Graphite-based Anode Research Articles

Waterborne LiNi0.5Mn1.5O4 Cathode Formulation Optimization through Design of Experiments and Upscaling to 1 Ah Li-Ion Pouch Cells

High-voltage spinel LiNi0.5Mn1.5O4 (LNMO) is a promising candidate as a lithium-ion battery cathode material to fulfill the high-energy density demands of the electric vehicle industry. In this work, the design of the experiment’s methodology has been used to analyze the influence of the ratio of the different components in the electrode preparation feasibility of laboratory-scale coatings and their electrochemical response. Different outputs were defined to evaluate the formulations studied, and Derringer–Suich’s methodology was applied to obtain an equation that is usable to predict the desirability of the electrodes depending on the selected formulation. Afterward, Solver’s method was used to figure out the formulation that provides the highest desirability. This formulation was validated at a laboratory scale and upscaled to a semi-industrial coating line. High-voltage 1 Ah lithium-ion pouch cells were assembled with LNMO cathodes and graphite-based anodes and subjected to rate-capability tests and galvanostatic cycling. 1 C was determined as the highest C-rate usable with these cells, and 321 and 181 cycles above 80% SOH were obtained in galvanostatic cycling tests performed at 0.5 C and 1 C, respectively. Furthermore, it was observed that the LNMO cathode required an activation period to become fully electrochemically active, which was shorter when cycled at a lower C-rate.

Optimization of Pore Characteristics of Graphite-Based Anode for Li-Ion Batteries by Control of the Particle Size Distribution

We investigate the reassembly techniques for utilizing fine graphite particles, smaller than 5 µm, as high-efficiency, high-rate anode materials for lithium-ion batteries. Fine graphite particles of two sizes (0.4–1.2 µm and 5 µm) are utilized, and the mixing ratio of the two particles is varied to control the porosity of the assembled graphite. The packing characteristics of the assembled graphite change based on the mixing ratio of the two types of fine graphite particles, forming assembled graphite with varying porosities. The open porosity of the manufactured assembled graphite samples ranges from 0.94% to 3.55%, while the closed porosity ranges from 21.41% to 26.51%. All the assembled graphite shows improved electrochemical characteristics properties compared with anodes composed solely of fine graphite particles without granulation. The sample assembled by mixing 1.2 µm and 5 µm graphite at a 60:40 ratio exhibits the lowest total porosity (27.45%). Moreover, it exhibits a 92.3% initial Coulombic efficiency (a 4.7% improvement over fine graphite particles) and a capacity of 163.4 mAh/g at a 5C-rate (a 1.9-fold improvement over fine graphite particles).

Investigation of Peptization Technique to Synthesize Si@TiO<sub>2</sub> for a Li-Ion Battery Anode Material

Electric vehicles (EVs) have a significant advantage in terms of energy efficiency and environmental friendliness. In lithium-ion batteries, silicon is seeking more attention than graphite-based anodes due to its high storage capacity. However, it faces severe structural degradation due to volume expansion which is responsible for fast capacity degradation. In the present study, the core shell is developed with the core as silicon and titania as shell (Si@TiO2) and utilized it as an anode in the 2016-coin cell. The material characterization (FE-SEM, TEM, EDS, XRD and XPS) of this developed core-shell material is recorded to confirm its elemental composition and structural validation. The electrochemical performance is measured using cyclic voltammetry (CV) and galvanostatic charge/discharge (GCD) test. Cyclic voltammetry profiles reveal the stable lithiation and delithiation process. Initial specific capacity of ≈3180 mAh/g is reported, capacity retention of 61% for the developed core-shell while 34% for the bare silicon is noted over 100 cycles. The proposed method (peptization technique) for the development of core-shell nanoparticles is also compared with the sol-gel approach. The result shows an increment of 5% in capacity retention after 100 cycles by following the peptization technique.

