Rate Capability Research Articles

Oxalate and adipate mediated fabrication of CuO nanocrystallites for their electrochemical and supercapacitance studies

Cupric oxide (CuO) has been comprehensively studied in the field of electrochemistry due to its high Tc-Superconducting property. The present work focus on two different CuO materials i.e. CuO-1 and CuO-2 nanocrystallites which are successfully synthesized from their oxalate and adipate precursors respectively. The calcination temperature for the synthesis of CuO from their precursors is ascertained by TGA analysis of the dicarboxylates. Both the CuO materials are thoroughly characterized by SEM–EDS, XRD, IR and XPS spectroscopic techniques. As a candidate for supercapacitor electrode material, CuO-1/C and CuO-2/C showed a specific capacitance of 4.15 F/g and 22.24 F/g using cyclic voltammetry, 10.4 F/g and 46.6 F/g using GCD curves respectively at a current density of 1 A/g. Also, the CuO-1/C and CuO-2/C showed a specific energy density (Es) 1.59 Wh kg−1 and 0.36 Wh kg−1 at a specific power density (Ps) of 0.02 kW kg−1 and 0.025 kW kg−1 respectively. Moreover, the CuO-2/C exhibits ≈ 96.1% coulombic efficiency following 1000 cycles, whereas, CuO-1/C lags in coulombic efficiency with only 51.8%. As a better candidate, CuO-2/C exhibited excellent rate capability with an outstanding cycling stability of 93.7% retention after 1,000 cycles. The factors contributing to the significant specific capacitance of CuO-2/C along with better stability and reproducibility are its low electrolyte resistance Rs (2.47Ω) and charge transfer resistance Rct (1.01 Ω).

Fabrication of Sandwiched NiCo-Layered Double Hydroxides/Carbon Nanoballs for Sustainable Energy Storage.

This study presents a promising method for creating high-performance supercapacitor electrodes. The approach involves crafting a unique composite material-nickel-cobalt-layered double hydroxides (NiCo-LDH) grown on carbon nanoballs (CNBs). This is achieved by first creating a special carbon material rich in oxygen and nitrogen from a polybenzoxazine source. At first, eugenol, ethylene diamine and paraformaldehyde undergo Mannich condensation to form the benzoxazine monomer, which undergoes self-polymerization in the presence of heat to produce polybenzoxazine. This was then carbonized and activated to produce CNBs containing heteroatoms. Then, through a hydrothermal technique, NiCo-LDH nanocages are directly deposited onto the CNBs, eliminating the need for complicated templates. The amount of CNBs used plays a crucial role in performance. By optimizing the CNB content to 50%, a remarkable specific capacitance of 1220 F g-1 was achieved, along with excellent rate capability and impressive cycling stability, retaining 86% of its capacitance after 5000 cycles. Furthermore, this NiCo-LDH/CNB composite, when combined with active carbon in a supercapacitor configuration, delivered outstanding overall performance. The exceptional properties of this composite, combined with its simple and scalable synthesis process, position it as a strong contender for next-generation sustainable energy storage devices. The ease of fabrication also opens doors for its practical application in advancing energy storage technologies.

The electrochemical comparisons of reduced graphene oxide synthesized from pristine and recovered graphite from spent Li-ion batteries

Two reduced graphene oxides (rGO) were synthesized using two carbon sources, namely pristine graphite (rGO-PG), and recovered graphite (rGO-RG) (graphite recovered from spent Li-ion batteries) by modified hummers method and followed by the chemical reduction method to compare their supercapacitive performances. Their supercapacitance is found to be highly competitive and comparable with each other, except for their rate capabilities. The rate capability of rGO-RG is found to be inferior compared to rGO-PG. The supercapacitive behavior of both rGO’s was evaluated using five different aqueous electrolytes. The specific capacitance, specific energy, specific power, and columbic efficiencies exhibited by rGO-RG and rGO-PG were superior in the presence of 1 M H2SO4 and are 36 F g1, 7.1 Wh kg1, 0.88 kW kg1 and 96.55 %; and 40 F g1, 7.9 Wh kg1, 0.66 kW kg1 and 97.36 %, respectively. Both the rGOs exhibited no deterioration in their performance up to 10,000 continuous charge and discharge cycles at a current density of 10 A g1; rather, they exhibited enhancement in their performances with an increase in charge and discharge cycles. The enhancement exhibited by rGO-RG is superior to that of rGO-PG, which is 844 % (272 F g1) higher than its initial performance (29 F g1).

