Dissolution Of Transition Metal Ions Research Articles

Constructing sulfur-rich interphase to promote the cycle stability of graphite/LiNi0.8Co0.1Mn0.1O2 pouch battery at elevated temperature

Lithium-ion batteries (LIBs) with LiNi0.8Co0.1Mn0.1O2 (NCM811) cathodes have a high energy density, but their long-cycle performance, especially at high temperature, should still be improved due to the instability of the NCM811 cathode-electrolyte interphase. In this work, 2, 2, 2-Trifluoroethyl p-Toluenesulfonate (TPTS) is introduced as a functional film-forming electrolyte additive design to improve the long-term stability of graphite/NCM811 batteries. The preferential redox reactions of TPTS molecules play a pivotal role in fostering the creation of a sulfur-riched interphase, characterized by low impedance. This interphase works to fortify the interfacial structure, effectively inhibiting the dissolution of transition metal ions. Therefore, in comparison to the graphite/NCM811 pouch batteries lacking additive, TPTS enhance the long-cycle capacity retention from 47 % to 80 % after 450 cycles at 45 °C. What's more, TPTS suppresses outgassing and demonstrates enhanced capacity maintenance for the battery even after storage at 60 °C. This work not only demonstrates the stabilizing impacts of TPTS on the electrode-electrolyte interphase and its enhancement of cycling performance at elevated temperatures but also introduces a novel approach for the practical utilization of functional electrolytes matching high-nickel LIBs.

Quenching-Induced Ultrathin LiF-Rich Interphases on LiNi0.8Co0.1Mn0.1O2 Cathode

Nickel-rich layered oxides (NCM) are a promising contender material for the cathode electrode of high-energy lithium-ion batteries (LIBs) due to their large reversible capacity and high operating voltage. However, the poor surface/interfacial stability and the dissolution of transition metal ions hinder the commercial application of NCM. To create an artificial cathode electrolyte interphase (CEI) with LiF-rich inorganic phase on the NCM surface, a practical and efficient way of quenching the NCM powder from high temperature in 1,1,2,2-Tetrafluoroethyl 2,2,2-trifluoroethyl ether (HFE) was devised. With this artificial CEI film, the side reactions between NCM and electrolytes are inhibited, and the dissolution of TM ions is retarded. The quenched-NCM achieved fantastic cycling performance and suppressed voltage decay. Our research offers an efficient and worthy approach for improving the surface/interfacial stabilization of nickel-rich cathode materials for high-energy-density LIBs.

High-performance lithium batteries achieved by electrospun MXene-Enhanced cation-selective membranes

Conventional separators applied in lithium batteries face limitations like low porosity, poor electrolyte wettability, lower cation selectivity, and thermal instability, which impact battery performance and safety characteristics. Besides the challenge in separator design, transition metal ion migration from positive electrodes during cycling greatly accelerates capacity fading because of unrestricted diffusion of transition metal cation across the separator. This study explores an innovative strategy for the separator design by incorporating MXene (spraying MXene solution on both sides of the separator), a two-dimensional material, into electrospun Polyacrylonitrile/Polyetherimide membranes with the function of cation selection. Li+ can be accelerated, and its transference number increases along with the anion limitation in the MXene layer. Ni, Co, and Mn ion dissolution from the positive electrode is inhibited due to the cation selectivity of the MXene layer. Leveraging electrospinning advantages, the resultant membranes exhibit high porosity, excellent liquid absorption, mechanical strength, and superior thermal properties. Benefiting from MXene's layered structure and excellent adsorption ability, the membrane significantly inhibits the dissolution of transition metal ions while enabling smooth lithium deposition due to its cation selectivity. Eventually, the Li||NMC811 batteries deliver outstanding cyclic performance (91.3 % capacity retention after 200 cycles) and robust lithium dendrite suppression (800 h of stable cycling). Moreover, the MXene-modified membrane demonstrates exceptional electrolyte wettability, significantly improving ionic transference number (0.67) and conductivity (1.6 mS/cm). Modification of membrane surfaces with MXene offers insights into addressing transition metal ion migration from the positive electrode material perspective, providing a promising avenue for high-performance LIBs.

