1C Rate Research Articles

Diatom-based biomass composites phase change materials with high thermal conductivity for battery thermal management

Battery thermal management systems (BTMs) are a significant strategy for controlling the operating temperature of lithium-ion batteries (LIBs) used in electric vehicles (EVs). A promising approach for mitigating the risk of battery exceeding the highest operating temperature is the utilization of composite phase change materials (CPCMs) in BTMs, which have the potential to be applied in EVs. In this study, a vacuum impregnation process was employed to prepare the biomass-based CPCMs (PPE-0, PPE-10, PPE-30 and PPE-50), consisting of diatomite as a supporting matrix, expanded graphite (EG) as an additive, and polyethylene glycol (PEG) as the phase change media. The PPE-10 exhibits an enhancement of melting enthalpy (116.81 J/g) and crystalline enthalpy (118.44 J/g). Meanwhile, the thermal conductivity of PPE-10 is 1.203 W/m·K, which is higher than PEG and PPE-0 by 4.02 times and 2.18 times, respectively. Furthermore, the battery modules with prepared CPCMs were carried out the charge and discharge processes at 1C and 2C discharge rates. The results illustrate that the battery modules with PPE-10 show excellent thermal management capability, which maintains the temperature below 60 °C during a 2C discharge rate. Consequently, this study provides a novel insight into developing biomass-based CPCMs with high thermal conductivity to enhance the safety of battery modules in EVs.

Ternary stabilization strategies for succinonitrile-based in situ polymerized electrolyte enabling high-performance solid lithium metal batteries

Solid-state lithium metal batteries with high energy density and safety have gained increasing attention due to their potential applications. However, the practical use of solid electrolytes is hindered by several challenges. These include poor compatibility at the electrode–electrolyte interface, low ionic conductivity at room temperature, and fast capacity degradation. To address these issues, here we propose ternary strategies by in-situ cross-linked plastic crystal electrolyte (in-situ PCE) based on succinonitrile (SN). Through the in-situ polymerization of SN with polyacrylonitrile/poly(vinylidene difluoride) (PAN/PVDF) nanofibers separator, excellent mechanical strength and compatibility at the electrode–electrolyte interface are achieved. The cross-linked structure of thermally polymerized ethoxylated trimethylolpropane triacrylate (ETPTA) immobilizes the SN molecule, preventing its contact with the lithium metal and inhibiting irreversible side reactions. Additionally, a LiF-rich passivation layer is employed to further protect the SN at the electrolyte-lithium metal interface. The dual protection from ETPTA and LiF offers excellent stability to lithium. Hence, the in-situ PCE exhibits high ionic conductivity (0.79 mS cm−1 at 30 °C) and wide electrochemical window (4.56 V, vs Li+/Li). The cells exhibit excellent cycling stability and high-rate performance. LiFePO4//Li cells retain 96.6 % capacity after 1000 cycles at 10C rate. This study provides valuable insights into the development of high-performance solid-state electrolytes.

Superior fast-charging Ni-rich cathode via promoted kinetic-mechanical performance

The sluggish Li-ion kinetics restrict the rapid charging capabilities and contribute to the structural deterioration of Ni-rich cathode materials. Notably, crack propagation during repeated charging cycles deteriorates the electrochemical stability, which hinders the further development of high-energy-density batteries for electric vehicles (EVs). In this paper, we proposed a simple yet effective method to enhance the Li-ion diffusion and mechanical properties of Ni-rich cathodes via straightforward Zr doping. In-situ high-rate XRD reveals that the detrimental uneven delithiation under the fast-charging process has been largely alleviated. Particularly, a robust structure with higher modulus and fracture strength is constructed owing to the higher Zr-O bond. By mitigating the kinetic hindrance and increasing the particle’s stiffness, the proposed Ni-rich cathode shows an impressive 97.6 % capacity retention under a 5 C rate current. This work provides a facile and efficient strategy for large-scale production of fast-charging Ni-rich cathode materials.

Composite Ionogel Electrodes for Polymeric Solid-State Li-Ion Batteries.

