High-voltage Lithium-ion Batteries Research Articles

Prop-1-ene-1,3-sultone as interfacial-engineering additive in nonflammable electrolyte for 4.45 V LiCoO2/Si-Graphite lithium-ion batteries with high performance

To achieve high energy density for lithium-ion batteries, employing high-voltage cathodes and Si-based anodes is available. Fluoroethylene carbonate-based electrolytes show potential for use in high-voltage lithium-ion batteries due to their superior oxidation stability. However, fluoroethylene carbonate is prone to reductively decompose on the anode and brings about adverse effects on the battery performance. In this work, prop-1-ene-1,3-sultone is incorporated as an efficacious film-forming additive into fluoroethylene carbonate/dimethyl carbonate electrolyte for the purpose of ameliorating the compatibility with Si-Graphite anode in high-voltage lithium-ion batteries. The flame retardant (ethoxy)pentafluorocyclotriphosphazene is also incorporated into the electrolyte to guarantee the nonflammable feature. This nonflammable electrolyte has an ideal conductivity higher than 8 mS cm−1 at 25 °C, and it grants competitive performances to a high-voltage LiCoO2/Si-Graphite pouch cell. This cell after 300 cycles test exhibits a capacity retention of over 80 % at 1C, and the discharge capacity at 8C exceeds 50 % of that at 1C. By virtue of X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy techniques, it is confirmed that prop-1-ene-1,3-sultone enhances interfacial properties of Si-Graphite anode and contributes to an optimized interface, which restrains the volume expansion of Si-Graphite and inhibits persistently reductive decomposition of electrolytes.

Ceramic–Polymer–Carbon Composite Coating on the Truncated Octahedron-Shaped LNMO Cathode for High Capacity and Extended Cycling in High-Voltage Lithium-Ion Batteries

Ceramic–Polymer–Carbon Composite Coating on the Truncated Octahedron-Shaped LNMO Cathode for High Capacity and Extended Cycling in High-Voltage Lithium-Ion Batteries

Ethyl Isopropyl Sulfone Modulating to Achieve Stable High-Voltage Electrolyte for Lithium-Ion Batteries.

The demand for efficient large-scale energy storage necessitates high-energy-density batteries, making research on high-voltage electrolytes particularly important. In this article, ethyl isopropyl sulfone (ES), which has a high dielectric constant, is added to traditional carbonate-based electrolyte solvents and analyzed. Based on calculated and analyzed results, different proportions of ES are added to the conventional carbonate-based electrolyte. The high-voltage performance, the influence on the surface of the electrode, the active material structure after cycling, the electrochemical behavior, and the impedance of the electrode were studied systematically. As a result, ES addition is applied in high-voltage lithium-ion batteries and exhibits excellent electrochemical properties. These results will provide support for the research and application of sulfone additives in increasing the decomposition voltage of lithium-ion battery electrolytes and improving battery cycle stability.

Ethylene Carbonate-Free Electrolytes for High Voltage Lithium-Ion Batteries: Progress and Perspectives

Ethylene Carbonate-Free Electrolytes for High Voltage Lithium-Ion Batteries: Progress and Perspectives

Fluorinated Linkers Enable High-Voltage Pyrrolidinium-based Dicationic Ionic Liquid Electrolytes.

Novel fluorinated, pyrrolidinium-based dicationic ionic liquids (FDILs) as high-performance electrolytes in energy storage devices have been prepared, displaying unprecedented electrochemical stabilities (up to 7 V); thermal stability (up to 370 °C) and ion transport (up to 1.45 mS cm-1). FDILs were designed with a fluorinated ether linker and paired with TFSI/FSI counterions. To comprehensively assess the impact of the fluorinated spacer on their electrochemical, thermal, and physico-chemical properties, a comparison with their non-fluorinated counterparts was conducted. With a specific focus on their application as electrolytes in next-generation high-voltage lithium-ion batteries, the impact of the Li-salt on the characteristics of dicationic ILs was systematically evaluated. The incorporation of a fluorinated linker demonstrates significantly superior properties compared to their non-fluorinated counterparts, presenting a promising alternative towards next-generation high-voltage energy storage systems.

