Success Of Lithium-ion Batteries Research Articles

Experimental investigation of the multi-layer wetting behavior of electrode-separator-composites in lithium-ion batteries

The success of lithium-ion batteries and their application in electromobility is highly dependent on their scalable and cost-efficient manufacturing. Herein, electrolyte filling and wetting are time-consuming and quality-critical process steps, which have been, on the material level, primarily researched on an intra-material level for single-cell components while lacking overarching investigations for inter-material effects during wetting. This study demonstrates for the first time an experimental methodology designed to systematically quantify the interaction effects between different electrode-separator-composites during wetting by varying product components and process parameters. The investigation reveals a quantifiable interaction within a two- or three-layer material combination of anode, separator, and cathode, which can be discerned into distinct anode and cathode interaction effects, maintaining consistency across the product and parameter variations. Through the analysis of activation energy using the Arrhenius equation, the study observe a combinatorial relationship for modeling multi-layer wetting. Multi-layer wetting rates increase by 215 % compared to single material rates. Higher temperatures boost penetration rates due to lower viscosity, but reduce the interaction effect. These insights contribute to an application-orientated understanding of electrode-separator-composite wetting behavior and open up more possibilities for an optimized manufacturing process through expanding methodical exploration of strategies for counterbalancing poor wettability.

Plasma-treated Bombyx mori cocoon separators for high-performance and sustainable lithium-ion batteries

The success of lithium-ion batteries (LIBs) and their unique advantages for electrochemical energy storage have sped up research in this field. A critical component of LIBs is the separator. Here, Bombyx mori silk cocoon separators have been treated with oxygen (O2) and nitrogen (N2) plasmas at different exposure times. The goal was to improve the electrochemical characteristics of these natural separators, without jeopardizing the major attributes of silk fibers. Major physical and chemical modifications have been identified at the submicrometer scale on the application of the plasmas: (1) Etching of the silk nanofibrils and concomitant increase of roughness (more effective with O2 plasma), corresponding to the destruction of the 5th structural hierarchy level of the silk fibers. (2) Creation of oxygen-containing functional groups carrying negative charges at the surface, causing a superhydrophobic-to-superhydrophilic transition, and favoring Li+ transport. The optimized cocoon separator exposed to O2 plasma for 30 s exhibited high electrolyte uptake (289%), high ionic conductivity (2.33 mS/cm at 25 °C), and low overall resistance. A cathodic half-cell of carbon-coated lithium iron phosphate incorporating this separator sample soaked in the ethylene carbonate/dimethyl carbonate/lithium hexafluorophosphate electrolyte demonstrated a performance boost with respect to the battery, including a raw cocoon separator: an outstanding increase (ca. 270%) of the discharge capacity (from 26.1 to 96.7 mAh/g at 5C-rate) and an impressive increase (291%) of the capacity retention (from 22.3% to 87.2%, from C/5 to 5C). This work proves that the O2 plasma exposure is a valid, simple, fast, clean, and safe top-down methodology to improve the properties of B. mori cocoon separators. The features of these plasma-treated separators, which surpass those of commercial separators, help in upgrading the performance of LIBs. This plasma-enhanced natural biomaterial separator technological platform pushes LIBs to the next performance-level, while guaranteeing the eco-friendly, sustainability, and safety labels.

Inorganic solids for dual magnesium and sodium battery electrodes

Despite the success of lithium-ion batteries, recognized through the award of the 2019 Nobel Prize in Chemistry, the forecast of a wide application of these systems to avoid the use of fossil fuels and their effect on global warming has raised doubts about their safety, sustainability, and performance. To make a post-lithium era possible, other reducing metals are investigated. While sodium shows certain analogies with lithium, some advantages with respect to its abundance and availability or the lack of Al alloy that could substantially reduce production costs make sodium-ion batteries a good alternative, particularly for stationary applications. On the other hand, other abundant multivalent elements such as Mg can provide even higher energy densities. The possibility of using dual ions can be a strategy to get the best of each element in a synergistic battery system. Dual Na+/Mg2+ systems have been considered a potential option by different researchers. In this review, we shall discuss different results on dual-metal-ion systems studied in our laboratory, particularly vanadium oxides and phosphates and layered manganese oxides.

