High-energy Lithium-ion Batteries Research Articles

Gradient design for Si-based microspheres as ultra-stable Li-storage anode

High-capacity Si-based microspheres are being spotlighted as a promising substitute for commercial spherical graphite anodes in the development of high-energy lithium-ion batteries. Nevertheless, the formidable challenge of their severe mechanochemical degradation during the (de)lithiation process remains unaddressed currently. Herein, we present a Si-based microsphere prepared by the oxygen pumping mechanism under a cost-efficiently low-temperature (250 °C) molten salt reduction environment. By optimally controlling oxygen gradient distribution, the resulted Si-based microspheres exhibit the unique coherent architecture ranging from ordered crystalline Si core to disordered SiO2(v) shell. Their structural coherence but regional difference in function achieves a perfect combination of structural compatibility and optimized chemo-mechanical effect, endowing the obtained Si-based microspheres with a nearly intact morphology after 1500 cycles and a 97% capacity retention after 1000 cycles at 2 A g-1. Our design broadens research directions for Si anode material design, which will accelerate the practical application of micro-sized Si anode materials.

Enhancing Stability and 6C Fast Charging in µSi||LiNi0.8Co0.1Mn0.1O2 Lithium-Ion Batteries Using Conductive Binders With Multiple Hydrogen Bonds.

Micro-sized silicon (µSi) anodes are an attractive alternative to graphite for high-energy lithium-ion batteries (LIBs) due to their low cost and high specific capacity. However, they suffer from severe volume expansion during lithiation, leading to fast capacity decay and poor rate capability. Herein, a new hybrid binder featuring a cross-linked conductive network and multiple hydrogen bonds for µSi anodes with high areal capacity is reported. This binder demonstrates multi-scale synergistic effects, including robust binder-derived solid electrolyte interphase, multiple networks to mitigate electrode pulverization and efficient ion/electron transfer pathways. As a result, the µSi anodes exhibit long-term cyclability and exceptional rate performance, achieving a high specific capacity of 1481.3 mAh g-1 at 12 A g-1 and maintaining 960.5 mAh g-1 at 20 A g-1. When paired with the LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode, the µSi||NCM811 full cell delivers an impressive capacity of 145.8 mAh g-1 under fast 6C charging conditions, along with high Coulombic efficiency during cycling. This research presents an effective strategy for enabling fast charging and stable cycling in high-energy µSi-based LIBs.

Achieving Enhanced High-Temperature Performance of Lithium-Ion Batteries via Salt-Inspired Interfacial Engineering.

Electrolyte additive engineering enables the creation of long-lasting interfacial layers that protect electrodes, thus extending the lifetime of high-energy lithium-ion batteries employing Ni-rich Li[Ni1-x-yCoxMny]O2 (NCM) cathodes. However, batteries face various limitations if existing additives are employed alone without an appropriate combination. Herein, the study reports the development of a molecular-engineered salt-type multifunctional additive, lithium bis(phosphorodifluoridate) triethylammonium ethenesulfonate (LiPENS), that leverages the different functionalities of phosphorous, nitrogen, and sulfur-embedded motifs, as well as the classical additive vinylene carbonate (VC), to construct protective interfacial layers. The thermally and electrochemically reinforced solid electrolyte interphase (SEI), achieved through the combined use of LiPENS and VC, conserves the lithiation level of the Graphite (Gr) anode with minimal SEI growth, whereas the inorganic-rich cathode-electrolyte interface (CEI) alleviates the irrevocable phase transition and mechanical fragility of the LiNi0.8Co0.1Mn0.1O2 (NCM811) secondary particles. The multifunctional roles of LiPENS are demonstrated in an NCM811/Gr full cell, showing a discharge capacity of 190.7 mAh g-1 with an enhanced capacity retention of 91.8% at 1 C and 45°C after 300 cycles. This advancement in electrolyte additive engineering based on salt structures can lead to more efficient, reliable, and commercially viable batteries for high-energy applications, including electric vehicles and portable electronics.