Enhancing interfacial properties on Silicon-Graphite anode by alkenyl-functionalization of fluorinated cyclotriphosphazene in high-voltage lithium-ion batteries

The pursuit for high energy density in lithium-ion batteries has driven the blended adoption of high-voltage cathode and high-capacity Silicon-based anode. Unfortunately, the carbonate-based electrolytes fail to be compatible with these electrode materials and the flammable nature of linear carbonates poses safety hazards to electrolytes. Fluorinated cyclotriphosphazenes can enhance the safety level of electrolytes and possesses the function of high-voltage additives. However, it is difficult to directly employ fluorinated cyclotriphosphazenes in high-voltage lithium-ion batteries containing Silicon-based anode. In this work, an alkenyl-functionalized cyclotriphosphazene- (3-butenoxy)pentafluorocyclotriphosphazene is constructed to enhance the compatibility between electrolytes and Silicon-Graphite anode. The mixed use of (3-butenoxy)pentafluorocyclotriphosphazene and (ethoxy)pentafluorocyclotriphosphazene not only makes electrolytes nonflammable but also renders preeminent performances to 4.45 V LiCoO2/Silicon-Graphite pouch cells at 25 °C. The capacity retention of the cell at 1C after 150 cycles surpasses 80 %, and the discharge capacity ratio of 8C/1C reaches around 53 %. With scanning electron microscopy and X-ray photoelectron spectroscopy technique, it is verified that the mixed flame retardant can build a robust interface film on the anode, which handles the adverse effects caused by the volume expansion of Silicon-Graphite.

A Case of Inverted Crosstalk in High-Voltage Lithium-Ion Batteries with Carbonate-Based Electrolytes and LiNi0.5Mn1.5O4 Cathodes

The deployment of spinel LiNi0.5Mn1.5O4 (LNMO) cathodes can be key to develop lithium-ion batteries (LIBs) with higher energy density and lower costs. However, the most common carbonate-based electrolytes for LIBs suffer from severe degradation at high potentials, potentially causing cell failure and safety hazards.[1,2] Therefore, investigating the degradation mechanisms in battery cells employing high-voltage battery cathodes such as LNMO is paramount. In this work [3], we studied the influence of linear carbonates on cycling and interfacial stability. Electrolytes consisting of LiPF6 dissolved in a mixture of cyclic (ethylene carbonate, EC), and linear carbonates (diethyl carbonate, DEC, or dimethyl carbonate, DMC), in a 3:7 EC:DEC/DMC weight ratio, were compared. Galvanostatic cycling and electrochemical impedance spectroscopy data of LNMO||Li cells indicate that the linear carbonate plays a fundamental role in cell failure. Specifically, cells with DEC-based electrolyte show early rollover failure, reaching 80% and 20% state of health at cycle 31 and 55, respectively. In contrast, cells with DMC-containing electrolyte have better stability, keeping 80% state of health until cycle 92, as shown in Figure 1. Three-electrode measurements and further characterizations, such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS), unveil that cell failure occurs due to instability of the cathode-electrolyte interface; when DEC-based electrolytes are used, a huge impedance build-up is correlated with the formation of a spotty deposit on LNMO particles. In contrast, these deposits are absent in cathodes cycled in the DMC-based electrolyte. These deposits can be explained as originating from electrolyte reduction products forming on the anode side as shown previously for layered oxide||Li cells.[4] Overall, this study provides an insightful discussion on an "inverted crosstalk", i.e., from anode to cathode, degradation mechanism. Importantly, improved cycling stability with DMC compared to DEC is also found for LNMO||graphite cells.[1] V. Nilsson, S. Liu, C. Battaglia, R.-S. Kühnel, Electrochim. Acta 427, 2022, 140867.[2] S. Liu, M. Becker, Y. Huang-Joos, H. Lai, G. Homann, R. Grissa, K. Egorov, F. Fu, C. Battaglia, R.-S. Kühnel, Batteries Supercaps 6, 2023, e202300220.[3] A. Curcio, W. Dachraoui, Ø. Dahl, N. P. Wagner, C. Battaglia, R.-S. Kühnel, submitted.[4] H.-J. Peng, C. Villevieille, S. Trabesinger, H. Wolf, K. Leitner, P. Novák, J. Power Sources 335, 2016, 91-97. Figure 1

Nonsolvating Fluoroaromatic Cosolvent Enabled Long-Term Cycling of High-Voltage Lithium-Ion Batteries with Organosulfur Electrolytes.

