Synthesis and performance evaluation of Na(2-x)LixFeP2O7 (x=0, 0.6) hybrid cathodes

This study reports hybrid cathodes formation by cation substitution in which Li+ substitution has been considered for Na+ in the structure of Na(2-x)LixFeP2O7 (x=0, 0.6) to form Na1.4Li0.6FeP2O7 cathodes. Na(2-x)LixFeP2O7 (x=0, 0.6) cathodes were synthesized using the solid-state synthesis technique and characterized by various methods. The structural analysis (XRD, FE-SEM) indicates that the submicron-sized, phase pure, and crystalline materials having irregular morphology have been developed. Moreover, Li+ substitution does not alter the triclinic parent structure of Na2FeP2O7. Thermogravimetric analysis (TGA) shows that Li+ substitution into Na2FeP2O7 improves its thermal stability up to 550 °C with only ∼5 % weight loss. The electrochemical performance of Na2FeP2O7 and Na1.4Li0.6FeP2O7 in both lithium (Li) and sodium (Na) half-cells is investigated using different electrochemical techniques. It is noticed that Na1.4Li0.6FeP2O7 is electrochemically active both in lithium (Li) and sodium (Na) cells with promising cyclability. However, compared with Na2FeP2O7, Na1.4Li0.6FeP2O7 suffers from inferior electrochemical performance, which might be associated with the lattice distortion of Na2FeP2O7 due to Li+ substitution having a lower ionic radius than the Na+. Considering Na2FeP2O7 as a baseline material, a new hybrid Na1.4Li0.6FeP2O7 cathode has been developed, which can be used to synthesize other new cathode materials with improved performance.This publication was made possible by NPRP Grant#NPRP11S-1225-170128 from Qatar National Research Fund (a member of the Qatar Foundation). Statements made herein are solely the responsibility of the authors. Ramazan Kahraman and all the contributors would like to acknowledge the financial support of QU internal grant-QUCG-CENG-20/21-2. FE-SEM analysis was accomplished at the Central Laboratory Unit (CLU), Qatar University, Doha, Qatar.Scopu

Synthesis & Performance Evaluation of Hybrid Cathode Materials for Energy Storage

Research into the development of novel cathode materials for energy storage applications is progressing at a rapid rate to meet the ever-growing demands of modern society. Amongst various options, batteries are playing a vital role to replace conventional energy sources such as fossil fuels with green technologies. Among various battery technologies, lithium-ion batteries (LIBs) have been well explored and have succeeded in being adjusted with find many commercial applications. At the same time, as an alternative to LIBs, Sodium-Ion Batteries (SIBs) are also gaining popularity due to the presence of Sodium (Na) in abundance and its similar electrochemical characteristics with lithium (Li). However, SIBs are suffering from many challenges such as slow ionic movement, instability in different phases, and low energy density, etc. Many strategies in the literature have been proposed to address the aforementioned challenges of SIBs. Among them, the substitution of Na with Li to form hybrid cathode materials has turned out to be quite promising. The present work aims to investigate the effect of Na substitution with Li in a pyrophosphate framework. Towards this direction, Na(2-x) LixFeP2O7 (x=0,0.6) hybrid cathode materials were synthesized, and their structural, thermal, and electrochemical properties were studied. It is noticed that the incorporation of Li in the triclinic structure of Na2FeP2O7 has a significant effect on its thermal and electrochemical performance. This study can be considered as a baseline to develop some other pyrophosphate-based high-performance hybrid cathode materials

Understanding the electrochemical performance of LiNi0. 5Mn1.5O4 coated with Yttria and distributed over graphene nanosheets as cathode in li-ion batteries

LiNi0.5Mn1.5O4 is a promising cathode material for lithium-ion batteries with a high-voltage spinel structure. A microwave-assisted chemical co-precipitation method was used to synthesize Y2O3 coated quasi-spheres of LiNi0.5Mn1.5O4. The coating of Y2O3 and subsequent wrapping of quasi-spheres in graphene nanosheets does not alter the volume or promote the formation of unwanted phases. TGA analysis shows high thermal stability in the material. The material has an initial capacity of 133 mAh g−1 at C/10 with a retention of 98% after 100 cycles. In addition, cathode samples show a good capacity of 132 g−1 after 20 cycles at higher temperatures (55 °C). Oxide coatings protect the particles from ionic leaching but limit the electrical conductivity of the materials. However, graphene enhances the conductivity of the synthesized material and wraps active particles in a conductive channel. Due to the synergistic design of the material and the robust manufacturing technique, parasitic reactions are suppressed without affecting the electrical conductivity. To increase their cyclic performance, the suggested material synthesis approach may successfully be applied to various electrode materials

