Commercial Electrolyte Research Articles

In situ generated of hybrid interface in poly(1,3-dioxolane) quasi solid electrolyte and extended sulfone cosolvent for lithium-metal batteries

The practical application of lithium metal batteries with high energy density are difficult to apply due to the problem of uncontrolled lithium dendrite growth with commercial liquid electrolytes. Herein, we designed a poly 1,3-dioxolane (PDOL) based quasi solid polymer electrolyte with in-situ polymerization. A small amount of lithium difluoro(oxalato)borate (LiDFOB) provides cationic initiation center for the polymerization of dioxolane (DOL). Sulfolane (SL) were further introduced into the system as a cosolvent and the ionic conductivity was increased to 3.22 × 10-4 S cm-1followed with a high Li+ transfer number of 0.73 at room temperature. Trace amount of SbF3 was introduced to form a robustness inorganic-rich hybrid interface that reduces the decomposition of electrolyte components and retards the formation of lithium dendrites during cycling. The superior rate performance and stable 5C long cycle performance are obtained in LiFePO4||Li full cell owing to the interaction between Li+, SL and PDOL. This work expands the choice of components in quasi solid electrolytes to manufacture qualified LMBs with enhanced performance.

Research Progress of Shear Thickening Electrolyte Based on Liquid–Solid Conversion Mechanism

As an essential component of the lithium-ion battery system, electrolyte plays a crucial role in ion transport between the electrodes. In the event of thermal runaway, commercial organic electrolytes are prone to internal disturbances and fires; hence, research on safe electrolytes has gradually become a hot topic during recent years. Shear thickening electrolyte, as a new type of smart electrolyte, can exhibit a liquid state in the absence of external force and rapidly converts to a quasi-solid state once the battery is subjected to drastic impact loading. In this paper, the recent progress of shear thickening electrolytes with liquid–solid switching performance is presented, including its working principles, synthesis and preparation procedure, and battery performance. Additionally, the perspective and challenges for practical application are discussed.

Fluorinated carbonate-based electrolyte engineering solvation structure for high-voltage Li||LiNiO2 cell

Ni-rich layered oxides are considered ideal positive electrode materials for next-generation state-of-the-art Li-based batteries owing to their high energy densities. However, the structural degradation of Ni-rich positive electrodes and electrolyte decomposition presents significant challenges, particularly at high cut-off voltages. Herein, we report a novel electrolyte consisting of fluorinated solvents that enables the long lifespan of a Li||LiNiO2 cell with a cut-off voltage of up to 4.5 V. The Li||LiNiO2 cell retains 93.8% of its initial capacity after 200 cycles. The cycling stability was ascribed to the fluorinated solvents dominating the first structural shell of Li+ and deriving a robust cathode-electrolyte interphase (CEI) on the positive electrode. Compared to commercial electrolytes, the fluorinated electrolyte inhibits the structural degradation, stress corrosion cracking, and interphase side reactions of the LiNiO2 electrode. On the Li negative electrode side, ideal Li plating/stripping and the inhibition of the attack of Ni2+ are achieved. Furthermore, the 4.5 V-Li||LiNiO2 cell exhibited a capacity retention of 80.2% after 100 cycles, even under extremely fast-charging conditions.

Li Plating Regulation on Fast-Charging Graphite Anodes by a Triglyme-LiNO3 Synergistic Electrolyte Additive.

Graphite anodes are prone to dangerous Li plating during fast charging, but the difficulty to identify the rate-limiting step has made a challenging to eliminate Li plating thoroughly. Thus, the inherent thinking on inhibiting Li plating needs to be compromised. Herein, an elastic solid electrolyte interphase (SEI) with uniform Li-ion flux is constructed on graphite anode by introducing a triglyme (G3)-LiNO3 synergistic additive (GLN) to commercial carbonate electrolyte, for realizing a dendrite-free and highly-reversible Li plating under high rates. The cross-linked oligomeric ether and Li3N particles derived from the GLN greatly improve the stability of the SEI before and after Li plating and facilitate the uniform Li deposition. When 51% of lithiation capacity is contributed from Li plating, the graphite anode in the electrolyte with 5 vol.% GLN achieved an average 99.6% Li plating reversibility over 100 cycles. In addition, the 1.2-Ah LiFePO4 | graphite pouch cell with GLN-added electrolyte stably operated over 150 cycles at 3 C, firmly demonstrating the promise of GLN in commercial Li-ion batteries for fast-charging applications.

