Negative Electrode For Li-ion Batteries Research Articles

Entropy Profiling for the Diagnosis of NCA/Gr-SiOx Li-Ion Battery Health

Graphite-silicon (Gr-Si) blends have become common in commercial Li-ion battery negative electrodes, offering increased capacity over pure graphite. Lithiation/delithiation of the silicon particles results in volume changes, which may be associated with increased hysteresis of the open circuit potential (OCP). The OCP is a function of both concentration and temperature. Entropy change measurement—which probes the response of the OCP to temperature—offers a unique battery diagnostics tool. While entropy change measurements have previously been applied to study degradation, the implications of Si additives on the entropy profiles of commercial cells have not been explored. Here, we use entropy profiling to track ageing markers in the same way as differential voltage analysis. In addition to lithiation/delithiation hysteresis in the OCP of Gr-Si blends, cells with Gr-Si anodes also exhibit differences in entropy profile depending on cycling direction, reflecting degradation-related morphological changes. For cycled cells, entropy change decreased during discharge, likely corresponding to graphite particles breaking and cracking. However, entropy change during charge increased with cycling, likely due to the volume change of silicon. Over a broad voltage range, these combined effects led to the observed rise in entropy hysteresis with age. Conversely, for calendar aged cells entropy hysteresis remained stable.

New Technique for Probing the Protecting Character of the Solid Electrolyte Interphase as a Critical but Elusive Property for Pursuing Long Cycle Life Lithium-Ion Batteries.

The formation of a protecting nanolayer, so-called solid electrolyte interphase (SEI), on the negative electrode of Li-ion batteries (LIBs) from product precipitation of the cathodic decomposition of the electrolyte is a blessing since the electrically insulating nature of this nanolayer protects the electrode surface, preventing continuous electrolyte decomposition and enabling the large nominal cell voltage of LIBs, e.g., 3.3–3.8 V. Thus, the protection performance of the nanolayer SEI is essential for LIBs to achieve a long cycle life. Unfortunately, the evaluation of this critical property of the SEI is not trivial. Herein, a new, cheap, and easily implementable methodology, the redox-mediated enhanced coulometry, is presented to estimate the protecting quality of the SEI. The key element of the methodology is the addition of a redox mediator in the electrolyte during the degassing step (after the SEI formation cycle). The redox mediator leads to an internal self-discharge process that is inversely proportional to the protecting character of the SEI. Also, the self-discharge process results in an easily measurable decrease in Coulombic efficiency. The influence of vinylene carbonate as an electrolyte additive in the resulting SEI is used as a case study to showcase the potential of the proposed methodology.

The Role of Silicon in Silicon-Graphite Composite Electrodes Regarding Specific Capacity, Cycle Stability, and Expansion