Graphene wrapped Y2O3 coated LiNi0.5Mn1.5O4 quasi-spheres as novel cathode materials for lithium-ion batteries

LiNi0.5Mn1.5O4 with a high-voltage spinel structure is a potential cathode material for high-energy lithium-ion batteries (LIBs). Y2O3 coated quasi-spheres of LiNi0.5Mn1.5O4 covered in graphene (LNMO-YO-G) have been synthesized by a microwave-assisted chemical co-precipitation technique. The coating of quasi-spheres with Y2O3 and subsequent wrapping in graphene nanosheets does not modify the bulk structure and inhibits the production of undesirable phases. Thermal analysis indicates that the developed materials demonstrate good thermal stability. The material exhibits an initial capacity of 133 mAh g−1 at the C/10 rate with a capacity retention of 98% after 100 cycles. Remarkably, a discharge capacity of 115 mAh g−1 is achieved in LNMO-YO-G at a 10C rate, reflecting its extraordinary improvement in the rate capability. Furthermore, after 20 cycles at higher temperature (55 °C), the cathode samples exhibit an excellent capacity of 132 mAh g−1. Y2O3 coating reduces the leaching of ions from the electrode, but such coatings reduce the electrical conductivity. Conversely, graphene increases the electrical conductivity, wraps the active particles along an electrically conductive path, and prevents agglomeration. Parasitic reactions are inhibited without compromising electrical conductivity due to the synergistic material design and fast microwave synthesis method. The proposed material synthesis strategy can be effectively extended to other classes of electrode materials to improve their cyclic performance.This publication was made possible by NPRP Grant # NPRP11S-1225-170128 from Qatar National Research Fund (a member of the Qatar Foundation). This publication was also made possible by the Qatar University Internal Grant ( QUCG-CENG-20/21-2 ). Open Access funding provided by the Qatar National Library. Statements made herein are solely the responsibility of the authors. Microstructural analyses (FE-SEM/EDX and HR-TEM) were accomplished at the Central Laboratory Unit (CLU), Qatar University, Doha, Qatar. XPS analysis was accomplished at the Gas Processing Center (GPC), Qatar University, Doha, Qatar.Scopu

Electrochemical Performance of Na3V2(PO4)2F3 Electrode Material in a Symmetric Cell

A NASICON-based Na3V2(PO4)2F3 (NVPF) cathode material is reported herein as a potential symmetric cell electrode material. The symmetric cell was active from 0 to 3.5 V and showed a capacity of 85 mAh/g at 0.1 C. With cycling, the NVPF symmetric cell showed a very long and stable cycle life, having a capacity retention of 61% after 1000 cycles at 1 C. The diffusion coefficient calculated from cyclic voltammetry (CV) and the galvanostatic intermittent titration technique (GITT) was found to be ~10−9–10−11, suggesting a smooth diffusion of Na+ in the NVPF symmetric cell. The electrochemical impedance spectroscopy (EIS) carried out during cycling showed increases in bulk resistance, solid electrolyte interphase (SEI) resistance, and charge transfer resistance with the number of cycles, explaining the origin of capacity fade in the NVPF symmetric cell. Finally, the postmortem analysis of the symmetric cell after 1000 cycles at a 1 C rate indicated that the intercalation/de-intercalation of sodium into/from the host structure occurred without any major structural destabilization in both the cathode and anode. However, there was slight distortion in the cathode structure observed, which resulted in capacity loss of the symmetric cell. The promising electrochemical performance of NVPF in the symmetric cell makes it attractive for developing long-life and cost-effective batteries.Funding: This publication was financially supported by Qatar University through the internal grant-QUCG-CENG-20/21-2. This work was also supported by the Qatar National Research Fund (a member of the Qatar Foundation) through the NPRP Grant#NPRP11S-1225-170128.Scopu

Sodium and lithium incorporated cathode materials for energy storage applications - A focused review