Realizing rechargeable cells with practical energy and power density requires electrodes with high active material loading, a remaining challenge for solid-state batteries. Here, we present a new strategy based on ionogel-derived solid-state electrolytes (SSEs) to form composite electrodes that enable high active material loading (>10 mg/cm2, ~9 mA/cm2 at 1C) in a scalable approach for fabricating Li-ion cells. By tuning the precursor and active materials composition incorporated into the composite lithium titanate electrodes, we achieve near-theoretical capacity utilization at C/5 rates and cells capable of stable cycling at 5.85 mA/cm2 (11.70 A/g) with over 99% average Coulombic efficiency at room temperature. Finally, we demonstrate a complete polymeric solid-state cell with a composite anode and a composite lithium iron phosphate cathode with ionogel SSEs, which is capable of stable cycling at a 1C rate.

Multi-objective optimization of efficient liquid cooling-based battery thermal management system using hybrid manifold channels

Maintaining a battery cell at an optimal temperature improves both its performance and lifespan. This study proposes a cold plate equipped with hybrid manifold channels, positioned at the bottom of a high-capacity 280 Ah LiFeO4 battery pack. Based on the developed whole battery pack model, the response surface method elucidates the functional relationship between design parameters (i.e., the width of parallel channels, the width of manifold channels, the height of parallel channels, and the inlet velocity) and responses (i.e., the flow pressure drop, the temperature difference of the entire battery modules, and the temperature difference of the cold plate). Multi-objective optimization of design parameters is performed to search the Pareto front to maximize thermal performance and minimize flow pressure drop, employing the NSGA-II algorithm. Results reveal that the maximum battery temperature can be limited to 30.73–33.78 °C with a coolant pressure drop ranging from 7.66 kPa to 1.76 kPa, at a heating power of 10 kW/m3 for the battery cell. The optimal design configuration, identified through TOPSIS, limits the maximum battery temperature to an acceptable temperature of 45 °C at a discharging rate of 3C, with a pressure drop below 4.2 kPa. Compared to the 280 Ah LiFeO4 battery with natural air cooling and forced flow immersion cooling systems, the maximum battery temperature with a discharging rate of 1C is reduced by 17.6 °C and 11.7 °C, respectively.

Iron, cobalt co-embedded in situ graphitized xerogel-derived carbon as sulfur host for ultrahigh rate and high-performance lithium-sulfur batteries

Lithium‑sulfur battery (LSB) is an enticing technology because of its high specific capacity, potential energy density, and natural abundance of sulfur in the earth's crust. However, some notorious issues need to mitigate before commercialization. Here we report a novel and scalable iron, cobalt co-embedded resorcinol formaldehyde derived carbon framework as sulfur host for high-performance LSB. To further increase the specific surface area and porosity of carbon, polyvinyl alcohol (PVA) is used as a sacrificial polymer. One pot synthesis method is used for preparing the Fe, Co co-embedded PVA incorporated RF xerogel-derived carbon (FC-PRFC) framework. The first-principles calculations suggest the advantage of bimetallic doping in enhancing the binding energy and reducing the energy gap of the carbon host for polysulfide anchoring. The porous structure and higher specific area of FC-PRFC enable high sulfur loading in the composite and show excellent rate performance and cyclability, as suggested by detailed electrochemical analysis. Moreover, the FC-PRFC cathode host with a high areal sulfur loading of 4.2 mg cm−2 delivers a high initial discharge capacity of 1283 mAh g−1 at 0.1C. During long-cycling at a high current rate of 4C, it retains a capacity of 372 mAh g−1 after 400 charge-discharge cycles with a capacity retention of 73 %. This scalable, innovative, low-cost fabrication technique has the potential to pave the way for developing an outstanding xerogel-derived carbon framework for high-performance LSBs for commercial applications.

A channel with hybrid twisted tapes for immersion cooling battery thermal management system