The structure-activity relationships of nonsolvating cosolvents for organosulfur-based electrolyte systems were revealed. The performance of nonsolvating dilutant fluorobenzene (FB) was compared to various fluorinated ether dilutants in high-voltage electrolytes containing a concentration of 1.2 M LiPF6 dissolved in fluoroethylene carbonate (FEC), ethyl methyl sulfone (EMS), and the dilutant. In a high-voltage and high-loading LiNi0.8Mn0.1Co0.1O2 (NMC811) full cell configuration, the organosulfur-based electrolyte containing FB dilutant enabled superior electrochemical performance compared to the electrolytes using other nonsolvating fluorinated ether formulations. Moreover, the FB-containing electrolyte exhibited the highest ionic conductivity and lowest viscosity among all organosulfur-based electrolytes containing nonsolvating dilutant. These improvements are attributed to the enhanced physical properties of electrolyte and lithium-ion mobility. Furthermore, by employing first-principles simulations, the observed suppression of side reactions at high voltage is linked to FB's lower reactivity toward singlet dioxygen, which is likely produced at the NMC interface. Overall, FB is considered an excellent diluent that does not impede cell operation by mass decomposition at the cathode.

Effect of alkali-metal phosphate additives on the interphase structure of 5-V LiNi0.5Mn1.5O4-based lithium–ion batteries

High-voltage (5-V) lithium–ion batteries (LIBs) have garnered substantial interest due to their superior energy density. Nevertheless, the unstable interphase of high-voltage LIBs can cause electrolyte decomposition, electrode collapse, transition metal dissolution, and lithium dendrite growth during cycling, which impedes their widespread commercial use. To mitigate these challenges, various alkali-metal phosphates were incorporated into a carbonate-based electrolyte as film-forming additives, aiming to improve the electrochemical performance of LiNi0.5Mn1.5O4 (LNMO)-based LIBs. Following a detailed comparison of the electrochemical performances of various alkali-metal phosphates, KH2PO4 and NaH2PO4 were selected for an in-depth investigation in this research. The highly protective passivation film generated by KH2PO4 and NaH2PO4 on the electrode surface provided significant protection by effectively inhibiting continuous electrolyte decomposition. This finding was supported by density functional theory calculations and a variety of electrochemical and characterization tests. The H2PO4− primarily contributed to the formation of the cathode electrolyte interphase film on the cathode surface. KH2PO4 (via the electrostatic shielding effect of K+ions) and NaH2PO4 (through the co-precipitation of Na+ and Li+ ions) both effectively inhibited the growth of lithium dendrites on the lithium metal anode. Additionally, the KH2PO4 and NaH2PO4 additives regulated the amount of HF in the electrolyte through acid–base equilibrium reactions. The electrolytes containing additives significantly enhanced the electrochemical performances of Li||Li, LNMO/Li, LNMO/graphite, and LNMO/Li4Ti5O12 cells. LNMO/Li half-cells with standard electrolyte (STD) supplemented with KH2PO4 and NaH2PO4 additives demonstrated capacity retentions of 92.9 % and 90.0 % after 500 cycles at 5 C, respectively, in contrast to only 79.4 % for the STD electrolyte alone. Furthermore, the LNMO/graphite full cell exhibited an increased capacity retention, reaching 81.1 % (STD+KH2PO4) and 78.29 % (STD+NaH2PO4), up from 70.8 % with the STD, after 100 cycles at 0.5 C. Given their ease of use, affordability, and widespread availability, KH2PO4 and NaH2PO4 additives show significant potential to enhance the electrochemical properties of high-voltage LIBs.

