs only in subsequent steps or is completely suppressed. Notably, β-fluorinated solvents retain high chemical stability even with α-H atoms because the LUMO electron density on α-H is negligible. Meanwhile, limited deep decomposition can still provide F⁻ species for SEI formation. These findings establish an atomic-level structure–reactivity relationship for fluorinated carboxylate ester solvents and provide theoretical guidance for designing stable electrolyte solvents for lithium metal batteries. Full article

The increasing demand for lithium-ion batteries (LIBs) raises concerns about the security of critical raw material supply and the management of hazardous waste. Efficient recycling can alleviate these issues by transforming spent batteries into high-value secondary materials for the circular economy. Industrial recycling has traditionally focused on the recovery of nickel (Ni) and cobalt (Co), whereas lithium (Li) recovery has often been sidelined due to technical complexities and fluctuating economic incentives. To meet the European Union (EU) Batteries Regulation target of 80% lithium recovery by the end of 2031, technically effective and economically viable lithium recovery strategies are required. This study investigates the use of food-grade sucrose as an organic reductant for the targeted recovery of lithium from NMC622 and NCA battery materials. The process combines sucrose-assisted reductive roasting with selective water leaching. The effects of roasting temperature, holding time, sucrose dosage, and heating rate were systematically evaluated and optimised. Under the best conditions of 600 °C, 15 min, 15 wt% sucrose, and a heating rate of 20 °C/min, lithium leaching efficiencies of 93.2% and 87.6% were achieved for separated NMC622 cathode material and NMC622-derived black mass, respectively. The method was also applicable to NCA-based black mass, reaching 83.7% lithium recovery under the same conditions. Mechanistic analysis revealed that lithium release was strongly controlled by the extent of transition metal reduction. Cobalt was fully reduced to its metallic state under all tested conditions. However, maximum lithium recovery required nickel to be reduced to metallic Ni and manganese-containing phases to be converted to MnO. The sucrose-assisted roasting process was rapid and holding times longer than 15 min decreased lithium recovery. This decrease was caused by the formation of poorly soluble lithium-containing phases, such as LiF and Li₃PO₄. F composition analysis showed the black mass (1.06 wt%) and anode fractions (2.26 wt%) to contain significantly more F than the cathode fraction (0.46 wt%), hence leading to the 5% Li leaching efficiency difference between cathode and black mass fractions under most conditions tested. Overall, these results demonstrate that sucrose-assisted reductive roasting, followed by selective water leaching, provides a rapid and effective route for high-efficiency lithium recovery from NMC- and NCA-based battery materials. Full article

Models of thermal runaway propagation in lithium-ion batteries are widely used for thermal safety analysis. Current methods, primarily lumped-parameter and 3D models, face challenges in balancing accuracy with computational efficiency. Three-dimensional models offer high accuracy at high computational cost, while lumped-parameter models are faster but less accurate. For instance, the battery shell is included in lumped-parameter models but often omitted in 3D models. This study focuses on a 37 Ah ternary lithium-ion battery, with Li(NiCoMn)_1/3O₂ as the cathode material and graphite as the anode material. The propagation of thermal runaway in the battery array is triggered by nail penetration. A lithium-ion battery thermal runaway propagation model is proposed, combining the lumped-parameter method with 3D modeling. The model primarily describes the heat transfer characteristics of the shell using a series connection of thermal capacitance and several thermal resistances. The shell temperature is then calculated by weighting the temperatures associated with the thermal capacitance and thermal resistances using specific weight coefficients. The joint model is detailed and applied to study thermal runaway propagation in one- and two-dimensional battery arrays. For the one-dimensional array, based on the three-dimensional simulation data and calculation time, the joint model shows only a 1.32% average deviation in propagation time compared to full 3D simulation, while maintaining good temperature agreement. It also reduces solution time by 70.22%. These findings confirm that the proposed model effectively enhances both the efficiency and accuracy of thermal runaway simulations, supporting improved safety analysis for lithium-ion battery systems. Full article

