Film-forming Additives Research Articles

Synergistic role of functional electrolyte additives containing phospholane-based derivative to address interphasial chemistry and phenomena in NMC811||Si-graphite cells

Herein, we report on the 2-phenoxy-1,3,2-dioxaphospholane (PhEPi) molecule as a novel functional phospholane-based electrolyte additive. The presence of PhEPi in optimal concentration in the baseline electrolyte (EC:EMC 3:7, 1 M LiPF6) significantly enhances the electrochemical performance of the NMC811||Si-graphite cell chemistry. To further optimize the cell's overall performance, two well-known film-forming additives, namely, vinylene carbonate (VC) and fluoroethylene carbonate (FEC), were used as co-additives with PhEPi, and the resulting cells thoroughly characterized by selected electrochemical and spectroscopic techniques. The addition of PhEPi to the VC-containing electrolytes showed the complementary advantages of high specific discharge capacity and prolonged cycle life of the considered cells and outperformed the overall performance of the FEC counterpart. To gain better understanding of the role of each additive on the individual positive and negative electrode interphases, we conducted a systematic investigation of both electrodes, which were pre-cycled against Li-metal electrode. Post mortem spectroscopic investigations of the corresponding interphases provided insights into the synergistic effect of VC and PhEPi in the NMC811||Si-graphite cell chemistry.

Organofluorophosphates as Oxidative Degradation Products in High-Voltage Lithium Ion Batteries with NMC or LNMO Cathodes

Organofluorophosphates (OFPs) have been reported to pose substantial health hazards due to their structural similarities to pesticides and nerve agents. Formation of OFPs in lithium ion batteries (LIBs) due to hydrolysis of the conducting salt lithium hexafluorophosphate (LiPF6) and the reaction with the organic carbonate solvents that make up the electrolyte has been discussed in literature. The oxidative formation of OFPs in electrolytes containing fluoroethylene carbonate (FEC) and vinylene carbonate (VC) as film-forming additives is presented in this study. Further the impact of potentially reactive positive electrode surfaces is investigated with the layered metal oxide NCM622 which is ascribed to release reactive oxygen species at high voltages and the spinel type LNMO as a typical high-voltage material. Cycling of the self-assembled LIB coin cells (CR2032) at cut-off voltages of 4.8 V gave rise to a number of degradation products including potentially highly toxic OFPs. Here, the presence of the film-forming additive had a massive impact on the amount of OFPs formed during electrochemical cycling experiments, which raises further concerns for the utilization of film-forming additives for high voltage applications. The formation pathway of OFPs through EC-polymerization proposed in literature is evaluated and an alternative mechanism with FEC/VC as the carbonyl carbon-donor is presented. Structure elucidation and separation of the formed OFPs is achieved by utilization of reversed-phase (RP) chromatography hyphenated to a high-resolution ion trap time-of-flight mass spectrometer (IT-TOF-MS). The findings presented in this study support further investigation of the formation of OFPs in film-forming additive-containing electrolytes, quantitative approaches and toxicological assessments due to the highly toxic nature of OFPs.

All-climate outstanding-performances lithium-ion batteries enabled by in-situ constructed gel polymer electrolytes

Lithium-ion batteries (LIBs) with gel polymer electrolytes (GPE) employing highly volatile and extremely flammable linear carbonate solvents still face the safety hazard of fire and combustion. Gamma-butyrolactone (GBL) as electrolyte solvent can greatly improve the safety and all-climate performance of LIBs due to its higher flash point, lower vapor pressure, better thermal stability and wider liquid temperature range than those of the carbonate solvents. However, the application of GBL solvent is hindered by its incompatibility with the most widely used graphite anode. Herein, an all-climate high-power LiMn2O4 + LiMn0.7Fe0.3PO4/graphite pouch cell is achieved by employing non-flammable GBL-based GPE. The interphacial instability of GBL/graphite is solved by introducing three synergistic film-forming additives, including lithium bis(oxalato)borate, 4-vinyl-1,3-dioxolan-2-one and 3-sulfolene. The developed non-flammable GBL-based GPE enables the all-climate high-power LIBs application with great room-temperature rate capability, excellent low-temperature cranking and long elevated-temperature durability. More importantly, the developed pouch cells exhibit excellent cold-cranking performance even at −18 °C and maintain a high-capacity retention of 80 % after 400 cycles at 1C at 25 °C.

