Journal of Power Sources最新文献

Open-framework crystal structured vanadates have been extensively investigated as cathode materials for aqueous zinc-ion batteries (ZIBs). However, the inherent challenges of poor electronic conductivity and structural instability compromise the rate capability and overall cycle life. Herein, we first successfully synthesized octahedral MIL-101(V) and prepared the Zn₃(OH)₂V₂O₇·2H₂O@C (ZVOH@C) composite by in-situ electrochemical conversion of MIL-101(V)-derived crystalline V₂O₃ and carbon composite (V₂O₃@C). The ZVOH@C composite of open-framework crystal structured Zn₃(OH)₂V₂O₇·2H₂O and conductive carbon skeleton not only possesses more active sites, more stable crystal structure and higher electrical conductivity, but also provides faster Zn²⁺ diffusion kinetics. As expected, the ZVOH@C composite electrode exhibits excellent capacity of 506.3 mAh/g at a current density of 1.0 A/g, exceptional rate performance (375.7 mAh/g at 20.0 A/g), and impressive long-term cycling stability, maintaining 314.5 mAh/g over 5000 cycles at 20.0 A/g. This study demonstrates a promising method for designing new cathode materials through in-situ electrochemical synthesis for ZIBs.

Triple ionic-electronic conducting (TIEC) oxides, as an emerging class of materials with complex conduction properties, are used in diverse electrochemical energy devices. Accurately determining the transport numbers ($t_x$) of TIEC oxides is significant. In this study, we theoretically evaluate the reliability of the electromotive force (EMF) method in determining $t_x$ of TIEC oxides and address the issue that $t_x$ obtained by the EMF method is an apparent value ($t_x^{app}$). Initially, based on a precise defect distribution model, it reveals the non-uniform distributions of transport numbers within the TIEC membrane. Subsequently, through a comprehensive multiple-factor analysis, it discloses that compared with temperature and thermodynamic parameters of defect reactions, the gradient of gas partial pressure in concentration cells is the primary influencing factor affecting $t_x^{app}$. Notably, under conditions of relatively small gradients of gas partial pressure, $t_x^{app}$ can be approximated as the average value of $t_x$ at both sides of the membrane. Motivated by these findings, we propose a new EMF method, which can determine the accurate $t_x$ of materials at a specific gas composition, rather than an apparent one. Overall, the finding of this study furnishes valuable insights into determining transport numbers of TIEC oxides.

The high specific capacity of the P2-type cathode endowed by the synergistic cation and anion redox makes it one of the most promising cathode materials for sodium-ion batteries (NIBs). However, the structural rearrangement and the irreversible oxygen release under highly desodiated states engender stability issues upon high-capacity operation. Herein, we show specifically how the structural degradation of the P2-type cathode is effectively stabilized by the substitution of bifunctional spectator ions. The rational incorporation of Ti and Si ions triggers the “pillar effect” and “inductive effect”, which eliminates the P2-O2/P2-P2′ structural evolution and mitigates the irreversible oxygen oxidation. Benefited from the highly reversible anion redox, the obtained Na_0·67Li_0·21Mn_0·59Si_0·01Ti_0·19O₂ represents a high reversible capacity of 220 mAh g⁻¹ at 0.1C (20 mA g⁻¹) within a Na-metal half-cell. Ex-situ XRD reveals a solid solution reaction without the formation of additional phases among the charge/discharge process, thus favoring stable cycling performance for up to 200 cycles at 2.5C (with a capacity retention rate of 88 %). This work shows, not only the specific strategies for improving the electrochemical performance of cathode materials, but also offers insights into the intrinsic mechanisms underlying the performance enhancement achieved through spectator ion substitution.