Engineering a polyaniline nanoneedles-coated multi-layered Co3O4/NiO microsphere as high-performance Li-ion battery anode

High energy-storage Li-ion battery needs a high-capacity anode. However, current graphite-based anode doesn’t meet this requirement, thus developing high performance anode materials is highly needed and significant. Here, we provide a rational engineering of a multi-layered hollow structure combining with surface coating of polyamine (PANI) layer, forming a Co3O4/NiO@PANI hybrid using for Li-ion battery anode. PANI is able to effectively improve the conductivity of active materials; besides, PANI is flexible, which can prevent the collapse of the structure caused by volume-expansion during charge and discharge. The multi-layered morphology improves the utilization ratio of voids inside the conventional hollow structured materials, which is significant to improve capacity in practical applications. The Co3O4/NiO@PANI hybrid-based anode shows a capacity of 1049 mAh g−1 along with a Coulombic efficiency of 99.3% after 100 cycles of 0.2 A g−1. Rate-performance of Co3O4/NiO@PANI exceeds that of the bare Co3O4/NiO. It is believed that the hierarchical structure combining multi-layered hollow morphology with surface coating of conductive polymer presented here would find broad applications for developing high-performance energy-storage hybrids.

Localized Average Voltage Distribution on the Surface of NMC622 Electrode Measured Using Integrated Al-Voltage Probes during the Cell Cycling at Different C-Rates

Studying localized voltage distribution of electrode surfaces in Li-ion batteries (LIBs) during cell cycling at constant current enables better understanding of the cell degradation phenomenon and prediction of the state of the health. In many studies, individual electrode potentials are analyzed during cell cycling at different C-rates using a reference electrode integrated into the cell, studying the electrochemical reaction mechanism of single electrodes [1,2]. However, for long length electrodes in pouch cells, nonuniform voltage distributions are developed on the electrode surfaces due to inhomogeneous lithiation and de-lithiation during cell cycling. This voltage distribution can cause a variety of issues including loss of energy, accelerated cell degradation, and overcharge or over-discharge of the cell at specific points on the electrodes. For example, recent literature shows that the region of the electrode closest to the current collector tab in pouch cells has the highest state of charge [3].Usually, pouch cells are constructed with different dimensions, depending on the application. However, there is a lack of information on the local voltages at electrode surfaces during charge and discharge at different C-rates. To understand the degradation mechanisms of active electrode materials in the pouch cell application, it is therefore important to spatially quantify the voltage distribution on the electrode surfaces at different C-rates.In this study, two pairs of thin film Al voltage probes were placed carefully onto the surface of NMC622 rectangular cathode to monitor the voltage distribution between equidistant points parallel and perpendicular to the tab direction along the electrode. Following this, a pouch cell was constructed with the cathode (2 mAhcm-2) sandwiched between two graphite-based anodes with an areal charge density of 2.4 mAhcm-2. The surface electrode potentials were measured individually against a standard reference Li/Li+ electrode in-operando during the formation cycle as well as during charge and discharge at rates of C/10, C/5, and C/3.The results show that the electrochemical potential close to the tab is always higher than that further away. A potential gradient exists perpendicular to the tab direction, which increases and decreases continuously during charging and discharging respectively. The potential difference between two lateral points parallel to the tab direction is significantly lower than the difference between two points perpendicular to the tab direction. This voltage distribution across the electrode usually manifests due to the inhomogeneous lithium diffusion along the plane of the electrode. This can be influenced by the electronic and ionic conductivity of the electrode along its plane. Therefore, in addition, Electrochemical Impedance Spectroscopy (EIS) measurements were performed, both perpendicular and parallel to the tab directions at different states of charge (SOC) of the cell. The EIS measurements confirm that the resistance perpendicular to the tab directions is higher than that parallel to the tab direction. Therefore, our results show that it is highly recommended to place voltage and temperature sensors closer to the tabs to monitor the state of health of the cell.[1] Sols L and Engineering A 1995 Current and Potential Distribution in Parallel Electrodes 244 236–44[2] Raccichini R, Amores M and Hinds G 2019 Critical review of the use of reference electrodes in li-ion batteries: A diagnostic perspective Batteries 5 1–24[3] Liu J, Kunz M, Chen K, Tamura N and Richardson T J 2010 Visualization of charge distribution in a lithium battery electrode J. Phys. Chem. Lett. 1 2120–3