Li Plating Regulation on Fast‐Charging Graphite Anodes by a Triglyme‐LiNO3 Synergistic Electrolyte Additive

AbstractGraphite anodes are prone to dangerous Li plating during fast charging, but the difficulty to identify the rate‐limiting step has made a challenging to eliminate Li plating thoroughly. Thus, the inherent thinking on inhibiting Li plating needs to be compromised. Herein, an elastic solid electrolyte interphase (SEI) with uniform Li‐ion flux is constructed on graphite anode by introducing a triglyme (G3)‐LiNO3 synergistic additive (GLN) to commercial carbonate electrolyte, for realizing a dendrite‐free and highly‐reversible Li plating under high rates. The cross‐linked oligomeric ether and Li3N particles derived from the GLN greatly improve the stability of the SEI before and after Li plating and facilitate the uniform Li deposition. When 51 % of lithiation capacity is contributed from Li plating, the graphite anode in the electrolyte with 5 vol.% GLN achieved an average 99.6 % Li plating reversibility over 100 cycles. In addition, the 1.2‐Ah LiFePO4 | graphite pouch cell with GLN‐added electrolyte stably operated over 150 cycles at 3 C, firmly demonstrating the promise of GLN in commercial Li‐ion batteries for fast‐charging applications.

Method for Benchmarking Li Metal Anodes: A Mandatory Step toward Reliable Lithium Metal Batteries

All-solid-state batteries are known to be the new energy storage holy grail that will lead to safer batteries with higher energy density than current Li-ion batteries. The use of a solid electrolyte enables the use of lithium metal as the anode material. However, its composition, its thickness, and the quality/nature of its passivation layer can strongly affect the performance of the battery. For this reason, we propose a simple benchmarking method that evaluates and compares the quality and electrochemical performance of various Li anodes. This method can be easily reproduced, especially concerning the electrochemical evaluation that uses a commercial liquid electrolyte and the widely spread coin-cell format. In total, ~285 coin cells were assembled to benchmark our in-house lithium metal foil (Lithium HQ) with two commercial ones and the results showed the superior performance of our Li metal anode. The performance of the cells seems closely related to the quality and uniformity of the Li surface. In addition, we propose including in the benchmarking method the effect of Li aging in a dry room on the electrochemical performance. This effect is important to consider because the fabrication of all-solid-state batteries is conducted in such an environment.

Scalable wet-slurry fabrication of sheet-type electrodes for sulfide all-solid-state batteries and performance enhancement via optimization of Ni-rich cathode coating layer

All-solid-state Li or Li-ion batteries (ASSLBs) have attracted much attention due to their potential high energy density, high safety, and low manufacturing costs compared to commercial liquid electrolyte Li-ion batteries. However, the rate capacity and cycling performance could not satisfy the practical application. Here, an island-like amorphous Li2O–ZrO2 (LZO) was coated on the surface of LiNi0.88Co0.10Al0.02 (NCA) via a sol-gel method and low-temperature sintering. The electrochemical performance and density functional theory calculation results demonstrate that the LZO coating layer significantly boosts Li-ions transfer. Targeting large-scale production, a sheet-type cathode was prepared by a wet-slurry process with PVDF-HFP as a binder, which exhibits an initial specific capacity of 181.91 mAh·g−1 at 0.13C and 25 °C. Remarkably, the wet-slurry cathode with a high NCA loading of 20 mg cm−2 delivers an initial areal capacity of 2.936 mAh·cm−2 and capacity retention of 69.93% after 1000 cycles at a rate of 0.64C. By employing X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy, we reveal that the LZO coating layer and PVDF-HFP binder inhibited the decomposition of sulfide electrolyte and detrimental structure evolution of NCA active material. This work would guide designing high-performance ASSLBs for practical application and commercialization.