Lithium-ion batteries used in electric vehicles (EVs) are highly sensitive to temperature variations, and excessive heat accumulation can adversely affect their performance, lifespan, and safety. Therefore, an effective battery thermal management system (BTMS) is essential for maintaining safe operating conditions. This study proposes a novel air-cooled BTMS incorporating circular vent holes in an acrylic enclosure to enhance airflow distribution and convective heat transfer around LiNiCoMnO₂ batteries. A computational fluid dynamics (CFD) model was developed to investigate the effects of discharge rate (1C–2C), inlet air velocity (1.0–3.0 m/s), and inlet air temperature (25–35 °C) on thermal behavior. The results indicate that the proposed BTMS effectively maintains battery temperatures below the critical limit of 40 °C. Optimal cooling performance was achieved at inlet air temperatures of 25–35 °C, 25–30 °C, and 25 °C for discharge rates of 1C, 1.5C, and 2C, respectively. The proposed design provides a simple, effective, and practical BTMS solution for EV applications. These findings confirm that the combination of forced air cooling and optimized vent design significantly improves thermal management performance. Full article

To date, lithium–ion batteries (LIBs) are considered one of the most promising and market-leading energy storage systems due to their high theoretical capacity and energy density. However, poor thermal and cyclic stability, low electrolyte uptake, and the possibility for frequent short circuits of typical separators and evolution of several gases during long cycle operation pose several problems for LIBs. Metal-organic frameworks (MOFs) have attracted widespread interest as a promising material for improving the cycle stability and safety of rechargeable batteries due to their inherent surface and structural properties such as high specific surface area, high porosity, and ionic conductivity. In this work, the aim is to provide detailed descriptions of the synthesis routes and parameters for obtaining various MOFs such as Zr-MOF-808 and Ni-MOF-74 nanoparticles and the fabrication of those MOF-integrated separators. To optimize the crystallinity, morphological and compositional characteristics, and several material characterizations such as XRD, SEM, and EDX have been applied. Afterwards, the synthesized MOF-integrated glass fiber (GF) separators have been developed for lithium–ion battery (LIB) applications. To investigate the electrochemical performance and the effect of MOF integration into the separators, electrochemical studies in the form of galvanostatic charge–discharge (GCD), electrochemical impedance spectroscopy (EIS) have been evaluated by preparing CR2032-type half-coin cells. This MOFs-integrated GF-separators and synthesized LiNi_0.6Mn_0.2Co_0.2O₂ (NMC622) cathode materials-based coin cell LIB exhibited higher cycle stability than bare GF-separator based LIB. This novel approach and extensive research suggest that development of MOF-integrated separators could significantly improve cycle stability by reducing the internal cell degradation for next generation energy storage devices. Full article

Liquid electrolytes in conventional lithium-ion batteries pose safety risks associated with flammability, leakage, and explosion, whereas solid polymer electrolytes are generally limited by insufficient ionic conductivity at ambient temperature, restricting the development of high-energy lithium batteries. To address these issues, flexible poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)-based gel polymer electrolyte membranes (GPEs) were prepared via a slit-coating process combined with UV curing. NASICON-type lithium aluminum titanium phosphate (Li_1.3Al_0.3Ti_1.7P₃O₁₂, LATP) and garnet-type tantalum-doped lithium lanthanum zirconate (Li_6.4La₃Zr_1.4Ta_0.6O₁₂, LLZTO) were introduced as inorganic ceramic fillers to improve the ion-transport and interfacial properties of the GPE. Among the investigated samples, the PVDF-HFP-based GPE containing 10 wt% LLZTO exhibited the best overall performance, with an ionic conductivity of 3.40 × 10⁻⁴ S·cm⁻¹ at ambient temperature and a Li⁺ transference number of 0.77. Cyclic voltammetry results showed that the LLZTO-modified electrolyte membrane exhibited sharper and more symmetric redox peaks, higher peak current response, and better curve overlap during repeated cycles, indicating improved electrochemical reversibility and interfacial stability. In addition, LLZTO incorporation enhanced the mechanical strength, broadened the electrochemical stability window, and improved the flame-retardant behavior of the membrane. The LiFePO₄/GPE/Li cell assembled with the optimized membrane delivered an initial discharge capacity of 160 mAh·g⁻¹ at 0.1 C and maintained 80 mAh·g⁻¹ at 1 C, demonstrating good rate capability. Moreover, a capacity retention of 96% was maintained after 100 cycles at 0.1 C, confirming excellent cycling stability. Therefore, this work provides an effective strategy for the structural optimization and scalable preparation of high-performance gel polymer electrolyte membranes for lithium battery applications. Full article