Insights into the Lithium Nucleation and Plating/Stripping Behavior from Ionic Liquid-Based Battery Electrolytes

Lithium-metal batteries are anticipated to become the next-generation battery technology, allowing for substantially higher energy densities. To maximize the energy density, however, a “zero excess” of lithium in the cell is a must, e.g., by initially storing all electrochemically active lithium in the positive electrode.1 Nevertheless, this requires the fully reversible deposition of metallic lithium, i.e., a Coulombic efficiency of essentially 100%.2 Herein, the investigation of the lithium nucleation and plating/stripping from ionic liquid-based electrolytes composed of N-butyl-N-methyl pyrrolidinium bis(fluorosulfonyl)imide (PYR14FSI) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) on nickel current collectors is reported, involving a comprehensive set of electrochemical techniques coupled with operando and in situ atomic force microscopy and ex situ X-ray photoelectron spectroscopy. It was found that the morphology of the deposited lithium, the chemical composition of the interphase formed on the nickel current collector, and the reversibility of the lithium plating and stripping is highly dependent on the ratio of the ionic liquid and the lithium salt. Moreover, the addition of suitable film-forming additives allows for lower overpotentials and greater reversibility by tuning the interphase composition. The results are anticipated to contribute to the development of advanced electrolyte systems for “zero excess” lithium-metal batteries.(1) Nanda, S., Gupta, A., and Manthiram, A. Anode-Free Full Cells: A Pathway to High-Energy Density Lithium-Metal Batteries. Adv. Energy Mater. 2021, 11, 2000804. DOI: 10.1002/aenm.202000804(2) Hobold, G.M., Lopez, J., Guo, R. et al. Moving beyond 99.9% Coulombic efficiency for lithium anodes in liquid electrolytes. Nat. Energy 2021, 6, 951–960. DOI: 10.1038/s41560-021-00910-w

Insight into the competitive reaction between LiDFP and LiFSI in lithium-ion battery at low temperature

Lithium-ion batteries (LIBs) suffering from severe performance degradation because of the unstable solid electrolyte interphase (SEI) on the anode at low temperature restricts their practical applications. Herein, lithium difluorophosphate (LiDFP) as the additive is introduced into lithium bis(fluorosulfonyl) imide (LiFSI) based electrolyte to improve the electrochemical performance of graphite/Li half-cells at low temperature. Contrary to the popular perception, we reveal at low temperature that LiDFP attenuates the decomposition of LiFSI by competing the hydrolysis reaction with LiFSI to generate a SEI film rich in LiF and Li3PO4 during prolonged cycling, rather than preferential decomposition. Additionally, the possible reaction equations and the interaction mechanism between LiDFP and LiFSI are proposed by combining in situ electrochemical impedance electrochemical (PRIs-EIS) tests, spectroscopic characterization techniques and density functional theory (DFT) calculations. It is demonstrated that the strong binding energy between LiF (from the decomposition of LiFSI) and LiDFP makes LiDFP easier deposit on the electrode surface. This work demonstrates the synergistic role combining the complementary advantage of film-forming additives and main lithium salts to improve the interfacial stability of LIBs at low temperature. Additionally, it can also pave the new pathway for the design of low temperature electrolytes in LIBs.

Synergistic Effect of Dual-Anion Additives Promotes the Fast Dynamics and High-Voltage Performance of Ni-Rich Lithium-Ion Batteries by Regulating the Electrode/Electrolyte Interface.

