Battery Energy最新文献

Nitrogen-doped carbide-derived carbons (N-CDCs) are promising materials for energy storage due to their tunable structure and chemistry. Here, we design a molecular architecture strategy to promote nitrogen incorporation and microstructural control during the synthesis of N-CDCs. By varying polymerization and pyrolysis conditions, we obtain materials with hierarchical porosity and high specific surface area (S_BET > 2000 m² g⁻¹) and nitrogen content between 1.8 and 6.4 wt.%. Electrochemical evaluation in aqueous 6 M KOH using both three- and two-electrode configurations, identifies nitrogen doping, defect density, and hierarchical porosity as key contributors to performance. The optimized N-CDC delivers a specific capacitance of 210 F g⁻¹ at 1 A g⁻¹, with high retention at elevated current densities. A proof-of-concept pouch cell shows 100 F g⁻¹ at 0.5 A g⁻¹ and stable cycling over 5000 cycles, resulting in superior coulombic efficiency. The practical applicability is demonstrated with two pouch cells connected in series to power an electronic watch (1.5 V). These findings demonstrate the effectiveness of molecular-level control in the design of high-performance carbon-based supercapacitor electrodes.

Half-cells have been employed to investigate the intrinsic electrochemical behavior of the cathode material, as the chemical potential of the alkali metal reference electrode remains relatively constant during discharge. However, in full cells, the discharge mechanism is anode-dependent. Herein, a rechargeable nonaqueous sodium ion battery (SIB) is fabricated using tungsten trioxide (WO₃) nanopowder on a graphite substrate as the anode and a nickel-hexacyanoferrate Prussian blue (PB) cathode to understand the dominant discharge mechanism. The battery cells are evaluated for reversibility and durability and exhibit reversible charge–discharge plateaus, confirming sodium-ion intercalation/deintercalation in both electrodes. The sodium-ion diffusion coefficient of 5.3 × 10⁻¹³cm².s⁻¹ calculated using electrochemical impedance spectroscopy (EIS) is consistent with a planar finite space diffusion mechanism. Cyclic voltammetry (CV) shows a broad reversible redox peak on the WO₃ anode, owing to its multiple valence states, also observed in potential versus differential capacitance (dQ/dV) and simulated density of states (DOS). The full cell demonstrates an open-circuit voltage (OCV) of 2.2 V (charged), a discharge capacity of 79 mAh.g⁻¹ at 0.1C rate, and retains 69% of its capacity after 500 cycles, indicating promising durability and reversibility for sodium-ion storage. The charge carrier concentration (ccc), DOS, electrical and thermal conductivities, and chemical potential simulations for the charged and discharged phases, in both electrodes, reveal that the anode determines the shape of the discharge curve and the cathode the capacity of the cell. This study paves the way to predicting the behavior of a full cell, including cycling curve shape, process, dependencies, and thermal runaway.

Sodium carboxymethyl cellulose (CMC) and polyacrylic acid (PAA) are state-of-the-art binders in aqueous-processed anodes for lithium-ion batteries. Binders act as dispersing agents and rheology modifiers in aqueous slurries, while also providing mechanical integrity of dry electrodes during battery fabrication and operation. However, despite their low concentration, they may have detrimental effects on the conductivity and electrochemical performance of batteries, for example, due to their adsorption on active material particles, which is supposed to limit Li⁺ insertion and extraction, but also affect electrode microstructure and adhesion to the current collector. Here, a commercially available, cross-linked acrylate binder (Carbopol® Ultrez10, x-PAA) with high thickening efficiency is applied for graphite anodes. At lower polymer content, anode slurries based on x-PAA exhibit high-shear viscosities similar to those of the CMC reference and provide a yield stress, which is advantageous for slurry stability. Furthermore, SBR content could be reduced without loss of adhesion strength compared to the CMC reference, since x-PAA does not adsorb onto graphite. Thus, the total binder content could be lowered by about 40% in comparison to reference anodes comprising CMC. The substantial reduction in total binder amount resulted in slightly lower long-term stability compared to the reference cell including CMC. Cells incorporating x-PAA, however, outperformed references under fast-charging conditions (up to 5C) presumably since x-PAA does not adsorb on graphite, thus enabling more effective Li⁺ insertion and extraction. Further refinement of crosslinking microstructure may enable fabrication of electrodes with higher energy density and higher capacity retention during cycling, irrespective of cycling rate.