Hierarchically Porous Carbon Microspheres Coated with MnO2 Nanosheets as the Sulfur Host for High-Loading Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries have emerged as a promising candidate for next-generation high-energy rechargeable lithium batteries, but their practical application is impeded by the sluggish redox kinetics and low sulfur loading. Here, we report the in situ growth of δ-MnO2 nanosheets onto hierarchical porous carbon microspheres (HPCs) to form an HPCs/S@MnO2 composite for advanced lithium-sulfur batteries. The delicately designed hybrid architecture can effectively confine LiPSs and obtain high sulfur loading up to 10 mg cm-2, in which the inner carbon microspheres with a large pore volume and large specific surface area can encapsulate high sulfur content, and the outer MnO2 nanosheets, as a catalytic layer, can improve the conversion reaction of LiPSs and suppress the shuttle effect. The thick HPCs/S@MnO2 electrode with 7 mg cm-2 sulfur loading delivers an areal capacity of 4.0 mAh cm-2 at 0.1 C and provides stable cycling stability with a low-capacity decay rate of 0.063 % per cycle after 200 cycles at 0.1 C. Furthermore, a Li-S pouch cell with a capacity of 2.5 A h is fabricated and demonstrates high cycling stability. This work offers a feasible method to build advanced sulfur electrodes with high areal loading and sheds light on their commercial application in high-performance Li-S batteries.

Liquid crystal elastomer-based solid electrolyte with intelligently regulated rigidity–flexibility toward high-energy lithium batteries

Liquid crystal elastomer-based solid electrolyte with intelligently regulated rigidity–flexibility toward high-energy lithium batteries

Oxidation-state Sn species in cyclized polyacrylonitrile as stable anodes for high-energy lithium-ion batteries

Oxidation-state Sn species in cyclized polyacrylonitrile as stable anodes for high-energy lithium-ion batteries

Boron doped Ti2Nb10O29 nanosheets core/shell arrays as advanced high-energy anode for fast lithium ions storage

Titanium niobium oxide (Ti2Nb10O29, TNO) as anode for high-energy lithium ion batteries (LIBs) typically suffers from sluggish kinetics and reaction activity because of its inferior electronic/ionic conductivity and easy aggregation feature. Herein, we present a novel synergistic strategy to tackle such problems of TNO by combining boron (B) doping and porous carbon nanosheet (PCN) arrays support. Experiment results and theoretical calculations demonstrate that the doped B substantially ameliorates the intrinsic electronic/ionic conductivity of TNO, increases the oxygen vacancy content in TNO, and accelerates lithium ion diffusion. Meanwhile, high-conductive PCN arrays as growth skeleton can avoid the agglomeration of B-TNO particles. As a result, the as-prepared PCN/B-TNO anode delivers an impressive specific capacity of 303 mAh g−1 at 1 C and 104 mAh g−1 at 20 C, superior to the PCN/TNO anode. Additionally, PCN/B-TNO anode also possesses a prominent long-time durability (85 % capacity retention after 2000 cycles). Our work paves a new way of rationally constructing high-energy anodes for fast energy storage and release.

(Battery Division Postdoctoral Associate Research Award Sponsored by MTI Corporation and the Jiang Family Foundation) Advancements and Challenges of Wide Temperature Electrolytes for Next-Generation Lithium Batteries

High-energy lithium batteries are highly desired for next-generation electric vehicles, electric aviation, and renewable energy storage. Rational electrolyte design and regulated interfacial chemistry are crucial for high-energy batteries to enhance electrochemical performance. This talk will focus on electrolyte design for lithium batteries over wide-temperature operation. Understanding the limiting factors of wide temperature operation is crucial for exploiting its potential to advance rechargeable lithium batteries, yet it poses substantial challenges. Jijian will provide an in-depth analysis of interplays between solvation chemistry and interfacial reactions, dissect the failure mechanism of lithium batteries in extreme temperatures, and advocate for innovative strategies in electrolyte design and interphase engineering to enhance electrochemical performance across a wide temperature range.