Mechanistic Study of Lithium Electrodeposition Using Dynamic Electrochemical Impedance Spectroscopy

Lithium metal batteries have increased energy density over standard graphite-based Li-ion anodes. However, Li metal anodes have difficulty forming stable passivation layer (called solid electrolyte interphase, SEI) leading to poor use of Li inventory. That is, LI metals require larger cathode loading, which reduces the energy density gain. A holistic approach to Li anode incorporation includes electrolyte design, mechanism understanding, and battery engineering. A factor that has not been fully appreciated is the nature of the Lithium metal itself, namely its SEI before incorporation into the battery device may affect the subsequent SEI formation. Here, we present a mechanistic study on lithium SEI formation on various lithium sources, as well as the Li cycling.We utilized dynamic impedance spectroscopy (dEIS) to probe the formation and evolution of the SEI during Li cycling of various Li sources. dEIS superimposes a multisine waveform atop the dc stimulus signal. After applying a sliding window FFT protocol that takes the complex ratio of the measured potential and current signals time-resolved complex impedance can be obtained. We will discuss the differences between the Li cycling profiles using Lipon (a glassy solid electrolyte) and a liquid electrolyte. We will relate the differences in cycling performance, particularly the SEI evolution to the surface chemistry of the as-received Li metal source.The US Department of Energy's Energy Efficiency and Renewable Energy Vehicles Technologies Office provided funding for this work under the US-German Cooperation on Energy Storage: Lithium-Solid-Electrolyte Interfaces program.

The Influence of Reduced Graphene Oxide on the Texture and Chemistry of N,S-Doped Porous Carbon. Implications for Electrocatalytic and Energy Storage Applications.

In this work, we study the influence of reduced graphene oxide (rGO) on the morphology and chemistry of highly porous N,S-doped carbon cryogels. Simultaneously, we propose an easily upscalable route to prepare such carbons by adding graphene oxide (GO) in as-received suspended form to the aqueous solution of the ι-carrageenan and urea precursors. First, 1.25-5 wt% GO was incorporated into the dual-doped polymer matrix. The CO2, CO, and H2O emitted during the thermal treatments resulted in the multifaceted modification of the textural and chemical properties of the porous carbon. This facilitated the formation of micropores through self-activation and resulted in a substantial increase in the apparent surface area (up to 1780 m2/g) and pore volume (up to 1.72 cm3/g). However, adding 5 wt% GO led to overactivation. The incorporated rGO has an ordering effect on the carbon matrix. The evolving oxidative species influence the surface chemistry in a complex way, but sufficient N and S atoms (ca. 4 and >1 at%, respectively) were preserved in addition to the large number of developing defects. Despite the complexity of the textural and chemical changes, rGO increased the electrical conductivity monotonically. In alkaline oxygen reduction reaction (ORR) tests, the sample with 1.25 wt% GO exhibited a 4e- mechanism and reasonable stability, but a higher rGO content gradually compromised the performance of the electrodes. The sample containing 5 wt% GO was the most sensitive under oxidative conditions, but after stabilization it exhibited the highest gravimetric capacitance. In Li-ion battery tests, the coulombic efficiency of all the samples was consistently above 98%, indicating the high potential of these carbons for efficient Li-ion insertion and reinsertion during the charge-discharge process, thereby providing a promising alternative for graphite-based anodes. The cell from the 1.25 wt% GO sample showed an initial discharge capacity of 313 mAh/g, 95.1% capacity retention, and 99.3% coulombic efficiency after 50 charge-discharge cycles.