Recycled micro-sized silicon anode for high-voltage lithium-ion batteries

Recycled micro-sized silicon anode for high-voltage lithium-ion batteries

Maleic Anhydride and (Ethoxy)pentafluorocyclotriphosphazene as Electrolyte Additives for High-Voltage LiCoO2/Si-Graphite Lithium-Ion Batteries.

Anhydride additives including maleic anhydride and succinic anhydride are initially selected as additives in the commercial electrolytes for high-voltage lithium-ion batteries with a Si-based anode. The introduction of (ethoxy)pentafluorocyclotriphosphazene as a flame retardant realizes the nonflammability of electrolytes, and the conductivity of electrolytes exceeds 10 mS cm-1 at 25 °C. Maleic anhydride and (ethoxy)pentafluorocyclotriphosphazene jointly contribute to the exceptional performances of 4.45 V LiCoO2/Si-graphite pouch cells at 25 °C. The capacity retention at 1C of 300 cycles reaches 78%, and the discharge capacity ratio of 6C/1C is approximately 83%. These results suggest that this nonflammable electrolyte has good application prospect. Scanning electron microscopy and X-ray photoelectron spectroscopy measurements are implemented to analyze the interface properties of electrodes.

Enhanced electrochemical performance of a cost-effective Sm2O3-coated spinel LiNi0.5Mn1.5O4 cathode for high-voltage lithium-ion batteries

Spinel LiNi0.5Mn1.5O4 (LNMO) has gained significant attention as a promising cathode material for lithium-ion batteries due to its high working voltage (>4.7 V) and energy density. However, challenges such as electrolyte decomposition-induced material interface erosion and transition metal dissolution under high operating voltage hinder its commercial use. In this study, a thin and uniform Sm2O3 layer has been successfully deposited on the surface of LNMO using a wet chemical method. A comprehensive investigation of surface morphology, crystal structure, and electrochemical performance of the modified LNMO is conducted. The results demonstrate that the Sm2O3 surface modification acts as a robust multifunctional protective layer, effectively shielding against hydrofluoric acid-induced chemical attack and enhancing the migration efficiency of lithium ions. Notably, the capacity retention rate of LNMO@Sm2O3 (3 wt%) remains up to 88 % after 280 cycles, significantly surpassing the uncoated counterpart. The coated material exhibits a capacity of 114 mAh g−1 even under 10 C rate conditions. Moreover, the AC impedance values and manganese dissolution of the modified material in the organic electrolyte are considerably lower than those of the uncoated counterpart. Theoretical calculations strongly support the experimental findings, revealing higher Mn vacancy formation energy and density of states at the Fermi energy level for the Sm2O3-modified electrodes. This research contributes to the field of surface modification and paves the way for further enhancements in the electrochemical performance of other high-voltage manganese-based lithium-ion batteries (LIBs).

Electronic structure and delithiation mechanism of vanadium and nickel doped Li2MnPO4F cathode material for lithium-ion batteries

This study calculates the energy band structure and density of states of Lithium manganese fluorophosphate (Li2MnPO4F, a lithium transition metal phosphate compounds) using the first-principles plane-wave pseudopotential approach within the density-functional theory. The model of Li2M0.5Mn0.5PO4F (M = V, Ni) with transition metal doped Mn sites is constructed by using the CASTEP module. The calculation findings indicate that the transition metal doping can regulate the energy band structure of the intrinsic system, and Li2MnPO4F makes the band gap decrease, and the volume increase with the Li ions of being deintercalated, and the electrons can be readily stimulated from the valence band to the conduction band. The findings indicate that Li2MnPO4F is a favorable cathode material for high-voltage lithium ion batteries (LIBs). The introduction of vanadium (V) and nickel (Ni) doping reduces the band gap, facilitating an easier excitation of electrons from the valence band to the conduction band. This study provides a theoretical study of new cathode materials for high performance LIBs.

