Performance Of Lithium-ion Batteries Research Articles

Tailoring cathode materials: A comprehensive study on LNMO/LFP blending for next generation lithium-ion batteries

Lithium-ion batteries (LIBs) play a crucial role in diverse applications, including electric vehicles, portable electronics, and grid energy storage, owing to their commendable features, such as high energy density, extended cycle life, and low self-discharge rates. Despite their widespread use, the growing market demands continuous efforts to enhance LIBs performance, particularly in terms of energy density and cycling stability. This paper details the development of a lithium nickel manganese oxide (LNMO - LiNi0·5Mn1·5O4)/lithium iron phosphate (LFP - LiFePO4) blended cathode for high-performance LIBs. The study investigates the impact of blending LFP and LNMO, examining morphological and electrochemical aspects. The usage of resonant acoustic mixing (RAM) technology is demonstrated to be a promising approach to improve the distribution of LFP and LNMO particles, leading to increased electrochemical performance. The blended LNMO/LFP cathode exhibits a specific capacity exceeding 125 mAh g−1 at C/10 and a capacity retention exceeding 80 % after 1000 cycles at 1C versus lithium. Moreover, in a full-cell configuration, the blended electrode displays a capacity retention close to 74 % after 100 cycles, showcasing a nearly 30 % improvement compared to the pure LNMO cathode. This research highlights the potential of blended cathode materials in advancing the capabilities of LIBs.

Interconnected MoO2/MoS2@NC nanosheets as anodes with high-rate and long-life for lithium-ion and sodium-ion batteries

The development of sustainable and cost-effective anode materials with the ability to achieve superior performance in both lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) continues to pose a major challenge. Among the various available options, molybdenum-based materials have emerged as highly promising anodic candidates for both LIBs and SIBs owing to their substantial specific capacity, rapid electrochemical dynamics, and outstanding electronic conductivity. In this work, we present the preparation of molybdenum dioxide/molybdenum disulfide@nitrogen-doped carbon nanosheets (MoO2/MoS2@NC) via air-thermal activation. We highlight their exceptional lithium and sodium storage capabilities, which originate from their intricate hierarchical structures. As a result, the MoO2/MoS2@NC-15 composite has a remarkably high specific capacity (1027 mAh g−1 after 100 cycles at 100 mA g−1), high rate capability (490 mAh g−1 at 15000 mA g−1), and excellent cycling performance (618 mAh g−1 after 2000 cycles at 800 mA g−1) in LIBs. Moreover, in SIBs, the reversible specific capacity remaining is 246 mAh/g after 200 cycles at 600 mA g−1, which is indicative of a minimal capacity decrease of 0.4 mAh/g per cycle. Furthermore, comprehensive investigations were conducted on full cells comprising LIBs (MoO2/MoS2@NC-15//LiFePO4) and SIBs (MoO2/MoS2@NC-15//NaNi1/3Fe1/3Mn1/3O2), demonstrating their high specific capacities and excellent cycling performance. This study might provide a viable pathway toward developing straightforward and universally applicable synthesis methods for cutting-edge electrode materials in energy storage systems.

Separator structural-chemical features dependency on lithium-ion battery performances

Rechargeable lithium-ion batteries (LIBs) increasingly attract emphasis. Porous construction evolutions during LIBs operation inevitably deteriorate separators mechanical and electrochemical performances. In this research, separators with serial porous constructions are prepared accurately to reveal the dependency mechanism of separator porous structure design on LIB performances. Porous structure analyses, mechanical properties, orientation parameters, and thermal stability diagnosis verify uniform drawing deformations of casting films centralize pore size, optimize pore channel linearity, and retain isotropic texture. Heterogeneous pores with coarse fibrils emphasize under asynchronous drawing, causing worse permeability and anisotropic features, which likely suffered from potential safety hazards caused by excessive unidirectional shrinkage. Electrochemical and battery performance measurements uncover that concentrated pores with superior connectivity determine homogeneous Li+ fluxes, uniformly expand electrodes to impose even compressive stress on separators, and thus reserve initial porous structure maximally to ensure cycling stability. Heterogeneous Li+ fluxes derived from uneven pores with inferior connectivity cause excessive local compression stress on separators. Consequently, mechanically deteriorated porous structure highlight, in reverse impedes Li+ transfer and worsens cell performances. This study suggests separator structural-chemical features function in ensuring LIB performances, which lays solid foundations for separator industrial manufacturing with suitable porous structures for LIBs.

