Performance Of Lithium-ion Batteries Research Articles

Achieving Enhanced High-Temperature Performance of Lithium-Ion Batteries via Salt-Inspired Interfacial Engineering.

Electrolyte additive engineering enables the creation of long-lasting interfacial layers that protect electrodes, thus extending the lifetime of high-energy lithium-ion batteries employing Ni-rich Li[Ni1-x-yCoxMny]O2 (NCM) cathodes. However, batteries face various limitations if existing additives are employed alone without an appropriate combination. Herein, the study reports the development of a molecular-engineered salt-type multifunctional additive, lithium bis(phosphorodifluoridate) triethylammonium ethenesulfonate (LiPENS), that leverages the different functionalities of phosphorous, nitrogen, and sulfur-embedded motifs, as well as the classical additive vinylene carbonate (VC), to construct protective interfacial layers. The thermally and electrochemically reinforced solid electrolyte interphase (SEI), achieved through the combined use of LiPENS and VC, conserves the lithiation level of the Graphite (Gr) anode with minimal SEI growth, whereas the inorganic-rich cathode-electrolyte interface (CEI) alleviates the irrevocable phase transition and mechanical fragility of the LiNi0.8Co0.1Mn0.1O2 (NCM811) secondary particles. The multifunctional roles of LiPENS are demonstrated in an NCM811/Gr full cell, showing a discharge capacity of 190.7 mAh g-1 with an enhanced capacity retention of 91.8% at 1 C and 45°C after 300 cycles. This advancement in electrolyte additive engineering based on salt structures can lead to more efficient, reliable, and commercially viable batteries for high-energy applications, including electric vehicles and portable electronics.

Concentrated, Gradient Electrolyte Design for Superior Low-Temperature Li-Metal Batteries

Improving the low-temperature performance of lithium-ion batteries is critical for their widespread adoption in cold environments. In this study, we designed a novel LHCE featuring a solvent polarity gradient, designed to maximize both room- and low-temperature ion mobility. Extremely polar fluoroethylene carbonate (FEC) and low-freezing-point, −135 °C, non-polar nonaflurobutyl methyl ether (NONA) were supplemented by two intermediate solvents with incremental step-downs in polarity. The intermediate solvents consist of methyl (2,2,2-triflooethyl) carbonate (FEMC) and either diethylene carbonate (DEC), ethyl methyl carbonate (EMC), or dibutyl carbonate (DBC). The four solvents were combined with 1 M lithium bis(fluorosulfonyl)amide (LiFSI) salt and were able to accommodate 37.5% diluent volume, resulting in ultra-low electrolyte freezing points below −120 °C. This contrasts with our previously investigated three-solvent LHCE, which only allowed for a 14% diluent volume and a −85 °C freezing point. Localized high salt concentrations were shown by less than 3% of FSI- anions being free in solution. The gradient LHCEs also showed room-temperature ionic conductivities above 10–3 S/cm and maintained high ion mobility below −40 °C. Lithium metal coin cells with LiFePO4 (LFP) cathodes featuring the gradient LHCEs, a reference three-solvent LHCE, and commercial (1 M LiPF6 in 1:1 EC:DEC) electrolyte were constructed. All gradient LHCEs outperformed both the three-solvent and commercial electrolytes at all temperatures, with the DEC-based gradient LHCE showing the best performance of 159.7 mAh/g at 25 °C and 109.2 mAh/g at −50 °C, corresponding to a 68% capacity retention. These findings highlight the potential of LHCE systems to improve battery performance in low-temperature environments and propose a new gradient design strategy for electrolytes to yield advantages of both polar and weakly polar solvents.

Enhanced lithium-ion battery performance with a novel composite anode: S-doped graphene oxide, polypyrrole, and fumed silica.