Synergistic dual electrolyte additives for fluoride rich solid-electrolyte interface on Li metal anode surface: Mechanistic understanding of electrolyte decomposition

Improving the quality of the solid-electrolyte interphase (SEI) layer is highly imperative to stabilize the Li-metal anodes for the practical application of high-energy–density batteries. However, controllably managing the formation of robust SEI layers on the anode is challenging in state-of-the-art electrolytes. Herein, we discuss the role of dual additives fluoroethylene carbonate (FEC) and lithium difluorophosphate (LiPO2F2, LiPF) within the commercial electrolyte mixture (LiPF6/EC/DEC) considering their reactivity with Li metal anodes using density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulations. Synergistic effects of dual additives on SEI formation mechanisms are explored systematically by invoking different electrolyte mixtures including pure electrolyte (LP47), mono-additive (LP47/FEC and LP47/LiPF), and dual additives (LP47/FEC/LiPF). The present work suggests that the addition of dual additives accelerates the reduction of salt and additives while increasing the formation of a LiF-rich SEI layer. In addition, calculated atomic charges are applied to predict the representative F1s X-ray photoelectron (XPS) signal, and our results agree well with the experimentally identified SEI components. The nature of carbon and oxygen-containing groups resulting from the electrolyte decompositions at the anode surface is also analyzed. We find that the presence of dual additives inhibits undesirable solvent degradation in the respective mixtures, which effectively restricts the hazardous side products at the electrolyte-anode interface and improves SEI layer quality.

Tailoring the Electrochemical Performance of Olivine Phosphate Cathode Materials for Li-Ion Batteries by Strain Engineering: Computational Experiments

The open-circuit voltage (OCV), Li-ion diffusion, and electronic properties of a cathode material can significantly affect the performance of lithium-ion batteries (LIBs). In this work, DFT + U was carried out to investigate the effect of strain engineering in terms of biaxial compressive and tensile strains (BCS and BTS) on the electrochemical properties of olivine-based LiMPO4 (M = Co and Ni). The results show that biaxial compressive strain decreased the average bond lengths of O–Co/Ni and O–P, which means a good improvement in the structural stability of LiCoPO4 (LCP) and LiNiPO4 (LNP). The deployment of BCS and BTS reduced the open-circuit voltage of the LCP and LNP systems. Precisely, imposing a biaxial strain of about ε = ±3.5% for LCP and ε = ±5.5% for LNP reduced the high OCV to values below 4.5 V vs Li/Li+, which is recommended for most commercial liquid electrolyte operation. In addition, it was found that biaxial strain reduces the energy barrier for Li+ diffusion, which promotes Li+ diffusion and increases its mobility in these olivine crystal structures. Further analysis of the electronic structures shows that BTS reduces the material’s band gap and improves electronic conductivity. These results are promising for the commercial utilization of LCP and LNP as potential cathode material in next-generation LIBs like their famous big brother LFP.

Prolonged Life Lithium Metal Batteries Enabled by Introducing Abundant Lithium Nitrate in Commercial Carbonate Electrolytes

AbstractCarbonate electrolytes have been extensively used as commercial electrolytes in lithium‐ion batteries (LIBs) because of its high oxidative stability. However, the organic‐inorganic solid electrolyte interphase (SEI) formed on the lithium (Li) metal surface is too fragile to endure huge volume fluctuation during Li plating/stripping cycles in carbonate electrolytes. Herein, a chemically stable inorganic‐rich SEI was constructed on Li metal anodes by dissolving 5.5 M LiNO3 in N,N‐dimethylformamide (DMF) into carbonate electrolytes as an additive. The Li+ solvation structure coordinated with NO3− and DMF molecules favors the formation of LixNy, LiNxOy, and LiF in the SEI film, which have been proved to increase the interfacial energy and improve the ionic diffusion as well as the mechanical strength of the SEI. Therefore, the designed carbonate electrolyte enhances the stable cycling of Li symmetric cells up to 700 h, with a high Coulombic efficiency (CE) of 99.0 % by Aurbach CE test. When paired with LiFePO4 cathode, the coin cells achieve an outstanding average CE of 99.5 % and 86.5 % retention of initial capacity after 300 cycles.

Decorating local Li+ solvation structure and optimizing solid electrolyte interphase with potassium trifluoroacetate for dendrites-free lithium metal anodes