Influence of the PET-PTFE Separator Pore Structure on the Performance of Lithium Metal Batteries.

The separator is a crucial component in lithium batteries, as it physically separates the cathode and the anode while allowing ion transfer through the internal channel. The pore structure of the separator significantly influences the performance of lithium batteries, particularly lithium metal batteries. In this study, we investigate the use of a Janus separator composed of poly(ethylene terephthalate) (PET)-polytetrafluoroethylene (PTFE) fibers in lithium metal batteries. This paper presents a comprehensive analysis of the impact of this asymmetric material on the cycling performance of the battery alongside an investigation into the influence of two different substrates on lithium-ion deposition behavior. The research findings indicate that when the rigid PET side faces the lithium metal anode and the soft PTFE side faces the cathode, it significantly extends the cycling lifespan of lithium metal batteries, with an impressive 82.6% capacity retention over 2000 cycles. Furthermore, this study demonstrates the versatility of this separator type in lithium metal batteries by assembling the lithium metal electrode with high cathode-loading capacities (4 mA h/cm2). In conclusion, the results suggest that the design of asymmetric separators can serve as an effective engineering strategy with substantial potential for enhancing the lifespan of lithium metal batteries.

Strategy for the Preparation of ZnS/ZnO Composites Derived from Metal-Organic Frameworks toward Lithium Storage.

The synergistic effect between multicomponent electrode materials often makes them have better lithium storage performance than single-component electrode materials. Therefore, to enhance surface reaction kinetics and encourage electron transfer, using multicomponent anode materials is a useful tactic for achieving high lithium-ion battery performance. In this article, ZnS/ZnO composites were synthesized by solvothermal sulfidation and calcination, with the utilization of metal-organic frameworks acting as sacrificial templates. From the point of material design, both ZnS and ZnO have high theoretical specific capacities, and the synergistic effect of ZnS and ZnO can promote charge transport. From the perspective of electrode engineering, the loose porous carbon skeleton that results from the calcination of metal-organic frameworks can enhance composite material conductivity as well as full electrolyte penetration and the area of contact between the electrolyte and active material, all of which are beneficial to enhancing lithium storage performance. As expected, ZnS/ZnO anode materials displayed remarkably high specific capacities and outstanding performance at different rates. Combining material design and electrode engineering, this paper provides another idea for preparing anode materials with excellent lithium storage properties.

Unlocking fast‐charging capabilities of lithium‐ion batteries through liquid electrolyte engineering

AbstractGlobal trends toward green energy have empowered the extensive application of high‐performance energy storage systems. With the worldwide spread of electric vehicles (EVs), lithium‐ion batteries (LIBs) capable of fast‐charging have become increasingly important. Nonetheless, state‐of‐the‐art LIBs have failed to satisfy the demands of prospective customers, including rapid charging, extended cycle life, and high energy density. Addressing these challenges through innovations in material science and other advanced battery technologies is essential for meeting the growing demands of prospective customers. Besides the choice of active materials, electrolyte formulation has a significant impact on the fast‐charging performance and cycle life of LIBs over a wide range of temperatures. The liquid electrolyte is typically composed of lithium salts to provide an ion source, solvents to carry Li+ ions, and functional additives to build a stable solid electrolyte interphase (SEI). To enable the fast movement of Li+ ions, the liquid electrolytes should have low viscosity and high ionic conductivity. Meanwhile, SEI layers must be thin, uniform and ionically conductive. Furthermore, the low binding energy of the solvent facilitates desolvation of the solvation sheath, enabling fast Li+ ion transport to the anode during fast charging. This review provides the latest insights into rapid Li+ ion transport during fast charging, focusing on ensuring a deeper understanding of liquid electrolyte chemistry. The involvement of existing electrolyte mechanisms in materials discovery will develop electrolyte engineering techniques to improve the fast‐charging performance of batteries over a wide temperature range and will also facilitate the development of EV‐adoptable advanced electrodes.image