H-Transfer Mediated Self-Enhanced Interphase for High-Voltage Lithium-Ion Batteries

H-Transfer Mediated Self-Enhanced Interphase for High-Voltage Lithium-Ion Batteries

Effect of lithium-containing inorganic phosphate additives in stabilization of carbonate-based electrolyte for 5 V LiNi0.5Mn1.5O4-based lithium-ion batteries

High-voltage lithium-ion batteries (LIBs) with LiNi0.5Mn1.5O4 (LNMO) cathode are considered promising energy sources due to their high energy density. However, enhancing the stability of the electrode/electrolyte interface remains critical for the practical application of LIBs. In this work, lithium-containing inorganic phosphates (LiPO3, Li3PO4, and LiH2PO4) were used as multifunctional inorganic additives to improve the stability of the electrode/electrolyte interface in 5.0 V, LNMO-based LIBs with carbonate-based electrolytes. Based on theoretical calculations and experimental evaluations of the electrochemical performance, LiPO3 was selected as the optimal additive for further study in LNMO/Li and LNMO/Li4Ti5O12 cells. The LNMO/Li half-cells with LiPO3 delivered an initial discharge capacity of 108.8 mAh∙g−1 and retained a capacity of 94.9 % after 500 cycles at 5C, compared to 75.1 mAh∙g−1 and 79.4 % for the standard electrolyte. The increased cycling stability was ascribed to the ability of the multifunctional, film-forming LiPO3 additive to form stable interfacial films on both the cathode and anode, thus, inhibiting side reactions between the electrodes and electrolyte. Moreover, as an HF scavenger, LiPO3 reduced the HF content in the electrolyte to ensure the structural integrity of LNMO and inhibit the dissolution of transition metal ions. In the LNMO/Li4Ti5O12 full cells, the addition of LiPO3 effectively enhanced the cycling performance, and the capacity retention after 400 cycles at 5C was 79.1 %, compared to only 12.3 % for the standard electrolyte. Considering its simplicity, low cost, and feasibility, the addition of LiPO3 as a multifunctional electrolyte additive showed excellent prospects for commercial applications.

Constructing stable electrode–electrolyte interfaces by sulfone-based additive to improve the high-voltage performance of LiCoO2

LiCoO2 battery can provide high reversible capacity at a high voltage of 4.6 V, however, maintaining its stability at high voltages remains a major challenge. To address this issue, ethyl methyl sulfone (EMS) is employed as an electrolyte additive to construct stable interfaces between the electrode and electrolyte under high-voltage condition. The characterization results indicate that the addition of EMS can inhibit the decomposition of the standard electrolyte (STD) and the dissolution of Co2+ from cathode, as well as the formation of lithium dendrites on the Li anode, thereby enhancing the stability of both cathode/electrolyte and anode/electrolyte interfaces. Consequently, the cycling performance of LiCoO2 battery using STD+3 %EMS is augmented by 16.9 % at 1 C under a cut-off voltage of 4.6 V over 100 cycles, delivering a specific capacity of 137 mA h g−1. This research provides novel insights into the design of electrolyte additives for high-voltage LiCoO2 batteries and contributes to the further development of high-voltage lithium-ion batteries.

A synergistic duo for enhanced cathode stability in high-voltage lithium-ion batteries

Lithium-ion batteries with high-nickel cathode materials are promising candidates for achieving significantly higher energy densities. However, when Ni-rich subjected to higher charging cutoff voltages accelerates both electrolyte decomposition and structural degradation, leading to compromised cycling stability and reduced lifespan. In this study, we have developed a dual-additive strategy using lithium difluoro bisoxalate phosphate (LiDFBOP), and 1,3-divinyl-1,1,3,3-tetramethyldisilazane (DTDS) to address these challenges and improve the battery's performance. Theoretical calculations and experimental results indicate that the LiDFBOP regulates Li⁺ solvation for robust CEI formation, while DTDS scavenges impurities and promotes the formation of an inorganic/organic interphase. The synergistic effect of these additives combination allows Li||NCM811 coin cell to retain a capacity retention 87.9 % at 4.6 V and Graphite||NCM811full cell achieved 90.5 % capacity retention at 4.5 V. Moreover, the 1Ah pouch full cells exhibit excellent cycling stability, with a capacity retention of 91.4 % after 610 cycles at a constant current of 500 mA and voltage of 4.5 V. This work offers guidance on designing multifunctional additives to achieve synergistic electrolyte engineering for high-energy lithium-ion batteries.