In this work, a novel composite anode material was developed, utilizing S-doped graphene oxide (SGO), polypyrrole (PPy), and fumed silica to enhance the performance of lithium-ion batteries (LIBs). The chronoamperometric approach was used to produce SGO, while the chemical method was employed to synthesize PPy. A composite of SGO, PPy, and fumed silica was prepared as an anode for a half-cell, using two samples: one with a high PPy ratio (S1) and the other with a low PPy ratio (S2) and compared the results with bare sample (S0). The S1 sample exhibited a good initial discharge capacity (648 mAh/g), with capacities of 207 and 131 mAh/g at 5C and 10C, respectively. S1 and S2 also demonstrated superior cycling stability at a high current (100 cycles at 10C), with a retention capacity of 99 and 87%, respectively compared with S0 which retained only 68%. Coin-type full cells with S1 as the anode and LiFePO4 (LFP) as the cathode were assembled and compared with commercial graphite anodes. The S1 full cell showed a high reversible capacity (164 mAh/g at 0.1C), with a capacity retention of 66% after 100 cycles at 10C. At the same time, the graphite anode exhibited a reversible capacity of 133 mAh/g at 0.1C, with a capacity retention of 58% after 100 cycles at 10C. The S1 full cell achieved a gravimetric energy density of 164 W h/kg at 0.1C and 49 W h/kg at 10C, which is 25% greater than that of the graphite full cell (39 W h/kg) at 10C. These distinguishing characteristics of S1 make it a viable substitute for graphite as a high-performance anode material in LIBs, opening the possibility for devices with reliable battery systems.

Characterization of interactions in battery slurry via MD simulation: Influence on miscibility, morphology, and dispersion with varying ACN content in HNBR.

This paper investigates the phase behaviors, morphology changes, and degree of dispersion of a multi-component cathode battery slurry system. The slurry comprises polyvinylidene fluoride (PVDF) as the binder, hydrogenated nitrile butadiene rubber (HNBR) as the dispersant with varying acrylonitrile (ACN) content, N-methyl-2-pyrrolidone (NMP) as the solvent, and carbon nanotubes/graphene (CNTs/GRA) as the conductive agent. Several analytical methods, including visualized imaging, solubility parameters, radial distribution function (RDF) analysis, β phase PVDF analysis, near-atom analysis, and potential of mean force (PMF) analysis, were employed to compare the slurry's characteristics. The results indicate that an increase in ACN content in HNBR improves the miscibility between HNBR and PVDF, while HNBR with low ACN content results in a crystalline structure and phase separation of HNBR and PVDF. Conversely, increasing the ACN content in HNBR has a negative impact, making it a poorer dispersant itself. These findings provide essential insights into effectively regulating the phase behavior, miscibility, and dispersion ability of multi-component slurry systems, thereby enhancing the performance of lithium-ion batteries.

Revealing the Dynamic Evolution of Electrolyte Configuration on the Cathode-Electrolyte Interface by Visualizing (De) Solvation Processes.

Electrolyte engineering is crucial for improving cathode electrolyte interphase (CEI) to enhance the performance of lithium-ion batteries, especially at high charging cut-off voltages. However, typical electrolyte modification strategies always focus on the solvation structure in the bulk region, but consistently neglect the dynamic evolution of electrolyte solvation configuration at the cathode-electrolyte interface, which directly influences the CEI construction. Herein, we reveal an anti-synergy effect between Li+-solvation and interfacial electric field by visualizing the dynamic evolution of electrolyte solvation configuration at the cathode-electrolyte interface, which determines the concentration of interfacial solvated-Li+. The Li+ solvation in the charging process facilitates the construction of a concentrated (Li+-solvent/anion-rich) interface and anion-derived CEI, while the repulsive force derived from interfacial electric field induces the formation of a diluted (solvent-rich) interface and solvent-derived CEI. Modifying the electrochemical protocols and electrolyte formulation, we regulate the "inflection voltage" arising from the anti-synergy effect and prolong the lifetime of the concentrated interface, which further improves the functionality of CEI architecture.

A Quantification Method for Micro-defect Size in Copper Foil Based on Motion-induced Eddy Current Signal Characteristics

Abstract Lithium batteries represent a pivotal technology in modern energy storage and have attracted significant attention. Copper foil is frequently employed as the current collector for the negative electrode; however, the presence of micro-defects can severely impair the electrochemical performance of lithium batteries. Therefore, developing a method that can accurately detect micro-defects during high-speed production processes and subsequently achieve precise quantification of defect sizes is of paramount importance. Motion-Induced Eddy Current (MIEC) techniques, characterized by relative motion, can detect defects in conductive materials during high-speed movement. However, no research has been conducted on defect size quantification based on motion-induced eddy current signals. Consequently, this study proposes a quantification method for micro-defect size in copper foil based on motion-induced eddy current signal characteristics. By combining wavelet soft-thresholding and morphological filtering, high-frequency noise and signal fluctuations caused by variations in lift-off distance are effectively removed from the measured signals. Additionally, eight different features are defined for the micro-defect motion-induced eddy current signals, and a feature dataset for various sizes of copper foil micro-defects is established under different motor speeds. The proposed IVY-CNN-BiLSTM-Attention model is then utilized for the quantification of micro-defect sizes, yielding excellent results.

