Solid Electrolyte Interface Film Research Articles

Unconventionally microspheric quasi-solid electrolyte interface approach for durable and highly reactive phosphorus for lithium-ion storage

Solid electrolyte interface (SEI) film is the most important separation layer between nonaqueous electrolytes and anodes to protect anode from corrosion and maintain continuous ionic diffusion tunnels. However, SEI film, especially for high-capacity anode materials, is still confined to continuous and stable ionic conductive layer despite the conventional SEI film is intrinsically poor to resist against the drastic volumetric changes of active centers. Herein, an unconventional spheric quasi-SEI film is thus strategically configured on cost-effective red phosphorus electrode materials by moderate phosphorylation combined with pore-forming process. Microstructure adjustment from solid microspheres structure to hollowed core–shell spheres is visibly taken place on this amazing spheric quasi-SEI film during the stabilization. Benefiting from the highly activated surface with weakened PP bond strength and the strengthened binding force between phosphorus and binders, the optimized phosphorus anode presents an outstanding long-term durability with a high discharge capacity of 1126.4 mAh/g over 400 cycles at 200 mA g−1 even at a high phosphorus load ratio of 70 wt%. This revolutionary configuration of quasi-SEI film provides high-capacity anode materials subject to large volumetric changes an unconventional approach from dependence on conductive framework/matrix.

Perspective of material evolution Induced by sinusoidal reflex charging in lithium-ion batteries

BackgroundLithium-ion batteries are globally prominent and extensively employed alternative energy sources with decisive applications. In depth understanding of influences of various charging and discharging cycles on electrode materials and life span of these batteries is critical as cycle-life and safety of lithium-ion batteries are closely related crystallinity of electrode materials. This study is a detailed investigation endeavor in observing the degree of damage to electrode materials under multiple charging and discharging cycles. Methodology: A constant current-sinusoidal reflex charging method (CC-Sinusoidal) was implemented to charge commercial cathode Lithium cobalt oxide (LiCoO2) electrodes and anode graphite electrodes in comparison to the conventional charging method of constant current-constant voltage (CC-CV). After 100, 300, and 500 cycles of charging and discharging, EIS, SEM, XRD, and Raman spectroscopies were used to compare the degree of electrode damage caused by different charging methods. Significant outcomesThe structure of positive LiCoO2 electrode of the battery was observed to be stable, with no significant change in both the charging methods after 500 cycles. The use of CC-CV charging method had caused severe damages to graphite electrode with generation of solid electrolyte interface (SEI) films. The CC-Sinusoidal charging method had maintained the electrode material in a relatively ideal state.

A Fully Methylated Cyclic Ether Solvent Enables Graphite Anode Cycling at Low Temperatures.

Graphite anode suffers from great capacity loss and larger cell polarization under low-temperature conditions in lithium-ion batteries (LIBs), which are mainly caused by the high energy barrier for the Li+ desolvation process and sluggish Li+ transfer rate across the solid electrolyte interface (SEI). Regulating an electrolyte with an anion-dominated solvation structure could synchronously stabilize the interface and boost the reaction kinetics of the graphite anode. Herein, a highly ionic conductive electrolyte consisting of a fully methylated cyclic ether solvent of 2,2,4,4,5,5-hexamethyl-1,3-dioxolane (HMD) and fluoroethylene carbonate (FEC) cosolvent was designed. The high electron-donating effect and steric hindrance of -(CH3)2 in HMD endow the HMD-based electrolyte with high ionic conductivity but lower coordination numbers with Li+, and an anion-dominated solvation structure was formed. Such configuration can accelerate the desolvation process and induce the forming of a LiF-rich SEI film on the anode, avoiding the solvent coembedding into graphite and enhancing the ion migration rate under low temperatures. The assembled Li||graphite cell with the tame electrolyte outperformed the conventional carbonates-based cell, showing 93.8% capacity retention after 227 cycles for the DF-based cell compared to 64.7% after 150 cycles. It also exhibited a prolonged cycle life for 200 rounds with 81% capacity retention under -20 °C. Therefore, this work offers a valuable thought for solvent design and provides approaches to electrolyte design for low-temperature LIBs.