Combining the Ni-rich layered cathode (Ni ≥ 80%) with high operating voltage is considered as a feasible solution to achieve high-energy lithium-ion batteries (LIBs). However, the working voltage is limited in practical applications due to the poor interface stability in traditional carbonate electrolytes. Herein, LiBF4 and LiNO3 are added as film-forming additives and 1.0 M LiPF6 in SL/FEC/EMC with 0.5 wt % LiBF4-LiNO3 (HVE) is obtained. A uniform and inorganic-rich cathode electrolyte interphase (CEI) as well as a dense and Li3N-LiF-rich solid electrolyte interphase (SEI) could be in situ generated on LiNi0.8Co0.1Mn0.1O2 (NCM811) and graphite (Gr) electrode in HVE, respectively. The robust interface film with electronic insulation and ionic conductivity effectively stabilizes the NCM811/Gr-electrolyte interfaces and improves the Li+ diffusion kinetics, enabling the high-load NCM811-Gr to maintain 85.2% capacity (∼180 mA h g-1) after 300 cycles under 4.4 V. Besides, the 4.2 V NCM811-Gr retains 90.4% of the initial capacity after 200 cycles at 2 C (∼6 mA h cm-2). Compared with the traditional carbonate electrolyte (LB301), HVE has obvious advantages in terms of high-voltage and fast dynamics performance. Especially, good thermal stability and economy make HVE a promising electrolyte for commercial high-energy LIBs.

Interfacial Chemistry of Thiophene As an Effective Film-Forming Additive on High Voltage Cathode Revealed By Operando Raman Spectroscopy

For decades intense research efforts have been aimed at increasing energy densities with new rechargeable lithium battery (RLB) designs to meet the anticipated increasing energy storage demands. These efforts have yielded much higher capacities with novel materials. However, the theoretical capacity of an RLB cell is seeded in the structure of the electrode, while its practical capacity, performance, cycle life, and safety are deep-rooted in the side reactions at the interphase between electrode and electrolyte (interphase is the phase at the electrode-electrolyte interface) 1,2.Interphases are essential for the operation of the cells and have been widely recognized as the "most important and the least understood" components of RLBs3. While their characteristics determine their performance, they are not part of the design of RLBs, but only form during the cell operation on the anodes and cathodes. They constitute passivation layers with mixed chemistries due to the electrolytes' electrochemical stability window (ESW) being smaller than the operating potential of RLBs. Although interphase formation is of functional importance, its formation imposes a heavy price on the cell's performance. Formation of the interphase consumes the electrolyte and active lithium stored in the cathode and causes a dramatic capacity loss, especially in the initial charge/discharge cycles. Also, the presence of the interphase introduces a high level of impedance to the cell, which interrupts the fast and constant flow of Li-ion between the anode and cathode. Last but not least, interphase is an active and complex medium that changes its chemical composition and transport properties during charge/discharge cycling and storing conditions. This results in a constant evolution of the interphase and capacity fading, which is more prominent in the high cell voltage applications. Achieving high cell voltage by increasing the cut-off voltage of LiNi x Co y Mn1−x−y O2 cathode (NMC) materials to 4.5 V is an effective way to enhance the energy density of RLBs4. However, a high level of parasitic and decomposition reactions result in severe capacity fading of the battery cell5.Many efforts have been made to improve the properties of the cathode interphase at high cut-off voltage by incorporating different strategies. The in vivo approach is one of the more successful attempts to design the cathode interphase by incorporating film-forming additives in electrolytes to suppress parasite reactions at the electrode-electrolyte interface6-8. In an ideal case, this film should be stable with cycling and have excellent conductivity for Li+ ions and low electronic conductivity9.Thiophene-based molecules are investigated as effective film-forming on NMC at high cut-off voltages of 4.5 V vs. Li/Li+. Electrochemical investigations show that thiophene oxidizes before carbonate-based electrolytes and forms a stable interphase with high conductivity for Li-ion. Also, the electrochemical performance of the cell is enhanced significantly in the presence of thiophene additive with capacity retention of 95% after 100 cycles (75% capacity retention of the benchmark system). To reveal the underlying mechanisms of the interphase formation and thiophene working principle on the surface of NMC cathode, we performed operando near-field Raman spectroscopy. The Raman and electrochemistry results indicate that a poly-thiophene film is formed that covers the surface of the cathode active materials uniformly, protecting further oxidation of the electrolyte and preventing transition metal dissolution and decomposition of the active cathode materials. (1) Freunberger SA Nature Chemistry 2019, 11, 761. (2) Yang Y, Yan C, Huang JQ Acta Physico-Chimica Sinica 2021, 37. (3) Winter M Zeitschrift Fur Physikalische Chemie-International Journal of Research in Physical Chemistry & Chemical Physics 2009, 223, 1395. (4) Fergus JW Journal of Power Sources 2010, 195, 939. (5) Yan GC, Li XH, Wang ZX, Guo HJ, Wang C Journal of Power Sources 2014, 248, 1306. (6) Zhang L, Zhang ZC, Wu HM, Amine K Energy & Environmental Science 2011, 4, 2858. (7) Liu QY, Yang GJ, Li SW, Zhang SM, Chen RJ, Wang ZX, Chen LQ Acs Applied Materials & Interfaces 2021, 13, 21459. (8) Zhu XB, Schulli T, Wang LH Chemical Research in Chinese Universities 2020, 36, 24. (9) Xu K Chemical Reviews 2014, 114, 11503.