Molecular design of highly Li-ion conductive cathode-electrolyte interface enabling excellent rate performance for lithium-ion batteries

The structural stability and ionic conductivity of the cathode electrolyte interface (CEI) film at high voltages are crucial to the nickel-rich layered cathode in Li-ion batteries (LIBs). These characteristics are largely determined by electrolyte components. Herein, an air-stable organic cyclophosphate salt named lithium 1, 3, 2-dioxaphosphinan-2-olate-2-oxide (LiDOP) is designed and synthesized as a CEI forming additive. It preferentially oxidizes and undergoes opening-ring polymerization under charging to form an organic–inorganic hybrid polymers with –LiPO4 segments and –(CH2)3– alternately connected on the cathode surface. Such a structure endows CEI film with high ionic conductivity, flexibility and mechanical strength, which can ameliorate the structure phase transformation, suppress the transition metal ion dissolution and enhance the interfacial stability at high cut-off voltage. The electrolyte with 0.2 wt% LiDOP endows 4.3 V-charged Li||LiNi0.8Co0.1Mn0.1O2 battery with 83.2 % capacity retention after 200 cycles at 5C rate. The graphite||NCM811 pouch cell shows a capacity retention of 85.6 % after 150 cycles under a 4.5 V voltage, while the cell without LiDOP shows only 23.5 %. Our work demonstrates the effectiveness of covalently coupled P-O-Li compounds as CEI film in stabilizing the interface, which provides a guidance for the electrolyte design in high-voltage LIBs.

Sodium Difluoro(oxalato)borate Additive‐Induced Robust SEI and CEI Layers Enable Dendrite‐Free and Long‐Cycling Sodium‐Ion Batteries

AbstractSodium‐ion batteries (SIBs) are a promising candidate for large‐scale energy storage due to the low cost and abundant sodium resources. However, the formation of sodium dendrites on the surface of hard carbon (HC) anodes is the most intractable challenge for full cells during charging, leading to severe performance degradation and safety hazards. Here, a robust additive‐induced borate and fluoride‐rich interphase is constructed by introducing sodium difluoro(oxalato)borate (NaDFOB) as additive in the ether‐based electrolyte to relieve the performance deterioration for SIBs. NaDFOB can participate in the passivation process of electrolyte‐electrode interfaces through preferential oxidation and reduction of DFOB− to effectively restrain the growth of sodium dendrites. Moreover, the electrolyte decomposition and dissolution of transition metal ions are effectively inhibited. Benefiting from that, FeMn‐based Prussian blue (FeMnHCF) || HC full cell with a negative/positive capacity ratio (N/P ratio) of 1.09 displays a capacity retention of 82.1%, especially with a low N/P ratio of 0.96 the cell still demonstrates a stable Coulombic efficiency of over 99.9% after 500 cycles via using NaDFOB as additive. As a practical demonstration, the designed 18650 full cells display enhanced cycling stability with NaDFOB additive. The findings provide insights into the additive‐induced inorganic‐rich interfacial layers for dendrite‐free SIBs.

Unlocking Electrode Performance of Disordered Rocksalt Oxides Through Structural Defect Engineering and Surface Stabilization with Concentrated Electrolyte

Abstract Li‐excess cation‐disordered rocksalt oxides can boost the energy density of rechargeable batteries by using anionic redox, but the inferior reversibility of anionic redox hinders its use for practical applications. Herein, a binary system of Li3NbO4–LiMnO2 is targeted and the systematic study on factors affecting electrode reversibility, i.e., percolation probability, electronic conductivity, defect concentrations, and electrolyte solutions, is conducted. A Mn‐rich sample, Li1.1Nb0.1Mn0.8O2, delivers a smaller reversible capacity compared with a Li‐rich sample, Li1.3Nb0.3Mn0.4O2, because of the limitation of ionic migration associated with insufficient percolation probability for disordered oxides. Nevertheless, a larger reversible capacity of Li1.3Nb0.3Mn0.4O2 originates from excessive activation of anionic redox, leading to the degradation of electrode reversibility. The superior performance of Li1.1Nb0.1Mn0.8O2, including Li ion migration kinetics and electronic transport properties, is unlocked by the enrichment of structural defects for nanosized oxides. Moreover, electrode reversibility is further improved by using a highly concentrated electrolyte solution with LiN(SO2F)2 through the surface stabilization on high‐voltage exposure. Superior capacity retention, >100 cycles, is achieved for nanosized Li1.1Nb0.1Mn0.8O2. The electrolyte decomposition and surface stabilization mechanisms are also carefully examined, and it is revealed that the use of highly concentrated electrolyte solution can effectively prevent lattice oxygen being further oxidized and transition metal ion dissolution.

