Performance Of Hard Carbon Research Articles

Regulating the active hydroxyl group of starch: Revealing the evolution of hard carbon structure and sodium storage behavior

The active hydroxyl group of starch has a crucial effect in regulating the microstructure of hard carbon anodes for sodium-ion batteries. By optimizing the chemical structure of starch and controlling the pyrolysis process, high-performance hard carbon materials can be obtained. These active hydroxyl groups are primarily located on the terminal and ring structures of glucose units, exerting significant influence on the formation and performance of hard carbon. Our results demonstrate that low-temperature oxidation treatment effectively modifies the terminal hydroxyl groups in precursor materials, facilitating chain cross-linking and leading to a more robust hard carbon structure. This cross-linking effect helps suppress excessive foaming during pyrolysis, thereby enhancing the stability of the hard carbon structure. Furthermore, by modifying the hydroxyl group on the ring structure of precursors, we can control the pyrolysis process, promote pore closure, and further improve the low plateau capacity of hard carbon anode materials from 153.95 to 219.58 mAh g −1. This study offers novel insights into harnessing and understanding starch's active hydroxyl groups in preparing hard carbon materials—a significant contribution towards optimizing their performance as anode materials.

From Waste Biomass to Hard Carbon Anodes: Predicting the Relationship between Biomass Processing Parameters and Performance of Hard Carbons in Sodium-Ion Batteries

Sodium-ion batteries (SIBs) serve as the most promising next-generation commercial batteries besides lithium-ion batteries (LIBs). Hard carbon (HC) from renewable biomass resources is the most commonly used anode material in SIBs. In this contribution, we present a review of the latest progress in the conversion of waste biomass to HC materials, and highlight their application in SIBs. Specifically, the following topics are discussed in the review: (1) the mechanism of sodium-ion storage in HC, (2) the HC precursor’s sources, (3) the processing methods and conditions of the HCs production, (4) the impact of the biomass types and carbonization temperature on the carbon structure, and (5) the effect of various carbon structures on electrochemical performance. Data from various publications have been analyzed to uncover the relationship between the processing conditions of biomass and the resulting structure of the final HC product, as well as its electrochemical performance. Our results indicate the existence of an ideal temperature range (around 1200 to 1400 °C) that enhances the formation of graphitic domains in the final HC anode and reduces the formation of open pores from the biomass precursor. This results in HC anodes with high storage capacity (>300 mAh/g) and high initial coulombic efficiency (ICE) (>80%).

Correlation of Structure and Performance of Hard Carbons as Anodes for Sodium Ion Batteries

Hard carbons are the material of choice as negative electrode in sodium ion batteries. Despite being extensively studied, there is still debate regarding the mechanisms responsible for storage in l...

(Invited) Anionic and Cationic Substitution to Control the Properties of Vanadium Fluorophosphates for Li and Na-Ion Batteries

Optimized carbon-coated Na3V2(PO4)2F3 showed exceptional rate and electrochemical cycling capabilities, more than 4000 times at 1 C rate, as demonstrated by performance of hard carbon//Na3V2(PO4)2F3 18650 prototypes of 75 Wh kg−1.1 These attractive results, among others, attract a renewed interest in the field of Na-ion and Li-ion batteries for vanadium fluoride phosphates. The control of their electrochemical performance requires the careful tuning of the oxygen and thus vanadyle-type defects’ concentration in these materials. Indeed, the competition between the ionic V3+−F bond and the covalent V4+=O bond has a major effect on the structure of the pristine materials, and thus on the phase diagram and redox mechanisms involved upon their cycling in batteries. It will be illustrated for series of LiVPO4F1-yOy 2,3 and Na3V2-xMx(PO4)2F3-yOy 1, 4-6 phases combining mainly Synchrotron X-ray diffraction and spectroscopy studies. Original, probably firstly unexpected, crystal chemistry and redox activity will be discussed. Acknowledgements: The authors thank the European Union’s Horizon 2020 Research and Innovation Program under grant agreement No 646433-NAIADES, the French National Research Agency (STORE-EX Labex Project ANR-10-LABX-76-01, HIPOLITE Progelec Project ANR-12-PRGE-0005-02 and SODIUM Descartes Project ANR-13-RESC-0001-02), and the French RS2E and European ALISTORE-ERI networks for funding. References T. Broux, F. Fauth, N. Hall, Y. Chatillon, M. Bianchini, T. Bamine, J.-B. Leriche, E. Suard, D. Carlier, Y. Reynier, L. Simonin, C. Masquelier, and L. Croguennec - Small Methods 2018, 1800215-1800226E. Boivin, R. David, J.-N. Chotard, T. Bamine, A. Iadecola, L. Bourgeois, E. Suard, F. Fauth, D. Carlier, C. Masquelier, and L. Croguennec - Chemistry of Materials 2018, 30 (16), 5682-5693E. Boivin et al., submittedT. Broux, T. Bamine, F. Fauth, L. Simonelli, W. Olszewski, C. Marini, M. Ménétrier, D. Carlier, C. Masquelier, and L. Croguennec - Chemistry of Materials 2016, 28(21), 7683-7692T. Broux, T. Bamine, L. Simonelli, L. Stievano, F. Fauth, M. Ménétrier, D. Carlier, C. Masquelier, and L. Croguennec - Journal of Physical Chemistry C 2017, 121(8), 4103-4111H. B. L. Nguyen et al., submitted