The promotion of transport electrification represents a pivotal strategy in addressing the energy crisis, wherein the adoption of the electric vehicles (EVs) plays a crucial role towards the realization of this goal. Immersion cooling battery thermal management systems (ICBTMS) emerge as an innovative strategy to guarantee the safe operation of the EVs. This study proposes an immersion cooling battery thermal management system with twisted tapes channel (TT-ICBTMS), offering effective temperature regulation of the battery pack. Drawing upon the experimental and simulation results associated with the high-capacity square battery, this paper selects a channel for further experimentation and simulation to elucidate the mechanisms by which various cooling methods and twisted tape configurations impact cooling efficacy. Subsequently, predicated on the comprehensive evaluation results, the channel with the hybrid twisted tapes (H-TT) is proposed. The H-TT, comprising both reverse twisted tapes (R-TT) and hollow reverse twisted tapes (HR-TT), serves to mitigate battery temperature rise, diminish pressure drop, and reduce the maximum temperature difference. This paper examines the heat transfer performance of the channel with the H-TT, revealing that, at the flow rate of 0.5 L/min and the discharge rate of 3C (Idischarge = 654 A), the maximum temperature of battery reaches merely 36.47 °C, with the maximum temperature difference of battery module being confined to 1.81 °C. Finally, a methodology employing the porous structure as the replacement for the H-TT in simulations is introduced in this study, a tactic validated through juxtaposition of experimental and simulation results, and subsequently applies this method in battery pack simulations. The simulation results demonstrate that, within the immersion cooling battery thermal management system with hybrid twisted tapes channel (H-TT-ICBTMS), the maximum temperature is confined to a mere 36.29 °C, with the maximum temperature difference limited to 2.63 °C, under the conditions of the flow rate of 22.5 L/min and the discharge rate of 3C (Idischarge = 654 A). This study posits that the H-TT-ICBTMS heralds novel thermal management paradigms for EVs.

A topology optimization-based-novel design and comprehensive thermal analysis of a cylindrical battery liquid cooling plate

In previous studies, the designs of the liquid cooling channel for battery packs usually paid emphasis on optimizing the predefined cooling channels. This significantly restricts the possibilities for geometric modifications of cooling channels, consequently placing limitations on the potential improvement in heat dissipation performance. To address these limitations, this study proposes a Topology optimization-based-novel design and comprehensive thermal analysis of a cylindrical battery liquid cooling plate. The aim of using topology optimization is to overcome these constraints, enabling more flexible and global domain designs. Three different inlet–outlet configurations of the cooling plate structure were designed using a dual-objective optimization function. A comprehensive numerical analysis was conducted and the topology-optimized liquid cooling plate system was compared with two other cooling pipe liquid cooling systems. The effects of coolant flow rate, battery discharge rate, and cooling plate thickness and quantity on the heat dissipation performance of the liquid cooling system were investigated. Findings demonstrate that the topology-optimized cold plate system with four inlets and two outlets exhibits optimal heat dissipation performance. Increases in coolant flow rate, cold plate thickness, and quantity contribute to enhanced cooling performance of the liquid cooling system. Taking into account factors such as pump power consumption, system weight, and heat dissipation performance, a liquid-cooled system with three cold plates and an inlet flow rate of 2.5 × 10-6 m3/s is considered the optimal choice for cooling the battery pack in this study. Under the cooling of this cold plate system, at a coolant and ambient temperature of 25 °C and a discharge rate of 3C, the battery pack’s maximum temperature and temperature difference are 30.9 °C and 4.87 °C, respectively.

VO2/VS4 heterostructures structure–modified 3D reduced graphene oxide aerogel as an advanced host for lithium–sulfur batteries

Lithium–sulfur batteries face challenges including volume expansion, slow reaction kinetics, and shuttle effects. To overcome these limitations, we utilized a combination of vanadium–based heterostructures and conductive porous reduced graphene oxide aerogels to improve charge transfer kinetics. The researchers synthesised vanadium–based reduced graphene oxide aerogels (VO2/VS4@RGO) via tube furnace calcination and a one–step hydrothermal method. Vanadium–based heterostructures were electrostatically adsorbed onto the surface of three–dimensional reduced graphene oxide aerogels. The fibrous structure of VO2/VS4 promoted charge transfer, while the high conductivity of VS bonds lowered the surface reaction barrier. The VO2/VS4@RGO–3/S cathode exhibited outstanding cycling stability at a high discharge rate of 2C, demonstrating an initial discharge specific capacity of 771.94 mAh g−1 and an average decay rate of 0.071 % after 700 cycles. It also maintained excellent electrochemical performance under high sulfur loading.