"Lasagna"-Structured SnS-TaS2 Misfit Layered Sulfide for Capacitive and Robust Sodium-Ion Storage.

Stannous sulfide (SnS), a conversion-alloying type anode for sodium-ion batteries, is strong Na+ storage activity, a low voltage platform, and high theoretical capacity. However, grain pulverization induced by intolerable volume change and phase aggregation causes quick capacity degradation and unsatisfactory rate capability. Herein, a novel "lasagna" strategy is developed by embedding a SnS layer into the interlayer of an electrochemically robust and electron-active TaS2 to form a misfit layered (SnS)1.15TaS2 superlattice. For Na+ storage, the rationally designed (SnS)1.15TaS2 anode exhibits high specific capacity, excellent rate capability, and robust cycling stability (729 mAh cm-3 at 15 C after 2000 cycles). Moreover, the as-assembled (SnS)1.15TaS2 || Na3V2(PO4)3 full cells achieve robust and fast Na+ storage performance with ≈100% capacity retention after 650 cycles at 15 C, which also demonstrates good low-temperature performance at -20°C with a capacity retention of 75% and 2 C high-rate charge/discharge ability.

"Lasagna"-Structured SnS-TaS2 Misfit Layered Sulfide for Capacitive and Robust Sodium-Ion Storage.

Stannous sulfide (SnS), a conversion-alloying type anode for sodium-ion batteries, is strong Na+ storage activity, a low voltage platform, and high theoretical capacity. However, grain pulverization induced by intolerable volume change and phase aggregation causes quick capacity degradation and unsatisfactory rate capability. Herein, a novel "lasagna" strategy is developed by embedding a SnS layer into the interlayer of an electrochemically robust and electron-active TaS2 to form a misfit layered (SnS)1.15TaS2 superlattice. For Na+ storage, the rationally designed (SnS)1.15TaS2 anode exhibits high specific capacity, excellent rate capability, and robust cycling stability (729 mAh cm-3 at 15 C after 2000 cycles). Moreover, the as-assembled (SnS)1.15TaS2 || Na3V2(PO4)3 full cells achieve robust and fast Na+ storage performance with ≈100% capacity retention after 650 cycles at 15 C, which also demonstrates good low-temperature performance at -20°C with a capacity retention of 75% and 2 C high-rate charge/discharge ability.

Ar/NH3 Radio‐Frequency Plasma Etching and N‐doping to Stabilize Metallic Phase 1T‐MoS2 for Fast and Durable Sodium‐Ion Storage

AbstractMetallic phase 1T‐MoS2 is considered a prospective anode material for sodium‐ion batteries (SIBs) due to its remarkable electrical conductivity and unique layered structure. However, 1T‐MoS2 is thermodynamically unstable and prone to phase transition to the 2H‐MoS2 phase. Herein, self‐supporting nitrogen‐doped and carbon‐coated 1T/2H mixed‐phase MoS2 nanosheets with rich sulfur vacancies on carbon cloth (C@N‐MoS2‐p/CC) are synthesized through a hydrothermal method and Ar/NH3 radio‐frequency (RF) plasma treatment process. Density‐functional‐theory (DFT) calculations demonstrate that after Ar/NH3 RF plasma treatment, nitrogen‐doping and etching effects are realized, which combine with carbon‐coating significantly reduce the phase transition energy of 1T‐MoS2, thus triggering the phase transition and enabling the stable existence of the highly active 1T‐MoS2. As a result, the C@N‐MoS2‐p/CC exhibits outstanding sodium storage performance, with initial charge–discharge capacities of 701.0/797.0 mAh g−1 at 1 A g−1, respectively. It also demonstrates exceptional rate capabilities and ultra‐high cyclic stability, maintaining a discharge capacity of 404.2 mAh g−1 after 910 cycles at a high rate of 2 A g−1. In a full cell with Na3V2(PO4)3/CC cathode, it exhibits excellent initial charge–discharge capacities of 102.3/102.9 mAh g−1 and maintains satisfactory cycling stability after 350 cycles (86.7 mAh g−1) at 0.1 C.