Polythiophene side chain chemistry and its impact on advanced composite anodes for lithium-ion batteries.

In the development of high-performance lithium-ion batteries (LIBs), the design of polymer binders, particularly through manipulation of side-chain chemistry, plays a pivotal role in optimizing electrode stability, ion transport, and adaptability to the volume changes during cycling. In particular, poly[3-(potassium-4-butanoate)thiophene-2,5-diyl] (P3KBT) increases magnetite and silicon capacity and cycling stability. This work explores the impact of polythiophene alkyl sidechain length on anode characteristics, aiming to enhance performance in LIBs. P3KBT and its alkyl chain alternatives, poly[3-(potassium-5-pentanoate)thiophene-2,5-diyl] (P3KPT) and poly[3-(potassium-6-hexanoate)thiophene-2,5-diyl] (P3KHT) were systematically investigated over 300 charge-discharge cycles. The experiments were designed to assess how varying side-chain length affects the stability, ion transport, and capacity retention of the electrodes. The results revealed that P3KHT, with its longer alkyl chain, exhibited superior capacity retention and reduced charge-transfer resistance after 300 cycles compared to its shorter chain analogs. The findings demonstrate that tailored side chains can improve ion transport, structural integrity, and capacity retention, addressing critical challenges in LIBs such as capacity fade and electrode degradation. This research contributes to the development of next-generation LIBs with enhanced performance and reliability.

Ultra-small CoxSy nanoparticles adhered to 3D-reduced graphene oxide as attractive anodes for lithium-ion batteries

A novel composite anode material, CoxSy/G, has been developed through a novel hydrothermal synthesis method complemented by an innovative high-temperature vulcanization technique. This process facilitates the deposition of CoxSy nanoparticles, each less than 10nm in size, onto a substrate of 3D rGO. This composite material combines the robust lithium storage capacity of CoxSy nanoparticles with the exceptional electrical conductivity and mechanical resilience of the 3D rGO framework, resulting in a significantly enhanced specific surface area and optimized mesoporous structure for CoxSy/G. Furthermore, it exhibits excellent electrochemical performance in lithium-ion batteries. Specifically, the CoxSy/G composites achieve a discharge capacity of 748.5mAh g⁻¹ at 50mAg⁻¹, notably exceeding the 647mAh g⁻¹ capacity demonstrated by pure CoxSy. Furthermore, these composites maintain an extraordinary cycle retention rate of 112.4% after undergoing 500 charge-discharge cycles at a continuous rate of 0.5Ag⁻¹. The reduced charge transfer resistance noted after cycling underscores the material’s enhanced performance attributes. This innovative creation of CoxSy/G composites offers critical insights and potential strategies for further development in the field of lithium-ion cobalt-sulfur electrodes.

Impact of low temperature exposure on lithium-ion batteries: A multi-scale study of performance degradation, predictive signals and underlying mechanisms

The rapid global expansion of electric vehicles and energy storage industries necessitates understanding lithium-ion battery performance under unconventional conditions, such as low temperature. This study investigates long-term capacity degradation of lithium-ion batteries after low temperature exposure subjected to various C-rate cycles. Findings reveal that low temperature exposure accelerates capacity degradation, especially with increased C-rates or longer exposure durations. A distinctive sunken region appears on the NMC H-stage peak as cycling progresses after low temperature exposure, indicating NMC particle damage and serving as a predictive signal for identifying low temperature exposure batteries. Electrochemical analyses and invasive detection indicate that low temperature exposure causes NMC particle cracking, leading to dead lithium generation. This dead lithium deposits on electrode surfaces, as well as the overconsumption of electrolyte, inhibiting reactions and reducing capacity. Additionally, dead lithium accumulates on separators, impeding ion transport and further accelerating capacity loss. NMC particle cracks develop faster after low temperature exposure due to stress concentration at internal slits. This stress concentration causes the maximum stress within the NMC particles to exceed tensile stress limits, resulting in rapid crack propagation. The internal cracks become larger with prolonged low temperature exposure, causing greater stress concentration and leading to faster crack propagation. Based on these insights, strategies from existing literature are discussed to mitigate the adverse impacts of low temperature exposure on lithium-ion battery performance and enhance the reliability and longevity of lithium-ion battery in extreme conditions.