Use of positron emission particle tracking to assess mixing of a graphite-based lithium-ion anode slurry in an Eirich mixer

The mixing of electrode slurries is a key processing step during the manufacturing of lithium-ion batteries, and poor mixing can have a profound effect on final cell electrochemical performance. This is complicated by the evolving non-Newtonian rheology of these slurries. In this study, Positron Emission Particle Tracking (PEPT) is used to determine the fluid dynamics and dispersion of a model graphite-based anode slurry in an Eirich EL1 mixer, equipped with a rotating pan, wall scraper and internal rotor. The main processes studied are the wetting of graphite particles and breakup of large graphite agglomerates. For experiments performed at different internal rotor tip speeds, with fixed outer pan speed, the dispersion dynamics change with the lowest rotor speed (2 m/s) leaving a large channel of poor mixing between the rotor region and the rotating pan, whilst the mixing within the vessel is mainly driven by the rotating pan. At higher mixing speeds (6 and 10 m/s) more of the vessel volume is active and there is no longer a poor mixing region observed, with 10 m/s tip speed producing the highest intensity of dispersion. An increasing mixer effectiveness (average dispersion across the mixing vessel) as well as an increasing dispersion co-efficient (rate of mixing) is also observed, which will be use to inform scale-up criteria.

In operando detection of Lithium plating via electrochemical impedance spectroscopy for automotive batteries

Reducing the charging time is one of the main goals towards increasing the acceptance of electric vehicles. One of the limits of fast charging lithium-ion batteries with graphite-based anodes is lithium plating, a process which occurs mainly at high charging rates, low temperatures and high state of charge. Detecting the onset of lithium plating during a charging procedure is essential in order to optimize fast-charging profiles. This paper introduces a new method that allows the detection of the onset of lithium plating in automotive lithium-ion batteries using on-line electrochemical impedance spectroscopy. Compared to similar approaches, the measurement itself does not result in a significant increase in the charging time. The detection is based on observing the real part of the impedance across the state of charge during the charging procedure. The onset of lithium plating can be detected by a deviation from the nominal behavior in the form of a drop towards lower impedance. The behavior is both explained theoretically using electrochemical equivalent circuits and shown experimentally. The impedance measurements are carried out using an integrated small-scale device to allow on-line impedance analysis in an automotive environment and an integration into future battery management systems.

Rational engineering NiMoO4 nanosheets or Mn3O4 nanowires on Fe2O3 microdiscs as novel hierarchical anodes for high-performance lithium-ion batteries

Since current graphite-based lithium-ion battery anode has a low theoretical capacity, the development of high-performance lithium-ion battery is severely restricted. Here, novel hierarchical composites composing of microdisc and the secondarily grown nanosheets and nanowires are developed, taking NiMoO4 nanosheets and Mn3O4 nanowires growing on Fe2O3 microdiscs as demonstrating examples. The growth processes of the hierarchical structures have been investigated by adjusting a series of preparation conditions. The morphologies and structures have been characterized by using scanning electron microscopy, transmission electron microscope and x-ray diffraction. Fe2O3@Mn3O4 composite-based anode displays a capacity of 713 mAh g−1 after 100 cycles at 0.5 A g−1 with a high Coulombic efficiency. A good rate-performance is also achieved. Fe2O3@NiMoO4 anode delivers 539 mAh g−1 after 100 cycles at 0.5 A g−1, which is obviously higher than that of pure Fe2O3. The hierarchical structure is conducive to improve the transport of electrons and ions, and provide numerous active sites, thus significantly enhancing the electrochemical performance. Moreover, the electron transfer performance is investigated by using density functional theory calculations. It is expected the findings presented here and the rational engineering of nanosheets/nanowires on microdiscs would be applicable for developing many other high-performance energy-storage composites.

2D Layered Materials for Fast-Charging Lithium-Ion Battery Anodes.