Isomeric dichloropyrazine of dual-function additives: Synergistic enhancement of lithium anode protection and sulfur redox kinetics in lithium–sulfur batteries

Lithium-sulfur batteries (LSBs) currently face challenges such as low sulfur utilization, inadequate cycling stability, and unstable lithium anode interfaces. In this study, dichloropyrazines (DCPs) are introduced as dual-functional additives into electrolyte and 2,5-DCP exhibits the most promising performance enhancement. This superiority can be attributed to its strong redox activity, lower molecular orbital energy gap, and more negative relative binding energy compared to the other DCP isomers. Specifically, DCPs demonstrate their dual functionality by promoting the formation of a stable organic-inorganic hybrid solid electrolyte interface (SEI) rich in LiCl on lithium anodes. This ensures uniform lithium deposition and suppresses dendrite growth. At sulfur cathodes, density functional theory (DFT) calculations confirm that DCPs facilitate lithium polysulfides (LiPSs) conversion kinetics through Li–N bond formation. LSBs with 2,5-DCP exhibit excellent stability at a 1C rate and retain 86.6 % capacity after 800 cycles. This study demonstrates DCPs' potential as effective dual-functional electrolyte additives in designing high-performance LSBs.

A numerical investigation of novel segmented PCM blocks filled with different phase change material cooling for Lithium-Ion battery

Phase Change Material (PCM) embedded systems have gained attention for their latent heat absorption and release capabilities in Battery Thermal Management. However, conventional PCM-cooled battery systems often exhibit low heat absorption rates, resulting in temperature irregularities and uneven melting. To overcome these challenges, this study introduces an innovative cooling system using segmented PCM blocks, each storing different types of PCMs. The PCM block is divided into three or four parts, employing distinct PCMs based on the observed heat propagation pattern during high-current discharging. A three dimensional numerical investigations are conducted in ANSYS Fluent using the MSMD battery model to explore three segmented and four segmented PCM blocks, comparing them with a single PCM block. The parametric variations considered in this work include varying PCM block thickness, PCM types, and discharging rates. Results show that increasing PCM thickness controls temperature rises but also raises the system’s weight. The study demonstrates that incorporating different PCMs in four segmented block maintains battery temperature at 319 K, with uniform distribution across the surface. The proposed PCM-based battery thermal management system reduces system weight by 17.84 % and enhances PCM heat absorption by 32.59 % compared to a conventional PCM block system when discharging at a high current rate of 4C to stay within the safe operating temperature range.

Exploring titanium niobium oxides recovered from columbotantalite mineral as lithium-ion batteries electrodes

Titanium niobium oxides (TNO) are chemically recovered from a mineral composed of cassiterite, columbotantalite, rutile and wollastonite. The process involves a series of steps, including pyrometallurgical processes, leaching, and liquid-liquid extraction. It takes advantage of the naturally occurring Ti in the extracted mineral, avoiding the separation of Ti and Nb to directly obtain the valuable Ti–Nb–O compounds. Two compositions can be obtained (Ti2Nb10O29 or TiNb2O7, named TNO-cal and TNO-black, respectively) depending on the thermal treatment after the chemical separation from the original mineral. These compounds have been characterized to describe their composition, morphology and crystallographic properties. The recovered material, without any further purification or functionalization, has been studied as anodes in Lithium-ion batteries (LIBs). Different electrochemical behavior has been observed for voltage ranges of 1–3 V and 0.01–3 V, being the second range which gives best results. In the 1–3V range, TNO-black exhibits a reversible capacity of up to 101.4 mA h g−1 at 1C and maintains 97 % capacity retention after 200 cycles, this is mainly due to Li + insertion/de-insertion processes. Additionally, when expanding the voltage range down to 0.01V, TNO-black displays a specific capacity of approximately 139.1 mA h g−1 after 200 cycles at 1C, whereas TNO-cal reaches a specific capacity of 169 mA h g−1. Extended cycling experiments at a 1C rate for both electrodes reveal that after 200 cycles samples deliver efficiencies relative to the maximum discharge capacity values of 83.4 % (TNO-cal) and 64.4 % (TNO-black), with mean coulombic efficiencies of 97.5 %. These results demonstrate that the recovered materials can effectively function as anodes for LIBs, offering promising application potential, despite the presence of residual silica from the mining process.