Impact of the Acid Treatment on Lignocellulosic Biomass Hard Carbon for Sodium-Ion Battery Anodes.

The investigation of phosphoric acid treatment on the performance of hard carbon from a typical lignocellulosic biomass waste (peanut shell) is herein reported. A strong correlation is discovered between the treatment time and the structural properties and electrochemical performance in sodium-ion batteries. Indeed, a prolonged acid treatment enables the use of lower temperatures, that is, lower energy consumption, for the carbonization step as well as improved high-rate performance (122 mAh g-1 at 10 C).

The Performance of Hard Carbon in a Sodium Ion Battery and Influence of the Sodium Metal in Observed Properties

This investigation includes the electrochemical testing protocols for a hard carbon sodium ion anode material, and discusses the use of a sodium metal counter electrode with respect to the material and cell stability during the electrochemical testing. A 3-electrode cell in compression fitting (‘Swagelok’) configuration was used with hard carbon as the working electrode and sodium metal as the counter and reference electrode. The cells were charged and discharged at high rates to investigate the polarisation effects of the sodium metal. The results indicate a significant contribution from the sodium metal electrode to the observed cell characteristics, depending on state-of-charge and rate. These contributions are significant and may lead to misinterpretation of the material and electrode performance when tested in 2-electrode arrangements with a sodium metal counter electrode.

The Performance of Hard Carbon in a Sodium Ion Battery and Influence of the Sodium Metal in Observed Properties

Since the 1990’s and the commercialisation of the first lithium ion cell by Sony there has been a large focus on new materials for lithium ion batteries, and the work in the 1970’s and 80’s in room temperature sodium ion materials was lapsed. However, due to the high current cost of lithium ion batteries, alternative sodium ion technologies may offer a cost and safety advantage over the typical lithium ion cells.1,2 Sodium is a much more abundant metal when compared to lithium which should result in lower cost materials. Although the mass of sodium is higher than lithium, the observed specific capacity of a sodium ion battery compared to lithium is not hugely compromised; this is because the proportion of the sodium and lithium content is small enough that the difference is minimal. Sharp Laboratories of Europe Ltd have been developing a new sodium ion cell chemistry based upon a layered oxide cathode3 and a hard carbon anode. The hard carbon anode is extremely sensitive to processing conditions and testing methods. In two electrode cells we have observed high hysteresis in the charge and discharge profiles and have experienced difficulties in reaching the low voltages required for complete sodiation of the hard carbon. In addition we have also observed high Coulombic inefficiencies during the testing in a sodium metal anode cell, and the instability of the sodium in certain solvents. By using 3-electrode cells we have been able to investigate the specific properties of the hard carbon in considerably more detail, and note that much of the hysteresis observed in two electrode measurements originates from the sodium metal anode. 3-electrode galvanic and potenstiostatic intermittent titration techniques have been used to investigate the properties of the hard carbon and sodium metal electrodes in more detail, and much of the hysteresis with regards to the performance of the carbon material in a 2-electrode cell can be shown to be related to the sodium metal deposition and stripping. Figure 1 shows the galvanic intermittent titration technique (G.I.T.T.) for hard carbon vs sodium metal in a 3-electrode arrangement visualising the difference between cell potential (red) and potential of the working electrode vs sodium reference (hard carbon, blue). V. Palomares, P. Serras, I. Villaluenga, K.B. Hueso, J. Carretero-Gonzalez and T. Rojo, Energy Environ. Sci. 2012, 5, 588,J. Barker, M.Y. Saidi and J. Swoyer, Electrochem. Solid-State Chem. 2003, 6, A1,E. Kendrick, R. Gruar et al, Tin containing compounds, WO2015177568A1, 2015-11-26 Figure 1