Dual LiF/LiCl‐Rich Solid Electrolyte Interphases with Robust and Li+‐conductive Characteristics for 4.8 V Lithium Metal Batteries

AbstractLithium metal batteries, which are constructed by lithium‐rich manganese‐based oxide (LRMO) cathode and Li metal anode, have attracted intensive attention due to its high energy density. However, the instability of both cathode and anode limits the practical application due to undesirable electrolyte decomposition at high voltage. To address these issues, an electrolyte engineering strategy is proposed for constructing robust, highly Li+‐conductive solid electrolyte interphases on both cathode and anode with chlorobenzene as the additive. Due to the high mechanical stability and interface dynamics of the LiCl‐endorsed, LiF‐rich cathode electrolyte interphase, both the electrolyte decomposition and transition metal ion dissolution are effectively inhibited. Meanwhile, robust LiF/LiCl‐rich solid electrolyte interphase can effectively repress the overgrowth of Li dendrites. The Li||LRMO battery with optimized 2.0 wt.% chlorobenzene demonstrates a high‐capacity retention of 86.1% after 200 cycles at 0.5 C.

Advanced TiO2/Al2O3 Bilayer ALD Coatings for Improved Lithium-Rich Layered Oxide Electrodes.

Surface modification is a highly effective strategy for addressing issues in lithium-rich layered oxide (LLO) cathodes, including phase transformation, particle cracking, oxygen gas release, and transition-metal ion dissolution. Existing single-/double-layer coating strategies face drawbacks such as poor component contact and complexity. Herein, we present the results of a low-temperature atomic layer deposition (ALD) process for creating a TiO2/Al2O3 bilayer on composite cathodes made of AS200 (Li1.08Ni0.34Co0.08Mn0.5O2). Electrochemical analysis demonstrates that TiO2/Al2O3-coated LLO electrodes exhibit improved discharge capacities and enhanced capacity retention compared with uncoated samples. The TAA-5/AS200 bilayer-coated electrode, in particular, demonstrates exceptional capacity retention (∼90.4%) and a specific discharge capacity of 146 mAh g-1 after 100 cycles at 1C within the voltage range of 2.2 to 4.6 V. The coated electrodes also show reduced voltage decay, lower surface film resistance, and improved interfacial charge transfer resistances, contributing to enhanced stability. The ALD-deposited TiO2/Al2O3 bilayer coatings exhibit promising potential for advancing the electrochemical performance of lithium-rich layered oxide cathodes in lithium-ion batteries.

Interface engineering strategy via electron-defect trimethyl borate additive toward 4.7 V ultrahigh-nickel LiNi0.9Co0.05Mn0.05O2 battery

The Li metal battery with ultrahigh-nickel cathode (LiNixM1−xO2, M = Mn, Co, and x ≥ 0.9) under high-voltage is regarded as one of the most promising approaches to fulfill the ambitious target of 400 Wh/kg. However, the practical application is impeded by the instability of electrode/electrolyte interface and Ni-rich cathode itself. Herein we proposed an electron-defect electrolyte additive trimethyl borate (TMB) which is paired with the commercial carbonate electrolyte to construct highly conductive fluorine- and boron-rich cathode electrolyte interface (CEI) on LiNi0.9Co0.05Mn0.05O2 (NCM90) surface and solid electrolyte interphase (SEI) on lithium metal surface. The modified CEI effectively mitigates the structural transformation from layered to disordered rock-salt phase, and consequently alleviate the dissolution of transition metal ions (TMs) and its “cross-talk” effect, while the enhanced SEI enables stable lithium plating/striping and thus demonstrated good compatibility between electrolyte and lithium metal anode. As a result, the common electrolyte with 1 wt% TMB enables 4.7 V NCM90/Li cell cycle stably over 100 cycles with 70% capacity retention. This work highlights the significance of the electron-defect boron compounds for designing desirable interfacial chemistries to achieve high performance NCM90/Li battery under high voltage operation.