Hollow TiO2@Fe2O3 nanofiber additives using template based approach for capture-conversion of polysulfides in Lithium-sulfur batteries

High theoretical capacity (1675 mA h g−1) and energy density (2600 Wh kg−1) in addition to low cost, non-toxicity and natural abundance stimulates the exploration of sulfur as a potential cathode material. However, serious capacity fade and poor reaction kinetics leads to untimely failure which prevents the practical commodification of these batteries. Here, a simple and versatile electrospinning technique has been employed to prepare a polymeric template to fabricate hollow metal oxide@metal oxide nanofibers. The hollow fibrous shell with large specific surface area is incorporated as an anchoring material comprising of distinct crystalline phases separated by amorphous domains. Meanwhile, the encapsulated metal oxide nanoparticles ensure efficient conversion of soluble polysulfides thereby, promoting the reaction kinetics and avoiding any surface passivation of anchoring material. The LSB cell with 5 % TiO2@Fe2O3 nanofiber additives delivers impressively in the rate capability test with stable capacities of 620 and 480 mA h g−1 at 1C and 2C rate, respectively. Moreover, an excellent cycling performance is attained with a fade rate of 0.092 % per cycle over 500 cycles at 0.5C-rate. The findings of this work shall provide a pathway for facile preparation of functional metal oxide composites for simultaneous trapping and conversion of polysulfide species in sulfur batteries.

The population-based effects of the FDA’s approval of durvalumab as consolidative therapy in patients with locally-advanced non-small cell lung cancer.

e20086 Background: In 2018, consolidative durvalumab (D) was FDA-approved in patients with locally advanced non-small cell lung cancer(NSCLC) because it increased PFS and was later found to increase overall survival (OS). This analysis will check the real-world effects of this agent prior to and after its approval. Methods: The SEER-17 database was queried from 2015-2020 and assessed for differences in OS/lung cancer specific survival (LCSS) and rates of second cancers (2C). Patients included were those with NSCLC who received chemotherapy and radiation with at least 7 months of follow-up. The population was split into two different groups, those diagnosed before and after D’s approval (2015-2017(BA) and 2018-2020(AA). Multi-variate analyses (MVA) were used to find prognostic factors which were used to adjust OS/LCSS rates for the BA and AA at 12, 24, and 30 months. Variables analyzed included patient characteristics, histopathology, and previous cancers (separated into alcohol, diet, smoking, virus and hormone related). Inverse propensity scores were weighted for OS factors to determine rates of second cancers. Results: Of 12,022 patients, 501 patients developed 2Cs. The OS was significantly better for AA group than the BA group ( p < 0.001, HR = 0.79(0.74, 0.85) with rates at 12, 24, and 30 months of 0.86, 0.68, and 0.62%; and 0.83, 0.62, and 0.55%. Multivariate analyses for OS demonstrated similar prognostic factors in both year groups and were worse with advanced age, male sex, unmarried status, squamous histology, advanced stage and non-Hispanic white race. The LCSS was significantly better in AP than the BA group ( p < 0.001, HR = 0.84 (0.7, 0.89) with rates at 12, 24, and 30 months of groups of 0.82,0.61, and 0.55%; and 0.80,0.56,and 0.48%. The prognostic factors for LCSS were the same in both group and included age, male sex, squamous histology, and advanced stage. The adjusted rates of 2C in 2018-2020 group were trending less than in 2015-2017 (HR = 0.80(0.63-1.03), p =0.07), largely driven by a reduction in smoking-related cancers (HR = 0.74(0.53-1.02, p= 0.07). The 2C rates at 12, 24, and 30 months were 1.0, 2.7, and 3.5% in the 2015-2017 and 0.9, 1.6, and 1.9% in 2018-2020 groups. MVA significant risk factors for 2Cs were age, history of previous cancer, male sex, and squamous histology in the BA group, but no factors were significant for 102 second cancers in the AA group. Conclusions: In the years after durvalumab's approval, there was a significant benefit in terms of overall survival and lung cancer specific survival, but prognostic factors remained similar. In addition to the OS/LCSS benefit, durvalumab's approval was associated with a strong trend for reducing the incidence of second cancers, especially in those with previous smoking related cancers.

