LiFePO4 Cells Research Articles

High-Entropy Polymer Electrolytes Derived from Multivalent Polymeric Ligands for Solid-State Lithium Metal Batteries with Accelerated Li+ Transport.

Solid-state polymer-based electrolytes (SSPEs) exhibit great possibilities in realizing high-energy-density solid-state lithium metal batteries (SSLMBs). However, current SSPEs suffer from low ionic conductivity and unsatisfactory interfacial compatibility with metallic Li because of the high crystallinity of polymers and sluggish Li+ movement in SSPEs. Herein, differing from common strategies of copolymerization, a new strategy of constructing a high-entropy SSPE from multivariant polymeric ligands is proposed. As a protocol, poly(vinylidene fluoride-co-hexafluoropropylene) (PH) chains are grafted to the demoed polyethylene imine (PEI) with abundant -NH2 groups via a click-like reaction (HE-PEIgPHE). Compared to a PH-based SSPE, our HE-PEIgPHE shows a higher modulus (6.75 vs 5.18 MPa), a higher ionic conductivity (2.14 × 10-4 vs 1.03 × 10-4 S cm-1), and a higher Li+ transference number (0.55 vs 0.42). A Li|HE-PEIgPHE|Li cell exhibits a long lifetime (1500 h), and a Li|HE-PEIgPHE|LiFePO4 cell delivers an initial capacity of 160 mAh g-1 and a capacity retention of 98.7%, demonstrating the potential of our HE-PEIgPHE for the SSLMBs.

A comparative study on multidimensional signal evolution during thermal runaway of lithium-ion batteries with various cathode materials

Cathode materials significantly affect the failure behavior of lithium-ion batteries, but there is a lack of comparative research on the multidimensional signal evolution for batteries with various cathode materials when subjected to thermal runaway (TR). This study investigates the effect of cathode materials on battery safety properties by conducting overheating and overcharging abuse experiments on LiNixCoyMn(1-x-y)O2 (NCM 523, 622, and 811) as well as LiFePO4 (LFP) batteries. The multidimensional signals, including expansion force, gas concentrations, temperature, and voltage, are comprehensively and quantitatively analyzed. The results demonstrate that expansion force shows the earliest anomalies regardless of the cathode material in both abuse conditions. Gas can be detected after venting, followed by significant anomalies in voltage and temperature. Additionally, under overheating conditions, LFP cells exhibit the longest TR warning time of 677 s. However, the force anomaly-based warning method is more suitable for low-nickel NCM cells under overcharging scenarios. Specifically, NCM 523 cells achieve an overcharging warning time of 992 s at temperatures as low as 42.9 °C, and hold the highest venting force of 9859 N and venting temperature at 114.1 °C. On this basis, a hierarchical warning strategy based on multidimensional signal fusion is proposed. This study provides valuable insights into TR early warning and safety management in LIBs with different cathode materials.

Lignin Derived Ultrathin All-Solid Polymer Electrolytes with 3D Single-Ion Nanofiber Ionic Bridge Framework for High Performance Lithium Batteries.

The lignin derived ultrathin all-solid composite polymer electrolyte (CPE) with a thickness of only 13.2µm, which possess 3D nanofiber ionic bridge networks composed of single-ion lignin-based lithium salt (L-Li) and poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) as the framework, and poly(ethylene oxide)/lithium bis(trifluoromethanesulfonyl)imide (PEO/LiTFSI) as the filler, is obtained through electrospinning/spraying and hot-pressing. t. The Li-symmetric cell assembled with the CPE can stably cycle more than 6000h under 0.5mA cm-2 with little Li dendrites growth. Moreover, the assembled Li||CPE||LiFePO4 cells can stably cycle over 700 cycles at 0.2 C with a super high initial discharge capacity of 158.5 mAh g-1 at room temperature, and a favorable capacity of 123 mAh g-1 at -20°C for 250 cycles. The excellent electrochemical performance is mainly attributed to the reason that the nanofiber ionic bridge network can afford uniformly dispersed single-ion L-Li through electrospinning, which synergizes with the LiTFSI well dispersed in PEO to form abundant and efficient 3D Li+ transfer channels. The ultrathin CPE induces uniform deposition of Li+ at the interface, and effectively inhibit the lithium dendrites. This work provides a promising strategy to achieve ultrathin biobased electrolytes for solid-state lithium ion batteries.