Enhancement of battery thermal management effect by a novel MOF based composite phase change material

The introduction of phase change materials (PCMs) into battery thermal management systems (BTMS) can effectively enhance the cooling performance, safety and practical thermal management applications of lithium-ion batteries (LIBs). However, further study is needed to address the low heat conductivity and rapid phase change leakage of PCMs. This study proposed a metal–organic framework based shape-stabilized composite PCM (MOF/expanded graphite (EG) /multi-walled carbon nanotube (MWCNT) /paraffin wax (PW)) to construe battery cooling system, and its effect of battery thermal management is experimentally tested under various conditions. The results show the CPCM reveals a superior thermal management effect under varying ambient temperatures and discharge multipliers and outperforms natural convection. Even in the harsh environment of 40 °C and 3 C, the maximum temperature (Tmax) and Tmax difference (ΔTmax) of the CPCM-cooled module are 61.38 and 2.67 °C, which are 22 and 9 °C below the natural air-cooled module. Remarkably, the ΔTmax of the CPCM-cooled battery module in discharge decreases with the temperature rise at the discharge rate of 3 C, which is the exact opposite to the case of the air-cooled module. Moreover, the ΔTmax of CPCM-cooled module is 1.69, 1.84, 2.67 °C, all below the safe 5 °C at high temperatures (40 °C) as the discharge rate increases. The designed MOF-CPCM cooling system can effectively improve the temperature uniformity and thermal safety of the battery in harsh environments. Therefore, this novel MOF-based CPCM shows great promise in BTM.

Simultaneous structure and surface engineering of metal-organic framework derived LiNi0.5-xFe2xMn1.5-xO4 cathode material for improving high voltage performance of lithium-ion batteries

This study presents a novel material synthesis approach utilizing a terephthalic acid-based metal-organic framework as a precursor and employing an ethanol-assisted hydrothermal treatment to produce high-performance Fe-doped LiNi0.5Mn1.5O4 (LNMO) cathode material. This strategy yields a well-crystallized spinel structure with uniformly distributed transition metal ions. Additionally, the appropriate quantity of Fe dopant can achieve the desired Mn3+/Mn4+ ratio, level of structural disordering, and crystal phase purity for Fe-doped LNMO. The synthesis process also aids in forming an amorphous Li2CO3 surface layer, approximately 1 nm thick, which protects the active material from excessive reaction with electrolyte. The typical Fe-doped LNMO cathode (S-05) exhibits superior performance compared to a commercialized LNMO counterpart. It delivers an initial discharge capacity of 135 mAh g-1 at 1 C with exceptional cycling stability over 500 cycles (capacity retention of 90%) under high voltage (5.0 V vs. Li+/Li). Furthermore, its rate capability significantly improves, with a capacity retention of 85% (5 C/0.2 C). This enhanced performance aligns with evidence of activated Ni2+/Ni3+/Ni4+ redox reactions and suppressed cathode electrolyte interphase resistance, leading to promoted Li+ diffusion. Moreover, it is found the cathode helps alleviate electrolyte degradation at high voltages by inhibiting the formation of singlet oxygen in the electrolyte.

Theoretical study on electrochemical and thermal behavior of GNP incorporated anode materials for lithium-ion batteries

In this paper, a theoretical investigation of the electrical and thermal performance of lithium-ion batteries employing an unexplored graphene nanoplatelets (GNP) incorporated lithium titanate (LTO-GNP) anode and lithium manganese oxide cathode is demonstrated by using the COMSOL Multiphysics modeling and simulation. The GNP proportions in the LTO active material matrix are varied from 0 to 3 wt%, to assess the improvements in cell potential, state of charge (SOC), variation in internal temperature, discharging capacity, and battery power density across four selected electrodes. The simulation results have indicated the positive effects of increasing the anode’s GNP concentration on the battery performance, alongside temperature-dependent open-circuit voltage (OCV) and SOC outputs of the battery. The analysis of the effects of thermal conductivity on heat accumulation and dissipation within the battery has indicated that the anode with 3 wt% of GNP consistently performed superior to the other electrodes by providing uniform temperature distribution and enhanced electrical performance by promoting better discharge capacity and power density. The LTO anode with 3 wt% GNP has shown 0.2V more cell potential and also has 12.5% improved thermal conductivity when compared to LTO anode without GNP, contributing to better heat distribution inside the battery. The simulation also emphasized the importance of optimal GNP loading in the Li-ion battery anode to attain more uniform temperature distribution with improved battery health and efficiency.