Experiment-Based Determination of Optimal Parameters in Constant Temperature–Constant Voltage Charging Technique for Lithium-Ion Batteries Using Taguchi Method

Charging methods significantly affect the performance and lifespan of lithium-ion batteries. Investigating charging techniques is crucial for optimizing the charging time, charging efficiency, and cycle life of the battery cells. This study introduces a real-time charging monitoring platform based on LabVIEW, enabling observation of battery parameters such as voltage, current, and temperature. The proposed system allows the precise control of charging parameters via a user-friendly interface. Utilizing a programmable DC power supply, it delivers specific charging waveforms, while data acquisition instruments record temperature changes. Key performance metrics, including charging time, efficiency, and temperature rise, are analyzed. Moreover, this paper conducts in-depth research on the constant temperature–constant voltage (CT-CV) charging technique and applies the Taguchi method to identify key parameter configurations that achieve the objectives of the shortest charging time, highest charging efficiency, and lowest average temperature rise. A comprehensive evaluation compares the optimized CT-CV method with conventional constant current–constant voltage (CC-CV) charging. The results demonstrate a 10.7% reduction in charging time compared to the 1C CC-CV method, indicating the efficacy of CT-CV in shortening charging duration while managing temperature rise.

Novel Ordinary Differential Equation for State-of-Charge Simulation of Rechargeable Lithium-Ion Battery

Lithium-ion battery energy storage systems are rapidly gaining widespread adoption in power systems across the globe. This trend is primarily driven by their recognition as a key enabler for reducing carbon emissions, advancing digitalization, and making electricity grids more accessible to a broader population. In the present study, we investigated the dynamic behavior of lithium-ion batteries during the charging and discharging processes, with a focus on the impact of terminal voltages and rate parameters on the state of charge (SOC). Through modeling and simulations, the results show that higher terminal charging voltages lead to a faster SOC increase, making them advantageous for applications requiring rapid charging. However, large values of voltage-sensitive coefficients and energy transfer coefficients were found to have drawbacks, including increased battery degradation, overheating, and wasted energy. Moreover, practical considerations highlighted the trade-off between fast charging and time efficiency, with charging times ranging from 8 to 16 min for different rates and SOC levels. On the discharging side, we found that varying the terminal discharging voltage allowed for controlled discharging rates and adjustments to SOC levels. Lower sensitivity coefficients resulted in more stable voltage during discharging, which is beneficial for applications requiring a steady power supply. However, high discharging rates and sensitivity coefficients led to over-discharging, reducing battery life and causing damage. These new findings could provide valuable insights for optimizing the performance of lithium-ion batteries in various applications.

Enhancing the Cathode/Electrolyte interface in Ni-Rich Lithium-Ion batteries through homogeneous oxynitridation enabled by NO3− dominated clusters

To meet the demand for higher energy density in lithium-ion batteries, extensive research has focused on advanced cathodes and metallic lithium anodes. However, Ni-rich cathodes suffer from the inactive phase-transition and side reactions at the cathode-electrolyte interfaces (CEI). In this study, we propose a novel approach to enhance the solubility of LiNO3 in carbonate electrolyte systems using a local high-concentrated addition strategy with triethyl phosphate as a co-solvent. Rather than the traditional solvent-dominated solvation clusters, the NO3− dominated electrolyte is examined to elucidate unique complexation phenomena. Two distinct clusters in NO3− dominated electrolyte arising from as a consequence of intramolecular interactions intrinsic to the constituents. This promotes the formation of a homogeneous oxynitride interphase and facilitates more expeditious lithium ion diffusion kinetics. Hence, the less stress fragmentation and irreversible phase transformation occur on the cathode surface with the homogeneous oxynitridation interface. This innovative design enables efficient cycling of the Li || NCM811 cell, offering a promising strategy to improve lithium-ion batteries performance.