Spent lithium-ion battery electrolytes contain fluorine-, sulfur-, and phosphorus-bearing toxins, necessitating deep detoxification and directional conversion into C₁–C₆ light hydrocarbons. To elucidate the specific catalytic roles and sequential activation of cathode metals (Li, Ni, Co, Mn), this work systematically deconvolutes their mono- and multi-metallic migration mechanisms over a CaO-ZSM-5* catalyst during vacuum catalytic pyrolysis (530 °C, 100 Pa). Results reveal that Li⁺ and Ni²⁺ dominate C–O bond cleavage in carbonates and CaO-ZSM-5*-assisted decarboxylation and oxygen fixation, significantly increasing the relative hydrocarbon content. Conversely, Co^2/3+ and Mn⁴⁺ release reactive oxygen species, causing deep oxidation of hydrocarbons into CO₂ and antagonizing the targeted conversion. In multi-metallic systems, forming composite metal oxides (M_xN_yO_z) increases the energy barrier for releasing active catalytic ions, hindering carbonate cleavage and leaving unreacted carbonate feedstocks. For detoxification, F and P are effectively immobilized as CaF₂ and Ca₂P₂O₇. The relative content of detected gas-phase nitriles is minimized to <2% due to the strong antagonistic effect of Ni²⁺ on Li⁺-promoted hexanedinitrile cleavage, while sulfur species derived from 1,3-propane sultone are converted to SO₂ and ultimately mineralized as calcium and metal-sulfur salts. Mechanistically, product distributions and crystallographic properties suggest a hypothesized sequential activation model—Li⁺ → Ni²⁺ → Mn⁴⁺—governing reactivity, whereas Co^2/3+ does not participate in the synergistic detoxification and selective upgrading process. This migration–reaction coupling framework provides critical insights for cathode-assisted in situ catalytic pyrolysis and closed-loop electrolyte recycling. Full article

Temperature affects the battery voltage response, and it is essential to take this influence into consideration for diagnosis purposes, as it could be misinterpreted for degradation. Temperature affects cell kinetics, and a good proxy to emulate this impact is to use electrode data at different C rates. This work further validates this concept by analyzing the relationship between temperature and rate at the electrode level for commercial graphite//LiFePO₄ and (silicon, graphite)//LiNi_0.8Mn_0.1Co_0.1O₂ cells. It will be shown that excellent emulation accuracy for both the voltage response and the capacity retention can be obtained for temperatures varying between −14 °C and 55 °C. Full article

This study investigates the formation mechanism of non-doped cubic lithium lanthanum zirconium oxide (c-LLZO) nanofibers using in situ synchrotron X-ray scattering techniques. Electrospun polymer precursor nanofibers were annealed at temperatures up to 800 °C, enabling real-time tracking of phase transitions via simultaneous small-angle X-ray scattering (SAXS), wide-angle X-ray scattering (WAXS), and evolved CO₂ gas analysis. The results reveal a three-step transformation pathway: polymer decomposition, formation of La₂Zr₂O₇ (LZO), and direct conversion of LZO to c-LLZO without intermediate tetragonal phases detected within the sensitivity of our in situ WAXS measurement. Cryo-electron energy loss spectroscopy (EELS) further elucidates the role of lithium diffusion, showing Li enrichment at fiber surfaces and Li deficiency in the interior, which stabilizes the cubic phase. This Li segregation effect in nanostructured LLZO materials extends beyond the previously reported size effect. This work advances the understanding of c-LLZO formation mechanisms and provides practical insights for optimizing synthesis routes to achieve phase-pure c-LLZO for solid-state battery applications. Full article