This study explores the development of calcium-ion batteries (CIBs) by focusing on the design of a novel electrolyte to overcome key challenges, such as poor calcium plating/stripping. Hydrated vanadium pentoxide (H-V₂O₅) served as the cathode, and graphite acted as the anode. Tricalcium dicitrate tetrahydrate (Ca-citrate) salt was used for the first time in an ethylene carbonate/propylene carbonate (EC/PC) solvent system. Ca-citrate showed marked improvement in ionic conductivity (up to 2.6 × 10⁻¹ S/cm) and electrochemical stability (~6 V) relative to traditional Ca-nitrate (2.5 V) and also displayed better capacity retention. To solve the solubility limitations of Ca-citrate in EC/PC, highly diluted (0.001 M) solution of EC/PC and modified electrolytes with cosolvents like poly(ethylene glycol) 200 (PEG 200) and trifluoroacetic anhydride (TFA) were studied. PEG 200 increased solubility and stability through hydrogen bonding, while TFA increased ionic mobility but decreased electrochemical stability. The PEG-modified electrolyte achieved a stability window of ~4 V with a charge/discharge capacity of ~198 mAh/g. Additionally, using ethylene glycol (EG) as an alternative solvent increased the electrochemically reversible, soluble, and capacitive Ca-citrate (up to 708 mAh/g, 85 mA/g). EG-based electrolyte showed high columbic efficiency (~99%–100%) and stable interfacial behavior.

In this study, a series of polydopamine (PDA)/MXene nanocomposites with varying weight ratios (90:10, 70:30, and 50:50) are synthesized via in situ polymerization and evaluated as cathode materials for both lithium-ion (LIBs) and potassium-ion batteries (KIBs). Electrochemical evaluations revealed superior performance of these composites in LIB systems, attributed to smaller ionic radius and faster diffusion kinetics of Li^⁺ compared to K^⁺. PDA exhibits low capacities of 98.6 and 96.1 mAh g^-1 for LIB and KIB, respectively. The incorporation of conductive MXene into PDA resulted in significantly improved performance. The PDA90MXene10, PDA70MXene30, and PDA50MXene50 nanocomposites delivered high specific capacities of 198.5, 297.8, and 246.6 mAh g⁻¹ for LIBs, and 165.3, 249.3, and 171.8 mAh g⁻¹ for KIBs, respectively, at 100 mA g⁻¹. These materials also exhibited excellent rate capabilities, with capacities of 133.1, 171.4, and 163.4 mAh g⁻¹ for LIBs, and 131.1, 151.5, and 125.2 mAh g⁻¹ for KIBs at a high current density of 5 A g⁻¹. Among all compositions, PDA70MXene30 demonstrated the most outstanding electrochemical performance, underscoring synergistic effect between redox-active PDA and highly conductive MXene nanosheets. This synergy facilitates improved electron transport and ion diffusion, making PDA70MXene30 a promising candidate for high-performance cathodes in both LIBs and KIBs.

Back Cover: Accurate state of health estimation is critical for battery management systems in electric vehicles. In article number BTE.20240126, Zhiqiang Lyu, Xinyuan Wei, Longxing Wu and Chunhui Liu leverages the open source battery cell data set to address the aging model SOH estimation. To handle nonlinearity and feature coupling, a flexible data-driven aging model is proposed, employing dual Gaussian process regressions and transfer learning to enhance model efficiency and accuracy. Adaptive filtering via the Particle filter further refines the model by integrating aging features and output capacity, resulting in a close loop data fusion approach for precise SOH.