Data-driven estimation of battery state-of-health with formation features

Accurately estimating the state-of-health (SOH) of a battery is crucial for ensuring battery safe and efficient operation. The lifetime of lithium-ion batteries (LIBs) starts from their manufacture, and the performance of LIBs in the service period is highly related to the formation conditions in the factory. Here, we develop a deep transfer ensemble learning framework with two constructive layers to estimate battery SOH. The primary approach involves a combination of base models, a convolutional neural network to combine electrical features with spatial relationships of thermal and mechanical features from formation to subsequent cycles, and long short-term memory to extract temporal dependencies during cycling. Gaussian process regression (GPR) then handles SOH prediction based on this integrated model. The validation results demonstrate highly accurate capacity estimation, with a lowest root-mean-square error (RMSE) of 1.662% and a mean RMSE of 2.512%. Characterization on retired cells reveals the correlation between embedded formation features and their impact on the structural, morphological, and valence states evolution of electrode material, enabling reliable prediction with the corresponding interplay mechanism. Our work highlights the value of deep learning with comprehensive analysis through the relevant features, and provides guidance for optimizing battery management.

Influence of ambient temperature on multidimensional signal dynamics and safety performance in lithium-ion batteries during overcharging process

Ambient temperature significantly influences the safety performance of lithium-ion batteries (LIBs), particularly their thermal runaway (TR) behaviors. Yet, the complexities of multidimensional signal dynamics in overcharged LIBs under different ambient temperatures are not well understood. In this study, we performed comprehensive overcharging abuse tests under cold (-10 °C and 0 °C), normal (20 °C), and high ambient temperatures (60 °C), to investigate the evolution of multidimensional signals of expansion force, gas concentration, surface temperature, and voltage. Results show that TR events are not triggered at ambient temperatures of −10 °C and 0 °C, with the maximum temperatures and corresponding rise rate reaching only 125 °C and 0.5 °C/s, respectively. In contrast, for batteries undergoing TR, the maximum temperatures and rates of temperature increase peaked at 410.3 °C and 20.6 °C/s, respectively. The ambient temperature has a minimal impact on the venting force of the battery, which varies from approximately 9500 N to 10000 N, primarily driven by an increase in internal gas pressure during overcharging—a factor relatively unaffected by temperature changes. After safety valve activation during overcharging, Hydrogen (H2) is consistently the first gas detected immediately across all ambient temperature scenarios. Additionally, an increase in ambient temperature results in earlier detection of abnormal expansion and venting behaviors, characterized by lower venting voltages and higher venting temperatures. This study contributes to a deeper understanding of battery failure mechanisms under various ambient temperatures and informs the development of early safety warning strategies for LIBs during the charging process.

Cobalt- and copper-doped NASICON-type LATP polymer composite electrolytes enabling lithium titania electrode for solid-state lithium batteries with high-rate capability and excellent cyclic performance