Silicon-based electrodes are promising candidates to enable the next generation of Lithium-ion batteries with high energy densities on the cell level beyond 350 Wh kg−1 [1, 2]. Nevertheless, the commercialization of silicon-based electrodes is still hindered due to the large volume expansion during cycling of up to 300% [3]. This volume expansion upon repeated (de-)lithiation of silicon particles worsens the electrode integrity by causing isolation of active material components [4-6]. Continuous electrolyte decomposition at the silicon/electrolyte interface, caused by the repeated volume expansion and contraction, results in a gradual loss of active lithium [7].While X-ray diffraction (XRD) as well as theoretical methods provide atomic scale information, dilatometry is an appropriate tool for the in-situ investigation of the volumetric work of battery composite electrodes on the macroscopic level. Therefore, the technique itself as well as the obtained data have a high potential for their industrial implementation [8].In this work, the expansion of a single-side-coated silicon-based anode is investigated with a commercial, high-precision dilatometer, which detects the thickness change perpendicular to the surface of the coating on the electrode level during cycling against a lithium metal counter electrode. The measured samples consist of 95 wt.% active material (0 - 20 wt.% of silicon in combination with 95 - 75 wt.% of graphite, respectively) and 5 wt.% of non-active components.The investigated samples in this work differ in their silicon and graphite content. Moreover, the samples were also investigated electrochemically via conventional coin cells. The comparable electrochemical behavior of the electrodes in both experiment methods is proof of the plausibility of the dilatometry results. Increasing the silicon content led to higher specific capacities of the SiG electrodes. The relative capacity loss and the thickness change increased linearly with the silicon content as well. Based on the characteristic thickness change for the SiGs, we concluded that silicon predominantly lithiated before graphite, and delithiated after graphite.The used non-commercial electrodes were designed and produced within the scope of the project “HighSafeII”, funded by the German Federal Ministry of Education and Research (BMBF) under grant number 03XP0306B. Literature [1] D. Andre, S.-J. Kim, P. Lamp, S. F. Lux, F. Maglia, O. Paschos, and B. Stiaszny, “Future generations of cathode materials: an automotive industry perspective”, J. Mater. Chem. A, 3 (13), 6709 (2015).[2] O. Gröger, H. A. Gasteiger, and J.-P. Suchsland, “Review—Electromobility: Batteries or Fuel Cells?”, J. Electrochem. Soc., 162 (14), A2605 (2015).[3] D. Ma, Z. Cao, and A. Hu, “Si-Based Anode Materials for Li-Ion Batteries: A Mini Review” Nano-Micro Lett, 6(4), 347 (2014).[4] M. N. Obrovac, L. Christensen, D. B. Le, and J. R. Dahn, “Alloy Design for Lithium-Ion Battery Anodes”, J. Electrochem. Soc., 154 (9), A849 (2007).[5] D. S. M. Iaboni and M. N. Obrovac, “Li15Si4 Formation in Silicon Thin Film Negative Electrodes”, J. Electrochem. Soc., 163 (2), 255 (2016).[6] M. N. Obrovac and V. L. Chevrier, “Alloy Negative Electrodes for Li-Ion Batteries”, Chem. Rev., 114, 11444 (2014).[7] R. Petibon, V. Chevrier, C. P. Aiken, D. S. Hall, S. Hyatt, R. Shunmugasundaram, and J. R. Dahn, “Studies of the Capacity Fade Mechanisms of LiCoO2/Si-Alloy: Graphite Cells”, J. Electrochem. Soc., 163 (7), 1146 (2016).[8] Daniel Sauerteig, Svetlozar Ivanov, Holger Reinshagen, Andreas Bund, „Reversible and irreversible dilation of lithium-ion battery electrodes investigated by in-situ dilatometry“, J. Power Sources, 342, 939-946 (2017).

(Digital Presentation) Do Silicon-Based Composite Electrodes for Li-Ion Batteries Need High Molecular Weight Polymeric Binder to Well Perform?