All‐Fluorinated Low‐Solvation Electrolytes for High‐Voltage Sodium Metal Batteries with Appealing Stability

AbstractHigh‐voltage sodium‐metal batteries (SMBs) are considered a promising battery system due to their abundant sodium source and high energy density. However, the instability of electrolytes, notorious reactivity of Na metal, and severe dissolution of solid electrolyte interface (SEI) film impede their long lifespan and high safety. Herein, a low‐solvation modulating strategy is proposed to design an all‐fluorinated electrolyte consisting of 1 m NaPF6 in fluoroethylene carbonate (FEC), methyl 2, 2, 2‐trifluoroethyl carbonate (FEMC), and lithium difluoro(oxalato)borate (LiDFOB), realizing high working voltage and excellent cycling stability of SMBs. Theoretical calculations and experimental characterizations confirm that the presence of FEMC significantly improves the antioxidant property of the electrolyte and contributes to the formation of high‐quality interfacial phases on both anode and cathode. While LiDFOB benefits to optimize the energy bandgap and the solvated structure and stabilizing the FEMC. Consequently, excellent oxidative stability up to 5 V and ultra‐stable cycling of Na||Na3(VOPO4)2F battery (with a capacity retention of 82.9% after 1800 cycles at 4.4 V) are obtained, exhibiting superior stability to its counterparts. The proposed strategy provides a new insight to design SMBs operated at high voltages.

Changes in performance and thermal stability of Ni0.8Co0.1Al0.1/graphite batteries with excessive water

AbstractDuring the production process of lithium‐ion batteries, there exists a scenario of excessive water inside the battery due to poor water control in the factory environment. In addition, the battery housing may be damaged by corrosion, external vibration etc., which would cause water to enter the battery. To the best of the authors’ knowledge, there is little literature to reveal the influencing mechanism related to the above issue. The effects of excessive water on battery performance and safety were discussed. The results show that when the battery absorbs excessive water, the capacity decreases and the self‐discharging rate increases rapidly. The self‐heating temperature of the battery shows an increasing trend. The thermal runaway temperature decreases significantly with the time from self‐heating to thermal runaway dramatically shortened. The thermal stability of the battery deteriorates throughout the reaction process. This is mainly due to the mechanisms by which the water absorbed in the battery reacts with the electrolyte and the electrode material, resulting in the decrease of the electrolyte conductivity and the corrosion of the electrode material, as well as the thickening of the Solid Electrolyte Interface film and the accumulation of impurities. The findings are of positive significance in demonstrating the quantitative relationship between excessive water and the performance and safety of batteries. Also, it can add to the understanding of the complex scenarios of battery spontaneous failure, which is vital for solving battery self‐thermal runaways.

Si/BiPO4 composite anode material for lithium ion batteries prepared by solvothermal method

Lithium ion batteries play an important role in various energy storage technologies due to their good safety performance. As an anode material, silicon has attracted attention for its higher theoretical capacity than commercial graphite. But large volume expansion and unstable solid electrolyte interface (SEI) during the cycling of silicon lead to rapid capacity decay, which limits the commercial application of silicon anode. In this article, Si/BiPO4 anode materials were prepared by solvothermal reaction. After morphology analysis and constant current charge discharge cycle analysis of Si/BiPO4 anode materials with different mass ratios, it was found that Si/BiPO4 anode materials with the mass ratio of 7:3 exhibited more excellent electrochemical performance. The conversion reaction of BiPO4 and Li generates Bi and Li3PO4, and the alloying reaction of Bi generates Li3Bi. Bi and Li3Bi reduce the internal resistance of the Si/BiPO4 composite, and Li3PO4 is distributed on the surface of Si material, participating in the formation of SEI film and improving the stability of the material. At a current density of 500 mA g−1, the first discharge specific capacity of the Si/BiPO4 anode is 2672.1 mA h g−1. After 200 cycles, the discharge specific capacity remains at 1308.9 mA h g−1. The electrochemical impedances of pure Si and Si/BiPO4 anode materials before and after cycling were analyzed. It was found that the resistance of the Si/BiPO4 anode before and after 100 cycles was lower than that of pure Si materials, which further proved that the addition of BiPO4 material helps to improve the charge transfer ability of pure silicon materials.