Flame-retardant, antibacterial, liquid-barrier, and wet-strength paper enabled by cellulosic fiber-derived additives

Cellulosic paper has combined characteristics of renewability, biodegradability, flexibility, and recyclability. Based on disassembly-initiated fiber processing, the conversion of regular paper into a multifunctional wet-strength product was explored. In this concept, disassembly generates cellulosic additives for surface engineering. Encouragingly, the use of the aqueous solvent system containing mixed metal salts allows controllable fiber disassembly and formation of room-temperature-stable cellulosic solutions, leading to wet and dry strengthening of paper following cellulose regeneration. In-situ generation of cellulosic film-forming additives led to the increase of dry and wet strengths by more than 8 and 35 times respectively, in the case of a typical grade of quantitative filter paper. The engineered paper shows flame-retardant, antibacterial, and liquid-barrier features. The combination of functional properties of cellulosic paper can shed light on diversified applications, e.g., replacement of difficult-to-degrade synthetic plastics.

Comparative study of 1,3-propane sultone, prop-1-ene-1,3-sultone and ethylene sulfate as film-forming additives for sodium ion batteries

Electrolyte additives play a pivotal role in improving the cyclability of the sodium-ion batteries (SIB) by modifying the composition of solid electrolyte interphase (SEI) film. Herein, we select three sulfur-based additives with similar molecular structure (1,3-propane sultone (1,3-PS), prop-1-ene-1,3-sultone (PES) and ethylene sulfate (DTD)), which is contrastively investigated using home-made Na(Ni0.4Mn0.4Cu0.1Ti0.1)0.999La0.001O2 (NMCT-La)/commercial hard carbon (HC) full-type cells within the voltage range of 1.2–4.4 V. It is shown that adding 2 wt% 1,3-PS or 2 wt% DTD in the base electrolyte (1 M NaPF6 in EC:DMC with 2 wt% FEC) can achieve an increasingly capacity retention rate from 58.7% to 82.0% and 79.4%, respectively, while PES has a negative effect. Electron microscopy characterizations (FESEM and TEM) and X-ray photoelectron spectroscopy (XPS) results confirm that 1,3-PS or DTD can generate a denser and more uniform SEI film on the HC electrode, meanwhile, be oxidized on the positive electrode to protect the NMCT-La material from the attack of the electrolyte during cycling. The formation of sulfates and sulfites (such as ROSO2Na and RSO3Na) through the decomposition of 1,3-PS and DTD can stabilize SEI film, resulting in a high-performance SIB with long lifespan.