Among all potential active materials for the anodes of Li-ion batteries, silicon is considered as one of the most promising candidate because of its high specific and volumetric capacities, about 3600 mAh.g-1 and 2200 mAh.cm-3 respectively,1 as well as its low operation voltage (0.4 versus Li/Li+), abundant resources (the second largest in the earth’s crust), and environmental benignity (non-toxic). However, during the lithiation (formation of LixSi, x ~ 3.75) the silicon undergoes an expansion of about 280% of its initial volume2 which induces numerous damages to the electrode. The silicon micrometer particles tend to be pulverized when the size of the particles are upper than 150 nm.3 However, nanosizing the materials leads to more electrolyte degradation due to a higher specific surface developed and requires more binder and eventually more conducting additive in the electrode formulation. The pulverized Si particles are scattered and become electrically isolated and the adhesion of the Si electrode to the current collector are also damaged by these volume variations4. This effects drastically reduces the electrochemical performance and lifetime of the Si electrode. As a result, these challenges have seriously restricted the commercialization of Si anodes in high energy LIBs.5 To deal with these problems many researches are developing advanced binders. This later has a crucial role since it reinforces the mechanical strength of the electrode and thus helps to preserve the electrode architecture upon cycling against the large Si volume change.6 It is generally accepted that binders of very high molar masses (polymers) are necessary to allow cycling of silicon-based electrodes, as they favor the formation of more robust molecular bridges and therefore are a priori more capable of maintaining particle-to-particle contacts and therefore cohesion in the electrode. Quite surprisingly, we have discovered that it is possible to obtain good cyclability of silicon-based electrodes by using an organic binder of low molar mass (molecule). This calls into question the understanding of the mechanism by which the binder operates in silicon-based electrodes.This low molecular weight binder is a natural polyphenol, namely tannic acid. Here we will highlight that Silicon-based composite electrodes of high areal capacity (~7 mAh.cm-2) when prepared with tannic acid as small binder show a stable cycling like the one obtained with one state-of-the-art binder such as carboxymethyl cellulose. We will report in-depth characterization of the interactions between tannic acid and the silicon particles surface as well as of the rheological behavior of the electrode slurries and the electrodes properties and electrochemical performances.References(1) Obrovac, M. N.; Chevrier, V. L. Alloy Negative Electrodes for Li-Ion Batteries. Chem. Rev. 2014, 114 (23), 11444–11502.(2) Jung, S. C.; Choi, J. W.; Han, Y.-K. Anisotropic Volume Expansion of Crystalline Silicon during Electrochemical Lithium Insertion: An Atomic Level Rationale. Nano Lett. 2012, 12 (10), 5342–5347.(3) Liu, X. H.; Zhong, L.; Huang, S.; Mao, S. X.; Zhu, T.; Huang, J. Y. Size-Dependent Fracture of Silicon Nanoparticles During Lithiation. ACS Nano 2012, 6 (2), 1522–1531.(4) Hernandez, C. R.; Etiemble, A.; Douillard, T.; Mazouzi, D.; Karkar, Z.; Maire, E.; Guyomard, D.; Lestriez, B.; Roué, L. A Facile and Very Effective Method to Enhance the Mechanical Strength and the Cyclability of Si-Based Electrodes for Li-Ion Batteries. Adv. Energy Mater. 2018, 8 (6), 1701787.(5) Ko, M.; Chae, S.; Cho, J. Challenges in Accommodating Volume Change of Si Anodes for Li-Ion Batteries. ChemElectroChem 2015, 2 (11), 1645–1651.(6) Eshetu, G. G.; Figgemeier, E. Confronting the Challenges of Next-Generation Silicon Anode-Based Lithium-Ion Batteries: Role of Designer Electrolyte Additives and Polymeric Binders. ChemSusChem 2019, 12 (12), 2515–2539.

Phase Diagram of Li-Graphite Intercalation Compound Formed by the Charge/Discharge Reaction in Li-Ion Battery

The graphite negative electrode for Li-ion batteries was subjected to precision charge/discharge measurements at low current loads. The derivatives of the potential vs capacity curve and the potential vs C/Li composition curve were used to analyze elementary charge/discharge reactions. The number of peaks in the potential-capacity derivative curve increased with decreasing current load, and the elementary reactions, based on the formation of an unconfirmed superlattice structure, could be clearly separated and analyzed. By synchronizing these results with operando synchrotron X-ray diffraction data, a phase diagram of the Li-graphite intercalation compound formed by the charge/discharge reaction in Li-ion battery was established.

Investigating the Perovskite Ag1-3xLaxNbO3 as a High-Rate Negative Electrode for Li-Ion Batteries.

The broader development of the electric car for tomorrow's mobility requires the emergence of new fast-charging negative electrode materials to replace graphite in Li-ion batteries. In this area, the design of new compounds using innovative approaches could be the key to discovering new negative electrode materials that allow for faster charging and discharging processes. Here, we present a partially substituted AgNbO3 perovskite material by introducing lanthanum in the A-site. By creating two vacancies for every lanthanum introduced in the structure, the resulting general formula becomes Ag1-3xLax□2xNbO3 (with x ≤ 0.20 and where □ is a A-site vacancy), allowing the insertion of lithium ions. The highly substituted Ag0.40La0.20□0.40NbO3 oxide shows a specific capacity of 40 mAh.g-1 at a low sweep rate (0.1mVs-1). Interestingly, Ag0.70La0.10□0.20NbO3 retains 64% of its capacity at a very high sweep rate (50mVs-1) and about 95% after 800 cycles. Ex situ 7Li MAS NMR experiments confirmed the insertion of lithium ions in these materials. A kinetic analysis of Ag1-3xLax□2xNbO3 underlines the ability to store charge without solid-state ion-diffusion limitations. Furthermore, in situ XRD indicates no structural modification of the compound when accommodating lithium ions, which can be considered as zero-strain material. This finding explains the interesting capacity retention observed after 800 cycles. This paper thus demonstrates an alternative approach to traditional insertion materials and identifies a different way to explore not-so common electrode materials for fast energy storage application.