The development of electric vehicles has received worldwide attention in the background of reducing carbon emissions, wherein lithium-ion batteries (LIBs) become the primary energy supply systems. However, commercial graphite-based anodes in LIBs currently confront significant difficulty in enduring ultrahigh power input due to the slow Li+ transport rate and the low intercalation potential. This will, in turn, cause dramatic capacity decay and lithium plating. The 2D layered materials (2DLMs) recently emerge as new fast-charging anodes and hold huge promise for resolving the problems owing to the synergistic effect of a lower Li+ diffusion barrier, a proper Li+ intercalation potential, and a higher theoretical specific capacity with using them. In this review, the background and fundamentals of fast-charging for LIBs are first introduced. Then the research progress recently made for 2DLMs used for fast-charging anodes are elaborated and discussed. Some emerging research directions in this field with a short outlook on future studies are further discussed.

Micro embossing of graphite-based anodes for lithium-ion batteries to improve cell performance

Patterning of lithium-ion battery anodes is widely accepted as a method to overcome the lack of fast-charging capability of high-energy electrodes. Structuring is mostly performed by ablative laser processes, whereby technological aspects such as loss of active material and scalability are still an obstacle to industrial implementation. In this paper, micro embossing is proposed as a novel material-preserving approach for graphite-based anodes to improve their performance. A metal stamp with well-defined laser-structured micro pins was developed first. Subsequently, a lab scale process was developed to imprint a defined perforation pattern on calendered graphite anodes. The electrochemical performance is compared to reference electrodes prior to any post-treatment. By micro embossing, hole geometries could be achieved compared to laser perforation known from the literature. Microscopy and tomography investigations of the embossed hole surface wall show lower porosity as well as alignment of graphite particles. Electrochemical impedance spectroscopy of symmetrical anode cells indicates a reduction in the ionic pore resistance of the embossed anodes. Moreover, fast-charging tests with full-cells revealed reduced cell overpotentials compared to pristine anodes. A cell test over 400 cycles showed improved retention of capacity of the embossed anodes compared to reference anodes. Half-cell capacity tests confirmed that there is practically no loss of active material due to micro embossing. Regarding the layer adhesion, no disadvantage could be found either. Moreover, this process has the potential to be integrated comparatively easily into electrode production, if it can be combined with the calendering process, thus, enhancing its industrial applicability.

Graphite-Based Composite Anodes with C-O-Nb Heterointerfaces Enable Fast Lithium Storage.

To better satisfy the increasing demands for electric vehicles, it is crucial to develop fast-charging lithium-ion batteries (LIBs). However, the fast-charging capability of commercial graphite anodes is limited by the sluggish Li+ insertion kinetics. Herein, we report a synergistic engineering of uniform nano-sized T-Nb2 O5 particles on graphite (Gr@Nb2 O5 ) with C-O-Nb heterointerfaces, which prevents the growth and aggregation of T-Nb2 O5 nanoparticles. Through detailed theoretical calculations and pair distribution function analysis, the stable existence of the heterointerfaces is proved, which can accelerate the electron/ion transport. These heterointerfaces endow Gr@Nb2 O5 anodes with high ionic conductivity and excellent structural stability. Consequently, Gr@10-Nb2 O5 anode, where the mass ratio of T-Nb2 O5 /graphite=10/100, exhibits excellent cyclic stability and incredible rate capabilities, with 100.5 mAh g-1 after 10000 stable cycles at an ultrahigh rate of 20 C. In addition, the synergistic Li+ storage mechanism is revealed by systematic electrochemical characterizations and in situ X-ray diffraction. This work offers new insights to the reasonable design of fast-charging graphite-based anodes for the next generation of LIBs.

“Pompon” graphene as a new promising anode for LIBs

The "pompon" graphene was obtained by the new modified controlled detonation gas synthesis tested as an anode of LIBs. Processing of Raman spectra by changing the position of the G-band shows the presence of a mixture of 2, 3 and 4-layer graphene structures. The results of the surface area measurement by the BET method have been shown the limited availability of the "pompons" for the penetration of lithium ions between its layers. Subsequent thermomechanical activation leads to partial "delamination” of the pompon and the production of both separate and 2-layer sheets of graphene, which is reflected in a sharp increase in its specific surface area. The specific capacity of graphene, as an anode of LIBs, increases in the range M0 < M20 < M40 and reaches of 500 mAh•g-1 at a current density of 37.2 mA•g-1 for the best M40 sample. The obtained values of specific capacity are 1.5 times higher than similar values for graphite-based anodes.