Enhancing Structural Rigidity of Ultrahigh-Ni Oxide Through Al and Nb Dual-Bulk-Doping for High-Voltage Lithium-Ion Batteries.

The pursuit of high energy densities propels the design of next-generation nickel-based layered oxide cathodes. The utilization of low-cobalt, ultrahigh-nickel layered oxide cathodes, and the extension of operating voltages promise enhanced energy density. However, stability and safety face challenges associated with nickel content, including structural degradation, lattice oxygen evolution, and thermal instability. In this study, a promising strategy of Al and Nb dual-bulk-doping is presented in high-Ni cathode materials of LiNi0.96Co0.04O2 (NC) to stabilize the bulk structure, suppress oxygen release, and attain superior electrochemical performance at high voltages. The introduction of Al and Nb effectively raises the migration energy of Ni2+ into Li sites and stabilizes lattice oxygen through strengthened Al─O and Nb─O bonds. Furthermore, the substitution of high-valence Nb ions reduces the charge depletion of lattice oxygen and induces an ordered microstructure. The Al and Nb dual-bulk-doping strategy mitigates strain and stress associated with the H2↔H3 phase transition, reducing the generation and propagation of microcracks. The resulting Li(Ni0.96Co0.04)0.985Al0.01Nb0.005O2 (NCAN) cathode exhibits superior cycling stability, with a capacity retention of 77.8% after 300 cycles, even when operating at a high-voltage of 4.4V, outperforming the NC (48.5%). This work provides a promising perspective for developing high-voltage and high-Ni cathode materials.

Effect of Fe and Zn co-doping on LiCoPO4 cathode materials for High-Voltage Lithium-Ion batteries

Lithium cobalt phosphate (LiCoPO4) has great potential to be developed as a cathode material for lithium-ion batteries (LIBs) due to its structural stability and higher voltage platform with a high theoretical energy density. However, the relatively low diffusion of lithium ions still needs to be improved. In this work, Fe and Zn co-doped LiCoPO4: LiCo0.9-xFe0.1ZnxPO4/C is utilized to enhance the battery performance of LiCoPO4. The electrochemical properties of LiCo0.85Fe0.1Zn0.05PO4/C demonstrated an initial capacity of 118 mAh/g, with 93.4 % capacity retention at 1C after 100 cycles, and a good capacity of 87 mAh/g remained under a high current density of 10C. In addition, the diffusion rate of Li ions was investigated, proving the improvement of the materials with doping. The impedance results also showed a smaller resistance of the doped materials. Furthermore, operando X-ray diffraction displayed a good reversibility of the structural transformation, corresponding to cycling stability. This work provided studies of both the electrochemical properties and structural transformation of Fe and Zn co-doped LiCoPO4, which showed that 10 % Fe and 5 % Zn co-doping enhanced the electrochemical performance of LiCoPO4 as a cathode material in LIBs.

Experimental and Model Analysis of the Thermal and Electrical Phenomenon of Arc Faults on the Electrode Pole of Lithium-Ion Batteries

Aiming at the electrical safety problem of a high-voltage lithium-ion battery system caused by an arc, and based on the establishment of a battery arc fault experimental platform, the evolution law of safety caused by an arc in the negative terminal of a battery system under different working conditions is discussed. On this basis, a battery arc evolution model based on magnetohydrodynamics is established to analyze the arc’s electro-thermal coupling characteristics to further obtain the distribution of the arc’s multi-physical field. The results show that the arc generated by the high-voltage grade battery pack will break down the cell’s shell and form a hole, resulting in electrolyte leakage. When the loop current is 10 A, the evolution law of arc voltage and current is basically the same under different supply voltages, charges, and discharges. The accuracy of the battery arc simulation model is verified by comparing the simulation with the experimental results. The research in this paper provides a theoretical basis for the electrical safety design of lithium-ion batteries caused by the arc, fills the gaps in the field of battery system arc simulation, and is of great significance for improving the safety performance of arc protection.