Ti1.1V0.7CrxNb1.0Ta0.6C3Tz high-entropy MXene freestanding films for charge storage applications

High-entropy (HE) MXenes are a new emerging class of materials with unique properties, diverse compositions, and potential uses in energy storage devices. Herein, high-entropy MXene, Ti1.1V0.7CrxNb1.0Ta0.6C3Tz(Tz = –F, –O, –OH), freestanding films are prepared and tested as electrodes for Zn-ion hybrid supercapacitors (ZHSC), delivering a capacity up to 77 mAh g−1 (245 mAh cm−3) at 0.5 A g−1 with a capacity retention of 87% after 10,000 cycles. This promising performance in ZHSC is achieved when using Zn(CF3SO3)2 or low-cost ZnCl2 solutions. Furthermore, HE MXene films can be used as a negative electrode for Li-ion batteries with a capacity up to 126 mAh g−1 (400 mAh cm−3) at 0.01 A g−1. This report sheds light on the use of a new class of MXene films for various charge storage applications.

How carbon coating or continuous carbon pitch matrix influence the silicon electrode/electrolyte interfaces and the performance in Li‐ion batteries

AbstractThe Si surface coating by carbon is an appealing strategy to improve both the electronic conductivity and to stabilize the solid electrolyte interphase (SEI). In the present study, the electrochemical performance comparison of three nanocrystalline silicon‐based electrodes confirms the advantage brought by the carbon presence either as coating or in a composite, to improve their performance in Li‐ion batteries (LIBs). To rationalize this behavior, a full study of the electrode/electrolyte interface was achieved through the analysis of the cumulated relative irreversible capacity and the impedance and X‐ray photoelectron spectroscopies measurements. The study highlighted that the carbon coating leads to more efficient and less resistive SEI than that formed on silicon or on the native oxide surface. The pitch carbon matrix offers the same advantages and avoids moreover the isolation of particles. The control of the Si/electrolyte interface has a crucial role in the performance of Si‐based electrodes as negative electrodes for LIB.

Composite Si–Ni nanoparticles produced by plasma spraying physical vapor deposition for negative electrode in Li-ion batteries

Si–Ni composite nanoparticles have been produced by a single and continuous plasma spray physical vapor deposition (PS-PVD) from Si and Ni powder feedstocks and their electrochemical performances as anode in lithium-ion batteries (LiB) are investigated. Si nanoparticles with 20–40 nm on which Ni is directly attached with Si/NiSi2 epitaxial interface are formed spontaneously through co-condensation of high temperature elemental gas mixtures during PS-PVD. When only a little amount of Ni is added to Si, the effect of the epitaxial Ni attachment on the Si nanoparticles becomes evident; the cycle capacity is appreciably improved to reach a 1.6 times higher capacity than that of the Si only cell after 50 cycles, due to reduced charge-transfer resistance and nanosized Si particle. In contrast, excessive Ni addition to Si feedstock leads to formation of various silicides as a result of the accelerated silicidation during PS-PVD, which results in a significant decrease in the cycle capacity due to reduction of the active Si phase amount despite reduced charge-transfer resistance.

Electrodeposition of silicon nanospheres on rGO coated copper substrate for lithium-ion batteries

In the present work, the electrodeposition of silicon nanospheres was carried out from water contaminated room temperature ionic liquid medium on the reduced graphene oxide (rGO) coated copper (Cu) substrates. The graphene oxide coated copper was reduced in hydrogen: argon mixture to obtained rGO coated copper substrate which was used for electrodeposition of silicon nanospheres. The silicon nanospheres were electrodeposited using 1 M SiCl4 in water contaminated 1-Butyl-3-Methylimidazolium-bis (Trifluoromethylsulfonyl) imide (BMImTf2N) ionic liquid at −1.5 V (vs. Pt). The X-ray diffraction (XRD) patterns at 44.8˚, 51.42˚, 75.12˚, and Raman peak at 521 cm−1 confirm the deposition of elemental silicon. The field emission scanning electron microscopy (FE-SEM) images show the electrodeposited silicon nanospheres of average particle size 125 nm. Further, the electrochemical measurements were carried out to explore the performance of the active material as a negative electrode in Li-ion batteries. The reversible specific capacity of electrodeposited Si nanospheres is obtained as 294 mAhg−1 at current density 250 µA cm−2.