This study reports cobalt- and copper-doped NASICON-type Li1.5Al0.5Ti1.7(PO4)3 (LATP) polymer composite solid-state electrolytes (CSEs) enabling Li4Ti5O12 (LTO) electrode with high-rate capability and excellent cyclic performance for solid-state lithium batteries. The fast Li+ conductor of Co- and Cu-doped LATP powders was successfully synthesized through a modified sol-gel method followed by thermal calcination. The equivalent series resistance as the linear decreasing function of the dopant concentration can be viewed, whereas the ionic conductivity showed an increasing function of the dopant amount. This reveals that the dopant concentration plays a positive role in facilitating the ionic conduction, and the ionic conductivity achieves as high as 3.18 × 10−4 S cm−1 (Co-doping) and 2.99 × 10−4 S cm−1 (Cu-doping) at ambient temperature. The changes in lattice characteristics and microstructure that the Co and Cu doping rely on are responsible for the elevated conductivity. The solid-state cell equipped with LTO-supported CSEs demonstrated not only high-rate capability at 5C (with a capacity retention of 84.6 % compared to the original capacity at 0.2C), but also superior cyclic stability with excellent Coulombic efficiency (> 99.2 %) over 425 cycles using Co- and Cu-doped LATP ceramics. With the aid of fast Li+ NASICON-type ceramics, the CSEs establish a conductive ionic pathway that facilitates Li+ ionic transport within the electrolyte while reducing the interfacial electrolyte/electrode resistance in solid-state cells (Li||CSE||LTO).

Closed-loop resynthesis of LiNiCoAlO2 cathode active materials from the industrial leachate of spent li-ion batteries

The burgeoning electric vehicle market is significantly leading to a substantial increase in spent lithium-ion batteries (LIBs), emphasizing the need for efficient recycling to address raw material supply challenges. The resynthesis of cathode active materials, one of emerging efficient LIB recycling methods, refers to the synthesis of precursors from the leachate of spent LIBs without the separation of each element. While the resynthesis of LiNixCoyMnzO2 (NCM) from the Mn-rich industrial leachate of spent LIBs becomes popular nowadays, there is no practical approach for the resynthesis of LiNixCoyAlzO2 (NCA) from the industrial leachate. For the resynthesis of NCA, an additional purification step of solvent extraction with di(2-ethylhexyl) phosphoric acid for Mn removal is necessary. NCA is resynthesized from the Mn-removed leachate, after adjusting the Ni:Co ratio of precursors and sintering with Li and Al sources. While the initial discharge capacity of resynthesized NCA is slightly reduced to the electrochemically inactive impurities of Mg and Mn, its rate capability and cyclability are improved compared to pristine NCA from virgin materials. The effects of major impurities of Mg and Mn on the crystal structure and electrochemical properties of resynthesized NCA are further elucidated. Whereas the controlled Mg/Mn doping positively impacts both rate capability and cyclability, excessive Mn leads to degraded cyclability. Overall, our study expands the scope of resynthesis process of cathode active materials from spent LIBs, highlighting the intricate role of impurities and their impact on LIB performance.

Solution-processed poly(vinylidene difluoride)/cellulose acetate/Li1+xAlxTi2-x(PO4)3 composite solid electrolyte for improving electrochemical performance of solid-state lithium-ion batteries at room temperature

To enhance energy density and secure the safety of lithium-ion batteries, developing solid-state electrolytes is a promising strategy. In this study, a composite solid-state electrolyte (CSE) composed of poly(vinylidene difluoride) (PVDF)/cellulose acetate (CA) matrix, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt, and Li1.3Al0.3Ti1.7(PO4)3 (LATP) fillers is developed via a facile solution-casting method. The PVDF/CA ratio, LiTFSI, and LATP fractions affect the crystallinity, structural porosity, and thermal and electrochemical stability of the PVDF/CA/LATP CSE. The optimized CSE (4P1C-40LT/20F) presents a high ionic conductivity of 4.9 × 10-4 S cm−1 and a wide electrochemical window up to 5.0 V vs. Li/Li+. A lithium iron phosphate-based cell containing the CSE delivers a high discharge capacity of over 160 mAh g−1 at 25 °C, outperforming its counterpart containing PVDF/CA polymer electrolyte. It also exhibits satisfactory cycling stability at 1C with approximately 90 % capacity retention at the 200th cycle. Additionally, its rate performance is promising, demonstrating a capacity retention of approximately 80 % under varied rates (2C/0.1C). The increased amorphous region, Li+ transportation pathways, and Li+ concentration of the 4P1C-40LT/20F CSE membrane facilitate Li+ migration within the CSE, thus improving the battery performance.