Molten Salt Synthesis and Growth Mechanism of Single Crystal Ni-Rich Layered Oxides As Cathode Materials

Responding to the growing demand for high-energy lithium ion batteries (LIBs), it is crucial to develop advanced materials which offer higher energy density than currently available commercial materials. The class of Ni-rich layered oxide has attracted great interest owing to their prime advantage of high reversible capacity.[1] However, conventional polycrystalline cathodes suffer from intergranular cracking that occurs within secondary particles during repeated cycling, leading to the loss of contact between active materials and an increase in the exposed fresh surfaces to further parasitic reactions with electrolytes.[2-3] Consequently, this phenomenon results in a significant impedance rise and rapid deterioration in performance.In response to the challenge of intergranular cracking, the utilization of a single crystal morphology has been proposed as a promising solution. Studies have demonstrated that eliminating grain boundaries allows a single crystal cathode to maintain structural integrity, suppress the formation of intergranular cracks, and ultimately enhance cycle stability.[4-5] Nevertheless, ongoing debates persist regarding gas evolution and rate performances. One reason for this lies in the diverse characteristics of single crystal particles, such as particle size and shape, the degree of agglomeration, and cation disorder, all of which exert a complex influence on their properties. To effectively manage these features, a comprehensive understanding of the synthesis process and the identification of critical factors that affect the properties of single crystal Ni-rich cathodes are necessary.In this study, we elucidated the synthesis mechanism of single crystal LiNi0.95Co0.05O2 (SC95) using the molten salt synthesis (MSS) method, employing a combination of lithium hydroxide (LiOH) and lithium sulfate (Li2SO4) as a salt mixture. Through a comparative analysis of the MSS process against the solid-state synthesis, we closely examined the mechanisms governing crystal growth and morphology evolution during MSS. By conducting a comprehensive analysis, including in situ heating XRD, SEM, and EPMA, we demonstrated that the unique synthesis behavior of MSS stemmed from both the formation process of a layered structure and the grain growth of SC95 proceeded through a liquid-solid phase reaction. The maintenance of the salt mixture in a molten state during the reaction facilitated the uniform coverage of the precursor, resulting in a homogeneous reaction and effective dispersion of SC95. Based on these findings, we successfully prepared discrete micron-sized SC95 particles with monodisperse particle size distribution. The SC95 cathode exhibited superior cyclability over 150 cycles with a capacity retention of 89 % at a 1 C rate. This study provides valuable insights necessary for designing highly dispersed single crystal Ni-rich cathodes.

(General Student Poster Award Winner, 3rd Place) Toward High Performance All-solid-state Lithium Batteries with Low Volume Change V-based High-capacity Positive Electrode Materials

Toward a sustainable society through the maximum use of electric vehicles and renewable energy, the development of high energy lithium-ion batteries is urgently required. Recently, Li8/7Ti2/7V4/7O2 (LTVO), a member of the binary system of x Li2TiO3−(1−x)LiVO2, has been reported to offer a high reversible capacity of 300 mA h g–1 with a near dimensionally invariable character during charge and discharge and has been applied for the positive electrode material of all-solid-state batteries.1 However, the synthesis of LTVO requires high-temperature calcination (at 900 °C) and high-energy ball milling (at 600 rpm for 36 h) for nanosizing, and the synthesized sample is a Li deficiency phase associated with partial oxidation of V ions. In this study, the optimized synthesis process for LTVO is explored to improve the efficiency of material synthesis and suppress the loss of initial Li content in LTVO. LTVO was synthesized by calcination at various temperatures for 12 h, and a single-phase sample was obtained at ≥700 °C. In addition, efficient synthesis is achieved by shorting the heating duration to 3 h. To reduce the particle size, the sample calcined at 700 °C for 3 h was mechanically milled with different rotation speeds for 6 h. Compared with the as-prepared sample, the mechanical milled samples deliver a larger reversible capacity because the ball-milling treatment significantly reduces the particle size and shorten the migration length of Li ions in active materials. The sample milled at 450 rpm delivers a larger capacity than the sample milled at 280 rpm, but further increase in the rotation speed from 450 to 600 rpm does not affect the reversible capacity. In addition, the initial Coulombic efficiency is lower than 100% for each sample, suggesting the suppression of the formation of Li deficient phases through mechanical milling.From these results, the mechanical milling at 450 rpm for 6 h is considered to be the best condition to synthesize nanosized LTVO. The impact of synthesis conditions on electrochemical properties of LTVO and the application of optimized LTVO to all-solid-state batteries will be discussed in detail. Acknowledgment : This work has been partly supported by the projects (SOLiD-Next, JPNP23005)”, commissioned by the New Energy and Industrial Technology Development Organization (NEDO).