Waste to life: Low-cost, self-standing, 2D carbon fiber green Li-ion battery anode made from end-of-life cotton textile

In this study, self-standing and flexible Li-ion battery negative electrodes made of interconnected two-dimensional carbonized cotton fibers are developed by using a controlled pyrolysis method, and their electrochemical performance in laboratory-scale lithium-based cells is investigated at ambient temperature. By applying this binder- and current collector-free cotton-based carbon fiber electrode, both the Li+-ion intercalation and capacity decay mechanisms are explored using conventional organic carbonate-based liquid electrolyte. The cotton-based carbon fiber electrode shows excellent cycling performance and delivers a high discharge capacity in the voltage range of 0.02 - 1.2 V. The post cycling analysis of carbon fiber using HR-TEM shows the major SEI layer components formed at the surface of the active fibers during the charge/discharge process. The same electrode is used to assemble a lab-scale Li-ion full cell with high mass loading LiFePO4-based composite electrode, which demonstrates excellent cycling stability, high Coulombic efficiency and remarkable rate capability at ambient temperature.

Li Diffusion in Thin-Film LiySi Electrodes: Galvanostatic Intermittent Titration Technique and Tracer Diffusion Experiments

LiySi is an interesting material for negative electrodes in Li-ion batteries. We carried out measurements with a galvanostatic intermittent titration technique (GITT) on ion-beam-sputtered amorphou...

Silicon-Reduced Graphene Oxide Composite as Negative Electrode of Li-Ion Batteries

Silicon-Reduced Graphene Oxide Composite as Negative Electrode of Li-Ion Batteries

Si Nanoparticles inside a Carbon Matrix As an Anode for Next Generation LIB

1. Introduction Lithium-ion batteries (LIB) are used in many applications such as cellular phones, mobile computers and electrical vehicles since they have high capacity and long cycle life. There is a continuing demand for advanced LIBs with higher energy density. However, graphite, conventional anode materials for commercial LIBs, are approaching their theoretical capacity limits. In this context, Si anodes have attracted much attention for the alternatives of graphite anodes because of their high capacity, low cost and environmental benignity. However, Si anodes suffer from drastic volume change and huge stress generation during the lithiation and delithiation process, which causes fracture of Si and deformation of the electrode. Such unfavorable phenomena arising from the severe volume change results in the poor cycle ability of Si anodes. These crucial problems hamper the direct utilization of Si anodes for next-generation LIBs.Amorphous SiO x (x<2) anodes have shown the cycle performance improvement since the amorphous structure and SiO2 phase serve as the buffer layer which suppresses the volume expansion during the lithiation delithiation process. However, the irreversible capacity of the first cycle is large due to the formation of inactive Li-Si-O phase from SiO2 phase. [1-2]Much research on composite anodes containing Si and graphite has been investigated, and improvement of the cycle performance of composite electrodes have been demonstrated. However, the amount of Si in the composite electrode is limited since there is a strong trade-off relationship between the capacity and the cycle performance in the composite electrode. [3-4]Recently, we have successfully synthesized Si nanoparticles inside a Carbon Matrix (SCM). Here, we show the electrochemical Li storage performance of SCM. 2. Experimental Synthesis of Si nanoparticles with Voids inside a Carbon Matrix (SCM) We synthesized SCM through chemical techniques. The cross-sectional SEM image of SCM is shown in Fig. 1. Si nanoparticles with voids inside the carbon matrix are observed. Electrode preparation SCM powder as active material, carbon powder as conductive additive and polyacrylate as binder at a mass ratio of 92:1:7 were mixed in water to form slurry. The slurry was coated onto Cu foil (10μm thickness) and dried at 90 ºC for 5 min, and then heated in vacuum at 100 ºC overnight. The electrode was punched into discs typically with a diameter of 13.8 mm. The weight of active material in the electrode is ranged from 3.0 to 4.0 mg. CR2032 cell preparation Coin type cell (CR2032) was assembled in the Ar-filled glove box. Li metal (Honjyou metal) was used as the counter electrode. Polypropylene was used as the separator. The liquid electrolyte used was 1.2 M LiPF6 in ethylene carbonate (EC)/diethyl carbonate (DEC) (1:1 vol %) with fluoroethylene carbonate (FEC) (2 vol %). 3. Results First charge –discharge curves of the SCM electrode with current rate of 0.1 C is shown in Fig. 2. During the first cycle, the electrode exhibited a reversible capacity of 680 mAhg-1 with an efficiency of 75.6 %. Cycle performance of the SCM electrode and shape of the SCM particle after cycling will be reported and discussed. 4. Reference [1] J. Yang et al. SiOx-based anodes for secondary lithium batteries. Solid State Ionics 152-153, 125-129 (2002).[2] M. N. Obrovac et al. Alloy Negative Electrodes for Li-Ion Batteries. Chem. Rev. 114, 11444−11502 (2014).[3] Y. liu et al. Silicon/carbon composites as anode materials for Li-ion batteries. Electrochem. Solid State Lett. 7 (10), A369-372 (2004).[4] U. Kasavajjula et al. Nano- and bulk-silicon-based insertion anodes for lithium-ion secondary cells. J. Power Sources 163, 1003-1039 (2007) Figure 1