Mitigating Swelling of the Solid Electrolyte Interphase using an Inorganic Anion Switch for Low-temperature Lithium-ion Batteries.

In overcoming the Li+ desolvation barrier for low-temperature battery operation, a weakly-solvated electrolyte based on carboxylate solvent has shown promises. In case of an organic-anion-enriched primary solvation sheath (PSS), we found that the electrolyte tends to form a highly swollen, unstable solid electrolyte interphase (SEI) that shows a high permeability to the electrolyte components, accounting for quickly declined electrochemical performance of graphite-based anode. Here we proposed a facile strategy to tune the swelling property of SEI by introducing an inorganic anion switch into the PSS, via LiDFP co-solute method. By forming a low-swelling, Li3 PO4 -rich SEI, the electrolyte-consuming parasitic reactions and solvent co-intercalation at graphite-electrolyte interface are suppressed, which contributes to efficient Li+ transport, reversible Li+ (de)intercalation and stable structural evolution of graphite anode in high-energy Li-ion batteries at a low temperature of -20 °C.

SYNTHESIS AND INVESTIGATION OF ELECTROCHEMICAL CHARACTERISTICS OF OXIDE Li-CONDUCTIVE MATERIALS WITH SPINEL AND PEROSKITE STRUCTURES

Lithium-ion batteries (LIBs) are widely used in electronic devices due to their numerous advantages, namely high energy density, high capacity, and long service life. One of the important components of a battery is the anode. In order to ensure high characteristics of LIB, the anode material must have high capacity, high ionic and electronic conductivities, and low cost. However, commonly used anode materials in lithium-ion batteries have a number of disadvantages. For example, a graphite-based anode is characterized by significant changes in volume during intercalation/deintercalation of lithium ions, high energy losses, and rapid deterioration of characteristics at high discharge/charge rates; Li4Ti5O12 have a low theoretical specific capacity, low electronic conductivity and low diffusion rate of lithium ions.
 Thus, the search for anode materials with high capacity and capability rate, as well as small volume change during lithium intercalation/deintercalation, remains an urgent task. A promising way may be the use of materials with intercalation pseudocapacitive behavior of charge accumulation, which occurs due to the intercalation of ions in tunnels or layers of active materials without a crystallographic phase transition. LixLa2/3-x/3TiO3 is well known as a superionic conductor with a high ionic conductivity σ ≈ 10–3 S/cm at room temperature. It crystallizes in a perovskite-type structure that consists of a framework of TiO6 octahedra stabilized by La atoms, and has nume­rous vacancies in the unoccupied positions 18d and 6a, that could participate in the stora­ge and motion of Li ions.
 Electrochemical characteristics of LixLa2/3-x/3TiO3 (x = 0.35 and 0.5) anode materials with a perovskite structure were investigated and compared with the electrochemical characteristics of Li4Ti5O12 with a layered spinel structure.

Cu Current Collector with Binder-Free Lithiophilic Nanowire Coating for High Energy Density Lithium Metal Batteries.

Despite significant efforts to fabricate high energy density (ED) lithium (Li) metal anodes, problems such as dendrite formation and the need for excess Li (leading to low N/P ratios) have hampered Li metal battery (LMB) development. Here, the use of germanium(Ge)nanowires (NWs) directly grown on copper(Cu) substrates (Cu-Ge) to induce lithiophilicity and subsequently guide Li ions for uniform Li metal deposition/stripping during electrochemical cycling is reported. The NW morphology along with the formation of the Li15 Ge4 phase promotes uniform Li-ion flux and fast charge kinetic, resulting in the Cu-Ge substrate demonstrating low nucleation overpotentials of 10mV (four times lower than planar Cu) and high Columbic efficiency (CE) efficiency during Li plating/stripping. Within a full-cell configuration, the Cu-Ge@Li - NMC cell delivered a 63.6% weight reduction at the anode level compared to a standard graphite-based anode, with impressive capacity retention and average CE of over 86.5% and 99.2% respectively. The Cu-Ge anodes are also paired with high specific capacity sulfur (S) cathodes, further demonstrating the benefits of developing surface-modified lithiophilic Cu current collectors, which can easily be integrated at the industrial scale.