From Solid‐Solution Electrodes and the Rocking‐Chair Concept to Today's Batteries

Lithium-ion batteries (LIBs) have become ubiquitous power sources for small electronic devices, electric vehicles, and stationary energy storage systems. Despite the success of LIBs which is acknowledged by their increasing commodity market, the historical evolution of the chemistry behind the LIB technologies is laden with obstacles and yet to be unambiguously documented. This Viewpoint outlines chronologically the most essential findings related to today's LIBs, including commercial electrode and electrolyte materials, but furthermore also depicts how the today popular and widely emerging solid-state batteries were instrumental at very early stages in the development of LIBs.

Carbon Dioxide As Electrolyte Additive for Silicon-Based Lithium Ion Full Cells

Following up the great success of lithium ion batteries (LIBs) in the field of consumer electronics in the recent decades, LIBs are today also widely used as energy storage devices for various types of electric vehicles (EVs). However, it is believed that a substantial breakthrough of the electromobility can only take place, if EVs are able to achieve driving ranges of more than 500 km and, therefore, gaining greater consumer acceptance. To achieve these driving ranges, the energy content of the used LIBs needs to be increased to values of 350 Wh/kg and 750 Wh/L at the cell level. These improvements can be achieved by replacing the state-of-the-art graphite anode by high-capacity anode materials like silicon (Si), which is able to provide a nearly 10 times higher specific capacity compared to graphite.[1] However, due to huge volume changes of up to 300% upon lithiation/de-lithiation, Si-based anodes often suffer from poor cycling performance related to cracking and pulverization of the Si particles and continuous solid electrolyte interphase (SEI) re-formation. Typically, these issues are addressed by decreasing the size of the active material particles to the nanoscale (i.e. nanoparticles, nanowires or thin films) or the fabrication of composites like intermetallic Si phases or Si/carbon composite materials to decrease the overall volume changes.[2] Although these strategies are reported to be effective to improve the performance of Si electrodes, it was revealed that the dominating failure mechanism of full cells containing Si-based negative electrodes lies in the consumption active lithium from the cathode related to continuous electrolyte reduction at the Si negative electrode. The addition of appropriate electrolyte additives such as fluoroethylene carbonate (FEC) or vinylene carbonate (VC) can significantly improve the capacity retention and Coulombic efficiency of Si-based full cells by forming a more stable SEI on the Si negative electrode.[3, 4] Recently, Krause et al. demonstrated that the addition of carbon dioxide in the form of dry ice significantly improved the performance of Si-based full cells and even outperformed the most commonly used additive FEC.[5] However, the exact working mechanism of the carbon dioxide additive and especially the reductive decomposition reactions including the resulting morphology and/or chemical composition of the formed SEI layer are still uncertain. Within this study, thin film Si electrodes prepared via magnetron sputtering are employed as model electrodes (i.e. no binder or conductive additive) therefore, possible effects of the carbon dioxide can be correlated to the Si active material. These Si thin film electrodes are coupled with NMC-111 positive electrodes to Si/NMC-111 full cells, which are used for the electrochemical investigations. As the solubility of carbon dioxide in the organic carbonate based electrolytes is rather low, diethylpyrocarbonate is added to the baseline electrolyte, as pyrocarbonates are known as carbon dioxide generators and, therefore, the carbon dioxide is released in-situ within the assembled full cell. The addition of the diethylpyrocarbonate electrolyte additive leads to significantly improved performance of the Si/NMC-111 full cells in terms of Coulombic efficiency and capacity retention full cells during prolonged cycling compared to the baseline electrolyte. The chemical composition of the SEI layer formed on the Si negative electrodes is investigated by means of X-ray photoelectron spectroscopy (XPS). The XPS investigations reveal that the improved performance of the carbon dioxide containing cells is related the improved passivation of the negative electrode by the formation of mainly lithium carbonate at the Si surface. Reference s : [1] D. Andre, H. Hain, P. Lamp, F. Maglia, B. Stiaszny, Future high-energy density anode materials from an automotive application perspective, Journal of Materials Chemistry A, 5 (2017) 17174-17198. [2] M.N. Obrovac, V.L. Chevrier, Alloy Negative Electrodes for Li-Ion Batteries, Chemical Reviews, 114 (2014) 11444-11502. [3] R. Nölle, A.J. Achazi, P. Kaghazchi, M. Winter, T. Placke, Pentafluorophenyl Isocyanate as an Effective Electrolyte Additive for Improved Performance of Silicon-Based Lithium-Ion Full Cells, ACS Applied Materials & Interfaces, 10 (2018) 28187-28198. [4] M. Klett, J.A. Gilbert, S.E. Trask, B.J. Polzin, A.N. Jansen, D.W. Dees, D.P. Abraham, Electrode Behavior RE-Visited: Monitoring Potential Windows, Capacity Loss, and Impedance Changes in Li1.03(Ni0.5Co0.2Mn0.3)0.97O2/Silicon-Graphite Full Cells, Journal of The Electrochemical Society, 163 (2016) A875-A887. [5] L.J. Krause, V.L. Chevrier, L.D. Jensen, T. Brandt, The Effect of Carbon Dioxide on the Cycle Life and Electrolyte Stability of Li-Ion Full Cells Containing Silicon Alloy, Journal of The Electrochemical Society, 164 (2017) A2527-A2533.