Silicon Monoxide As Anode Material for Lithium Ion Batteries

Silicon monoxide (SiO) is a very promising anode material for the next generation high energy lithium ion batteries due to its high theoretical specific capacity of 1710 mAh/g and volumetric capacity of 1547 Ah/L.[1] Compared to commercially used graphite, SiO can offer 18% cell stack level improvement in volumetric energy density and 11% in gravimetric energy density (calculated based on the same cell stack model), enabling utilization of smaller and lighter batteries. It also offers more stable cycle performance compared to Si due to less volume change (134% initial volume expansion and 117% reversible volume expansion), making it a more practical choice for lithium ion batteries in the near future.SiO is composed of Si nanodomains in a SiO2 matrix. An interphase region of transitional stoichiometry (SiOx, 0 < x < 2) is also present between Si and SiO2 and takes up 20-25 at.% of the entire composition.[2] During the lithiation and delithiation, the Si nanodomains react reversibly with lithium, similar to amorphous silicon, to give the reversible capacity. The SiO2 matrix reacts irreversibly with lithium to form lithium silicates and lithium oxide. Therefore, the Si domain size and interphase suboxide between Si and SiO2 have effect on the electrochemical performance of SiO. In this study, we gradually changed the microstructure of SiO via annealing treatment and thoroughly studied the change of the SiO microstructure and its impact on the electrochemical performance of the SiO. Together with electrode formulation optimization, up to 99% capacity retention during 50 cycles was obtained in full cells when using pure SiO as anode and LiNi0.5Mn0.3Co0.2O2 as cathode. Acknowledgement We gratefully acknowledge the support from Peter Faguy at the U.S. Department of Energy’s (DOE) office of Energy Efficiency & Renewable Energy (EERE) - Vehicle Technologies Office. This work is conducted under the Cell Analysis, Modeling, and Prototyping (CAMP) Facility at Argonne National Laboratory. Argonne National Laboratory is a U.S. Department of Energy Office of Science Laboratory operated under Contract No. DE-AC02-06CH11357.Reference: Obrovac, M. N.; Chevrier, V. L., Alloy Negative Electrodes for Li-Ion Batteries. Chemical Reviews 2014, 114 (23), 11444-11502.Hirata, A.; Kohara, S.; Asada, T.; Arao, M.; Yogi, C.; Imai, H.; Tan, Y.; Fujita, T.; Chen, M., Atomic-scale disproportionation in amorphous silicon monoxide. Nature Communications 2016, 7, 11591.