Back Cover Image, Volume 1, Issue 2, April 2022

Battery EnergyVolume 1, Issue 2 20230007 COVEROpen Access Back Cover Image, Volume 1, Issue 2, April 2022 First published: 22 April 2022 https://doi.org/10.1002/bte2.20230007AboutPDF ToolsExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Abstract Back Cover: The operating temperatures of current LIBs (−20~60°C) cannot meet the demands of frigid zones and other extreme application fields. In article number 20210006, Chen et al. give a comprehensive overview of the promising strategies towards widetemperature applications in terms of solvent combination, lithium salts and film-forming additives design. Volume1, Issue2April 202220230007 RelatedInformation

Influence of film-forming additives on the interface performance of potassium ion battery cathode

The addition of electrolyte additives is widely regarded as one of the most effective methods of improving the electrochemical performance of a battery. This study uses succinonitrile as a typical representative of nitrile film-forming additives to improve the film-forming stability of δ-MnO2/KMnF3 as the potassium ion battery cathode. The strong interaction between the –CN group of the nitrile and the metal ion on the cathode surface will enhance the stability of the solid electrolyte interface film. Electrochemical impedance spectroscopy is used to study the interface phenomena during charge and discharge. The mechanism of the film-forming additives is predicted and explained. These new design concepts will create a higher possibility of improving the battery cycle stability.

High Energy, Long Cycle, and Superior Low Temperature Performance Aqueous Na-Zn Hybrid Batteries Enabled by a Low-Cost and Protective Interphase Film-Forming Electrolyte.

A hybrid aqueous Na-Zn ion battery derived from the Na3V2(PO4)3 cathode is one of the most promising systems among aqueous batteries because it exhibits higher energy density than a pure Zn ion battery due to different ion intercalation mechanisms related to various electrolytes. However, it is more difficult to improve the electrochemical performance of the hybrid aqueous Na-Zn ion battery versus Zn ion battery. In addition, searching for suitable protective interphase film-forming electrolyte additives in order to increase cycling stability and developing a new electrolyte recipe to improve the low temperature performance are significant and still big challenges for the hybrid aqueous Na-Zn battery. Herein, the introduction of protective interphase film-forming additives (VC), an economical 10 M NaClO4-0.17 M Zn(CH3COO)2-2 wt % VC electrolyte, was proposed. Based on such an electrolyte, the carbon-coated single crystalline Na3V2(PO4)3 nanofiber//Zn aqueous Na-Zn hybrid battery involving high energy, long cycle, and outstanding low temperature performance was successfully obtained. For example, it delivered a remarkable output voltage of 1.48 V and excellent cycle stability (retained 84% after 1000 cycles). The capacities were 94.4 mA h/g at 0.2 A/g at -10 °C and 90.0 mA h/g at 0.2 A/g at -20 °C, respectively.

Revealing the critical effect of solid electrolyte interphase on the deposition and detriment of Co(Ⅱ) ions to graphite anode

“Dissolution, migration, and deposition” of transition metal ions (TMIs) result in capacity degradation of lithium-ion batteries (LIBs). Understanding such detrimental mechanism of TMIs is critical to the development of LIBs with long cycle life. In most previous works, TMIs were directly introduced into the electrolyte to investigate such a detrimental mechanism. In these cases, the TMIs are deposited directly on the fresh anode surface. However, in the practical battery system, the TMIs are deposited on the anode covered with solid electrolyte interphase (SEI) film. Whether the pre-presence of SEI film on anode surface influences the deposition and detriment of TMIs is unclear. In this work, the deposition of Co element on graphite anode with and without SEI film were systematically studied. The results clearly show that, in comparison with that of fresh graphite (SEI-free), the presence of SEI film aggravates the deposition of Co ions due to the Li+–Co2+ ion exchange between the SEI and Co2+-containing electrolyte without the driving of the electric field, leading to faster capacity fading of graphite anode. Therefore, how to regulate electrolytes and film-forming additives to design the components of SEI and prevent its exchange with TMIs, is a crucial way to inhibit the deposition and detriment of TMIs on graphite anode.