Surface Engineering through In Situ Construction of CoxB‐Spinel Dual Coating Layers for High‐Voltage Stable Sodium‐Ion Batteries

AbstractTransition metal layered oxides (NaxTMO2), boasting a high theoretical specific capacity and affordability, have emerged as prominent cathodes for sodium‐ion batteries (SIBs). Their potential, however, is hindered when operating at higher voltage range (4.0–4.3 V) due to irreversible phase transition, heterogeneous surface reconstruction, and side reaction. Herein, using a straightforward room‐temperature liquid‐phase reductive method, a dual conformal protective layer is in situ constructed on the surface of NaNi1/3Fe1/3Mn1/3O2(NFM). This layer comprises both a spinel structure and an amorphous CoxB coating, thereby achieving a layered‐spinel‐CoxB configuration. The spinel structure provides 3D Na+ transport channels and works as a pillar to anchor the intrinsic layered structure. Simultaneously, the external CoxB layer effectively mitigates O loss, transition metal ion dissolution, and undesired side reactions on the surface. Benefiting from the synergistic effects on both the material's bulk and surface, the 1wt% CoxB coated cathode displays superior stability. After 300 cycles, the capacity retention is 79.6% between 2 and 4 V, significantly outperforming pristine‐NFM's(p‐NFM) 51.4%. When charged to 4.3 V, its capacity retention stands at 70%, much higher than that of p‐NFM (51.2%). This work provides new insights into exploiting high‐voltage stable cathode through constructing a dual conformal protective layer for high energy density SIBs.

Insight into Nb-sbustitution effects on Li1.17Mn0.57Ni0.24Nb0.02O2 cathode material for lithium-ion batteries application

Lithium-rich layered oxides (LLOs) have been intensively studied due to their high energy density, but still face the drawbacks such as capacity decay and voltage decay, and poor cycling stability. In this work, the Nb substituted Li1.17Mn0.57Ni0.24Nb0.02O2 (LMN-Nb) is successfully prepared, and the effects of Nb substitution on the microstructure, voltage attenuation, cycling stability and electrochemical kinetics are characterized and investigated compared with the host material Li1.17Mn0.58Ni0.25O2 (LMN). A proper amount of Nb substitution not only extends the interlayer spacing and increases conductivity of LMN-Nb, but also inhibits the release of lattice oxygen, the migration of transition metal ions into lithium layer and the dissolution of transition metal ions in the electrolyte. As a result, LMN-Nb exhibits significantly improved initial coulombic efficiency, specific capacity and excellent cycling stability (99.1 % remaining after 150 cycles at 2C rate). In addition, the LMN-Nb also shows good electrochemical performance in pouch-type cell (full cell). This results demonstrate that the strategy of using 4d/5d transition metals substitution to design high-performance LLOs is feasible in the following work.

(Invited) First Principles Examination of Multiple Criteria of Organic Solvent Oxidative Stability in Batteries