Pre-Lithiation of Anode for Lithium Ion Batteries

Silicon monoxide (SiO), as an anode for lithium ion batteries (LIB), offers a specific capacity of 1750 mAh/g and a volumetric capacity of 1547 Wh/L,[1] which is less than Si, but still a significant improvement from the current commercial graphite anode, which has a specific capacity of 350 mAh/g and a volumetric capacity of 719 Wh/L. Compared to Si, SiO offers much more stable cycling, and is therefore the more practical material for near-future applications. The drawback of SiO is the large capacity loss observed in the initial cycles. The 1st cycle coulombic efficiency of silicon monoxide is usually lower than 70% due to the parasitic reactions between lithium and the oxide.To address the problem, prelithiation reagents can be added to either anode or cathode electrodes to compensate for the lithium loss caused by the irreversible reactions. However, dead weight left by the pre-lithiation agent adversely affects the energy density of LIB. Electrochemical pre-lithiation will only put the lithium ions into the anode and leaves no other compound behind, which is considered an ideal prelithiation method. In addition, the electrochemical pre-lithiation on the anode has the potential to be compatible with the existing roll-to-roll manufacturing line and could be immediately applicable to the current state-of-the-art LIB anodes.In this work, we conducted the electrochemical pre-lithiation of large size graphite and SiO anode electrodes in pouch cells to prove the concept. After pre-lithiation, no damage and handling issues were encountered during subsequent cleaning, drying, cell fabrication, and testing. Good electrochemical performance of the pre-lithiated graphite and SiO electrodes were obtained in both half cells and full cells. According to calculation, the pre-lithiation speed is challenging and needs to be addressed to match roll-to-roll electrode coating speed. Additionally, electrochemical pre-lithiation on graphite powder was attempted and results will be discussed. Acknowledgements: We gratefully acknowledge the support from Peter Faguy at the U.S. Department of Energy’s (DOE) office of Energy Efficiency & Renewable Energy (EERE) Vehicle Technologies Office. This work is conducted under the Cell Analysis, Modeling, and Prototyping (CAMP) Facility at Argonne National Laboratory. Argonne National Laboratory is a U.S. Department of Energy Office of Science Laboratory operated under Contract No. DE-AC02-06CH11357.[1] Obrovac, M. N.; Chevrier, V. L., Alloy Negative Electrodes for Li-Ion Batteries. Chemical Reviews 2014, 114 (23), 11444-11502.

Carbonization of polysaccharides in FeCl3/BmimCl ionic liquids: Breaking the capacity barrier of carbon negative electrodes in lithium ion batteries

Polysaccharide-derived carbonaceous materials were prepared using an ionothermal carbonization approach in iron-containing ionic liquids (i.e. mixtures of 1-butyl-3-methylimidazolium chloride, BmimCl, and iron(III) chloride, FeCl3). The as-prepared ionochars were subsequently pyrolyzed to yield carbon materials. These carbons were thoroughly characterized and investigated as negative electrodes for Li-ion batteries. The use of four polysaccharides (i.e. starch, chitosan, pectin and alginic acid) and three different FeCl3/BmimCl ratios allowed obtaining a set of porous carbons with different textural properties (specific surface area and pore volume) and nitrogen contents. Besides, the amount of residual iron within the carbonaceous framework was adjusted through a washing step before pyrolysis, which provided an additional control over the degree of graphitization. The best electrochemical performance in battery was obtained for the carbons prepared from chitosan (i.e., the carbon displaying the highest nitrogen content) and pre-treated in the ionic liquid with the lowest FeCl3/BmimCl ratio (i.e., 0.5, which yielded carbons with higher pore volumes). This work further highlights the versatility offered by the ionothermal approach towards textural, structural and electrochemical properties of the as-prepared carbon materials.