Metal-free heteroatom integrated defect engineering of flexible carbon networks on tin oxide nanoparticles to enhance lithium-ion battery performance

Metal-free heteroatom integrated defect engineering of flexible carbon networks on tin oxide nanoparticles to enhance lithium-ion battery performance

Rechargeable Li-Ion Batteries, Nanocomposite Materials and Applications

Lithium-ion batteries (LIBs) are pivotal in a wide range of applications, including consumer electronics, electric vehicles, and stationary energy storage systems. The broader adoption of LIBs hinges on advancements in their safety, cost-effectiveness, cycle life, energy density, and rate capability. While traditional LIBs already benefit from composite materials in components such as the cathode, anode, and separator, the integration of nanocomposite materials presents significant potential for enhancing these properties. Nanocomposites, including carbon–oxide, polymer–oxide, and silicon-based variants, are engineered to optimize key performance metrics, such as electrical conductivity, structural stability, capacity, and charging/discharging efficiency. Recent research has focused on refining these composites to overcome existing limitations in energy density and cycle life, thus paving the way for the next generation of LIB technologies. Despite these advancements, challenges related to high production costs and scalability remain substantial barriers to the widespread commercial deployment of nanocomposite-enhanced LIBs. Addressing these challenges is essential for realizing the full potential of these advanced materials, thereby driving significant improvements in the performance and practical applications of LIBs across various industries.

Synergy of molybdenum carbide nanosheets with PMIA separator for regulated Li+ transport in high-performance lithium-ion batteries

Separators should not only guarantee the safety performance of lithium-ion batteries (LIBs), but also enable better electrochemical performance, especially in enhancing the power density of LIBs. In this work, Mo2C/PMIA composite separator was prepared by adding molybdenum carbide (Mo2C) nanosheets to m-phenylene isophthalamide (PMIA) via a non-solvent induced phase separation process. The incorporation of Mo2C nanosheets induced a non-homogeneous interfacial modification of the PMIA separator, resulting in the increased porosity of the separator. Furthermore, the electrolyte uptake and its retention were further improved while the Li+ migration resistance was reduced, which manifested into a lower interfacial impedance (73.17 Ω). The Mo2C nanosheets significantly enhanced the adsorption energy of the Mo2C/PMIA composite separator for Li+, which in turn promoted the desolvation effects in the Li-EC of Li+ within the electrolyte and boosted the mobility of Li+. This led to a relatively high ionic conductivity of 0.57 mS cm−1 along with a Li+ mobility number of 0.77. Fast-moving Li+ reduced the concentration polarization of the LIBs, and no polarization was observed after 400 h of cycling with a lithium symmetric battery (Li||Li), suggesting that the generation of lithium dendrites was successfully suppressed using the Mo2C/PMIA composite separator. LiFePO4||Li batteries assembled with the Mo2C/PMIA composite separator demonstrated the ability to retain 90 % of their capacity throughout 150 cycles at a current density of 0.5C, achieving a discharge specific capacity of 128.5mAh g−1, which enables high-performance LIBs.

Metalation of porphyrin units in a porous organic polymer stabilizing its anodic cycling performance in lithium-ion battery

Organic materials have attracted tremendous interest as electrodes materials for lithium-ion battery, however, they still suffer from intractable problems including inherent low electronic conductivity, poor cycling stability and high solubility in electrolyte etc. Herein, a porphyrin-based porous organic polymer (POP) is employed to serve as anode material by virtue of its good insolubility, unique π-π interaction and abundant active sites. The POP electrode exhibits a high specific capacity of 584 mAh g−1 at 100 mA g−1 originated from fast redox activity while unfortunately undergoes a severe capacity fading during long-term cycles. It is found that the metalation of porphyrin moiety in POP by Ni2+ (Ni-POP) enables an excellent cycling stability of 380 mAh g−1 with a capacity retention of 99 % for 500 cycles. We revealed that porphyrin unit is decomposed from the cleavage of the C-N/C=N bonds in porphyrin units, while Ni coordination stabilizes porphyrin units during fast redox process as affirmed by ex situ X-ray photoelectron spectroscopy. The easy fabrication, low-cost and excellent performance make Ni-POP great potential as anode material for lithium-ion battery.

Perovskite-Type CaVO3 Nanocomposite as High-Performance Anode Material for Lithium-Ion Batteries.