Oxidative instability of the liquid electrolyte at or near battery cathode oxide surfaces has significant detrimental effects on batteries. Organic solvent molecules are often the fuel and precurors of such degradation processes, releasing electrons and protons that react with cathode oxides and electrolyte anions. These reactions contribute to cathode electrolyte interphase (CEI) film formation, transition metal ion dissolution, and phase transformation of the surface regions of the cathode. Here we apply Density Functional Theory calculations to examine four criteria of oxidative stability (oxidation potential, hydrogen removal energies, and initial reactivity on two types of oxide facets) using four different solvent/additive molecules (ethylene carbonate, fluoroethylene carbonate, 1,3-dioxolane, and dimethyl ether). The ranking of molecular stability differs with each criterion. Surprisingly, the all-oxygen terminated basal planes of layered oxides exhibit lower reaction barriers than spinel surface facets with exposed transition metal cations, especially for ether solvents; the calculations also suggest basal planes contribute to the dissolution of transition metal ions. The structure-degradation relation complexity underscores the challenge of understanding the function of the CEI, but also offers a guide to future degradation-mitigation strategies including facet-engineering. Our predictions and models help establish a framework for future studies relevant to high voltage conditions.Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525. This paper describes objective technical results and analysis. Any subjective views or opinions that might be expressed in the document do not necessarily represent the views of the U.S. Department of Energy or the United States Government.

Anionic Additive-Integrated Electrolyte Therapy: Enhancing High-Voltage Stability and Performance in Lithium-Ion Batteries

Significant endeavours have been undertaken to advance the development of eco-friendly, abundant, cost-effective, and high-performance cathode materials for lithium-ion batteries. Among the various contenders for next-generation energy storage systems, spinel LiNi0.5Mn1.5O4 has emerged as a leading high-voltage cathode candidate, owing to its aforementioned benefits. Nonetheless, the widespread adoption of LNMO-based lithium-ion batteries is substantially impeded by the electrochemical instability of conventional carbonate electrolytes above 4.5 V. High-voltage cycling of such batteries results in rapid capacity degradation and metal-ion dissolution from the LNMO electrode into the electrolyte, particularly at elevated temperatures, further causing deposition of metal-ions on anode electrode. Therefore, stabilizing the electrode/electrolyte interface is crucial to achieve improved electrochemical performance of the Li-ion cell at high voltages. The utilization of sacrificial electrolyte additives is regarded as a straightforward and efficacious method to accomplish this objective. These additives form a protective layer on the cathode surface, mitigating electrolyte decomposition and transition metal-ion dissolution and deposition on anode’s surface. Various additives facilitating high-voltage cathode materials have been documented, encompassing fluorides and sulfonates. However, borate salt-containing additives are particularly promising within this context.In the present study, we endeavour to elucidate the surface modifications transpiring on the electrode’s surface when minute quantities of borate-based salt are employed as an additive in the conventional EC:EMC electrolyte for high-voltage operation. We explored the impact of the additive salt in a standard LiPF6-EC/EMC base electrolyte on the discharge capacity and rate performance of the LiNi0.5Mn1.5O4/Graphite based Li-ion cell. The electrochemical behaviour, morphological behaviour, and electrode-electrolyte interphase layer stability on the electrode were meticulously examined using high-resolution transmission electron microscopy (HR-TEM), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). These characterisations conformed the presence of an electrode-electrolyte interface forming a thin-layer via the sacrificial decomposition of the utilised additive. The introduction of this salt exhibits favourable effects on enhancing the electrochemical performance of the LiNi0.5Mn1.5O4/Graphite in high-voltage lithium-ion batteries. Notably, the utilised additive excels in mitigating irreversible capacity loss and reducing cycling fade, as it preferentially decomposes and forms a conductive, protective film that impedes subsequent electrolyte decomposition, thereby substantially enhancing cell performance.

Potassium Selenocyanate (KSeCN) Additive Enabled Stable Cathode Electrolyte Interphase and Iron Dissolution Inhibition toward Long‐Cycling Potassium‐Ion Batteries

AbstractPotassium‐ion batteries (KIBs) are promising energy storage devices owing to the close redox potential of potassium (K) to lithium and rich abundance of K resource, thus promoting the exploration of efficient cathode materials for K‐ions storage. Fe‐based Prussian blue analogues (KFeHCF) are promising cathode materials for KIBs due to their combined advantages in low cost and high energy density. However, the rapid capacity decay induced by unstable cathode electrolyte interphase (CEI) and dissolution of transition metal ions leads to limited lifespans (e.g., hundreds of cycles) of K∥KFeHCF batteries. Incorporating additives into electrolytes is an economical and effective way to construct robust CEI for high‐performance KIBs. Herein, a multifunctional electrolyte additive, potassium selenocyanate (KSeCN), is introduced to effectively construct stable, homogeneous and conductive CEI films, which leads to the inhibition of Fe dissolution and stabilization of KFeHCF structure during cycling. With 0.5 wt% of KSeCN in conventional carbonated electrolyte, the K∥KFeHCF battery exhibits promoted cycling performance with a capacity retention rate of 87% after 500 cycles at 4.5 V cutoff voltage. This finding provides a new paradigm for developing and designing potassium‐ion battery electrolytes.