Quantitative and time-resolved detection of lithium plating on graphite anodes in lithium ion batteries

The ability of fast and safe charging is critical for the further success of lithium ion batteries in automotive applications. In state-of-the-art lithium ion batteries, the charging rate is limited by the onset of lithium plating on the graphite anode. Despite its high importance, so far no analytical technique has been available for directly measuring lithium plating during battery charge. Herein, we introduce operando electron paramagnetic resonance (EPR) spectroscopy as the first technique capable of time-resolved and quantitative detection of lithium metal plating in lithium ion batteries. In an exemplary study, the C-rate dependence of lithium metal plating during low-temperature charging at −20 °C is investigated. It is possible to quantify the amount of ‘dead lithium’ and observe the chemical reintercalation of plated lithium metal. In this way, it is possible to deconvolute the coulombic inefficiency of the lithium plating/stripping process and quantify the contributions of both dead lithium and active lithium loss due to solid electrolyte interphase (SEI) formation. The time-resolved and quantitative information accessible with operando EPR spectroscopy will be very useful for the optimization of fast charging procedures, testing of electrolyte additives, and model validation.

Improved Performance and Reduced Cost through Advanced Electrode Drying Technology

The commercial success of lithium ion batteries hinges on significant improvements in both cost and energy density. The electrode coating operation presents the highest leverage opportunity to address both challenges. Navitas ASG with Lambda Technologies has recently demonstrated and scaled up a patent-pending advanced drying process (ADP) technology that breaks through the limitations on electrode thickness and drying rate that are inherent in the present coating technology. This technology can improve electrode loading by at least 50% and accelerate coating rates by >2X. The technology is drop-in compatible with capital equipment in operation at battery OEM plants. The technology will enable cathodes that can match emerging high capacity silicon alloy anode materials. The expected impact of this technology will be >20% improvement in the cell level Wh/kg and 8% reduction in the system level EV battery cost. Microwave drying introduces key advantages over radiant and convective cooling for electrode drying (figure 1). Microwaves efficiently transfer energy through selective absorption by polar solvent (e.g. NMP) or water molecules. Microwave energy is also uniformly deposited through the bulk of the coated electrode. Electrode drying, however, introduces two barriers to use of microwave energy: avoiding arcing with the presence of metal foil current collectors, and supporting roll-to-roll coating without leakage of the microwave field through the coating web entry and exit ports. Navitas worked with a microwave processing company Lambda Technologies to resolve these barriers through the use of variable frequency microwaves (VFM). VFM-dried electrodes were validated by Navitas through accelerated life testing and failure analysis of prototype cells. Navitas worked closely with Lambda to design a VFM module able to support continuous web drying operation – a key challenge. Navitas installed a VFM module onto our Toyo WI pilot coating line and performed pilot scale electrode coating validation for several established commercial anode and cathode formulations to demonstrate accelerated drying with the absence of any deleterious effects on the electrode. The work by Navitas also involved the production of state of the art commercial baseline (i.e. non-VFM dried) benchmark electrodes. The VFM process showed significant advantages, with drying acceleration of >2X for NMP and >5X for water borne slurries. Thorough evaluation of adhesion, cohesion, conductivity, binder distribution etc. has shown the VFM electrode physical properties are as good as or better than the baseline (identical electrode coating passed through coater at lower speed with VFM module toggled off). The Navitas pilot coating trials validated potential cost savings and provided data for presentation to prospective commercial partners to establish confidence that existing coating lines can be retrofitted with VFM. In the course of the validation runs the Navitas team observed that VFM electrodes showed significantly less binder segregation than conventionally dried electrodes. This is attributed to the fact that VFM deposits the drying energy more uniformly in the bulk of the electrode. Uniform energy distribution enables transport of the solvent to the surface as vapor phase rather than as a liquid that drags dissolved or suspended binder to the surface where radiant/convective drying energy transfer predominates. Our observation of reduced binder segregation led to the realization that the critical-to-quality features that limit the ability to coat cathodes at loadings >5mAh/cm2 in high volume production are greatly improved in the VFM process. These limitations include poor adhesion to the current collector (binder deprivation), cracking due to residual stress (binder deprivation), and defects or performance limitations associated with excess binder at surface. Data will be presented comparing VFM electrodes to commercial state of the art electrodes for electrode loading ranging from 3 to 8 mAh/cm2 Figure 1