The idea of lithium (Li)/sodium (Na) incorporated cathodes for both Li/Na-ion batteries has gained significant consideration throughout the past decade. The encouraging performance of various reported Li/Na incorporated cathode systems has the potential to review their exciting developments made so far to clearly understand the effect of numerous variables in improving the electrochemical performance. The current manuscript provides a focused review on the synthesis and electrochemical performance of these Li/Na incorporated cathode materials for Na/Li-ion batteries. Furthermore, the ruling mechanisms affecting the electrochemical performance of Li/Na incorporated cathode materials have been summarized. The majority of the synthesized Li/Na incorporated cathodes demonstrate good electrochemical cyclic stability, capacity retention, rate capability, charge/discharge capacity, etc. Li incorporated Na-based cathodes, show improved performance that can be attributed to the prevention of phase transformation at high voltages and loss of transition metal from the cathode. In the case of Na addition to Li-based cathodes, the Na pillaring effect significantly improves the Li interface layer stability, increases Li-ion diffusion, and retardation of Li and/or transition metal disordering. Various factors affecting the performance of Li/Na incorporated cathode families have been discussed that can be taken into account for development of future novel cathode materials demonstrating decent performance.The authors would like to acknowledge the financial support of Qatar University (QU) internal grant-QUCG-CENG-20/21-2. This publication was also made possible by NPRP Grant # NPRP11S-1225-170128 from Qatar National Research Fund (QNRF) (a member of the Qatar Foundation). Open Access funding provided by the Qatar National Library. Statements made here are the responsibility of the authors.Scopu

Improved electrochemical performance of SiO2-coated Li-rich layered oxides-Li1.2Ni0.13Mn0.54Co0.13O2

Lithium-rich layered oxides (LLOs) such as Li1.2Ni0.13Mn0.54Co0.13O2 are suitable cathode materials for future lithium-ion batteries (LIBs). Despite some salient advantages, like low cost, ease of fabrication, high capacity, and higher operating voltage, these materials suffer from low cyclic stability and poor capacity retention. Several different techniques have been proposed to address the limitations associated with LLOs. Herein, we report the surface modification of Li1.2Ni0.13Mn0.54Co0.13O2 by utilizing cheap and readily available silica (SiO2) to improve its electrochemical performance. Towards this direction, Li1.2Ni0.13Mn0.54Co0.13O2 was synthesized utilizing a sol-gel process and coated with SiO2 (SiO2 = 1.0 wt%, 1.5 wt%, and 2.0 wt%) employing dry ball milling technique. XRD, SEM, TEM, elemental mapping and XPS characterization techniques confirm the formation of phase pure materials and presence of SiO2 coating layer on the surface of Li1.2Ni0.13Mn0.54Co0.13O2 particles. The electrochemical measurements indicate that the SiO2-coated Li1.2Ni0.13Mn0.54Co0.13O2 materials show improved electrochemical performance in terms of capacity retention and cyclability when compared to the uncoated material. This improvement in electrochemical performance can be related to the prevention of electrolyte decomposition when in direct contact with the surface of charged Li1.2Ni0.13Mn0.54Co0.13O2 cathode material. The SiO2 coating thus prevents the unwanted side reactions between cathode material and the electrolyte. 1.0 wt% SiO2-coated Li1.2Ni0.13Mn0.54Co0.13O2shows the best electrochemical performance in terms of rate capability and capacity retention.This publication was made possible by NPRP Grant # NPRP11S-1225-170128 from Qatar National Research Fund (a member of the Qatar Foundation). Statements made herein are solely the responsibility of the authors. FE-SEM analysis was accomplished at the Central Laboratory Unit (CLU), Qatar University, Doha, Qatar, TEM analysis was conducted at the Core Labs., QEERI, HBKU, Qatar and XPS analysis was accomplished at the Gas Processing Center (GPC), Qatar University, Doha, Qatar.Scopu

Fast and Scalable Synthesis of LiNi0.5Mn1.5O4 Cathode by Sol-Gel-Assisted Microwave Sintering