Solid-state electrolytes (SSEs) are essential for achieving long-term stability and fast-charging performance in secondary batteries. Although Li_1.3Al_0.3Ti_1.7(PO₄)₃ (LATP) offers high ionic conductivity, its practical application is restricted by high-temperature sintering requirements and interfacial reduction at the lithium anode. In contrast, Li-based oxide electrolytes can be sintered below 600 °C, offering improved compatibility with conventional electrodes such as graphite and silicon. In this study, a Li₂O–LiCl–B₂O₃–Al₂O₃ (LCBA)/LATP composite SSE was fabricated via hot-press co-sintering at 600 °C. Composites with LCBA:LATP weight ratios of 8:2, 7:3, 6:4, 5:5, 3:7, and 2:8 were prepared to identify the optimal composition. The 3:7 composite achieved a sintered density of 2.40 g/cm³ and an ionic conductivity of 2.5 × 10⁻⁴ S/cm. Phase evolution and sintering behavior were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Compared to single-phase LCBA or LATP, the composite electrolyte exhibited improved interfacial stability and lower interfacial resistance against lithium metal. Full article

Thanks to their low cost and environmental sustainability, sodium-ion batteries have emerged as a highly attractive alternative to lithium-ion systems in the field of large-scale energy storage; however, issues such as insufficient energy density and poor cycle stability have hindered their widespread adoption. We have rationally designed a Mg/Li co-doped P2-type NLMMO (Na_0.8Mg_0.22Li_0.08Mn_0.7O₂) cathode material that enables reversible anion redox reactions through synergistic interactions, enhancing the stability of the layered framework. The material exhibits an exceptional initial discharge capacity of 158 mAh g⁻¹ at 2.0–4.4 V and retains 68% of its capacity after 400 cycles at 0.1 A g⁻¹, surpassing the performance of both lithium-doped (Na_0.8Li_0.3Mn_0.76O₂, NLMO) and magnesium-doped (Na_0.8Mg_0.3Mn_0.7O₂, NMMO) materials. In situ XRD shows that NLMMO has structural stability, and the Mg doping modification strongly inhibits the phase transition and stabilizes the interlayer structure. Ex situ XPS analysis indicates that the lattice oxygen in the cathode material underwent changes. This study provides a new path for designing cathodes with synergistic anionic and cationic redox reactions. Full article

The severe performance degradation of lithium-ion batteries at low temperatures limits their applications in extreme environments. Herein, we report the development of a low-temperature-capable 2.5 Ah 18650 cylindrical battery employing a LiNi_0.8Co_0.15Al_0.05O₂ cathode with optimized conductive additive formulations. The ternary conductive architecture is rationally designed based on dimensional complementarity: a zero-dimensional Super P (SP) nanoparticle ensures percolation through point-to-point contacts, a one-dimensional multi-walled carbon nanotube (MWCNT) establishes long-range electron highways via line-to-point bridging, and a two-dimensional graphene nanoplatelet (GNP) provides face-to-point encapsulation of active particles, mechanically buffering volume expansion and suppressing interfacial degradation. This hierarchical point–line–plane network generates redundant electron transport pathways while steric hindrance effects mitigate aggregation of each component. Through systematic comparative investigation of GNP/MWCNT/SP ternary and MWCNT/SP binary conductive systems, we elucidate the distinct roles of low-dimensional nanocarbons in electrochemical performance enhancement. Film resistivity measurements reveal that the ternary system achieves a 67% reduction in cathode resistivity (to 9.1 Ω·cm at 20 °C) compared to conventional SP (27.5 Ω·cm), outperforming previously reported binary nanocarbon systems for high-nickel cathodes (typically 40–55% reduction at comparable loadings). This enhancement is achieved at a constant total conductive additive loading of 2.5 wt%, demonstrating that dimensional optimization rather than quantity increase governs electrical transport properties. Electrochemical evaluations demonstrate that the fabricated 18650 cells deliver exceptional rate capability (10C continuous and 20C pulse discharge) and remarkable low-temperature performance (76.8% capacity retention at −40 °C under 1C). Notably, while both conductive formulations exhibit comparable rate performan ce and temperature adaptability, the ternary GNP/MWCNT/SP system demonstrates significant superiority in cycling stability, achieving 94.9% capacity retention after 1000 cycles at ambient temperature versus inferior retention for the binary counterpart. Electrochemical impedance spectroscopy analyses indicate reduced polarization and enhanced lithium-ion diffusion kinetics in the ternary system. This study establishes a high-performance low-temperature 18650 battery chemistry and provides quantitative mechanistic insights into how dimensional synergy in conductive additive design governs the rate capability, thermal behavior, and cycling stability of nickel-rich cathodes operating under extreme conditions. Full article