Experimental and numerical analysis of a liquid-air hybrid system for advanced battery thermal management

This study introduces an innovative hybrid Battery Thermal Management System (BTMS) that combines air and liquid cooling mechanisms for optimal thermal control in small-scale EV applications. Recognizing the limitations of the existing single-method cooling systems, we developed a novel Hybrid Battery Thermal Management System that combines air and liquid cooling to provide superior temperature management. Additionally, we performed a detailed experimental evaluation to verify the accuracy of our heat generation model for lithium-ion batteries. This included the construction and testing of the proposed hybrid cooling system in a controlled environment using a climate chamber that simulated various ambient temperatures. We assessed the system performance under different operational stresses, specifically at 1C and 2C discharge rates. The tests encompassed a range of temperatures, starting at a standard room temperature (20 °C) and increasing through three levels of ambient temperature: 30, 35, and 40 °C. Initial tests under natural convection conditions showed a non-uniform temperature distribution and temperatures near the upper safety limits, with a maximum of 51 °C. While the addition of an air-cooling system provided some improvement, it still resulted in localized hotspots. However, the hybrid battery thermal management system effectively addressed these challenges, achieving marked improvements in cooling efficiency and temperature uniformity, yielding a 21.04 % improvement in cooling by reducing the maximum temperature at 2C from 51.2 °C (no cooling) to 40.9 °C while also improving the uniformity of the temperature distribution among the packs. Further tests at elevated ambient temperatures confirmed the robustness and adaptability of this system. These findings highlight the scalability of the system and suggest its potential applicability to larger battery systems, opening avenues for future research and practical implementation.

Coupling of ion-conducting interphase with lithiophilic-solid-oxide-electrolyte interlayer toward fast-charging lithium metal batteries

The uncontrollable dendritic Li growth and limited Coulombic efficiency have long impeded the implementation of fast-charging lithium metal batteries. Contrary to the widely accepted attempt of using a sintering dense ceramic electrolyte to realize dendrite-free deposition, we report a coupling architecture of ion-conducting-Li3PO4-Li3N interphase with lithiophilic-solid-oxide-electrolyte interlayer for Li-metal anode using a reactive lithiophilic solid oxide electrolyte (RLSE) rather than dense ceramics. The synergistic interphase and protection layer can facilitate the Li-ion transport and enhance the lithiophilicity. As a result, an ultrahigh Li plating/stripping current density of 10 mA cm−2 and areal capacity of 10 mAh cm−2 for over 1000 h, and a remarkable Coulombic efficiency of 99.8 % are achieved simultaneously. Moreover, the use of interphase-interlayer synergistic protection enables a stable long-term 3000-cycling of Li||Li4Ti5O12 cell at 2C rate. More importantly, high-current–density (e.g. 1.8 mA cm−2) cycling of Li||LiNi0.8Co0.1Mn0.1O2 batteries with a practical area capacity of 3.6 mAh cm−2 is achieved in both carbonate and quasi-solid electrolytes. This study demonstrates an alternative approach of solid oxide electrolytes to stabilize Li-metal anode and enable fast-charging lithium metal batteries.

Stabilizing NASICON-type Na4MnCr(PO4)3 by Ti-substitution toward a high-voltage cathode material for sodium ion batteries

The sodium superionic conductor Na4MnCr(PO4)3 gains increasing attention owing to its three-dimensional structure and the three-electron reaction. However, rapid structure degradation during cycling is the major challenge for its practical application. Herein, Ti4+ is utilized to replace a portion of Mn2+ in Na4MnCr(PO4)3. The low redox voltage and d0 electronic configuration of the Ti4+ ions are helpful to suppress the structure alteration and improve electronic conduction. Consequently, the as-prepared Na3.4Mn0.7Ti0.3Cr(PO4)3/C cathode exhibits a remarkable good 91.0% capacity retention after 500 cycles at 10C rate, with exceptional rate capacities of 99.5 mAh g−1 and 81.0 mAh g−1 at 5C and 10C rate, respectively. Furthermore, based on ≈2.86-electron reactions involving Mn2+/Mn3+ (3.5 V), Mn3+/Mn4+ (4.1 V), Cr3+/Cr4+ (4.3 V), and Ti3+/Ti4+ (2.1 V), the material can provide an energy density of approximately 541.6 Wh kg−1, slightly surpassing that of Na4MnCr(PO4)3. Ex-situ XRD investigation further elucidates that throughout the entire charge–discharge process, the Ti-substituted material experiences highly reversible solid-solution and two-phase reactions. Additionally, Ti substitution can greatly promote the interfacial charge transfer of the material and suppress the decomposition of the electrolyte during cycling. This work might open a new insight for designing sodium-ion battery cathode materials with good cycling stability and high energy density.