(Invited) A Study of Si-based Metallic Glass Anodes for Li-ion Batteries

Silicon has been considered a promising low-cost negative electrode material for high-energy lithium-ion batteries due to its high gravimetric (400 Wh kg–1) and volumetric energy density (> 800 Wh L–1), low operating voltage (~0.3 V) and abundance in the Earth crust. During the past decades, development of Si-based negative electrodes has been greatly accelerated by modification of morphology, size, composition, and surface engineering. Accordingly, the cycle life of Si-based cells has improved dramatically over the years and is now approaching performance targets showing > 300 Wh kg–1 even after 1,000 cycles. However, as Si is gradually adopted into commercial batteries, the calendar life of the Si-based cells with high silicon content (>40%) is identified to be insufficient (1-2 years) and thus represents a major roadblock to widespread deployment. Interfacial instability of silicon in organic carbonate carbonate electrolytes and continuous electrolyte decomposition lead to a gradual electroyte consumption and shift of active lithium inventory in the cell. A steady growth of the SEI layer accompanies is linked with active lithium loss, which causes severe cell capacity fade and impedance rise. To prevent such a Si negative electrode and cell degradation mechanism, it is essential to exercise better control over the kinetics of electrolyte reduction and SEI layer formation process.Among various approaches to improve the interfacial as well as mechanical stability of silicon, embedding metallic inactive phases into amorphous Si matrix was widely studied. Dahn et al. has demonstrated this idea through a series of studies of over 200 different Si-based amorphous alloys1-3. Amorphous Si-alloys suppress two-phase coexistence of the Li-rich and Li-poor phase which leads to lattice mismatch and crack propagation. Thus, amorphous alloy films showed better capacity retention with less swelling and particle collapse. Furthermore, the inactive metal matrix serves as a buffer for the large volume expansion of Si (~280%), thus improving cycle stability without a significant decrease in the volumetric energy density.In this study we report on the synthesis and evaluation of Silicon-Me amorphous alloys (Me: Ni, Cu, Mn, Ti, Fe) for applications as negative electrodes in high-energy density Li-ion batteries with improved calendar life. Numerous Si-Me metallic glass alloy model electrodes were synthesized, using ultra-fast laser and splat quenching techniques to screen, evaluate, and optimize their electrochemical performance with a focus on the long-term interfacial stability in Li-ion batteries. Si0.85Ni0.15 has emerged as the best performing metallic glass alloy composition and its fabrication was successfully scaled-up with melt spinning technique. The melt-spun Si0.85Ni0.15 thin ribbon was ball-milled into fine powder to be used in conventional composite electrode fabrication for Li-ion batteries. Metallic glass Si0.85Ni0.15 anode showed improved passivation behavior and outperformed a conventional nano-sized Si electrode in both cycle and calendar life tests.AcknowledgementsThis research was supported by the US Department of Energy (DOE)’s Vehicle Technologies Office under the Silicon Consortium Project directed by Brian Cunningham and managed by Anthony Burrell. The work at the Molecular Foundry was supported by the Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract no. DE-AC02-05CH11231. This research also used resources of the Advanced Light Source, a U.S. DOE Office of Science User Facility under contract no. DE-AC02-05CH11231; in particular, Beamline 2.4 was used. Melt-spinning production rates and metrics are provided from ECO FM Co. References Fleischauer, M. D.; Dahn, J. R., Combinatorial Investigations of the Si-Al-Mn System for Li-Ion Battery Applications. J. Electrochem. Soc. 2004, 151 (8), A1216.Hatchard, T. D.; Topple, J. M.; Fleischauer, M. D.; Dahn, J. R., Electrochemical Performance of SiAlSn Films Prepared by Combinatorial Sputtering. Electrochemical and Solid-State Letters 2003, 6 (7), A129.Fleischauer, M. D.; Topple, J. M.; Dahn, J. R., Combinatorial Investigations of Si-M (M = Cr + Ni, Fe, Mn) Thin Film Negative Electrode Materials. Electrochemical and Solid-State Letters 2005, 8 (2), A137.