A highly stable insertion type V1-xTixP solid solution as an anode material for high-rate lithium-ion batteries

As electric vehicles (EVs) grow in popularity, the demand for lithium-ion batteries (LIBs) simultaneously grows, and the fast-charging capability is becoming increasingly important. However, it is generally believed that graphite anode still suffers from a poor rate capability for fast-charging applications, and other insertion-type oxide anodes with a high rate capability exhibit too high Li+-ion insertion/extraction potential, which cannot meet a requirement for high energy density anodes. In this work, the hexagonal structure of V1-xTixP (x = 0.0, 0.25, and 1.0) phases were introduced as insertion-type anode materials for LIBs with a low reaction potential of Li+-ion insertion/extraction. The crystal structure and the corresponding electrochemical reaction mechanism of insertion-type anodes of TiP, VP, and MoP were compared. A facile strategy forming a substitutional solid solution is suggested to improve the electrochemical properties of anode materials by combining the end members among insertion-type VP, TiP, and MoP as forming V1-xTixP and V1-xMoxP compounds. V1-xTixP (x = 0.25) electrode, substituting V atoms with Ti atoms in VP structure, shows excellent long-term cycle stability at 1 A/g with a cycle retention of 87.7 % during 2500 cycles, delivering a two times higher capacity of 211.1 mAh g−1 compared to that of the commercial graphite electrode.

3D Printing of Tungstate Anion Modulated 1T‐MoS2 Composite Cathodes for High‐Performance Lithium–Sulfur Batteries

AbstractLithium–sulfur (Li–S) batteries can offer high capacity and energy‐density, but face challenges like low conductivity, lithium polysulfides (LiPSs) shuttling, and limited reaction kinetics. In this study, the electronic configuration of Mo 4d orbital in MoS2 is modulated through a one‐step method involving tungstate anion (WO42−) modulation to form a stable 1T‐MoS2/carbon composite (1T‐W‐MoS2/C). When WO42− is introduced, it causes a transfer of electrons to Mo in 2H‐MoS2, resulting in the generation of a stable 1T phase. In the composite, 1T‐MoS2 nanosheets exhibit remarkable electronic conductivity, hydrophilicity, and catalytic activity, facilitating the LiPSs adsorption and Li+ transport. Meanwhile, the WO42− modulation can create abundant adsorption/catalytic sites with defects on the basal surface and edges of MoS2, facilitating the efficient catalysis of LiPSs conversion. Furthermore, the 3D‐printed electrodes without utilization of binders and current collectors can ensure high mass loading and promote ion diffusion and electrolyte penetration. Theoretical and experimental results confirm that 1T‐W‐MoS2/C can catalyze LiPSs conversion, suppress LiPSs shuttling, and enhance sulfur reaction kinetics. Therefore, the 3D‐printed 1T‐W‐MoS2/C/S cathode exhibits a high initial capacity and excellent rate capability, achieving an areal capacity of 7.37 mAh cm−2 with a sulfur loading of 8.89 mg cm−2.