Inhibiting Dendrites by Uniformizing Microstructure of Superionic Lithium Argyrodites for All‐Solid‐State Lithium Metal Batteries

AbstractThe all‐solid‐state lithium metal battery is considered the next‐generation energy storage device with the potential to double the energy density of state‐of‐the‐art Li‐ion batteries and eliminate safety hazards. Achieving stable Li plating/stripping without dendrite propagation within the solid electrolyte is crucial for delivering the promised high energy density. In this study, through the comparison of various synthesis routes, a novel cube‐shaped microstructure in the Li5.3PS4.3ClBr0.7 argyrodite electrolyte, synthesized using the high‐speed mechanical milling followed by annealing method (BMAN‐LPSCB) is identified. The uniform microstructure allows for the production of an electrolyte pellet with significantly reduced porosity through cold pressing. The removal of defects has significantly enhanced the electrolyte's ability to inhibit dendrite formation, with a critical current density reaching 3.8 mA cm−2. The lithium symmetric cell with BMAN‐LPSCB electrolyte exhibits stable Li plating/stripping for over 150 h at a high current density and cutoff capacity of 3 mA cm−2 / 3 mAh cm−2. The all‐solid‐state Li/NCM battery utilizing the BMAN‐LPSCB electrolyte also demonstrates excellent durability, with a capacity retention of 96% over 1000 cycles at a 1C rate. This study emphasizes that the microstructure of the sulfide electrolyte is a critical factor influencing mechanically‐driven Li dendrite propagation in all‐solid‐state batteries.

Molecular design of highly Li-ion conductive cathode-electrolyte interface enabling excellent rate performance for lithium-ion batteries

The structural stability and ionic conductivity of the cathode electrolyte interface (CEI) film at high voltages are crucial to the nickel-rich layered cathode in Li-ion batteries (LIBs). These characteristics are largely determined by electrolyte components. Herein, an air-stable organic cyclophosphate salt named lithium 1, 3, 2-dioxaphosphinan-2-olate-2-oxide (LiDOP) is designed and synthesized as a CEI forming additive. It preferentially oxidizes and undergoes opening-ring polymerization under charging to form an organic–inorganic hybrid polymers with –LiPO4 segments and –(CH2)3– alternately connected on the cathode surface. Such a structure endows CEI film with high ionic conductivity, flexibility and mechanical strength, which can ameliorate the structure phase transformation, suppress the transition metal ion dissolution and enhance the interfacial stability at high cut-off voltage. The electrolyte with 0.2 wt% LiDOP endows 4.3 V-charged Li||LiNi0.8Co0.1Mn0.1O2 battery with 83.2 % capacity retention after 200 cycles at 5C rate. The graphite||NCM811 pouch cell shows a capacity retention of 85.6 % after 150 cycles under a 4.5 V voltage, while the cell without LiDOP shows only 23.5 %. Our work demonstrates the effectiveness of covalently coupled P-O-Li compounds as CEI film in stabilizing the interface, which provides a guidance for the electrolyte design in high-voltage LIBs.

Relationship between particle shape and fast-charging capability of a dry-processed graphite electrode in lithium-ion batteries

Improving lithium-ion transport in electrodes by controlling electrode microstructure is a promising option for enhancing the fast-charging capability of graphite anodes in lithium-ion batteries. Dry processing of electrodes based on a polytetrafluoroethylene binder has attracted considerable attention as an alternative to solvent-based wet processing. The morphology of graphite particles has a significant impact on electrode microstructure, but few reports have been published on dry-processed graphite anodes. In this work, we found that the morphology of graphite particles is a key factor to determine the fast-charging capability of the dry-processed graphite electrode as well as the microstructure of the dry-processed graphite electrode. X-ray microscopy combined with mercury porosimetry and symmetrical cell electrochemical impedance spectroscopy reveal that the difference in porosity between the top and bottom layers of a dry electrode with spherical graphite particles is greater than that of flake-shaped graphite particles, resulting in enhanced lithium-ion transport in the electrode and improved fast-charging capability at a high charging rate of 5C (17.5 mA cm−2). These findings supply insights into the effective design of dry-processed graphite anodes with an emphasis on fast-charging capability as well as the development of graphite anode materials for dry-processing based lithium-ion batteries.