Front Cover: Insight Into Puncture-Induced Thermal Runaway in Lithium-Ion Batteries to Reduce Fire Risks in Electric Vehicle Collisions. In article number BTE.20250036, Hong Zhao, Xiangkun Bo, Zhiguo Zhang, Li Wang, Walid A. Daoud and Xiangming He provided an analysis of experimental and modeling studies to establish the hierarchy of thermal runaway initiation and its influencing factors, including battery status and penetration protocols. Furthermore, he proposed materials-by-design approaches for developing intrinsically safe lithium-ion batteries (LIBs) that maintain energy density while achieving automotive-grade mechanical robustness (ISO 6469-1 compliance), ultimately advancing collision-resilient electric vehicle battery systems.

Simulation models are of great importance in understanding the complexities of the internal electrochemical processes within batteries, aiding in design optimization and advancing energy storage technologies. One of the central challenges lies in predicting battery lifespan and elucidating side reactions under extreme operating conditions. This study aims to design an electrochemical model that considers multiple side reactions to predict the cycle life of lithium-ion batteries in high temperature environments. First, a basic simulation framework is established using a simplified electrochemical-mechanical coupling model. Subsequently, multiscale characterization of aged batteries is performed to identify five types of side reactions, encompassing phenomena such as solid electrolyte interphase (SEI) growth, cracking of negative electrode particles, electrolyte oxidation and decomposition/deposition of active materials. A comprehensive battery life prediction model is constructed by modeling these side reactions. Finally, the accuracy of the life prediction is validated using high temperature cycling data. The conclusions reveal that electrolyte decomposition and the loss of active material are the primary causes of battery degradation under high temperature conditions.

This study presents a detailed comparative study of lactone-based electrolytes (γ-valerolactone, GVL and γ-butyrolactone, GBL) combined with lithium imide-based salts, namely lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and lithium bis(fluoromethanesulfonyl)imide (LiFSI). Propylene carbonate is employed as a reference electrolyte solvent. The physicochemical properties of these electrolyte systems are determined experimentally and further calculated using our developed computational model. Besides, in-silico investigations are used to reveal valuable insights into the molecular interactions of the electrolyte components, such as self-diffusion coefficients and radial distribution functions. Furthermore, the suitability of lactone-based electrolytes for electrochemical applications is demonstrated by their promising rate capability and cycling stability over 200 cycles in graphite half-cells, especially with 1 M LiTFSI and 2 wt% vinylene carbonate, together with their favorable performance on lithium iron phosphate. An excellent capacity retention achieved in a full-cell configuration (> 80% after 200 cycles) further validates the potential of lactones as battery solvent alternatives, with GVL standing out due to its bio-based origin.

Capacity fading during cycling remains a significant challenge for silicon-based anode materials in Li-ion batteries. Amorphous, sub-stoichiometric silicon carbide (a-SiC_x) nanoparticles have proven to be more stable than pure silicon, albeit with lower lithiation capacities. The incorporation of carbon during the nanoparticle synthesis is highly effective in the suppression of crystalline phases during both synthesis and cycling. In this study, a-SiC_x materials with varying carbon concentrations (up to 22 wt.%) were produced via gas-phase synthesis in a hot-wall reactor. The primary objective is to understand the mechanism of carbon incorporation into the silicon particles, and secondly its impact on material properties and battery performance. Based on extensive materials science investigations and NMR analyses, we have determined that carbon is incorporated together with hydrogen, which further promotes amorphization. Furthermore, cycling analysis shows a strongly increased stability with 85% retention after 200 cycles for materials with more than 10 wt.% carbon, probably mainly due to a reduced buildup of internal resistances and reduced volume expansion. Furthermore, crystalline Si-Li-phases cannot be formed in this material during lithiation enabling deep lithiations, and Coulombic efficiency is increased. These results suggest that a-SiC_x is a promising alternative to pure silicon as an anode material.