Barrel effect of high-rate capability determined by anode for LiNi0.5Co0.2Mn0.3O2/graphite lithium-ion battery

To date, charging time remains a critical issue that impedes the widespread application of lithium-ion batteries (LIBs). A comprehensive understanding of the attenuation mechanism of LIBs at high (dis)charging rates is essential for clarifying application strategies for extreme operating conditions and environments, thereby enhancing battery control, and guiding the design of advanced batteries with superior rate capability. In line with this focus, particular commercial NCM/graphite batteries were explored under various high-rate (dis)charging procedures, alongside the investigation of the impact of constant voltage steps on battery performance. This exploration revealed that capacity degradation occurs in three stages, and the rate of capacity decay is directly proportional to the (dis)charging rate. Furthermore, the in-situ temperature and stress of the battery during cycling, primarily caused by side reactions, were monitored to confirm the thermal effects and stress variations under high-rate conditions. By characterizing the morphology and composition of the electrode surface after post-mortem analysis, the “barrel effect” of high-rate capability determined by the anode electrode for LIBs is proposed. This research aims to establish optimal guidelines for designing batteries with excellent high-rate properties and to provide solutions for improving the safety and reliability of batteries applied in high-rate conditions.

Oriented Structures for High Safety, Rate Capability, and Energy Density Lithium Metal Batteries.

Lithium metal batteries (LMBs) have emerged in recent years as highly promising candidates for high-density energy storage systems. Despite their immense potential, mutual constraints arise when optimizing energy density, rate capability, and operational safety, which greatly hinder the commercialization of LMBs. The utilization of oriented structures in LMBs appears as a promising strategy to address three key performance barriers: 1) low efficiency of active material utilization at high surface loading, 2) easy formation of Li dendrites and damage to interfaces under high-rate cycling, and 3) low ionic conductivity of solid-state electrolytes in high safety LMBs. This review aims to holistically introduce the concept of oriented structures, provide criteria for quantifying the degree of orientation, and elucidate their systematic effects on the properties of materials and devices. Furthermore, a detailed categorization of oriented structures is proposed to offer more precise guidance for the design of LMBs. This review also provides a comprehensive summary of preparation techniques for oriented structures and delves into the mechanisms by which these can enhance the energy density, rate capability, and safety of LMBs. Finally, potential applications of oriented structures in LMBs and the crucial challenges that need to be addressed in this field are explored.

Oriented Structures for High Safety, Rate Capability, and Energy Density Lithium Metal Batteries.

Lithium metal batteries (LMBs) have emerged in recent years as highly promising candidates for high-density energy storage systems. Despite their immense potential, mutual constraints arise when optimizing energy density, rate capability, and operational safety, which greatly hinder the commercialization of LMBs. The utilization of oriented structures in LMBs appears as a promising strategy to address three key performance barriers: 1) low efficiency of active material utilization at high surface loading, 2) easy formation of Li dendrites and damage to interfaces under high-rate cycling, and 3) low ionic conductivity of solid-state electrolytes in high safety LMBs. This review aims to holistically introduce the concept of oriented structures, provide criteria for quantifying the degree of orientation, and elucidate their systematic effects on the properties of materials and devices. Furthermore, a detailed categorization of oriented structures is proposed to offer more precise guidance for the design of LMBs. This review also provides a comprehensive summary of preparation techniques for oriented structures and delves into the mechanisms by which these can enhance the energy density, rate capability, and safety of LMBs. Finally, potential applications of oriented structures in LMBs and the crucial challenges that need to be addressed in this field are explored.

Superior Electrochemical Performance and Cyclic Stability of WS2@CoMgS//AC Composite on the Nickel-Foam for Asymmetric Supercapacitor Devices

Two-dimensional (2D) sulfide-based transition metal dichalcogenides (TMDs) have shown their crucial importance in energy storage devices. In this study, the tungsten disulfide (WS2) nanosheets were combined with hydrothermally synthesized cobalt magnesium sulfide (CoMgS) nanocomposite for use as efficient electrodes in supercapattery energy storage devices. The characteristics of the WS2@CoMgS nanocomposite were better than those of the WS2 and CoMgS electrodes. XRD, SEM, and BET analyses were performed on the nanocomposite to examine its structure, morphology, and surface area in depth. In three-electrode assemblies, the composite (WS2@CoMgS) electrode showed a high specific capacity of 874.39 C g−1 or 1457.31 F g−1 at 1.5 A g−1. The supercapattery device (WS2@CoMgS//AC) electrode demonstrated a specific capacity of 325 C g−1 with an exceptional rate capability retention of 91% and columbic efficiency of 92% over 7000 cycles, according to electrochemical studies. Additionally, the high energy storage capacity of the WS2@CoMgS composite electrode was proved by structural and morphological investigations.