Fabricating a stable and robust solid electrolyte interphase to realize the dendrites-free lithium (Li) deposition morphology in the existing commercial electrolytes remains challenging. Here, the cost-effective potassium trifluoroacetate is proposed as an electrolyte additive, in which TFA− anions have the capability to involve in constructing solid electrolyte interphase with abundant inorganic species by modulating local Li+ solvation structure. It is found that TFSI− and NO3− anions in the electrolyte can be recruited into Li+ primary solvent sheath to replace partial solvent molecules confirmed by classical molecular dynamic simulations. This is due to the strong polar interaction between TFA− anions and Li+, which is favorable for weakening the coordination of solvent molecules proved by density functional theory calculation. Besides, with the assistance of electrostatic shielding of K+, the Li deposition morphology is greatly improved. Benefiting from the potassium trifluoroacetate additive, Li+ transference number (tLi+) of 0.68, considerable ionic conductivity (σLi+) of 8.93 × 10−4 S cm−1, and stable cycling over 400 h at 1.0 mA cm−2 are obtained. Moreover, the full cells coupling with LiFePO4 cathode exhibit a low overpotential of 212.41 mV and high capacity retention of 87.67% after 283 cycles under the current density of 1.0 C.

Flame-retardant oligomeric electrolyte additive for self-extinguishing and highly-stable lithium-ion batteries: Beyond small molecules

Preparing both safe and high-performance lithium-ion batteries (LIBs) based on commonly used commercial electrolytes is highly desirable, yet challenging. To overcome the poor compatibility of conventional small-molecular flame-retardants as electrolyte additives for safe LIBs with graphite anodes, in this study, we propose and design a novel low-cost flame-retardant oligomer that achieves an accurate and complete reconciliation of fire safety and electrochemical performance in LIBs. Owing to the integration of phosphonate units and polyethylene glycol (PEG) chains, this oligomer, which is a phosphonate-containing PEG-based oligomer (PPO), not only endows commercial electrolytes with excellent flame retardancy but also helps stabilize the electrodes and Li-ion migration. Specifically, adding 15 wt% of PPO can reduce 70% of the self-extinguishing time and 54% of total heat release for commercial electrolytes. Moreover, LiFePO4/lithium and graphite/lithium cells as well as LiFePO4/graphite pouch full cells exhibit good long-term cycling stability.

Sodium Nitrate/Formamide Deep Eutectic Solvent as Flame‐Retardant and Anticorrosive Electrolyte Enabling 2.6 V Safe Supercapacitors with Long Cyclic Stability

Safe operation of electrochemical capacitors (supercapacitors) is hindered by the flammability of commercial organic electrolytes. Non‐flammable Water‐in‐Salt (WIS) electrolytes are promising alternatives; however, they are plagued by the limited operation voltage window (typically ≤2.3 V) and inherent corrosion of current collectors. Herein, a novel deep eutectic solvent (DES)‐based electrolyte which uses formamide (FMD) as hydrogen‐bond donor and sodium nitrate (NaNO3) as hydrogen‐bond acceptor is demonstrated. The electrolyte exhibits the wide electrochemical stability window (3.14 V), high electrical conductivity (14.01 mS cm−1), good flame‐retardance, anticorrosive property, and ultralow cost (7% of the commercial electrolyte and 2% of WIS). Raman spectroscopy and Density Functional Theory calculations reveal that the hydrogen bonds between the FMD molecules and ions are primarily responsible for the superior stability and conductivity. The developed NaNO3/FMD‐based coin cell supercapacitor is among the best‐performing state‐of‐art DES and WIS devices, evidenced by the high voltage window (2.6 V), outstanding energy and power densities (22.77 Wh kg−1 at 630 W kg−1 and 17.37 kW kg−1 at 12.55 Wh kg−1), ultralong cyclic stability (86% after 30 000 cycles), and negligible current collector corrosion. The NaNO3/FMD industry adoption potential is demonstrated by fabricating 100 F pouch cell supercapacitors using commercial aluminum current collectors.

Probing Sodium Storage Mechanism in Hollow Carbon Nanospheres Using Liquid Phase Transmission Electron Microscopy.

Carbonaceous materials are promising sodium-ion battery anodes. Improving their performance requires a detailed understanding of the ion transport in these materials, some important aspects of which are still under debate. In this work, nitrogen-doped porous hollow carbon spheres (N-PHCSs) are employed as a model system for operando analysis of sodium storage behavior in a commercial liquid electrolyte at the nanoscale. By combining the ex situ characterization at different states of charge with operando transmission electron microscopy experiments, it is found that a solvated ionic layer forms on the surface of N-PHCSs at the beginning of sodiation, followed by the irreversible shell expansion due to the solid-electrolyte interphase (SEI) formation and subsequent storage of Na(0) within the porous carbon shell. This shows that binding between Na(0) and C creates a Schottky junction making Na deposition inside the spheres more energetically favorable at low current densities. During sodiation, the SEI fills the gap between N-PHCSs, binding spheres together and facilitating the sodium ions' transport toward the current collector and subsequent plating underneath the electrode. The N-PHCSs layer acts as a protective layer between the electrolyte and the current collector, suppressing the possible growth of dendrites at the anode.