A particle filter-based approach for real-time temperature estimation in a lithium-ion battery module during the cooling-down process

Temperature exerts a remarkable influence on the safety, performance, and lifespan of lithium-ion (Li-ion) batteries. Consequently, the real-time monitoring of this variable within battery cells emerges as both crucial and a significant challenge for battery thermal management systems. This paper introduces an approach for real-time temperature estimation in a Li-ion battery module during the cooling-down process by applying the particle filter (PF) technique. A battery module comprising fifteen cylindrical lithium cobalt oxide cells connected in series was employed for experimentation. The battery module was arranged into three rows, the PF employs real-time temperature measurements from the first cell of each string, based on a fractal-time model and an artificial evolution approach for parameter estimation, to estimate two unknown parameters and the temperature of the remaining twelve cells. Furthermore, the temperature measured on the surface of each cell in the module was compared both the PF and computational fluid dynamics (CFD) approach. The results exhibit a favorable agreement between the cell temperature estimates derived from the PF, the CFD simulations, and their respective experimental measurements. Finally, the proposed approach facilitates real-time temperature monitoring in battery modules with a reduced number of temperature sensors, thereby implying a cost reduction in the data acquisition system.

Empowering lithium-ion batteries: The potential of 2D o-Al2N2 as an exceptional anode material through DFT analysis

Finding an appropriate new anode material with high electrochemical performance for lithium-ion batteries (LIBs) is considered one of the significant challenges for both the academic and industrial research communities. Herein, we propose to explore the efficiency of a newly designed two-dimensional (2D) material, named orthorhombic dialuminium dinitride (o-Al2N2), as an alternative anode material for LIB systems through first-principles calculations and ab initio molecular dynamics (AIMD) simulations. The obtained results show that orthorhombic-Al2N2 exhibits a high specific capacity of 1144.2913 mAhg−1, an operating voltage around 0.575 V, and a low kinetic diffusion barrier of 0.26 eV. These results prove the suitability of the o-Al2N2 monolayer as a promising anode material for LIBs with high structural stability, strong binding energy towards lithium adsorbent, fast lithium diffusion, and a high theoretical capacity. These features rank the 2D o-Al2N2 monolayer among the best choices for the anode part of the next-generation rechargeable LIBs.

Comprehensive study of high-temperature calendar aging on cylinder Li-ion battery

Calendar aging at high temperature is tightly correlated to the performance and safety behavior of lithium-ion batteries. However, the mechanism study in this area rarely focuses on multi-level analysis from cell to electrode. Here, a comprehensive study from centimeter-scale to nanometer-scale on high-temperature aged battery is carried out. After short-time high-temperature aging, measurements of electrochemical performance show notable decay of capacity and increase of internal resistance. The thermal safety behavior is studied through accelerating rate calorimeter (ARC), which indicates that the heat output of the aged battery during thermal runaway is largely increased. The aging mechanism of high temperature is investigated under various scales. Incremental capacity (IC) curves depict the deterioration of electrodes and increase of ohmic resistance. Computational Tomography (CT) reveals structure evolution of aged battery at millimeter scale, indicating gas generation after high-temperature aging. Scanning electron microscope (SEM) shows thickened solid-state-electrolyte (SEI) on anode and cracks on cathode at sub-micrometer scale. X-ray diffraction (XRD) patterns present crystallographic evolution of both anode and cathode. Thus, the cell degradation-mechanism after high-temperature aging is interpreted at multi-level, that high temperature induces deterioration of electrodes, formation of SEI and evolution of gas.

Arc-Discharge In Situ Synthesis of Dual-Carbonaceous-Layer-Coated SnS Nanoparticles with High Lithium-Ion Storage Capacity.