Superior Anodic Lithium Storage in Core–Shell Heterostructures Composed of Carbon Nanotubes and Schiff‐Base Covalent Organic Frameworks

Covalent organic frameworks (COFs) after undergoing the superlithiation process promise high‐capacity anodes while suffering from sluggish reaction kinetics and low electrochemical utilization of redox‐active sites. Herein, integrating carbon nanotubes (CNTs) with imine‐linked covalent organic frameworks (COFs) was rationally executed by in‐situ Schiff‐base condensation between 1,1′‐biphenyl]‐3,3′,5,5′‐tetracarbaldehyde and 1,4‐diaminobenzene in the presence of CNTs to produce core–shell heterostructured composites (CNT@COF). Accordingly, the redox‐active shell of COF nanoparticles around one‐dimensional conductive CNTs synergistically creates robust three‐dimensional hybrid architectures with high specific surface area, thus promoting electron transport and affording abundant active functional groups accessible for electrochemical utilization throughout the whole electrode. Remarkably, upon the full activation with a superlithiation process, the as‐fabricated CNT@COF anode achieves a specific capacity of 2324 mAh g−1, which is the highest specific capacity among organic electrode materials reported so far. Meanwhile, the superior rate capability and excellent cycling stability are also obtained. The redox reaction mechanisms for the COF moiety were further revealed by Fourier‐transform infrared spectroscopy in conjunction with X‐ray photoelectron spectroscopy, involving the reversible redox reactions between lithium ions and C=N groups and gradual electrochemical activation of the unsaturated C=C bonds within COFs.

A Nanostructured Phenazine‐based Conjugated Microporous Polymer Hybrid Anode Boosts Power and Practicability of Organic‐Manganese Hydronium‐ion Batteries

Organic‐manganese hydronium‐ion batteries are gaining attention for their safety, sustainability, and high rate capabilities. However, their electrochemical performance faces challenges due to organic active‐materials' inferior properties, including low conductivity and solubility, and limited content (<60 wt%) and loading (<2 mg/cm2) in the anode. To address this, we developed a high‐performance battery using a phenazine‐based conjugated microporous polymer hybrid anode (IEP‐27‐SR), utilizing hydronium‐ion coordination/un‐coordination chemistry. The IEP‐27‐SR features enhanced structural characteristics, such as high BET specific surface area, mixed micro‐/mesoporosity, nanostructurization, and hybridization, enabling rapid hydronium‐ion mobility. The resulting IEP‐27‐SR//MnO2@GF full‐cell demonstrates high capacity (101 mAh/g at 2C), excellent rate performance (41 mAh/g at 100C), ultrafast‐charging capability (80% charged in 18 seconds), and impressive cyclability with 83% capacity retention over 20400 cycles at 30C with a regular polymer mass loading of 2 mg/cm2, despite its high content (80 wt%) in the anode. Moreover, it shows operability at low temperatures (63 mAh/g at ‐40 ºC). Most importantly, full‐cell with a high‐mass‐loading polymer anode (30 mg/cm2) achieves practically relevant areal capacity (3.4 mAh/cm2 at 4 mA/cm2) and sustains 2 mAh/cm2 under an extremely high areal current (50 mA/cm2). This breakthrough highlights the progress of organic hydronium‐ion batteries, representing progress toward practical battery solutions

Dynamic magnesiothermic reduction of various silica to porous silicon structures for lithium battery anodes

