Tag: Structural stability

Long-Life, Ultra-Fast Charging Zinc-Ion Battery with Stable Performance over 10,000 charge–discharge cycles

Long-Life, Ultra-Fast Charging Zinc-Ion Battery with Stable Performance over 10,000 charge–discharge cycles

This study contributed to advancing Aqueous Zinc-Ion Battery (AZIB) technology by developing a novel vanadium (V)-based cathode material that offers both high specific capacity and long offers both high specific capacity and long cycle life.

Research Background and Goals

Lithium-ion batteries (LIBs) are widely used as key energy storage devices across various industries, ranging from consumer electronics to electric vehicles and grid-scale energy storage systems (ESS), due to their high energy density and excellent cycle life. However, lithium’s scarcity, high cost, and associated fire hazards have led to growing demand for next-generation alternatives.
Aqueous zinc-ion batteries, which use water-based electrolytes, are emerging as promising candidates due to their superior safety, cost-effectiveness, and high volumetric energy density. Nonetheless, they face critical limitations: structural degradation of the cathode material during repeated charge-discharge cycles results in rapid performance decline. In particular, vanadium pentoxide (V2O5), a commonly used cathode material, offers high theoretical capacity but suffers from poor structural stability and limited. It also undergoes dissolution and re-precipitation during cycling, degrading its electrochemical performance.
To address these challenges, this study proposes a new vanadium-based cathode material—Na2V6O16・2H2O (NaVO)—prepared by pre-intercalating sodium ions (Na+). This material stabilizes the structure and enhances the electrochemical performance of AZIBs.

Methods

The research focused on a structural stabilization strategy via Na+ pre-intercalation to improve the electrochemical performance of AZIBs. NaVO was synthesized through a sonochemical method, which expanded the interlayer spacing and allowed Na⁺ ions to function as structural pillars, thereby enhancing cycling stability.
The material’s physical and chemical characteristics were thoroughly analyzed, including real-time structural monitoring using synchrotron X-ray diffraction (XRD). Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were employed to evaluate charge transfer resistance and rate capability. Density functional theory (DFT) calculations confirmed that NaVO exhibits a significantly lower Zn2+ diffusion energy barrier compared to V2O5 , as well as reduced structural expansion—key advantages for long cycle life. Furthermore, Na+ ions were found to suppress dendrite formation on the Zn anode surface.

Results and Discussion

The study evaluated the effectiveness of cation pre-intercalation in improving the structural integrity and electrochemical performance of vanadium-based cathodes. Through a simple and efficient sonochemical synthesis method, Na+ ions were successfully intercalated into V2O5 to form NaVO, expanding the interlayer distance to approximately 4.3–8.4 Å.
This structural modification led to significant performance enhancements. A NaVO/Zn battery demonstrated a specific capacity of 126.3 mAh g-1 at a high current density of 10 A g⁻¹ and retained 91.8% of its capacity even after 10,000 charge-discharge cycles. hese results represent 1.68- and 1.99-fold improvements over conventional V2O5 cathodes.
In-situ analyses revealed the mechanisms underlying the performance improvements. The flexible valence change of vanadium during Zn2+ insertion and extraction contributed to structural stability, while Na+ ions served as internal pillars to maintain structural integrity. The expanded interlayer spacing facilitated faster Zn2+ insertion, improving rate performance. DFT simulations further confirmed that Na+ pre-intercalation is crucial for enhancing structural stability and ion diffusion, thereby improving the overall electrochemical performance of vanadium-based cathodes.

Read more on PAL website

Synchrotron light reveals hidden benefits in cobalt-free battery materials

Synchrotron light reveals hidden benefits in cobalt-free battery materials

An international study led by researchers at the ALBA Synchrotron has analysed the effect of cobalt removal from Lithium-rich cathodes using operando multi-edge X-ray absorption spectroscopy. The research, published in Materials Today Energy, reveals that Cobalt-free cathode compositions outperform those with cobalt by reducing oxygen release and improving structural stability. These results point towards a new avenue for sustainable and high-performance battery technologies.

The development of more sustainable and efficient energy storage solutions is one of the main challenges facing society today. At the heart of these initiatives are lithium-ion batteries, powering electric vehicles and enabling sustainable renewable energy storage systems. Their widespread use is driven by their high energy density, stability, and greater efficiency compared to other technologies.

Transition metals like nickel (Ni), manganese (Mn), and cobalt (Co) are frequently used in lithium-ion battery cathodes because they promote electrochemical reversible redox reactions, providing high energy density and reliable performances. However, these compositions also suffer from voltage fade and structural instability, leading to performance degradation over multiple cycles. Cobalt was thought to play a particular crucial role in stabilizing the layered structure of these cathode materials by improving electronic conductivity. Yet, its high cost, limited supply, and safety concerns have driven researchers to look for alternatives to reduce or eliminate cobalt from cathodes while enhancing battery performance.

This study, led by researchers at the ALBA Synchrotron, used advanced operando X-ray spectroscopy techniques to observe how cobalt removal affects the material at the atomic level, uncovering key structural and electronic transformations in real time. The main innovation lies in the multi-modal experimental approach, where multi-edge operando X-ray absorption spectroscopy coupled the results obtainable from both the x-ray absorption near edge structure (XANES) and extended x-ray absorption fine structure (EXAFS) spectral regions. Moreover, the hard x-ray operando absorption data collected at CLAESS beamline have been coupled with high-resolution transmission X-ray microscopy in the soft x-ray energy range conducted at MISTRAL beamlines, in both cases ALBA beamlines. This approach allowed the researchers to better understand the charge compensation mechanisms during cycling and the specific role of each transition metal and oxygen species.

The study compared two lithium-rich NMC cathodes. NMC is a layered oxide material made of nickel, manganese and cobalt. One of the studied cathodes presented a low cobalt content and the other was Co-free variant, both synthesized via co-precipitation followed by a solid-state reaction. These cathodes were assembled into coin-cell batteries to assess their electrochemical performance through charge and discharge cycles. During cycling, the researchers employed operando multi-edge X-ray Absorption Spectroscopy (XAS) to monitor real-time oxidation state changes in transition metals and, indirectly, on the oxygen species. Automated big data post processing has been applied. While the XANES region have been analysed with advanced statistical methods, automated fitting techniques were also exploited to extract complementary quantitative information from the EXAFS signals. Additionally, full-field Transmission X-ray Microscopy (TXM) was used to analyse nanoscale morphological and structural transformations.

The combination of all these techniques provided critical insights into Co’s role in stabilizing the layered structure along cycling and how its absence impacts battery performance.Operando XANES measurements confirmed that in the Co-free material, nickel undergoes a more complete and faster oxidation process during the first charge cycle, which enhances charge compensation and reduces irreversible oxygen loss. The X-ray Microscopy analysis further revealed that removing Co suppresses the formation of the Mn spinel phase in the bulk of the material particles, a key factor in capacity fading. The finding explained the reasons of the observed higher capacity retention over many charging cycles in the Co-free cathode, making it a strong candidate for next-generation lithium-ion batteries.

These findings identify a pathway toward more sustainable, high-performance lithium-ion batteries without relying on scarce and expensive cobalt.

“The study confirms that cobalt-free cathodes can outperform those with cobalt and provides a deeper understanding of the involved mechanisms. The use of advanced X-ray spectroscopy techniques allowed us to further refine cathode materials and enhance their efficiency and longevity”, says Laura Simonelli, group leader at the CLAESS beamline and main author of the study.

As the demand for cleaner energy storage solutions rises, this research contributes to the ongoing development of safer, more affordable, and environmentally friendly battery technologies.

Read more on ALBA website