Flame-retardant in-situ formed gel polymer electrolyte with different valance states of phosphorus structures for high-performance and fire-safety lithium-ion batteries

Lithium-ion batteries (LIBs) have been widely used today owing to portability, high energy storage, and reusability. However, commercial liquid electrolytes in LIBs possess intensive mobility and terrible flammability. Accordingly, leakage, combusting, and even exploding can frequently occur when LIBs work under abuse conditions. Herein, a novel flame-retardant gel polymer electrolyte (GPE) containing + 3 and + 5 phosphorus valence states of phosphorus structures was designed by in-situ thermal polymerization of tri(acryloyloxyethyl) phosphate (TAEP), diethyl vinylphosphonate (DEVP), and pentaerythritol tetraacrylate in electrolytes. After being ignited by fire, this GPE extinguished quickly with a combusting time of only 0.9 s, showing much lower flammability. Besides, the GPE is compatible with graphite anode, LiFePO4 (LFP), and even LiNi0.8Co0.1Mn0.1O2 (NCM811) cathodes. The as-assembled LFP and NCM811-based pouch cells (1 Ah-type) with TD-GPE achieved stable cycling, maintaining 88.52 % and 95.2 % of the initial capacities, respectively after 200 and 190 cycles at 0.5C. Moreover, the as-prepared TD-GPE dramatically reduced the fire hazard of NCM811 batteries without sacrificing the electrochemical performance. The thermal abuse test demonstrates that the leakage and combustion of NCM811||TD-GPE||Graphite pouch cell could be significantly suppressed in the test process, indicating that battery safety improves significantly via the combined use of different phosphorus valence structures. This is because the + 5 phosphorus valence of TAEP promoted the formation of carbon layers, and the + 3 phosphorus structure in DEVP captured free radicals by quenching effect. This work paves a different path for designing safe and high-performance GPEs in LIBs based on gaseous-phase and condensed-phase mechanisms.

Enhancing the Lithium Storage Performance of the Nb2O5 Anode via Synergistic Engineering of Phase and Cu Doping.

Nb2O5 has been viewed as a promising anode material for lithium-ion batteries by virtue of its appropriate redox potential and high theoretical capacity. However, it suffers from poor electric conductivity and low ion diffusivity. Herein, we demonstrate the controllable fabrication of Cu-doped Nb2O5 with orthorhombic (T-Nb2O5) and monoclinic (H-Nb2O5) phases through annealing the solvothermally presynthesized Nb2O5 precursor under different temperatures in air, and the Cu doping amount can be readily controlled by the concentration of the precursor solution, whose effect on the lithium storage behaviors of the Cu-doped Nb2O5 is thoroughly investigated. H-Nb2O5 shows obvious redox peaks (Nb5+/Nb4+ and Nb4+/Nb3+) with much higher capacity and better cycling stability than those for the widely investigated T-Nb2O5. When introducing appropriate Cu doping, the optimized H-Cu0.1-Nb2O5 electrode shows greatly enhanced conductivity and lower diffusion barrier as revealed by the theoretical calculations and electrochemical characterizations, delivering a high reversible capacity of 203.6 mAh g-1 and a high capacity retention of 140.8 mAh g-1 after 5000 cycles at 1 A g-1, with a high initial Coulombic efficiency of 91% and a high rate capacity of 144.2 mAh g-1 at 4 A g-1. As a demonstration for full-cell application, the H-Cu0.1-Nb2O5||LiFePO4 cell displays good cycling performance, exhibiting a reversible capacity of 135 mAh g-1 after 200 cycles at 0.2 A g-1. More importantly, this work offers a new synthesis protocol of the monoclinic Nb2O5 phase with high capacity retention and improved reaction kinetics.

Nano-Interfacial Supramolecular Adhesion of Metal-Organic Framework-Based Separator Enables High-Safety and Wide-Temperature-Range Lithium Batteries.

Polyolefin separators are the most commonly used separators for lithium batteries; however, they tend to shrink when heated, and their Li+ transference number (t Li +) is low. Metal-organic frameworks (MOFs) are expected to solve the above problems due to their high thermal stability, abundant pore structure, and open metal sites. However, it is difficult to prepare high-porosity MOF-based membranes by conventional membrane preparation methods. In this study, a high-porosity free-standing MOF-based safety separator, denoted the BCM separator, is prepared through a nano-interfacial supramolecular adhesion strategy. The BCM separator has a large specific surface area (450.22 m2 g-1) and porosity (62.0%), a high electrolyte uptake (475 wt%), and can maintain its morphology at 200°C. The ionic conductivity and t Li + of the BCM separator are 1.97 and 0.72 mS cm-1, respectively. Li//LiFePO4 cells with BCM separators have a capacity retention rate of 95.07% after 1100 cycles at 5 C,a stable high-temperature cycling performance of 300 cycles at 80°C, and good capacity retention at -40°C. Li//NCM811 cells with BCM separators exhibit significantly improved rate performance and cycling performance. Pouch cells with BCM separators can work at 120°C and have good safety at high temperature.