Selective construction of amorphous/crystalline heterostructure high entropy oxide for Li-ion batteries

High entropy oxides (HEO) are widely used as anode for lithium-ion batteries due to their exceptional chemical stability and mechanical strength. However, HEO encounters challenges such as low initial coulomb efficiency (ICE) and poor capacity. To address these issues, a simple mechanochemical method is employed to selectively amorphized and densely embed LiF within the HEO matrix. Taking advantage of the differing chemical properties of LiF and HEO, the transformation of LiF’s crystal structure not only overcomes its poor ionic conductivity but also successfully constructs an amorphous LiF/crystalline HEO heterostructure, which also improves the transport capacity of lithium ions. Additionally, the presence of abundant defects (e.g., oxygen vacancies, dislocations, and stacking faults) boosts the material's lithium transport and storage capacity. Furthermore, LiF facilitates the formation of a stable solid electrolyte interface (SEI) film on the HEO surface, preventing the corrosion of active materials and minimizing side reactions, effectively improving the ICE. The as-prepared LiF/HEO-48 demonstrates a superior initial capacity of 1632.9/1158.5 mAh g−1, along with an ICE of 70.9%. It maintains a high reversible capacity of 552.2 mAh g−1 after 1000 cycles at 0.5 A g−1, and even after 400 cycles at 2 A g−1, it retains 99.4% of its capacity. This study may open up new ways to selectively construct amorphous/heterostructures to improve the ICE and capacity of lithium-ion anodes.

In situ and Real-time Monitoring the Chemical and Thermal Evolution of Lithium-ion Batteries with Single-crystalline Ni-rich Layered Oxide Cathode.

High-capacity Ni-rich layered oxides are promising cathode materials for fabrication of lithium-ion batteries (LIBs) with high energy density. However, thermal runaway of LIBs with these cathodes leads to great safety concerns. In this study, single crystalline LiNi0.9Co0.05Mn0.05O2 (NCM-SC) has been prepared and a flexible optical fiber was buried inside the pouch-type LIBs with NCM-SC cathode to in situ study its real-time temperature evolution during charge/discharge process. NCM-SC exhibits an enhanced Li+ ions transportation efficiency and electrode reaction kinetics, which can effectively reduce the generation of polarization heat and mitigate the internal temperature rise of the pouch-type battery. Meanwhile, solid-electrolyte interface (SEI) film decomposition and gas accumulation are effectively alleviated, due to the enhanced thermal stability of SEI film formed on NCM-SC. Moreover, the single crystal architecture can effectively retard layered to spinal and rock-salt phase transition, mitigate the crack formation and structural collapse. Consequently, NCM-SC exhibits an excellent electrochemical performance and enhanced thermal stability.

In situ and Real‐time Monitoring the Chemical and Thermal Evolution of Lithium‐ion Batteries with Single‐crystalline Ni‐rich Layered Oxide Cathode

AbstractHigh‐capacity Ni‐rich layered oxides are promising cathode materials for fabrication of lithium‐ion batteries (LIBs) with high energy density. However, thermal runaway of LIBs with these cathodes leads to great safety concerns. In this study, single crystalline LiNi0.9Co0.05Mn0.05O2 (NCM‐SC) has been prepared and a flexible optical fiber was buried inside the pouch‐type LIBs with NCM‐SC cathode to in situ study its real‐time temperature evolution during charge/discharge process. NCM‐SC exhibits an enhanced Li+ ions transportation efficiency and electrode reaction kinetics, which can effectively reduce the generation of polarization heat and mitigate the internal temperature rise of the pouch‐type battery. Meanwhile, solid‐electrolyte interface (SEI) film decomposition and gas accumulation are effectively alleviated, due to the enhanced thermal stability of SEI film formed on NCM‐SC. Moreover, the single crystal architecture can effectively retard layered to spinal and rock‐salt phase transition, mitigate the crack formation and structural collapse. Consequently, NCM‐SC exhibits an excellent electrochemical performance and enhanced thermal stability.