Size Dependent Fast Li Ion Storage Based on Size Regulated TiO&lt;sub&gt;2&lt;/sub&gt;(B) Nanosheet Electrodes with Vertical, Horizontal and Random Alignment

TiO2(B) has a high theoretical capacity of 335 mAh g−1 for Li+ intercalation and thus has been considered as a candidate for lithium-ion capacitor and Li-ion battery negative electrodes. For high rate lithium storage, i.e. high power density, it is important to shorten the Li+ diffusion path by using nanostructured TiO2(B). In this work, TiO2(B) nanosheet with different equivalent diameter of 300 nm and 30 nm were prepared. In addition, the orientation of the TiO2(B) nanosheets was manipulated by altering the deposition method and drying process. Smaller size TiO2(B) nanosheets had better Li+ intercalation ability compared to larger sized TiO2(B) nanosheets. The effect of alignment of the TiO2(B) nanosheets was evident for small-sized TiO2(B) nanosheets; vertical or random alignment of small-sized TiO2(B) afforded higher capacity compared to horizontally oriented nanosheets.

Solid-electrolyte interphase nucleation and growth on carbonaceous negative electrodes for Li-ion batteries visualized with in situ atomic force microscopy

Li-ion battery performance and life cycle strongly depend on a passivation layer called solid-electrolyte interphase (SEI). Its structure and composition are studied in great details, while its formation process remains elusive due to difficulty of in situ measurements of battery electrodes. Here we provide a facile methodology for in situ atomic force microscopy (AFM) measurements of SEI formation on cross-sectioned composite battery electrodes allowing for direct observations of SEI formation on various types of carbonaceous negative electrode materials for Li-ion batteries. Using this approach, we observed SEI nucleation and growth on highly oriented pyrolytic graphite (HOPG), MesoCarbon MicroBeads (MCMB) graphite, and non-graphitizable amorphous carbon (hard carbon). Besides the details of the formation mechanism, the electrical and mechanical properties of the SEI layers were assessed. The comparative observations revealed that the electrode potentials for SEI formation differ depending on the nature of the electrode material, whereas the adhesion of SEI to the electrode surface clearly correlates with the surface roughness of the electrode. Finally, the same approach applied to a positive LiNi1/3Mn1/3Co1/3O2 electrode did not reveal any signature of cathodic SEI thus demonstrating fundamental differences in the stabilization mechanisms of the negative and positive electrodes in Li-ion batteries.

Smart Binders for Silicon Based Composite Electrode in Li-Ion Batteries

Silicon is one of the most promising alloying anode materials for Li-ion batteries thanks to its high specific and volumetric capacity. In comparison with the commercially available graphite, silicon delivers 10 times higher specific capacity (up to 3600 mA.h.g-1) and 3 times higher volumetric capacity ( up to 2200 mA.h.cm-3) [1]. However, silicon suffers from high volumic expansion upon lithiation (up to 280 %). It induces the pulverization of the micrometric silicon particle, the perpetual solid electrolyte interface renewal and decohesion between constitutive elements of the electrode, drastically reducing its lifespan [2].To tackle those issues we propose the formulation of composite electrode with improved binder. It is composed of carboxymethyl cellulose sodium salt (NaCMC, as a binding network) and zinc sulfate dissolved in a pH 3 buffer solution (composed of citric acid and potassium hydroxide). The originality and improvement comes from the use Zn2+ ions as coordination agents, binding to carboxylate groups from the CMC and citric acid. Among benefits, we believe that the coordination helps to mitigate the stress inside the electrode because of the improved reticulation of the network, thus improving its resilience [3]. To support this hypothesis, we provide physico-chemical characterizations of the binder as well as the electrochemical performances of our electrodes. [1] M.N. Obrovac, V.L. Chevrier, Alloy Negative Electrodes for Li-Ion Batteries. Chem. Rev. 2014, 114, 11444-11502. [2] A. Etiemble, A. Tranchot, T. Douillard, H. Idrissi, E. Maire, L. Roué., Evolution of the 3D Microstructure of a Si-Based Electrode for Li-Ion Batteries Investigated by FIB/SEM Tomography, J. Electrochem. Soc. 2016,163, A1550-A1559 [3] D. Mazouzi, R. Grissa, M. Paris, Z. Karkar, L. Huet, D. Guyomard, L. Roué, T. Devic, B. Lestriez, CMC-citric acid Cu(II) cross-linked binder approach to improve the electrochemical performance of Si-based electrodes. Electrochim. Acta 2019, 304, 495-504.