Direct Contact Prelithiation of Silicon-Dominant Anodes Using Ultra-Thin Lithium Foils

With the steady growth of the electric vehicle market, the development of high-energy-density lithium-ion batteries is increasingly coming into focus. Silicon has a nearly ten times higher specific capacity for lithium storage than conventionally used graphite, making silicon a promising anode material for high-performance lithium-ion battery applications[1]. However, silicon shows a high volume expansion upon lithiation, leading to a rapid capacity fade due to the loss of active lithium associated with continuous solid electrolyte interphase formation[2]. Direct contact prelithiation is a method to compensate for the loss of active lithium by incorporating additional lithium metal during battery cell production. The use of lithium foil is a facile approach but depends on the availability of ultra-thin lithium foils[3].In this study, silicon-dominant anodes with a silicon content of ca. 70 % were prelithiated by lithium foils with a thickness of 5 and 10 µm using a calendering process. A glove box integrated calender under an argon atmosphere was used to transfer the ultra-thin lithium foils from a carrier foil on the entire anode surface. This facilitates a homogenous prelithiation of the anode and equal compression force over the entire anode surface. A process study was conducted to find suitable process parameters for the full-surface lithium foil application on the anodes. The formed anode-lithium-composite was investigated with and without the presence of an electrolyte. Pouch cells with nickel-rich cathodes were built to show the performance improvement through the presented prelithiation technique in the full cell setup.An increase of 16 % in full cell capacity shows the potential of direct contact prelithiation to boost the energy density of already high-energy lithium-ion battery material systems. The incorporated lithium metal compensates for the loss of active lithium and thereby enhances the cycle life of the battery cells, making the proposed prelithiation method an enabler for the use of silicon-dominant anodes for high-performance applications.

Surface Engineering of LiNi0.8Co0.1Mn0.1O2 By Ultrathin Al2O3 Via Atomic Layer Deposition

Nickel-rich Li(NixCoyMn1-x-y)O2 (NCM) is considered one of the most promising cathode materials for next-generation high-energy lithium-ion batteries (LIBs). However, nickel-rich NCM suffers from short battery lifespan, poor rate performance, and structural instability during cycling due to side reactions between the cathode material and the electrolyte. To overcome the aforementioned problems, coating the surface of nickel-rich NCM powders is an efficient and straightforward strategy. In recent years, atomic layer deposition (ALD) has been gaining attention for its utility in preparing LIB electrode materials. Compared to traditional coating methods, ALD can form uniform and ultrathin coating layers, which protect the cathode from reactions with the electrolyte while maintaining electrical conductivity and fast electron transport. More importantly, this process is energy-efficient, rapid (taking only a few minutes), and does not damage the electrode. Nevertheless, attempts to directly deposit ALD coatings onto nickel-rich NCM composite electrodes to enhance the electrochemical performance of NCM have not been widely reported.This study provides an efficient technique based on ALD to enhance the electrochemical performance of Ni-rich NCM cathode materials. The surface of the Li(Ni0.8Co0.1Mn0.1)O2 (NCM811) composite electrode was directly coated with a high-quality ultrathin layer of aluminum oxide (Al2O3). The thickness of the coating layer was precisely controlled at the sub-nanometer scale by the number of ALD cycles. It could protect the surface of the active NCM811 powder and maintain interparticle electron pathways, thereby enhancing electrochemical performance. The optimal thickness of the Al2O3 coating for maximizing the electrochemical performance of NCM811 was grown via 10 ALD cycles. The ALD-based ultrathin Al2O3 coating on the NCM811 was performed using a rotary ALD system. The morphology of the samples was confirmed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Energy-dispersive X-ray spectroscopy (EDS) elemental mapping was collected in scanning transmission electron microscopy (STEM) mode. X-ray diffraction (XRD) patterns were collected using X-ray powder diffraction equipment. The chemical composition of the coating was analyzed using X-ray photoelectron spectroscopy (XPS) with Al Kα radiation. Cell testing was conducted using a coin-type half-cell with lithium metal as the anode.