Dual Additives for Stabilizing Li Deposition and SEI Formation in Anode‐Free Li‐Metal Batteries

Anode‐free Li‐metal batteries are of significant interest to energy storage industries due to their intrinsically high energy. However, the accumulative Li dendrites and dead Li continuously consume active Li during cycling. That results in a short lifetime and low Coulombic efficiency of anode‐free Li‐metal batteries. Introducing effective electrolyte additives can improve the Li deposition homogeneity and solid electrolyte interphase (SEI) stability for anode‐free Li‐metal batteries. Herein, we reveal that introducing dual additives, composed of LiAsF6 and fluoroethylene carbonate, into a low‐cost commercial carbonate electrolyte will boost the cycle life and average Coulombic efficiency of NMC||Cu anode‐free Li‐metal batteries. The NMC||Cu anode‐free Li‐metal batteries with the dual additives exhibit a capacity retention of about 75% after 50 cycles, much higher than those with bare electrolytes (35%). The average Coulombic efficiency of the NMC||Cu anode‐free Li‐metal batteries with additives can maintain 98.3% over 100 cycles. In contrast, the average Coulombic efficiency without additives rapidly decline to 97% after only 50 cycles. In situ Raman measurements reveal that the prepared dual additives facilitate denser and smoother Li morphology during Li deposition. The dual additives significantly suppress the Li dendrite growth, enabling stable SEI formation on anode and cathode surfaces. Our results provide a broad view of developing low‐cost and high‐effective functional electrolytes for high‐energy and long‐life anode‐free Li‐metal batteries.

A critical review on composite solid electrolytes for lithium batteries: Design strategies and interface engineering

The rapid development of new energy vehicles and 5G communication technologies has led to higher demands for the safety, energy density, and cycle performance of lithium-ion batteries as power sources. However, the currently used liquid carbonate compounds in commercial lithium-ion battery electrolytes pose potential safety hazards such as leakage, swelling, corrosion, and flammability. Solid electrolytes can be used to mitigate these risks and create a safer lithium battery. Furthermore, high-energy density can be achieved by using solid electrolytes along with high-voltage cathode and metal lithium anode. Two types of solid electrolytes are generally used: inorganic solid electrolytes and polymer solid electrolytes. Inorganic solid electrolytes have high ionic conductivity, electrochemical stability window, and mechanical strength, but suffer from large solid/solid contact resistance between the electrode and electrolyte. Polymer solid electrolytes have good flexibility, processability, and contact interface properties, but low room temperature ionic conductivity, necessitating operation at elevated temperatures. Composite solid electrolytes (CSEs) are a promising alternative because they offer light weight and flexibility, like polymers, as well as the strength and stability of inorganic electrolytes. This paper presents a comprehensive review of recent advances in CSEs to help researchers optimize CSE composition and interactions for practical applications. It covers the development history of solid-state electrolytes, CSE properties with respect to nanofillers, morphology, and polymer types, and also discusses the lithium-ion transport mechanism of the composite electrolyte, and the methods of engineering interfaces with the positive and negative electrodes. Overall, the paper aims to provide an outlook on the potential applications of CSEs in solid-state lithium batteries, and to inspire further research aimed at the development of more systematic optimization strategies for CSEs.

Developing multifunctional amide additive by rational molecular design for high-performance Li metal batteries

Rechargeable lithium batteries based on lithium metal anodes and high-nickel cathodes have unparalleled advantages in energy density. However, the massive growth of lithium dendrites and the rapid degradation of high-nickel ternary oxides in commercial electrolyte have greatly hindered their application. To circumvent this issue, we design a series of analogs as electrolyte additives by adopting acetyls as connecting units to splice multiple functional groups. Among these additives, N-methyl-N-(trimethylsilyl) trifluoroacetamide (MSTFA) stands out due to the rational molecular configuration and the synergistic complementarity of amide, trifluoromethyl and trimethylsilyl groups. The cycling reversibility of the lithium metal anode (1050 h at 1 mA cm−1 to 1 mAh cm−1) and the capacity retention of the LiNi0.9Co0.05Mn0.05O2 cathode (85.9 % at 3–4.3 V after 300 cycles) in MSTFA modified carbonate electrolyte are tremendously enhanced. In addition, the safety of the battery and the tolerance to harsh working conditions (high & low temperature, high-voltage) are also ameliorated. This work sheds light on the relationship between structure and activity of molecules as well as provides a novel idea for modular design of additives.