Effects of pre-carbonization on the structure and performance of hard carbon in lithium cells

The amount of lithium reversibly incorporated in the hard carbon (the reversible capacity), the faradic losses during the first charge–discharge cycle (the irreversible capacity), and the profile of the voltage curves all depend on the structure, the texture, and the heteroatom content which are affected significantly by fabrication method of hard carbon material. We demonstrate herein a simple mass production routine to prepare hard carbon with advanced electrochemistry performance by pyrolysing resin precursors. Pre-carbonization before high temperature pyrolysis (1000 °C) by controlled process conditions, such as temperature and ramp rates, has an important effect on the structure and performance of hard carbon as anode material. Hard carbon material was characterized by X-ray diffraction (XRD), Raman spectroscopy, Brunauer–Emmett–Teller (BET) surface area, and scanning electron microscope (SEM). The hard carbon treated by pre-carbonization process resulted in increasing Raman I G/I D ratio, BET specific surface area, and micropore volume, which can serve as high reversible capacity anode material for Li-ion batteries. The 500-1 sample performed a first discharge capacity and reversible capacity of 540 and 390 mAh g−1, respectively, which was much higher than that of non-pretreatment (NP) (without pre-carbonization) sample (290 and 210 mAh g−1, respectively).

Electrochemical Performance of Hard Carbon as Negative Electrode in Lithium Ion Capacitor

The electrochemical properties of hard carbon (HC) have been investigated for use as negative electrode for lithium ion capacitors. The HC electrode was characterized by scanning electron microscope (SEM) method. The HC negative electrode was galvanostatically prelithiated at 0.1C for three cycles between 0.05-2 V. The LIC with activated carbon and HC electrodes was characterized by cyclic voltammetric analysis at the scan rate of 0.1 mV s-1 with different voltage ranges. The rate capability of the LIC was tested up to 100C and the retention is 54 %. The cycle performance is retained up to 86% at 50C and 80% at 100C even after 10,000 cycles. The results indicate that hard carbon is suitable as negative electrode materials for high power energy applications.

Effects of post-treatments on the performance of hard carbons in lithium cells

The main disadvantage of hard carbons when they are used for the negative electrode of lithium-ion batteries is a large irreversible capacity generally attributed to their important specific surface area. Our goals were to estimate the amount of residual lithium, i.e. not involved in the solid electrolyte interface (SEI) after a full deinsertion, and to reduce the irreversible capacity due to the SEI formation. Galvanostatic charge/discharge of carbon lithium cells was performed with carbon materials to which an additional pyrolysis has been applied in various conditions. Electrode materials made from as-received carbon have been analysed ex situ by electron paramagnetic resonance (EPR) at different steps of the insertion/deinsertion process. We found that 20% of the irreversible capacity is due to residual lithium trapped in the carbon matrix. Post-treatments up to 900°C resulted in decreasing the irreversible capacity from 260 to 65 mAh/g thanks to modifications of the surface functionality and possible improvement of the carbon network structure.

Influence of Pyrolysis Conditions on the Performance of Hard Carbons as Anodes for Lithium Batteries

Electrochemical lithium insertion/deinsertion has been correlated with the pyrolysis parameters of a polymeric precursor, the microtexture and chemical composition of the obtained hard carbon. A specific reversible capacity of 450 mAh/g (i.e. composition LiC4.5) has been estimated for the optimal carbons from the galvanostatic charge/discharge characteristics. Voltammetry experiments and galvanostatic relaxation curves demonstrated that lithium insertion/extraction process is not kinetically controlled by diffusion, for the current load (20 mA/g) and scan rate used for our experiments. The sites for lithium insertion and/or intercalation were estimated from ex-situ 7Li NMR experiments for differently lithiated samples. A Knight shift of 60 ppm characteristic of lithium clusters has been found for carbons obtained under strains.