Cobalt-Free Layered Nickel Oxides with Antisite Defects for Long-Lived Lithium-Ion Batteries

Toward the realization of sustainable society, the development of high-energy lithium-ion batteries is required. LiNiO2 is considered a promising positive electrode candidate owing to its high capacity. However, the gradual loss of electrode reversibility at high voltage region coupled with Ni migration to tetrahedral site on charging is observed on cycling.1 In this study, to improve electrode reversibility of LiNiO2, Li- deficient Li1–x Ni1+x O2 are synthesized and their electrochemical properties were examined. Stoichiometric LiNiO2 and Li-deficient Li1–x Ni1+x O2 were synthesized by mixing LiOH・H2O and Ni(OH)2 and calcined for 12 h at 650 oC under oxygen atmosphere. As shown Figure 1, Li deficiency significantly reduces particle size and crystallinity. In addition, the peak intensity ratio of 003 and 104 diffraction lines is decreased as Li content decreases, which indicates the increase of Ni ion occupation in Li layers. Compared with stoichiometric LiNiO2, Li deficient samples deliver a smaller discharge capacity, but higher electrode reversibility is achieved (Fig. 2). These facts suggest that Ni migration to adjacent tetrahedral sites is effectively suppressed by the presence of extra Ni ions in Li layers for the Li-deficient samples, leading to the high electrode reversibility.2 The impact of Li deficiency on electrochemical properties of LiNiO2 will be discussed in detail. N. Ikeda et al., and N. Yabuuchi, J. Mater. Chem. A, 9, 15963 (2021).I. Konuma et al., and N. Yabuuchi, Energy Stor. Mater. 66, 103200 (2024). Figure 1

Synergistic doping chemistry enable the cycling properties of single-crystal Ni-rich cathode for lithium-ion batteries

Nickel-rich cobalt-low layered oxides have attracted much attention as positive electrode materials for high-energy lithium-ion batteries due to their high capacity and low cost, but their inherent stress accumulation and severe cationic mixed reactions will deteriorate the cycling performance. Herein, the nickel-rich single-crystalline LiNi0.90Co0.06Mn0.04O2 cathode material doped with W and Mg (NCM-WM) has been fabricated to overcome its structure degradation issues. It can be found that the Li/Ni cation mixture can be suppressed by the introduction of Mg2+ into Li+ situs and the replacement of transition metal ions by W6+. Meanwhile, the co-doing strategy synergistically depresses the irreversible H2-H3 phase transition to weaken the internal stress, and employs the heteroatoms as the pillar ions to prevent layer structure collapse. In addition, the reduced particle size induced by the W6+ and increased free electron resulted by Mg2+ can cooperatively improve the migration kinetics of ions and electrons in the process of cycling. As expected, the above advanced effects result in the prominent cycling properties (capacity retention of 86.7 %, 150 cycles, 2C) of the designed Ni-rich electrode materials. These results demonstrate that the co-doped design is a greatly effective strategy to reinforce the cycling performance of Ni-rich single-crystalline materials.

Looking into failure mode identification driven by differential capacity in Ni-rich layered cathodes

Nickel-rich layered cathodes are one of the ideal electrode materials for high-energy lithium-ion batteries, yet suffer from capacity decay and structural degradation during cycling. Although the degradation mechanisms of electrode materials are flourishing, the analysis of performance decay and physicochemical properties dynamic evolution during cycling have not been well developed. Here, we propose a coupling analysis strategy based on differential capacity that distinguishes the failure behavior of electrode materials during cycling by the characteristic evolution of the dQ dV–1 curve recorded cycle-by-cycle. By coupling in-situ electrochemical tests with differential capacity characterization and comparing them with electrochemical characteristics recorded at different aging upper cut-off voltages cycles, the capacity decay mechanism and physicochemical properties evolution of electrode materials can be dynamically analyzed. The potential failure modes include loss of active Li inventory (LALI), loss of active structure integrity (LASI), and various dominant combinations of these factors. In addition, the distinction of aging behavior can also be applied to the failure level classification of spent electrode materials. Our findings demonstrate a general strategy for analyzing the dynamic failure mechanisms of electrode materials, thereby offering valuable insights for subsequent technology route selection in terms of recycling and reuse.