Constructing flame retardant microspheres for safe and stable poly (ethylene oxide) based All-Solid-State batteries at high voltage

The development of all-solid-state polymer electrolytes (ASSPE) based on poly (ethylene oxide) (PEO) is facing a series of challenges, such as poor ionic conductivity, low Li+ transference number, flammability, and the limited electrochemical windows of 4 V. Herein, we report our recent effort to meet these challenges by introducing flame retardant microspheres (TH) into PEO-based ASSPE to form stable solid cathode electrolyte interface (CEI) films and enhance safety performance. TH is constructed by reacting tetrabromobisphenol A (TBBA) with hexachlorocyclotriphosphazene (HCCP). With the presence of only 5 wt% TH, the LiNi0.8Mn0.1Co0.1O2 (NCM811)//Li cell achieves a high capacity retention rate of 77.61 % after 100 cycles at the cutoff voltage of 4.3 V and 0.5C, and achieves a capacity retention of 75.7 % at the voltage range of 3–4.5 V after 50 cycles at 0.5C. In addition, the PEO-based ASSPE with TH (TH-PEO/PE) shows excellent flame retardancy, which endows the NCM811//Li pouch cell with good resistance to fire and mechanical abuse. This simple process is compatible with the existing production lines in the battery industry, which exhibits enormous promise in manufacturing commercialized all-solid-state lithium metal batteries (ASSLMBs) with high energy density and safety capabilities.

Enhancing Li-S Battery Performance with Limiting Li[N(SO2F)2] Content in a Sulfolane-Based Sparingly Solvating Electrolyte.

By enhancing the stability of the lithium metal anode and mitigating the formation of lithium dendrites through electrolyte design, it becomes feasible to extend the lifespan of lithium-sulfur (Li-S) batteries. One widely accepted approach involves the utilization of Li[N(SO2F)2] (Li[FSA]), which holds promise in stabilizing the lithium anode by facilitating the formation of an inorganic-dominant solid electrolyte interface (SEI) film. However, the use of Li[FSA] encounters limitations due to inevitable side reactions between lithium polysulfides (LiPSs) and [FSA] anions. In this study, our focus lies in precisely controlling the composition of the SEI film and the morphology of the deposited lithium, as these two critical factors profoundly influence lithium reversibility. Specifically, by subjecting an initial charging process to an elevated temperature, we have achieved a significant enhancement in lithium reversibility. This improvement is accomplished through the employment of a LiPS sparingly solvating electrolyte with a restricted Li[FSA] content. Notably, these optimized conditions have resulted in an enhanced cycling performance in practical Li-S pouch cells. Our findings underscore the potential for improving the cycling performance of Li-S batteries, even when confronted with challenging constraints in electrolyte design.

Achieving High Initial Coulombic Efficiency and Capacity in a Surface Chemical Grafting Layer of Plateau-type Sodium Titanate.