Re-evaluating common electrolyte additives for high-voltage lithium ion batteries

Further increase in the specific energy/energy density of lithium ion batteries can be achieved via further increase of charge cell voltage. However, an enhanced electrode cross-talk, i.e., transition metal (TM) dissolution from cathode and deposition on the anode, drastically limits the cycle life, even leading to rollover failure. In this work, the commonly used film-forming electrolyte additives vinylene carbonate (VC), fluoroethylene carbonate (FEC), and lithium difluorophosphate (LiDFP) are thoroughly evaluated regarding their ability to suppress the issues originating from electrode cross-talk. Neither the VC- nor the FEC-containing electrolytes can suppress it, as evidenced by the presence of Ni, Co, and Mn on the graphite anode; although different for the FEC, the deposited TMs and intertwined Li deposits are homogeneously distributed in the presence of VC. Despite suppression of rollover failure in this manner, VC still cannot compete with LiDFP because LiDFP is able to complex TMs and provide TM-scavenging agents, i.e., PO 3 F − and PO 4 2− , thus, effectively suppressing electrode cross-talk in the first place and effectively preventing the concomitant failure cascade. TM-based electrode cross-talk causes Li dendrites and rollover failure Neither VC nor FEC can suppress electrode cross-talk At a minimum, VC promotes homogeneous TM deposition and suppresses rollover failure LiDFP is most effective because it suppresses electrode cross-talk via scavenging Further increases in energy density of Li-ion batteries can be realized by increasing the charge voltage. However, the enhanced transition-metal dissolution from the cathode and deposition on the anode causes severe safety and performance issues. Klein et al. show that scavenging of transition metals can ameliorate those issues.

Elasto-hydrodynamic friction changes on steel surfaces arising from the modified surface energy of the steel due to additive boundary films

The effect of three different film-forming additives mixed in PAO oil on the elasto-hydrodynamic (EHD) friction was investigated and compared to cases with the base oil only. When the boundary films were formed on the surfaces, the organic friction modifier (OFM) decreased the EHL friction by up to 8.7%, the ionic liquid (IL) decreased it by up to 6.4%, while the polymeric organic friction modifier (pOFM) increased it by up to 4.2%. In contrast, if the boundary films were not formed, the EHL friction remained the same as with the base oils only. The oils’ surface tension and viscosity were analysed at 25 °C and 100 °C as potential influencing effects, and the most important parameter for friction changes was found to be the surface energy. The mechanism behind this EHL friction reduction is, therefore, the effect of the boundary films on the poor oil-surface wetting and the consequent boundary slip. This study confirms the poor wetting arising from additive boundary-film formation as a relevant EHL friction-reduction mechanism. This observation is similar to that observed previously for surface coatings, thus suggesting that the boundary films of the surface-energy-reducing additives is a parameter with the potential to reduce the EHL friction.

Research on Green Building Materials in Civil Engineering Management System

The development of the real estate industry has increased the application market capacity of green building materials, and the demand for green building materials has also greatly increased. The formation of the concept of pollution-free, energy-saving and environmentally friendly housing by consumers has gradually changed the choice of traditional civil engineering construction materials and Cost control. The application and promotion of a large number of green building materials in civil engineering construction has laid a material foundation for the construction of energy-saving and environmentally friendly buildings in China. The article is based on this, using inorganic raw materials potassium silicate, sodium silicate, and silica sol as base materials, add a certain proportion of organic silicon modified styrene-acrylic emulsion, and then add titanium dioxide, kaolin, talc, nano-titanium dioxide and other fillers and coating film-forming additives to prepare water-based inorganic coatings. The test results show that the prepared coating has good physical and chemical properties, environmental protection performance, and fire resistance performance, and can be widely used in the construction industry with obvious social and economic benefits and environmental protection benefits.