(Invited) Solution-Processable Li and Na Superionic Conductors for All-Solid-State Batteries

Recently, rechargeable batteries have been emerging as the key to large-scale energy storage devices. For electric vehicles (EVs), lithium-ion batteries (LIBs) are considered to be the most competitive because of their high operating voltage and light weight of electrode materials. For larger-scale applications than electric vehicles, energy grid or energy storage systems, the use of Na rather than Li may be more reasonable to satisfy the requirements of cost and environmental effects. This has leaded to the explosive research efforts on Na-ion batteries (NIBs). The success of LIBs and the promising results for NIBs are primarily indebted to development of novel electrode materials. However, their operation becomes possible by employment of liquid electrolytes in which the charge carriers, Li or Na ions, can move between negative and positive electrodes. Due to the high operating voltages of LIBs and NIBs, the electrolytes for them are based on organic liquid solvents. However, their intrinsic properties give rise to serious safety concerns such as flammability and leakage. Development of all-solid-state batteries employing inorganic solid electrolytes (SEs) is an ultimate solution to tackle the safety issues.1 Thin film all-solid-state lithium batteries (ASLBs) based on LiPON as SE is commercially available type of batteries, and exhibit excellent electrochemical performances. However, they are not suitable for large-scale applications for EVs or energy storage systems due to the high fabrication cost. In contrast, bulk-type all-solid-state batteries in which particulate mixtures of active materials, SEs, and conductive additives may compete with the LIBs because the powder-based manufacturing process similar to that for LIBs might be adaptable.1 To date, promising electrochemical performances of bulk-type ASLBs have been demonstrated by the use of state-of-the-art sulfide SE materials. The sulfide SE show not only extremely high conductivities which is comparable to that for liquid electrolytes but also excellent deformability which makes it possible to achieve two-dimensional contacts with active materials by pressing at room temperature. Despite the intrinsically good deformability of sulfide SEs, achieving full surface coverage of SEs on active materials has been hindered by restriction of synthesis protocols for SEs.2,3 A proof-of-concept that direct coating of SEs on active materials can effectively enhance the electrochemical performance of bulk-type ASLBs was demonstrated by using laser vapor deposition.4 The next step inspired by this approach should be developments of commercially meaningful protocols for SE coating. In this context, solution-process of SEs is of prime importance. However, only a few works on the wet chemistry of SEs, overlooking the possibility of its application to the SE coating, has been reported so far. This might be because of unavailability of solvents, considering the severe reactivity of sulfide materials with common solvents.3 By the aforementioned backgrounds, recently our group have succeeded to develop new, highly conductive (>10-4 S cm-1) Li-ion and Na-ion conductive solid electrolytes by scalable solution process using cheap and environmentally-benign solvents.5 The solution-process was directly applied for the SE-coating on active materials for ASLBs and ASNBs, demonstrating its excellence in enhancement of electrochemical performances. In this presentation, our recent results on solution-processable Li- and Na-ion SEs and their applications to all-solid-state Li- and Na-ion batteries will be presented. References Y. S. Jung, D. Y. Oh, Y. J. Nam, K. H. Park, Israel J. Chem. 55, 472 (2015).Y. J. Nam, S. J. Jo, D. Y. Oh, J. M. Im, S. Y. Kim, J. H. Song, Y. G. Lee, S. Y. Lee, Y. S. Jung, Y. S. Nano Lett. 15, 3317 (2015).D. Y. Oh, Y. J. Nam, K. H. Park, S. H. Jung, S.-J. Cho, Y. K. Cho, Y.-G. Lee, S.-Y. Lee, Y. S. Jung, Adv. Energy Mater. 5, 1500865 (2015).A. Sakuda, A. Hayashi, T. Ohtomo, S. Hama, M. Tatsumisago, Electrochem. Solid-State Lett. 13, A73 (2010).K. H. Park, D. Y. Oh, Y. E. Choi, Y. J. Nam, L. Han, J.-Y. Kim, H. Xin, F. Lin, S. M. Oh, Y. S. Jung, Adv. Mater. 28, 1874 (2016).