Effect of Si Content on Extreme Fast Charging Behavior in Silicon–Graphite Composite Anodes

Commercial Li-ion batteries typically incorporate a small amount of high-capacity silicon (Si)-based materials in the composite graphite-based anode to increase the energy density of the battery. However, very little is known about the effects of Si on the fast-charging behavior of composite anodes. Herein, we examine the effects of the Si/graphite ratio in the composite anode on the fast-charging behavior of full cells. We show that addition of Si increases the rate capability from 1C to 8C and improves the capacity retention in early cycles at 6C due to reduced overpotential in constant current charging cycles. The impacts of Si content on fast-charging aging were identified by Post-Test characterization. Despite realizing benefits of available capacity and reduced Li plating at 6C, silicon–electrolyte interactions lead the time-dependent cell performance to fade quickly in the long term. The Post-Test analysis also revealed the thickening of the electrode and nonuniform distribution of electrolyte decomposition products on the Si-containing anodes, as well as the organic-rich solid electrolyte interphase (SEI), which are the factors behind cell degradation. Our study sheds insight on the advantages and disadvantages of Si/graphite composite anodes when they are used in fast-charging applications and guides further research in the area by designing an optimized composition of Si incorporated in a mature graphite matrix.

Gas induced formation of inactive Li in rechargeable lithium metal batteries

The formation of inactive lithium by side reactions with liquid electrolyte contributes to cell failure of lithium metal batteries. To inhibit the formation and growth of inactive lithium, further understanding of the formation mechanisms and composition of inactive lithium are needed. Here we study the impact of gas producing reactions on the formation of inactive lithium using ethylene carbonate as a case study. Ethylene carbonate is a common electrolyte component used with graphite-based anodes but is incompatible with Li metal anodes. Using mass spectrometry titrations combined with 13C and 2H isotopic labeling, we reveal that ethylene carbonate decomposition continuously releases ethylene gas, which further reacts with lithium metal to form the electrochemically inactive species LiH and Li2C2. In addition, phase-field simulations suggest the non-ionically conducting gaseous species could result in an uneven distribution of lithium ions, detrimentally enhancing the formation of dendrites and dead Li. By optimizing the electrolyte composition, we selectively suppress the formation of ethylene gas to limit the formation of LiH and Li2C2 for both Li metal and graphite-based anodes.

From Lab to Manufacturing Line: Guidelines for the Development and Upscaling of Aqueous Processed NMC622 Electrodes

Lithium-ion batteries (LIBs) have facilitated the transition to a more sustainable energy model. Paradoxically, current high energy cathodes are industrially processed using organic solvents, which are deleterious for the environment. In this work, LiNi0.6Mn0.2Co0.2O2 (NMC622) high-energy cathode electrode was prepared at laboratory scale following a more environmentally friendly aqueous route. Several steps in the preparation of the electrodes (such as the drying temperature, drying air flux or pH buffering) were thoroughly optimized to enhance the quality of the water-processed electrodes. Afterwards, the recipe developed at laboratory scale was upscaled to a semi-industrial electrode coating line, to analyze the viability of the developed processing conditions into a realistic electrode manufacturing environment. The electrodes obtained were tested in full coin cells using graphite-based anodes as counter electrodes. Interestingly, the cycling performance of the cells based on water-processed electrodes was higher than that of organic-processed ones. It is evidenced that it is possible to manufacture electrodes for high energy density LIBs following environmentally friendly, cheaper, and industrially implementable electrode processing methods with no-penalty in the electrochemical performance.