Revealing the Impact of Film-Forming Electrolyte Additives on Lithium Metal Batteries via Solid-State NMR/MRI Analysis

Because of the high specific capacity and low redox potential, lithium metal constitutes a promising material and might be an option for high energy density next-generation battery technologies, though application of lithium metal batteries (LMBs) is currently limited by poor long-term performance and severe safety issues when liquid electrolytes are used. These challenges arise from formation of “dead” lithium or inhomogeneous lithium deposits as well as ineffective solid electrolyte interphase (SEI) layers on lithium metal electrodes. Notably, lithium consumed by SEI formation and fractions of “dead” lithium was derived from in situ 7Li nuclear magnetic resonance (NMR) of pouch-type cells, while 19F 1D magnetic resonance imaging (MRI) profiling along with operando optical microscopy analysis revealed the nature of lithium deposits, considering the impact of electrode kinetics on the occurrence of dendritic lithium microstructures, governed by processes of electrodeposition and electrodissolution. Various electrolyte formulations were compared in view of different cell configurations, including Li||Li symmetric cells as well Li||Cu cells, Cu||NMC cells, and finally NMC||Li full cell systems, establishing the origin and likely contributions to irreversible capacity losses while systematically evaluating different active materials (including electrolyte formulations, cathode material, and lithium metal anodes). Indeed, a mixture of film-forming additives—fluoroethylene carbonate (FEC) and lithium difluorophosphate (LiPO2F2)—was demonstrated to afford both “better” interfacial/interphasial properties and more homogeneous lithium deposition, thus exhibiting promising electrochemical performance.

In Operando Lithiation of Lithium Free Cathodes

Lithium and lithium-rich containing cathodes such as LiCoO2, LiFePO4, LiNixMnyCozO2, Li-rich anti-fluorite Li5FeO4 have dominated the portable battery energy storage market. Compounds without lithium in their lattice seldomly have been used as positive electrodes either due to incapability for reversible reactions or require metallic lithium metal electrode. These limitations have prevented the development of new positive electrodes to a larger extent in lithium-ion batteries. Examples of such materials are sulfur, vanadium oxides, FeS2, MnO2, FeF3, etc. However, these materials demonstrate tremendously high specific capacities, and high operating voltages, possibly realizing advanced next-generation batteries. To practically realize them, it is pertinent to address the lithiation strategies, namely pre-lithiation of the anode,blended cathodes, lithium additives, and film-forming additives. These methods result in modification of cell voltage on account of Li+ ion voids in the cathode, whereas pre-lithiation of anode compensates initial lithium consumption. Nevertheless, the pre-lithiation process is one of the unique techniques connected with the complicated, multistep, moisture-sensitive, expensive process, which is not feasible in large-scale applications.In situ lithiation of cathode or anode electrodes for the development of longer-lasting rechargeable batteries uses metallic lithium-electrode as a booster and reservoir. The presence of third reservoir electrode in the lithium-ion battery (LIB), i.e., metallic lithium, is brought into electrochemical reactions initially during the lithiation process and later as a booster to rejuvenise LIBs after the capacity fade on account of cycling. Here, we report the usage of V2O5 cathode with tailored silicon-carbon-graphite composite to fabricate high specific capacity and high energy-density LIBs. The tri-electrode system delivered a high initial charge specific capacity of 240 mAh g-1. After 100 cycles, re-boosting was provided, and at the end of 200th cycle the cell delivered a high average capacity of 140 mAh g-1. The tri-electrode system provided an initial high energy density of 960 Wh kg-1 and an average of 560 Wh kg-1 after 200 cycles. Using thermal signatures from multiple module calorimetry, the safety features of the proposed tri-electrode system were studied and compared to conventional LIBs. Using this novel concept of reservoir boosting would be of prime importance and value in space, healthcare, electric vehicles, UPS, grid-storage, etc. applications.