Due to the high energy density, non-aqueous lithium-oxygen (Li–O₂) batteries attract significant attention. However, batteries' high capacity attenuation rate under deep charge and discharge conditions remains a significant challenge. This paper presents a multi-cycle deep charge and discharge model for non-aqueous lithium-oxygen batteries, which predicts the performance of the battery during multiple deep charge and discharge cycles at high and low discharge-specific capacities. The parameter states during different discharge stages in different discharge cycles are investigated by analyzing the battery's cathode porosity, product volume fraction, and oxygen concentration changes. The study shows that as the number of cycles increases, the deposition of a small number of discharge products in the cathode altered the distribution of the newly generated products, thereby affecting the cathode structure and oxygen transport in the subsequent discharge. Moreover, depositing a small amount of discharge products can result in significant capacity attenuation in the battery. This model can accurately evaluate the deep charge and discharge performance attenuation process of non-aqueous Li–O₂ batteries, which helps improve the understanding of the deep discharge attenuation mechanism of non-aqueous Li–O₂ batteries.

Oxide ion conductors hold significance in various applications, such as electrolytes in solid oxide fuel cells. This study focuses on synthesizing and systematically investigating the structural, morphological, and electrical properties of NaNb_1-xZr_xO_3-0.5x (0 $\le$ x $\le$ 0.15) solid electrolyte. X-ray photoelectron spectroscopy (XPS) analysis shows that introducing a small quantity of zirconium into NaNbO₃ induces an environment of unbalanced charge neutrality, creating oxygen vacancies. This phenomenon establishes a pathway for the mobility of oxygen ions. Temperature-dependent ac conductivity, analyzed through impedance data, follows Jonscher's power law, with the 's' parameter indicating a correlated barrier hopping mechanism. Enhanced conductivity is observed with Nb⁵⁺ substitution by Zr⁴⁺. The reduced activation energy value is observed for x = 0.1, which suggests enhanced ion hopping and, hence, enhanced conductivity. NaNb_0.9Zr_0.1O_2.95 exhibits predominantly ionic conduction with a total conductivity of 6.2 × 10⁻⁴ S cm⁻¹ and bulk conductivity of 1.72 × 10⁻³ S cm⁻¹ at 700 °C. This study shows the promising potential of Zr-doped NaNbO₃ as a solid electrolyte for various electrochemical applications.

The Electrochemical impedance spectroscopy (EIS) of three novel cathode channels designs square, boot, and triangular for open cathode polymer electrolyte cathode fuel cell stacks are analyzed. Fundamental mechanisms such as oxygen reduction reaction, proton conductivity, bulk resistance of stack, capacitance and structure features of the porous carbon electrode etc. are investigated with the help of Nyquist/Bode plots and Randles circuit. Operational parameters including airflow rate, current, H₂ gas condition (humidified and dry), and stack temperature are studied focused on understanding the trend of high and low frequency resistance. The minimum resistance and temperature mapping for cross-section designs at different operating conditions is utilized for parametric optimization. Overall, it is recommended to operate the stacks at minimum resistance obtained just before the peak power density and its corresponding temperature ∼40 $°$C. Finally, a data-driven hybrid model integrating EIS and artificial intelligence is presented with root mean square error of ∼0.98.

Alloy-type anodes have attracted extensive attention in magnesium-ion batteries (MIBs) due to their low reaction potentials and high theoretical specific capacities. However, the kinetically sluggish Mg insertion/extraction and diffusion in electrode materials, as well as the huge volume changes resulting in the capacity decay limit their further development. Herein, a series of porous-Bi (P-Bi_x) anodes are fabricated through a facile dealloying strategy based on the Sn_100-xBi_x (x = 1, 5, 10, 43, at.%) precursor alloys. Among them, the P–Bi₁₀ anode delivers a high discharge specific capacity (376.0 mAh g⁻¹ at 500 mA g⁻¹), greatly improved rate capability (363.3 mAh g⁻¹ at 1000 mA g⁻¹) and good cycling stability even at 2000 mA g⁻¹ (104.0 mAh g⁻¹ after 1000 cycles). Furthermore, operando X-ray diffraction (XRD) is performed to unveil the magnesiation/demagnesiation mechanisms of the P–Bi₅ and P–Bi₁₀ anodes, indicating a simple two-phase reaction process. Additionally, the P–Bi₁₀ anode displays good compatibility with conventional Mg salt electrolytes such as Mg(TFSI)₂. Our findings could provide useful information on design of high-performance alloy-type anode materials for MIBs.

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 - LiNi_0·5Mn_1·5O₄)/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.