Experimental study on behaviors of lithium-ion cells experiencing internal short circuit and thermal runaway under nail penetration abuse condition

This work compared the macro-phenomenon, voltage response, surface temperature, mass loss and material characteristics of LiCoO2 (LCO), LiMn2O4 (LMO), Li(NixCoyMnz)O2 (NCM), LiFePO4 (LFP) cells with the same capacity under penetration tests. The tests provided an in-depth study on behaviors and properties of internal short circuit (ISC) and thermal runaway (TR). From the results, a feature was discovered that the parameters of different types of cells showed different tendencies when penetrated with a series of diameter nails, determined by cathode materials. The LFP cell experienced a slight ISC. Temperature rise rate and maximum temperature increased with larger diameter of nails. The NCM, LCO and LMO cells experienced a severe ISC. The maximum temperature of cells increased, however, the temperature rise rate reduced and macro-phenomena delayed and weakened with larger diameter of nails. For different type of cells, the order of ISC sensitivity was as follows: LCO > LMO > NCM > LFP. As state of charge (SOC) increased, the cells had a higher risk of TR, evidenced by higher surge current and temperature rise rate. The results of nail penetration tests at 100 % SOC indicated that the hazard of TR was arranged in the order of LCO > NCM > LMO > LFP. Due to the fragmentation of secondary particles during the extrusion of nail, the cathode composed of secondary particles suffered more damage than composed of primary particles. The research can provide support for the safety design of cells.

Retarding anion migration for alleviating concentration polarization towards stable polymer lithium-metal batteries

Traditional dual-ion lithium salts have been widely used in solid polymer lithium-metal batteries (LMBs). Nevertheless, concentration polarization caused by uncontrolled migration of free anions has severely caused the growth of lithium dendrites. Although single-ion conductor polymers (SICP) have been developed to reduce concentration polarization, the poor ionic conductivity caused by low carrier concentration limits their application. Herein, a dual-salt quasi-solid polymer electrolyte (QSPE), containing the SICP network as a salt and traditional dual-ion lithium salt, is designed for retarding the movement of free anions and simultaneously providing sufficient effective carriers to alleviate concentration polarization. The dual salt network of this designed QSPE is prepared through in-situ crosslinking copolymerization of SICP monomer, regular ionic conductor, crosslinker with the presence of the dual-ion lithium salt, delivering a high lithium-ion transference number (0.75) and satisfactory ionic conductivity (1.16 × 10−3 S cm−1 at 30 °C). Comprehensive characterizations combined with theoretical calculation demonstrate that polyanions from SICP exerts a potential repulsive effect on the transport of free anions to reduce concentration polarization inhibiting lithium dendrites. As a consequence, the Li||LiFePO4 cell achieves a long-cycle stability for 2000 cycles and a 90% capacity retention at 30 °C. This work provides a new perspective for reducing concentration polarization and simultaneously enabling enough lithium-ions migration for high-performance polymer LMBs.

3D cross-linked POSS-containing borate single ion conductor organic-inorganic hybrid gel electrolytes for dendrite-free lithium metal batteries

At present, lithium (Li) metal has become the most promising anode for the next generation of batteries due to its excellent theoretical capacity and low electrochemical potential. Nevertheless, low lithium-ion transference numbers and poor stability between conventional electrolytes and electrodes limit its development. In this work, a novel three-dimensional cross-linked hybrid borate single ion conductor polymer electrolyte (POSS-BSICP) was constructed by coupling of novel synthesized lithium bis-allylmalonate borate (LiBAMB), poly (ethylene glycol) diacrylate (PEGDA) and vinyl-containing caged poly(sesquisiloxane) (MAPOSS) in the presence of pentaerythritol tetrakis(mercaptoacetate) (PETMP) as cross-linker and PVDF-HFP as support materials through UV-thermal Dual-Curing procedures. As expected, the lithium-ion transference number and electrochemical stability of the hybrid electrolyte membranes improve with the incorporation of MAPOSS. The tLi+ is up to 0.82 and the electrochemical window reaches 5.50 V. The Li/Li cell assembled with the POSS-containing single ion conductor gel polymer electrolytes can be subjected to stripping/plating cycles without short circuit over 2700 h at 0.1 mA cm−2, the peak of the SiO bond at 102.3 eV in the Si 2p spectrum confirms that the POSS participate in the formation of SEI, indicating that the incorporation of MAPOSS could increase the compatibility between the electrolytes and electrode. The Li|POSS-BSICP|LiFePO4 cell exhibits excellent cycle performance with a capacity retention over 90 % after 170 cycles and 82.0 % after 290 cycles at 0.1 C.