High-voltage spinel LiNi0.5Mn1.5O4 (LNMO) is a promising cathode material for high-energy-density and high-power-density lithium-ion batteries (LIBs). The high cost of the currently available LIBs needs to be addressed urgently for wide application in the transport sector (electric vehicles, buses) and large-scale energy storage systems (ESS). Of significance, herein, novel fast and scalable microwave-assisted synthesis of LNMO is reported, which leads to a production cost cut. X-ray diffraction (XRD) analysis confirms the formation of the desired phase with high crystallinity. Field emission scanning (FE-SEM) and transmission electron microscopy (TEM) analyses indicate that the synthesized phase is of nanometric size (50–150 nm) due to an extremely short sintering time (20 min). The material synthesized at 750 °C shows a higher initial discharge capacity (130 mA h g−1) than that synthesized at 650 °C (115 mA h g−1). The materials heat treated at higher temperatures show better electrochemical performance in terms of initial capacity, rate capability, and improved cycling. The improved electrochemical performance of LNMO at 750 °C is attributed to the formation of a stable crystal structure, low charge transfer resistance at the electrode/electrolyte interface, high electrical conductivity due to the presence of a disorder structure, and improved ionic diffusivity.This publication was made possible by NPRP Grant # NPRP11S-1225-170128 from the Qatar National Research Fund (a member of the Qatar Foundation). Statements made herein are solely the responsibility of the authors. The authors would like to acknowledge the technical support from Oak Ridge National Laboratory (ORNL), Oak Ridge, TN, USA, and the Central Laboratory Unit (CLU), Qatar University, Doha, Qatar. The authors also acknowledge Core Labs. at Qatar Environment and Energy Research Institute (QEERI), HBKU, Qatar, for FE?SEM and TEM analysis. Open Access funding provided by the Qatar National Library.Scopu

Electrochemical Performance of Na3V2(PO4)2F3 Electrode Material in a Symmetric Cell

A NASICON-based Na3V2(PO4)2F3 (NVPF) cathode material is reported herein as a potential symmetric cell electrode material. The symmetric cell was active from 0 to 3.5 V and showed a capacity of 85 mAh/g at 0.1 C. With cycling, the NVPF symmetric cell showed a very long and stable cycle life, having a capacity retention of 61% after 1000 cycles at 1 C. The diffusion coefficient calculated from cyclic voltammetry (CV) and the galvanostatic intermittent titration technique (GITT) was found to be ~10−9–10−11, suggesting a smooth diffusion of Na+ in the NVPF symmetric cell. The electrochemical impedance spectroscopy (EIS) carried out during cycling showed increases in bulk resistance, solid electrolyte interphase (SEI) resistance, and charge transfer resistance with the number of cycles, explaining the origin of capacity fade in the NVPF symmetric cell. Finally, the postmortem analysis of the symmetric cell after 1000 cycles at a 1 C rate indicated that the intercalation/de-intercalation of sodium into/from the host structure occurred without any major structural destabilization in both the cathode and anode. However, there was slight distortion in the cathode structure observed, which resulted in capacity loss of the symmetric cell. The promising electrochemical performance of NVPF in the symmetric cell makes it attractive for developing long-life and cost-effective batteries

Synthesis and Performance Evaluation of Na (2‐x)

This study reports hybrid cathodes formation by cation substitution in which Li+ substitution has been considered for Na+ in the structure of Na(2-x)LixFeP2O7 (x=0, 0.6) to form Na1.4Li0.6FeP2O7 cathodes. Na(2-x)LixFeP2O7 (x=0, 0.6) cathodes were synthesized using the solid-state synthesis technique and characterized by various methods. The structural analysis (XRD, FE-SEM) indicates that the submicron-sized, phase pure, and crystalline materials having irregular morphology have been developed. Moreover, Li+ substitution does not alter the triclinic parent structure of Na2FeP2O7. Thermogravimetric analysis (TGA) shows that Li+ substitution into Na2FeP2O7 improves its thermal stability up to 550 °C with only ∼5 % weight loss. The electrochemical performance of Na2FeP2O7 and Na1.4Li0.6FeP2O7 in both lithium (Li) and sodium (Na) half-cells is investigated using different electrochemical techniques. It is noticed that Na1.4Li0.6FeP2O7 is electrochemically active both in lithium (Li) and sodium (Na) cells with promising cyclability. However, compared with Na2FeP2O7, Na1.4Li0.6FeP2O7 suffers from inferior electrochemical performance, which might be associated with the lattice distortion of Na2FeP2O7 due to Li+ substitution having a lower ionic radius than the Na+. Considering Na2FeP2O7 as a baseline material, a new hybrid Na1.4Li0.6FeP2O7 cathode has been developed, which can be used to synthesize other new cathode materials with improved performance.This publication was made possible by NPRP Grant#NPRP11S-1225-170128 from Qatar National Research Fund (a member of the Qatar Foundation). Statements made herein are solely the responsibility of the authors. Ramazan Kahraman and all the contributors would like to acknowledge the financial support of QU internal grant-QUCG-CENG-20/21-2. FE-SEM analysis was accomplished at the Central Laboratory Unit (CLU), Qatar University, Doha, Qatar.Scopu