The Sodium-Ion Battery: Effect of Electrolyte Additives on the SEI Layer of Hard Carbon Anodes

Since their discovery, lithium-ion batteries (LIBs) have dominated the energy storage and power market due to their attractive attributes. However, LIBs cannot cope with the ever-growing energy demand and new alternatives must be explored. The low cost, and abundance of sodium, as well as its similar chemical properties to lithium, make the sodium-ion battery (SIB) a promising alternative for the future.1-5 SIBs often suffer from a short cycle lifespan, which is mainly attributed to the formation of an unstable solid electrolyte interphase (SEI) layer on the hard carbon anode surface. During the first cycle, the electrolyte solution is reduced, and its decomposition products form a passivation film (SEI) on the anode. Ideally, the SEI should protect the electrolyte from further decomposition during subsequent cycling, while being permeable to sodium ions. To reach this ideal situation, the employment of film-forming electrolyte additives in small amounts is necessary.6-11 In this study, in-operando electrochemical quartz crystal microbalance is used to monitor how additives affect the mass variation during the sodium intercalation/de-intercalation process. Mass spectrometry is further employed to identify and quantify the generated gaseous species during the initial SEI formation. After cycling, scanning electron microscopy and X-ray photoelectron spectroscopy are used to explore the additives effect on the SEI thickness and composition. A range of additives are considered including 1,3-propane sultone, succinonitrile and sodium-difluoro(oxalato)borate. The results of this study will be presented, along with suggestions for future research. Reference s : [1] P. K. Nayak, L. Yang, W. Brehm, P. Adelhelm, Angew. Chem. Int. Ed. 57 (2018) 102–120.[2] S. Roberts, E. Kendrick, Nanotechnol. Sci. Appl.11 (2018) 23-33.[3] H. Li, X. Zhang, Z. Zhao, Z. Hu, X. Liu, G. Yu, Energy Storage Mater. 26 (2020) 83–104.[4] J. Deng, W. B. Luo, S. L. Chou, H. K. Liu, S. X. Dou, Adv. Energy Mater. 8 (2018) 1–17.[5] L. Li, Y. Zheng, S. Zhang, J. Yang, Z. Shao, Z. Guo, Energy Environ. Sci., 11 (2018) 2310–2340.[6] G. Eshetu, M. Martinez-Ibañez, E. Sánchez-Diez, I. Gracia, L. Chunmei, L. M. Rodriguez-Martinez, T. Rojo, H. Zhang, M. Armand, Chem. Asian J. 13 (2018) 2770-2780.[7] M. Dahbi, T. Nakano, N. Yabuuchi, S. Fujimura, K. Chihara, K. Kubota, J.Y. Son, Y.T. Cui, H. Oji, S. Komaba, ChemElectroChem, 3 (2016) 1856–1867.[8] G. Yan, K. Reeves, D. Foix, Z. Li, C. Cometto, S. Mariyappan, M. Salanne, J.M. Tarascon, Adv. Energy Mater. 4 (2019) 36244–36251.[9] S. Komaba, W. Murata, T. Ishikawa, N. Yabuuchi, T. Ozeki, T. Nakayama, O. Atsushi, G. Kazuma, K. Fujiwara, Adv. Funct. Mater. 21 (2011) 3859-3867.[10] A. Bouibes, N. Takenaka, T. Fujie, K. Kubota, S. Komaba, M. Nagaoka, Appl. Mater. Interfaces. 10 (2018) 28525-28532.[11] M.A. Muñoz-Márquez, D. Saurel, J.L. Gómez-Cámer, M. Casas-Cabanas, E. Castillo-Martínez, T. Rojo, Adv. Energy Mater. 7 (2017) 1-31.

Assessment of worm gears life with changes in the wear intensity and the rate of growth of the dynamic coefficient when using film-forming additives

Тhe resource of the worm gear was assessed by the criterion of extreme wear, taking into account the change in the dependence of the wear intensity and the rate of growth of the dynamic coefficient on the load when using nanomodified film-forming lubricants.