Manipulating interphases in batteries

Charge-transfer across electrolyte/ electrode interfaces dictates kinetics and reversibility of cell reactions within electrochemical devices. When the device operates beyond the thermodynamic stability limits of electrolytes, ‘interphases’ form at the interfaces [1,2]. In the pursuit of new battery chemistries that promise ambitious energy densities, electrolytes often take the blame for failing to support the cell reactions, while in most cases the real culprit is the interphase instead of the bulk electrolyte components themselves. Being able to manipulate the chemistry and morphology of such an important sub-component holds the key to the success of these new battery chemistries. Electrolytes and interphases are independent but intimately related entities, with the former serving as the chemical parent to the latter.The importance of interphase is best highlighted by lithiumion batteries (LIB), whose intercalationchemistry is made possible only with the formation of interphases during the cell activation. Although not fully recognized in pre-LIB era, interphases are prevalent in nearly all batteries operating above 3.0 V, with the venerable Li/thionyl chloride primary battery as an example [3]. It was the success of LIB that brought the science of interphases under the spotlight.The fundamental understanding achieved in the past two decades has allowed us to effectively manipulate the chemistry and properties of interphases, hence decoupling them further from bulk properties. The most extreme example is perhaps represented by the ‘Water-in-Salt’ electrolyte, where the electrochemical stability window of water was expanded to >3.0 V thanks to a designed interphase based on LiF, far beyond what Pourbaix limits (1.23 V) define for hydrogen and oxygen evolutions [4,5].This successful separation of interphases from their aqueous parental electrolyte opens an avenue to the ‘uncharted water’ of high-voltage aqueous electrochemistries [6], inspiring more aggressive manipulation of interphases for new battery chemistries. It is generally accepted now that an interphase must insulate electrons while conducting ions that are of significance to the cell reactions (such as Li+ for LIB). It was this electrolyte nature that earned it the popular name ‘SEI’ (solid electrolyte interphase) [7]. Due to significant departure of their potentials from the thermodynamic limits of electrolytes, anode surfaces in LIB induce most of the interphasial chemistry [2]. Chemical analyses on these interphase have identified the electrolyte solvents as the major chemical contributors to interphases, while the salt anion participation remains elusive. This remains true in part because of the ‘diluted’ electrolyte solutions (∼1.0 M) used in the state-of-the-art LIB, in which the Li+-solvation-sheath is sufficiently populated with solvent molecules. According to the formationmechanismproposed by Xu et al. [8–10], such a primary solvation-sheath serves as the chemical precursor of SEI via a transient ternary intercalation compound stage, so reduction of solvent molecules (mostly carbonate esters) dominates the surface chemistry (Fig. 1, left). This ‘solvent-signature’ on SEI will be reduced or even eliminated when the salt is used at unusually

Spinel materials for high-voltage cathodes in Li-ion batteries

The success of lithium-ion batteries in small-scale applications translates to large-scale applications, with an important impact in the future of the environment by improving energy efficiency and reduction of pollution. In this review, we present the progress that allows lithium-insertion compounds with the spinel structure to become the active cathode element of a new generation of Li-ion batteries, namely the 5 V cathodes, which promise to improve the technologies of energy storage and electric transportation, thereby addressing the replacement of the gasoline engine and the increasing demand for green energy power sources. The compounds considered here include the spinel LiNi0.5Mn1.5O4 and its related Cr-doped structure. Emphasis is placed on the control of physical properties that is needed to guarantee the reliability and the optimum electrochemical performance of these materials as the active cathode element of Li-ion batteries. We also report the structural evolution of the spinel phase in both charge (Li extraction) and discharge (Li insertion) reactions.