The plateau-type sodium titanate with suitable sodiation potential is a promising anode candidate for high safe and high energy density of sodium-ion batteries (SIBs). However, the poor initial Coulombic efficiency (ICE) and cyclic instability of sodium titanate are attributed to the unstable interfacial structure along with the decomposition of electrolytes, resulting in the continuous formation of solid electrolyte interface (SEI) film. To address this issue, a chemical grafting method is developed to fabricate a highly stable interface layer of inert Al2 O3 on the sodium titanate anode, rendering the high ICE and excellent cycling stability. Based on theoretical calculations, NaPF6 are more likely adsorption on the Al2 O3 surface and produce sodium fluoride. The formation of a thin and dense SEI film with rich sodium fluoride achieves the low interfacial resistances and charge-transfer resistances. Benefitting from our design, the obtained sodium titanate exhibits a high ICE from 67.7 % to 79.4 % and an enhanced reversible capacity from 151 mAh g-1 to 181 mAh g-1 at 20 mA g-1 , along with an increase in capacity retention from 56.5 % to 80.6 % after 500 cycles. This work heralds a promising paradigm for rational regulation of interfacial stability to achieve high-performance anodes for SIBs.

Design principles of heterointerfacial redox chemistry for highly reversible lithium metal anode

High electrochemical reversibility is required for the application of high-energy-density lithium (Li) metal batteries; however, inactive Li formation and SEI (solid electrolyte interface)-instability-induced electrolyte consumption cause low Coulombic efficiency (CE). The prior interfacial chemical designs in terms of alloying kinetics have been used to enhance the CE of Li metal anode; however, the role of its redox chemistry at heterointerfaces remains a mystery. Herein, the relationship between heterointerfacial redox chemistry and electrochemical transformation reversibility is investigated. It is demonstrated that the lower redox potential at heterointerface contributes to higher CE, and this enhancement in CE is primarily due to the regulation of redox chemistry to Li deposition behavior rather than the formation of SEI films. Low oxidation potential facilitates the formation of the surface with the highly electrochemical binding feature after Li stripping, and low reduction potential can maintain binding ability well during subsequent Li plating, both of which homogenize Li deposition and thus optimize CE. In particular, Mg hetero-metal with ultra-low redox potential enables Li metal anode with significantly improved CE (99.6%) and stable cycle life for 700 cycles at 3.0 mA cm-2. This work provides insight into the heterointerfacial design principle of next-generation negative electrodes for highly reversible metal batteries.

Regulating Lithium Nucleation at the Electrolyte/Electrode Interface in Lithium Metal Batteries

AbstractLithium (Li) metal has emerged as a viable alternative anode material to address the current energy density shortfalls in Li batteries. However, its integration into widespread implementation remains somewhat constrained due to the substandard reversibility issues and safety concerns arising from erratic Li deposition. To effectively tackle these obstacles, considerable endeavors have been exerted to modulate the morphology of Li deposition. Nevertheless, it is exceedingly challenging for Li nuclei that tend to dendritic growth thermodynamically to transform into dense Li morphologies during their growth process. Therefore, it is crucial to understand what influences the formation process of Li nuclei and how to improve the state of Li nuclei. Herein, Li nucleation mechanisms involving mass transport across the solid electrolyte interface from electrolyte to electrode and electrode interfacial reactions are elucidated. Inspired by the understanding of Li nucleation, the corresponding design principles, including enhancing and homogenizing mass transport, stabilizing solid electrolyte interface film, and regulating surface interaction/selection, are summarized for optimizing Li nucleation and further inducing dendrite‐free Li deposition. In light of the competition among these design principles, a perspective on the existing challenges and opportunities for further promoting the application of Li metal batteries is proposed.

Stages assessment of state of health in a lifetime based on the capacity variance of lithium batteries

To avoid the overuse or underutilization of lithium battery in practical applications, the state of health (SOH) of lithium battery should be assessed in time to ensure safety and maximize utilization. A health indicator (HI) is proposed to show the SOH of lithium battery in this paper. Firstly, the degradation mechanism of lithium battery is described based on the working principle and the aging phenomenon of lithium-iron phosphate battery, and the existing problems in the current research on battery aging phenomenon are expounded. Secondly, to deal with the hidden dangers caused by the aging problem of the battery, the variation of capacity variance is selected to construct the HI of lithium battery. Finally, the performance degradation state of lithium battery is divided into four stages according to the changing trend of the constructed indicators in the whole lifetime, which are the formation stage of the first solid electrolyte interface (SEI) film stage, the normal working stage, the new SEI film stage and the internal resistance rise stage. The battery data set from MIT-Stanford-Toyota Research Center is utilized to verify the proposed method. The results show that the performance of lithium batteries will accelerate degradation with temperature rapidly rising in the new SEI film stage; the internal resistance will increase sharply in the internal resistance rise stage, which can easily lead to accidents such as thermal runaway. The proposed health state assessment method compares with other methods, and it is shown that the proposed method helps to ensure safety and maximize the utilization of lithium batteries.