Surface Modification Driven Initial Coulombic Efficiency and Rate Performance Enhancement of Li1.2 Mn0.54 Ni0.13 Co0.13 O2 Cathode.

Due to its high energy density and low cost, Li-rich Mn-based layered oxides are considered potential cathode materials for next generation Li-ion batteries. However, they still suffer from the serious obstacle of low initial Coulombic efficiency, which is detrimental to their practical application. Here, an efficient surface modification method via NH4 H2 PO4 assisted pyrolysis is performed to improve the Coulombic efficiency of Li1.2 Mn0.54 Ni0.13 Co0.13 O2 , where appropriate oxygen vacancies, Li3 PO4 and spinel phase are synchronously generated in the surface layer of LMR microspheres. Under the synergistic effect of the oxygen vacancies and spinel phase, the unavoidable oxygen release in the cycling process was effectively suppressed. Moreover, the induced Li3 PO4 nanolayer could boost the lithium-ion diffusion and mitigate the dissolution of transition metal ions, especially manganese ions, in the material. The optimally modified sample yielded an impressive initial Coulombic efficiency and outstanding rate performance.

Bifunctional self-assembled molecular layer enables stable Ni-rich cathodes

Ni-rich layered oxides (LiNixCoyMnzO2, x ≥ 0.8, x + y + z = 1) are attractive cathode material candidates for building high-energy-density batteries owing to their higher specific capacity compared to their lower-Ni-content analogues. However, the high nickel content also brings challenges, such as storage instability in ambient conditions and poor cycle life. In this work, we propose a surface chemistry regulation strategy to simultaneously enhance the air storage stability and electrochemical stability of high-nickel cathode materials. A bifunctional ultrathin layer composed of trimethoxy(1H,1H,2H,2H-perfluorodecyl)silane (PFDTMS) was constructed on the surface of single-crystal LiNi0.83Co0.12Mn0.05O2 (NMC811) particles via molecular self-assembly. The passivating PFDTMS layer forms a superhydrophobic surface on the modified NMC811 particles, effectively mitigating deactivation reactions of NMC811 in air, and ensuring an uncompromised electrochemical performance of NMC811-based electrode after storing in air for two weeks. Furthermore, the self-assembled PFDTMS layer contributes to the formation of an electrochemical stable cathode–electrolyte interphase (CEI) on the NMC811 surface, improving the cycling stability of NMC811 at high cut-off voltages. The PFDTMS-based CEI also alleviates the chemical corrosion of NMC811 by the electrolyte, slows down the dissolution of transition metal ions during long term cycling. These findings present a straightforward, effective, eco-friendly, and cost-efficient approach to tackle the stability challenges inherent to Ni-rich layered cathode materials.

Multipoint adsorption constructs stable interface chemistry for high-nickel cathode material

LiNi0.83Co0.12Mn0.05O2 (NCM), a common commercial material, has been applied widely in electric mobility and large-scale energy storage fields with its high energy density and voltage platform. Nonetheless, the battery life of long-term operation is significantly harmed by the unstable crystal structure and cathode-electrolyte interface. Among these, capacity decay is closely associated with the dissolution of transition-metal ions. In the present work, a surface-modified strategy is proposed, that is, ethyl α-cyanoacrylate (ECA) is adsorbed to the transition metal site by polar functional group and then initiates its polymerization to obtain poly(ethyl α-cyanoacrylate) (PECA) coating. The functional coating can lessen the degradation of interface by-products and construct a thinner CEI film for lithium-ion fast conduction. Furthermore, the conformal and complete coating alleviates the structural degradation after the long-term cycle. The above benefits explain the improved performance of PECA modified material and perform well even at high-temperature and high-voltage tests, thus reflecting that the modification strategy provides practical guidance for improving the performance of lithium-ion power batteries.