Electric vehicles' rapid development has put higher requirements on the performance of lithium-ion batteries (LIBs). However, the specific capacity of a commercial graphite anode (372 mAh g-1) has become the bottleneck for further improvement. Therefore, it is urgent to develop novel anode materials with superior performance. Herein, we propose crystalline-amorphous dual-phase CaVO3 nanocomposites as LIB anodes. Benefiting from the stable perovskite structure and high conductivity of CaVO3, the nanocomposite follows the intercalation mechanism, resulting in no capacity decay during 5000 cycles. In addition, due to the multielectron transfer provided by amorphous high-valent vanadium oxide, the nanocomposite can provide a high specific capacity of 442.8 mAh g-1 with a suitable average working potential of 0.95 V. The ingenious strategy of constructing nanocomposites through spontaneous oxidation of nanoparticles is expected to be extended to the perovskite oxide family, inspiring the development of more high-performance LIB anodes.

Improving Fast-Charging Performance of Lithium-Ion Batteries through Electrode-Electrolyte Interfacial Engineering.

The solid-electrolyte interphase (SEI) is a key element in anode-electrolyte interactions and ultimately contributes to improving the lifespan and fast-charging capability of lithium-ion batteries. The conventional additive vinyl carbonate (VC) generates spatially dense and rigid poly VC species that may not ensure fast Li+ transport across the SEI on the anode. Here, a synthetic additive called isosorbide 2,5-dimethanesulfonate (ISDMS) with a polar oxygen-rich motif is reported that can competitively coordinate with Li+ ions and allow the entrance of PF6 - anions into the core solvation structure. The existence of ISDMS and PF6 - in the core solvation structure along with Li+ ions enables the movement of anions toward the anode during the first charge, leading to a significant contribution of ISDMS and LiPF6 to SEI formation. ISDMS leads to the creation of ionically conductive and electrochemically stable SEI that can elevate the fast-charging performance and increase the lifespan of LiNi0.8Co0.1Mn0.1O2 (NCM811)/graphite full cells. Additionally, a sulfur-rich cathode-electrolyte interface with a high stability under elevated-temperature and high-voltage conditions is constructed through the sacrificial oxidation of ISDMS, thus concomitantly improving the stability of the electrolyte and the NCM811 cathode in a full cell with a charge voltage cut-off of 4.4V.

From Lithium-Ion to Sodium-Ion Batteries for Sustainable Energy Storage: A Comprehensive Review on Recent Research Advancements and Perspectives.

A significant turning point in the search for environmentally friendly energy storage options is the switch from lithium-ion to sodium-ion batteries. This review highlights the potential of sodium-ion battery (NIB) technology to address the environmental and financial issues related to lithium-ion systems by thoroughly examining recent developments in NIB technology. It is noted that sodium is more abundant and less expensive than lithium, NIBs have several benefits that could drastically lower the total cost of energy storage systems. In addition, this study examines new findings in important fields including electrolyte compositions, electrode materials, and battery performances of lithium-ion batteries (LIBs) and NIBs. The article highlights advancements in anode and cathode materials, with a focus on improving energy density, cycle stability, and rate capability of both LIBs and NIBs. The review also covers the advances made in comprehending the electrochemical mechanisms and special difficulties associated with NIBs, such as material degradation and sodium ion diffusion. Future research directions are discussed, with an emphasis on enhancing the scalability and commercial viability of sodium-ion technology over lithium on Electric Grid. Considering sustainability objectives and the integration of renewable energy sources, the review's assessment of sodium-ion batteries' possible effects on the future state of energy storage is included in its conclusion.

Optimizing Si─O Conjugation to Enhance Interfacial Kinetics for Low-Temperature Rechargeable Lithium-Ion Batteries.

With the growing demand for high-voltage and wide-temperature range applications of lithium-ion batteries (LIBs), the requirements for electrolytes have become increasingly stringent. While fluorination engineering has enhanced the performance of traditional solvent systems, it has also raised concerns regarding cost, environmental hazards, and low reduction stability. Through strategic molecular bond design, a novel class of low-temperature (LT) solvents-siloxanes-is identified, meeting the demands of LT and high-voltage applications in LIBs. The d-p conjugation of the Si─O bond enhances voltage resistance and weakens the Li+-solvent interactions. By modulating the number of Si─O conjugated bonds, the type of anion clusters in the solvation structure can be controlled, ultimately leading to the formation of a LiF and Si─O-rich interfacial layer and facilitating rapid Li+ conduction. Consequently, the graphite||NCM811 pouch cell (2.3 Ah, 4.45 V) with a siloxane-based electrolyte retains 75.1% of room temperature capacity (RTC) at -50°C. The rapid interface kinetics allow a superior reversible charging capacity retention of 67.6% at -40°C, with good cycle stability at -20°C. This study provides new insights into solvent design to fortify LIB performance in harsh conditions.