Effect of Fluorinated Carboxylic Acid Ester on Lithium Solvation as an Additive in Electrolyte and Low-Temperature Insight on Battery Performance

The fluorinated carboxylic acid esters are effective additives to improve the performance of lithium-ion batteries (LIBs). Among them, 2,2,2-trifluoroethylbutyrate (TFEB) has been reported as a good additive to enhance battery performance, especially at low temperatures. It becomes a consensus that the solvation structure around lithium ion plays a crucial role in LIBs. However, it remains a mystery how such additives impact lithium solvation and how the impact changes at low temperatures. In this work, classical molecular dynamics (MD) simulations were conducted to investigate microcosmic mechanisms of the influence of TFEB on a typical commercial electrolyte composed of lithium hexafluorophosphate (LiPF6)/ethylene carbonate (EC)/ethyl methyl carbonate (EMC) in LIBs. Although TFEB is a minority species, it can significantly modify the lithium solvation structure. The introduction of TFEB facilitates the participation of anion in the solvation shell, due to its weaker coordination ability compared to EC/EMC, which was elucidated by the detailed analyses including radial distribution functions, cluster analysis, cage residence time, etc. We further investigated a series of TFEB analogs (TFEA, ETFA, and MPFP) and found that a moderately weak coordination ability is essential in the design of electrolytes. Furthermore, it was uncovered not only that the coordination number of the anions will decrease at low temperatures but also that their orientations are significantly changed. We demonstrated that the introduction of TFEB will alleviate this tendency, which may be advantageous to low-temperature performance. In summary, the critical role of fluorinated additives is uncovered by our MD simulations in modulating the Li+ solvation structure and improving the low-temperature performance of LIB, which provides references to the design strategy of novel low-temperature fluorine-containing additive-based electrolytes.

High-Voltage and High-Temperature LiCoO2 Operation via the Electrolyte Additive of Electron-Defect Boron Compounds

Commercial LIBs have the problem of instability interface of electrolyte/cathode at high voltage and high temperature. This work reports a novel series of electron-defect boron compounds to construct stable interfaces of LCO/electrolyte. The results of theoretical calculation indicate that compounds of DPD scaffold can win in the competitive oxidation decomposition for interface regulation. F-rich and B-rich interface is designed by modifying the functional group of DPD scaffold. This strategy of in situ interface design successfully suppresses the dissolution of harmful transition metal ions and the nucleophilic reaction between electrolyte and cathode. Li/LCO cell can remain stable at high voltage (4.5 V) and high temperature (70 °C) in commercial carbonate electrolyte after DPD-F interphase formation. Meanwhile, faster Li+ extraction and insertion kinetics of DPD-F-interface make the Li/LCO cell stable at 4.6 V. Spectral characterizations and theoretical calculations uncover the secret of the forming process of this DPD-F-interface.

Electrode-compatible fluorine-free multifunctional additive regulating solid electrolyte interphase and solvation structure for high-performance lithium-ion batteries

The rapid development and widespread application of lithium-ion batteries (LIBs) have increased demand for high-safety and high-performance LIBs. Accordingly, various additives have been used in commercial liquid electrolytes to severally adjust the solvation structure of lithium ions, control the components of solid electrolyte interphase, or reduce flammability. While it is highly desirable to develop low-cost multifunctional electrolyte additives integrally that address both safety and performance on LIBs, significant challenges remain. Herein, a novel phosphorus-containing organic small molecule, bis(2-methoxyethyl) methylphosphonate (BMOP), was rationally designed to serve as a fluorine-free and multifunctional additive in commercial electrolytes. This novel electrolyte additive is low-toxicity, high-efficiency, low-cost, and electrode-compatible, which shows the significant improvement to both electrochemical performance and fire safety for LIBs through regulating the electrolyte solvation structure, constructing the stable electrode-electrolyte interphase, and suppressing the electrolyte combustion. This work provides a new avenue for developing safer and high-performance LIBs.