A dynamic magnesiothermic reduction (DMR) of various silica having different size and porosity is conducted to study the effects of silica properties on the ⅰ) DMR reaction kinetics, ⅱ) properties of resulting porous silicon (pSi) microparticles, and ⅲ) performances of pSi/C composites as anodes in lithium batteries. A DMR kinetic study using the Ginstling–Brounstein diffusion model shows that the smaller the silica particle size, the higher the reduction rate and the lower the apparent activation energy. Irrespective of silica properties, all the resulting pSi particles have mesoporous structures. The pSi particles comprise interconnected small primary silicon nanoparticles (approximately 30–40 nm in diameter) to render similar particle morphologies to those of the parent silica. Owing to these appealing features of pSi particles, pSi/C composites exhibit excellent cycling performance for over 200 cycles and high rate capabilities, whereas SiMP/C (prepared with a non-porous silicon microparticles) loses most of its capacity in early cycles owing to high resistance build-up during cycling. Overall, the DMR of silica precursors of several micrometers or less in size (preferably porous precursors) are desirable for the production of high-purity pSi microparticles for use in high-capacity and stable anodes for advanced lithium batteries.

Seracam: characterisation of a new small field of view hybrid gamma camera for nuclear medicine

BackgroundPortable gamma cameras are being developed for nuclear medicine procedures such as thyroid scintigraphy. This article introduces Seracam® – a new technology that combines small field of view gamma imaging with optical imaging – and reports its performance and suitability for small organ imaging.MethodsThe count rate capability, uniformity, spatial resolution, and sensitivity for 99mTc are reported for four integrated pinhole collimators of nominal sizes of 1 mm, 2 mm, 3 mm and 5 mm. Characterisation methodology is based on NEMA guidelines, with some adjustments necessitated by camera design. Two diagnostic scenarios – thyroid scintigraphy and gastric emptying – are simulated using clinically relevant activities and geometries to investigate application-specific performance. A qualitative assessment of the potential benefits and disadvantages of Seracam is also provided.ResultsSeracam’s performance across the measured characteristics is appropriate for small field of view applications in nuclear medicine. At an imaging distance of 50 mm, corresponding to a field of view of 77.6 mm × 77.6 mm, spatial resolution ranged from 4.6 mm to 26 mm and sensitivity from 3.6 cps/MBq to 52.2 cps/MBq, depending on the collimator chosen. Results from the clinical simulations were particularly promising despite the challenging scenarios investigated. The optimal collimator choice was strongly application dependent, with gastric emptying relying on the higher sensitivity of the 5 mm pinhole whereas thyroid imaging benefitted from the enhanced spatial resolution of the 1 mm pinhole. Signal to noise ratio in images was improved by pixel binning. Seracam has lower measured sensitivity when compared to a traditional large field of view gamma camera, for the simulated applications this is balanced by advantages such as high spatial resolution, portability, ease of use and real time gamma-optical image fusion and display.ConclusionThe results show that Seracam has appropriate performance for small organ 99mTc imaging. The results also show that the performance of small field of view systems must be considered holistically and in clinically appropriate scenarios.

Digital holographic microscope for high spatial and temporal resolution in situ observation of dynamic phenomena of metals

A digital holographic microscope (DHM) was developed for the purpose of simultaneous observation and measurement of surface relief formation during deformation and phase transformation of steels. It was designed to accommodate the sample mounting component of a custom tensile tester. The Gabor wavelet transform method was used in the image reconstruction. To verify performance, the DHM was used to observe and measure height of slip bands formed during the monotonic loading 316L stainless steel. Data obtained has high temporal resolution (limited only by the camera’s frame rate capability) with lateral resolution approaching the diffraction limit. The results clearly show the evolving microstructures with height information available within each captured image.

A Nanostructured Phenazine‐based Conjugated Microporous Polymer Hybrid Anode Boosts Power and Practicability of Organic‐Manganese Hydronium‐ion Batteries