An ethylene carbonate/propylene carbonate electrolyte for improved cycle life and safety of silicon-graphite/NMC (Ni = 80–83 %) high-energy lithium-ion battery cells

High energy Silicon-Carbon (Si-C) electrodes have been paired with ‘high Nickel’ NMC cathodes and used to optimize a ‘linear alkyl carbonate-free’ electrolyte. The optimization was conducted via the screening of 23 electrolyte formulations using two sets of silicone carbon composite electrodes in coin cells. The best electrolyte formulation was then ‘validated’ in a setting closer to their final application, using single layer pouch cells and a commercial surfactant coated separator to solve the wetting issue met with this family of electrolytes with both conventional and ceramic coated separators. Despite its lower rate capability above 1C, this electrolyte allows a 45 % increase of the capacity retention in pouch cell with a 9 % Si-C-based anode and a NMC83 cathode. The safety of the electrolyte is also improved markedly. During cycling up to 4.3V and 5.0V, the total volume of hydrogen evolved was reduced more than 3.6 times over 3 cycles for the electrolyte free of linear carbonates. In fine, accelerating rate calorimetry shows that the use of these electrolytes improves the overall cell safety for this electrolyte, which shows that, for high energy applications, EC/PC electrolytes with the right additive combination can allow both longer cycle life and improved safety.

Remote SOC and SOH Estimation of High Energy Lithium Batteries Based on Dual-Mode Extended Kalman Filter Algorithm

Lithium battery, as its main power source, needs to ensure the safety of drivers and passengers not only under some complex external conditions, but also under harsh use conditions, even when damaged. At some point throughout this process, it is required to evaluate the status of the battery itself in order to assure safe usage of the battery and to develop a more effective battery management plan. SOC, SOH, and condition of power are all variables that are commonly used to describe the state of a lithium battery (SOP). The ability of the battery to constantly provide or receive power, the remaining service the life cycle of the battery, and the ability of the battery to output or receive power promptly are all described by these three characteristics. In order to effectively evaluate the health status of batteries, this paper proposes a dual-mode extended Kalman filter (EKF) algorithm for the remote estimation of SOC and SOH of high-energy lithium batteries. In the estimating procedure, the open circuit voltage (OCV) is also included as a state variable in the iterative process, which allows for more accurate results. In this paper, the state space equation is established based on the first-order RC equivalent circuit model, and the battery state estimation and parameter identification are completed by using the double EKF (the dual extended Kalman filtering, DEKF) algorithm, resulting in the realization of the estimation of SOC and SOH.

Surface Reconstruction Reduces Internal Stress of Ni-Rich Cathode Particles.

High-voltage Ni-rich layered cathode materials are undoubtedly a powerful driving force for high-energy density lithium batteries. However, residual lithium impurities on the surface of Ni-rich materials can cause more severe side reactions under high-voltage, leading to rapid decay. There is still no reliable mechanistic explanation for this phenomenon. It has been detected that residual alkali on the cathode surface under high voltage can cause obvious side reactions. This side reaction will affect the capacity retention of the material and increase the internal stress of the particles. In addition, the surface reconstruction of Ni-rich cathodes is achieved through simple chemical reactions, turning waste into treasure. The newly generated Ti-based layer not only repairs the structure of the nickel-rich material but also optimizes the material from a dynamic perspective. Removing residual lithium components on the cathode surface effectively reduces the hydrolysis and self-catalytic side reactions of PF6 - at the electrolyte cathode interface and suppresses gas generation during cycling, promoting the application of the next generation of high-energy density Ni-rich layered cathode-based lithium batteries with high-voltage.

Artificial Electron Channels Enable Contact Prelithiation of Li-Ion Battery Anodes with Ultrahigh Li-Source Utilization.

Contact prelithiation is widely used to compensate for the initial capacity loss of lithium-ion batteries (LIBs). However, the low utilization of the Li source, which suffers from the deteriorated contact interfaces, results in cycling degeneration. Herein, Li-Ag alloy-based artificial electron channels (AECs) are established in Li source/graphite anode contact interfaces to promote Li-source conversion. Due to the shielding effect of the Li-Ag alloy (50 at. % Li) on Li-ion diffusion, the dry-state interfacial corrosion is restricted. The unblocked electronic conduction across the AEC-involved interface not only facilitates the Li-source conversion but also accelerates the prelithiation kinetics during the wet-state process, resulting in an ultrahigh Li-source utilization (90.7 %). Implementing AEC-assisted prelithiation in a LiNi0.5Co0.2Mn0.3O2 pouch cell yields a 35.8 % increase in energy density and stable cycling over 600 cycles. This finding affords significant insights into the construction of an efficient prelithiation technology for the development of high-energy LIBs.