Designing Compatible Ceramic/Polymer Composite Solid-State Electrolyte for Stable Silicon Nanosheet Anodes.

The commercialization of silicon anode for lithium-ion batteries has been hindered by severe structure fracture and continuous interfacial reaction against liquid electrolytes, which can be mitigated by solid-state electrolytes. However, rigid ceramic electrolyte suffers from large electrolyte/electrode interfacial resistance, and polymer electrolyte undergoes poor ionic conductivity, both of which are worsened by volume expansion of silicon. Herein, by dispersing Li1.3 Al0.3 Ti1.7 (PO4 )3 (LATP) into poly(vinylidene fluoride)-hexafluoropropylene (PVDF-HFP) and poly(ethylene oxide) (PEO) matrix, the PVDF-HFP/PEO/LATP (PHP-L) solid-state electrolyte with high ionic conductivity (1.40 × 10-3 Scm-1 ), high tensile strength and flexibility is designed, achieving brilliant compatibility with silicon nanosheets. The chemical interactions between PVDF-HFP and PEO, LATP increase amorphous degree of polymer, accelerating Li+ transfer. Good flexibility of the PHP-L contributes to adaptive structure variation of electrolyte with silicon expansion/shrinkage, ensuring swift interfacial ions transfer. Moreover, the solid membrane with high tensile limits electrode structural degradation and eliminates continuous interfacial growth to form stable 2D solid electrolyte interface (SEI) film, achieving superior cyclic performance to liquid electrolytes. The Si//PHP-L15//LiFePO4 solid-state full-cell exhibits stable lithium storage with 81% capacity retention after 100 cycles. This work demonstrates the effectiveness of composite solid electrolyte in addressing fundamental interfacial and performance challenges of silicon anodes.

Constructing three-dimensional architectures to design advanced anodes materials for sodium-ion batteries: from nanoscale to microscale

Sodium-ion batteries (SIBs) are emerging as a possible substitute for lithium-ion batteries (LIBs) in low-cost and large-scale electrochemical energy storage systems owing to the lack of lithium resources. The properties of SIBs are correlated to the electrode materials, while the performance of electrode materials is significantly affected by the morphologies. In recent years, several kinds of anode materials involving carbon-based anodes, titanium-based anodes, conversion anodes, alloy-based anodes, and organic anodes have been systematically researched to develop high-performance SIBs. Nanostructures have huge specific surface areas and short ion diffusion pathways. However, the excessive solid electrolyte interface film and worse thermodynamic stability hinder the application of nanomaterials in SIBs. Thus, the strategies for constructing three-dimensional (3D) architectures have been developed to compensate for the flaws of nanomaterials. This review summarizes recent achievements in 3D architectures, including hollow structures, core-shell structures, yolk-shell structures, porous structures, and self-assembled nano/micro-structures, and discusses the relationship between the 3D architectures and sodium storage properties. Notably, the intention of constructing 3D architectures is to improve materials performance by integrating the benefits of various structures and components. The development of 3D architecture construction strategies will be essential to future SIB applications.