Organic‐manganese hydronium‐ion batteries are gaining attention for their safety, sustainability, and high rate capabilities. However, their electrochemical performance faces challenges due to organic active‐materials' inferior properties, including low conductivity and solubility, and limited content (<60 wt%) and loading (<2 mg/cm2) in the anode. To address this, we developed a high‐performance battery using a phenazine‐based conjugated microporous polymer hybrid anode (IEP‐27‐SR), utilizing hydronium‐ion coordination/un‐coordination chemistry. The IEP‐27‐SR features enhanced structural characteristics, such as high BET specific surface area, mixed micro‐/mesoporosity, nanostructurization, and hybridization, enabling rapid hydronium‐ion mobility. The resulting IEP‐27‐SR//MnO2@GF full‐cell demonstrates high capacity (101 mAh/g at 2C), excellent rate performance (41 mAh/g at 100C), ultrafast‐charging capability (80% charged in 18 seconds), and impressive cyclability with 83% capacity retention over 20400 cycles at 30C with a regular polymer mass loading of 2 mg/cm2, despite its high content (80 wt%) in the anode. Moreover, it shows operability at low temperatures (63 mAh/g at ‐40 ºC). Most importantly, full‐cell with a high‐mass‐loading polymer anode (30 mg/cm2) achieves practically relevant areal capacity (3.4 mAh/cm2 at 4 mA/cm2) and sustains 2 mAh/cm2 under an extremely high areal current (50 mA/cm2). This breakthrough highlights the progress of organic hydronium‐ion batteries, representing progress toward practical battery solutions

Rational Design of Electrolyte Additives for Improved Solid Electrolyte Interphase Formation on Graphite Anodes: A Study of 1,3,6-Hexanetrinitrile

The construction of a thin, uniform, and robust solid electrolyte interphase (SEI) film on the surface of active materials is pivotal for enhancing the overall performance of lithium-ion batteries (LiBs). However, conventional electrolytes often fail to achieve the desired SEI characteristics. In this work, we introduced 1,3,6-hexanetrinitrile (HTCN) in the baseline electrolyte (BE) of 1.0 M LiPF6 in Ethylene Carbonate/Dimethyl Carbonate (EC/DMC) (3:7 by volume) with 5 wt.% fluoroethylene carbonate (FEC), denoted as BE-FH. By systematically investigating the influence of FEC: HTCN weight ratios on the electrochemical performance of graphite anodes, we identified an optimal composition (FEC:HTCN = 5:4 by weight, denoted as BE-FH54) that demonstrated greatly improved initial Coulombic efficiency, rate capability, and cycling stability compared with the baseline electrolyte. Deviations from the optimal FEC:HTCN ratio resulted in the formation of either small cracks or excessively thick SEI layers. The enhanced performance of BE-FH54-based LiB is mainly ascribed to the synergistic effect of FEC and HTCN in forming a robust, thin, homogeneous, and ion-conducting SEI. This research highlights the importance of rational electrolyte design in enhancing the electrochemical performance of graphite anodes in LiBs and provides insights into the role of nitrile-based additives in modulating the SEI properties.

Rational Design of Electrolyte Additives for Improved Solid Electrolyte Interphase Formation on Graphite Anodes: A Study of 1,3,6-Hexanetrinitrile

The construction of a thin, uniform, and robust solid electrolyte interphase (SEI) film on the surface of active materials is pivotal for enhancing the overall performance of lithium-ion batteries (LiBs). However, conventional electrolytes often fail to achieve the desired SEI characteristics. In this work, we introduced 1,3,6-hexanetrinitrile (HTCN) in the baseline electrolyte (BE) of 1.0 M LiPF6 in Ethylene Carbonate/Dimethyl Carbonate (EC/DMC) (3:7 by volume) with 5 wt.% fluoroethylene carbonate (FEC), denoted as BE-FH. By systematically investigating the influence of FEC: HTCN weight ratios on the electrochemical performance of graphite anodes, we identified an optimal composition (FEC:HTCN = 5:4 by weight, denoted as BE-FH54) that demonstrated greatly improved initial Coulombic efficiency, rate capability, and cycling stability compared with the baseline electrolyte. Deviations from the optimal FEC:HTCN ratio resulted in the formation of either small cracks or excessively thick SEI layers. The enhanced performance of BE-FH54-based LiB is mainly ascribed to the synergistic effect of FEC and HTCN in forming a robust, thin, homogeneous, and ion-conducting SEI. This research highlights the importance of rational electrolyte design in enhancing the electrochemical performance of graphite anodes in LiBs and provides insights into the role of nitrile-based additives in modulating the SEI properties.