SnS-based carbon composites have garnered considerable concentration as prospective anode materials (AMs) for lithium-ion batteries (LIBs). Nevertheless, most SnS-based carbon composites underwent a two-phase or multistep preparation process and exhibited unsatisfactory LIB performance. In this investigation, we introduce a straightforward and efficient one-step arc-discharge technique for the production of dual-layer carbon-coated tin sulfide nanoparticles (SnS@C). The as-prepared composite is used as an AM for LIBs and delivers a high capacity of 1000.4 mAh g-1 at 1.0 A g-1 after 520 cycles. The SnS@C still maintains a capacity of 476 mAh g-1 after 390 cycles despite a higher current of 5.0 A g-1. The high specific capacity and long life are mainly attributed to a unique dual-carbon layers coating structure. The dual-carbon layers not only could effectively improve electrical conductivity and reduce charge-transfer resistance but also limit the alteration in bulk and self-aggregation of SnS nanoparticles. The SnS@C produced by the arc-discharge technique emerges as a promising applicant for AM in LIBs, and the arc-discharge technique provides an alternative way for synthesizing other transition metal sulfides supported on carbonaceous materials.

Structural modulation of Nb2O5 for enhanced Lithium-ion battery Performance: Insights from density functional theory and electrochemical characterization

Lithium-ion batteries (LIBs), extensively utilized today, encounter challenges with anode materials, such as capacity degradation and shortened cycle life during prolonged cyclic charging and discharging. These issues significantly hinder further advancements and applications of LIBs. Among various innovative anode materials, niobium pentoxide (Nb2O5) has garnered considerable interest due to its high specific capacity and exceptional cycling stability. However, different crystal types of Nb2O5 have different structures and properties, so they need to be studied in depth to find better anode materials for LIBs. In this paper, pseudo-hexagonal (TT-Nb2O5), orthorhombic (T-Nb2O5), and monoclinic (H-Nb2O5) crystalline forms of Nb2O5 have been prepared by simple ball milling and calcination methods. We have calculated the structural model of the material based on the density flooding theory (DFT), and the results have demonstrated that the T-Nb2O5 has a large structural advantage, which is characterized by a very low diffusion energy barrier, a low internal resistance, and a higher conductivity. The electrochemical properties of the material were also analyzed, and T-Nb2O5 has excellent cycling stability and rate performance. After 200 cycles (at 0.1A/g), the specific capacity of T-Nb2O5 was maintained at 440.8mAh/g. 3000 cycles at high current (at 5A/g) maintained a specific capacity of 95mAh/g. T-Nb2O5 has great potential, which has already been proved. With the continuous pursuit and development of energy storage technology, we believe that the research of different crystalline types of Nb2O5 will provide us with more efficient and reliable energy storage solutions.

Boosting the Electrochemical Performance of Primary and Secondary Lithium Batteries with Mn-Doped All-Fluoride Cathodes.

Transition metal fluorides are potentially high specific energy cathode materials of next-generation lithium batteries, and strategies to address their low conductivity typically involve a large amount of carbon coating, which reduces the specific energy of the electrode. In this study, MnyFe1-yF3@CFx was generated by the all-fluoride strategy, converting most of the carbon in MnyFe1-yF3@C into electrochemical active CFx through a controllable NF3 gas phase fluorination method, while still retaining a tightly bound graphite layer to provide initial conductivity, which greatly improved the energy density of the composite. This synergistic effect of nonfluorinated residual carbon (∼11%) and Mn doping ensures the electrochemical kinetics of the composite. The loading mass of the active substance had been increased to 86%. The theoretical and actual discharge capacity of MnyFe1-yF3@CFx composite was up to 765 mAh g-1 (pure FeF3 is 712 mAh g-1) and 728 mAh g-1, respectively. The discharge capacity at the high-voltage (3.0 V) platform was more than three times higher than that of the non-Mn-doped composite (FeF3@CFx).