Investigation of the internal physical and chemical changes of a cylindrical lithium-ion battery during thermal runaway

This study delves into the critical safety issue of thermal runaway (TR) in lithium-ion batteries (LIBs), particularly focusing on the physical and chemical changes occurring in the electrode materials during temperature escalation. We investigate a commercial 18650 type 2.6 Ah Li[Ni5Co2Mn3]O2/graphite battery, tracing changes from room temperature to the point of TR. Our findings reveal that the negative electrode experiences gradual decomposition and regeneration of the solid electrolyte interface (SEI) film, reacting with the electrolyte to form compounds such as Li2CO3 and LiF on its surface. Similarly, the positive electrode also generates Li2CO3 on its surface as temperature rises. Notably, at 185 °C, there is a partial disintegration of the positive electrode particles, accompanied by a structural transformation from the LiMO2 (M representing Ni, Co, and Mn) R-3m layered structure to a disordered spinel LiM2O4. This research contributes to a deeper understanding of the TR mechanism in LIBs, offering valuable insights for material researchers in designing safer battery systems.

Exploring inexpensive electrodes for safer and evolved dual-ion batteries using modified electrolytes for enhanced energy density

The current era of energy-storage systems has been inspired by lithium dual-ion batteries (Li-DIBs) owing to their advantages, including low cost, safer features, faster charging ability, and high energy density. Herein, we employed a rust-derived rhombohedral hematite nanosphere (Fe2O3-NS) anode for lithium-ion batteries (LIBs) synthesized using simple high-energy ball milling at different milling times (12, 24, and 36 h), followed by an annealing process. Specifically, the Fe2O3-NS-24 h electrode exhibited a superior electrochemical performance for LIBs owing to its large surface area and mesoporous nature, which are responsible for fast kinetics with a 4.41 × 10-10 cm2 s−1 diffusion coefficient. Li-DIBs were successfully designed with Fe2O3-NS-24 h as the anode, LiPF6 (1.0 M) in 1:1 (V/V) ethylene carbonate: di-ethylene carbonate with 0.013 M LiNO3 additive as the electrolyte, and expanded graphite as the cathode [referred to as Fe2O3-EG Li-DIB@LN]. Its performance was compared with those of Li-DIBs without additives. This investigation proves that LiNO3 additives deliver numerous advantages, including inexpensive high-voltage batteries, enhanced energy density, and Coulombic efficiency (CE). This could be owing to the creation of a smooth, flat, and intact solid electrolyte interface film on the electrode interface, improved cyclability and capacity, and safer fast-charging for Li-DIBs. Fe2O3-EG Li-DIB@LN exhibited a specific capacity of 69.1 mAh g−1 after the 50th cycle at a 0.1 A g−1 rate and had a modest specific energy density of ∼ 238.3 Wh kg−1 with stable CE. These findings highlight a new route for employing LiNO3 additives to intensify the energy density, CE, and overall performance of Li-DIBs.

Achieving High-Energy-Density Graphene/Single-Walled Carbon Nanotube Lithium-Ion Capacitors from Organic-Based Electrolytes.

Developing electrode materials with high voltage and high specific capacity has always been an important strategy for increasing the energy density of lithium-ion capacitors (LICs). However, organic-based electrolytes with lithium salts limit their potential for application in LICs to voltages below 3.8 V in terms of polarization reactions. In this work, we introduce Li[N(C2F5SO2)2] (lithium Bis (pentafluoroethanesulfonyl)imide or LiBETI), an electrolyte with high conductivity and superior electrochemical and mechanical stability, to construct a three-electrode LIC system. After graphite anode pre-lithiation, the anode potential was stabilized in the three-electrode LIC system, and a stable solid electrolyte interface (SEI) film formed on the anode surface as expected. Meanwhile, the LIC device using LiBETI as the electrolyte, and a self-synthesized graphene/single-walled carbon nanotube (SWCNT) composite as the cathode, showed a high voltage window, allowing the LIC to achieve an operating voltage of 4.5 V. As a result, the LIC device has a high energy density of up to 182 Wh kg-1 and a 2678 W kg-1 power density at 4.5 V. At a current density of 2 A g-1, the capacity retention rate is 72.7% after 10,000 cycles.