Sulfur-Rich Additive-Induced Interphases Enable Highly Stable 4.6 V LiNi0.5Co0.2Mn0.3O2||graphite Pouch Cells.

High-voltage lithium-ion batteries (LIBs) have attracted great attention due to their promising high energy density. However, severe capacity degradation is witnessed, which originated from the incompatible and unstable electrolyte-electrode interphase at high voltage. Herein, a robust additive-induced sulfur-rich interphase is constructed by introducing an ultrahigh S-content of 34.04% additive (methylene methyl disulfonate, MMDS) in 4.6 V LiNi0.5Co0.2Mn0.3O2 (NCM523)||graphite pouch cell. The MMDS does not directly participate the inner Li+ sheath, but the strong interactions between MMDS and PF6- anions promote the preferential decomposition of MMDS and broaden the oxidation stability, and facilitate the formation of an ultrathin but robust sulfur-rich interfacial layer. The electrolyte consumption, gas production, phase transformation and dissolution of transition metal ions were effectively inhibited. As expected, the 4.6 V NCM523||graphite pouch cell delivers a high capacity retention of 87.99% even after 800 cycles. This work shares new insight into the sulfur-rich additive-induced electrolyte-electrode interphase for stable high-voltage LIBs.

Sulfur‐Rich Additive‐Induced Interphases Enable Highly Stable 4.6 V LiNi0.5Co0.2Mn0.3O2||graphite Pouch Cells

AbstractHigh‐voltage lithium‐ion batteries (LIBs) have attracted great attention due to their promising high energy density. However, severe capacity degradation is witnessed, which originated from the incompatible and unstable electrolyte‐electrode interphase at high voltage. Herein, a robust additive‐induced sulfur‐rich interphase is constructed by introducing an additive with ultrahigh S‐content (34.04 %, methylene methyl disulfonate, MMDS) in 4.6 V LiNi0.5Co0.2Mn0.3O2 (NCM523)||graphite pouch cell. The MMDS does not directly participate the inner Li+ sheath, but the strong interactions between MMDS and PF6− anions promote the preferential decomposition of MMDS and broaden the oxidation stability, facilitating the formation of an ultrathin but robust sulfur‐rich interfacial layer. The electrolyte consumption, gas production, phase transformation and dissolution of transition metal ions were effectively inhibited. As expected, the 4.6 V NCM523||graphite pouch cell delivers a high capacity retention of 87.99 % even after 800 cycles. This work shares new insight into the sulfur‐rich additive‐induced electrolyte‐electrode interphase for stable high‐voltage LIBs.

Lithium-Ion Conductor Li2ZrO3-Coated Primary Particles To Optimize the Performance of Li-Rich Mn-Based Cathode Materials.

A lithium-rich manganese-based cathode material (LRMC) is currently considered as one of the most promising next-generation materials for lithium-ion batteries, which has received much attention, but the LRMC still faces some key scientific issues to break through, such as poor rate capacity, rapid voltage, capacity decay, and low first coulomb efficiency. In this work, homogeneous Li2ZrO3 (LZO) was successfully coated on the surface of Li1.2Mn0.54Ni0.13Co0.13O2 (LRO) by molten salt-assisted sintering technology. Li2ZrO3 has good chemical and electrochemical stability, which can effectively inhibit the side reaction between electrode materials and electrolytes and reduce the dissolution of transition metal ions. Thus, the as-prepared LRO@LZO composites are expected to improve the cycling performance. It can be found that the discharge specific capacity of LRO is 271 mAh g-1 at 0.1 C, and the capacity retention rate is still 93.7% after 100 cycles at 1 C. In addition, Li2ZrO3 is an excellent lithium-ion conductor, which is prone to increasing the lithium-ion transfer rate and improving the rate capacity of LRO. Therefore, this study provides a new solution to improve the structure stability and electrochemical performance of LRMCs.