Solid-state Zn-ion batteries using composite cellulose polyethylene oxide materials-Illustration of reaction and capacity fading mechanisms

In this work, the composite materials of cellulose and poly(ethylene oxide) (PEO) materials as the solid-electrolyte separator was electrochemically and mechanically characterized before being incorporated into solid-state Zn-ion batteries (SSZIBs) with LiFePO4 cathode and Zn anode. As understanding fading mechanisms and operational settings is essential to developing long lasting batteries, we further investigated the mechanisms of LiFePO4 lithiation and de-lithiation in SSZIBs. The capacity fading mechanism was elucidated using ex-situ high energy synchrotron XANES measurements on our developed Zn-ion devices at varying charge rates. Long-term cycling was the focus of these investigations, which tracked and assessed chemical and structural changes. The results show that an increase in inactive FePO4 proportional to the loss of active lithium is the primary driver of capacity fading once the lithium source is depleted. XRD confirm that LiFePO4 exists in an olivine phase and reveal that the insertion and deinsertion behaviour of lithium ions in LiFePO4 changes with cycling. The two phases (LiFePO4, FePO4) and the loss of the lithium source may contribute to the reduced rate capability and capacity fading of LiFePO4 cells during prolonged cycling.

Non‐Resonant Structure Induces N‐Rich Solid Electrolyte Interface toward Ultra‐Stable Solid‐State Lithium‐Metal Batteries

AbstractThe practical application of all‐solid‐state lithium metal batteries (ASSLMBs) is limited by lithium (Li) anode instability including Li dendrite formation and deteriorating interface with electrolytes. Here, a functional additive, isosorbide mononitrate (ISMN) with a non‐resonant structure (O2−N−O−) is reported, which improves its reactivity and is utilized to build a stable N‐rich solid electrolyte interface, effectively alleviating Li dendrite and side reactions for poly(vinylidene fluoride) (PVDF)‐lithium bis(trifluoromethane sulfonyl) imide (LiTFSI)‐based electrolyte (PLE‐ISMN). In addition, the ion‐dipole interaction between ISMN and Li ions facilitates the dissociation of LiTFSI to form carrier ions, improving the ionic conductivity (4.4 × 10−4 S cm−1) and transference number (0.50) of PLE‐ISMN. Consequently, the Li/Li symmetric cell delivers a high critical current density of 2.0 mA cm−2 and stable Li stripping/plating cycling over 5000 h with a capacity of 1.0 mAh cm−2. Moreover, the Li|LiFePO4 cell delivers an excellent initial discharge capacity of 154.0 mAh g−1 with an outstanding capacity retention of 88.9% after 500 cycles at 0.5 C. The Li|LiNi0.8Co0.1Mn0.1O2 cell also exhibits a good cycling performance at 4.4 V at 1 C.

Coordination polymer-reinforced composite polymer electrolyte for all-solid-state Li-metal batteries

Composite polymer electrolytes (CPEs) have garnered significant interest due to their lightweight, flexible, and suitability for large-scale processing. However, current CPEs still face challenges such as unsatisfactory ionic conductivity (σ), low Li+ transference number (t+), and poor interfacial stability. This study presents the synthesis of a coordination polymer by coordinating Co2+ with terpyridine-end-capped polyethylene glycol (Co(tpy)-PEG). The resulting Co(tpy)-PEG-reinforced PEO-based CPE exhibits exceptional properties, including a high σ of 0.22 mS cm−1, large t+ of 0.75, and superior durability in both Li|Li (1400 h at 0.2 mA cm−2) and Li|LiFePO4 cells (70% capacity retention after 1000 cycles at 1C) at 60 °C, comparable to the best available CPEs. The incorporation of Co(tpy)-PEG filler plays a vital role in enhancing the σ by disrupting the PEO crystallinity and creating additional Li+ conducting pathways. Additionally, it can free Li+ to increase t+ through Lewis acid-base interactions between Co2+ and TFSI−/O atoms, as well as NO3− and Li+. Furthermore, Co(tpy)-PEG facilitates the formation of a stable multicomponent solid electrolyte interphase containing beneficial Li2Sx, LiF, and Li3N. This work introduces a promising strategy for designing and preparing multifunctional fillers capable of simultaneously reinforcing the σ, t+, and interfacial stability of CPEs.

In-situ polymerisation of fluorene to achieve theoretical capacity in LiFePO4 cells

This study aims to enhance the electrochemical properties of solid-state lithium-ion batteries by modifying the cathode material, LiFePO4 (LFP), via fluorene addition and in-situ polymerisation. The first modification process involves creating a shell structure (the film thickness of 10 nm) around each LFP particle and establishing a net-like structure to connect the particles before the in-situ polymerisation. Then, electrochemical in-situ polymerisation during battery cycling with a low current and obtaining the composite cathode of lithium iron phosphate (LFP) and polyfluorene. The results demonstrate that adding 20 wt.% fluorene significantly reduces the transfer resistance and enhances the rate performance with the capacity retention of 95.2 % (from 0.1C to 2C and return to 0.2C) of the solid-state batteries. Additionally, the modified LFP cathode demonstrates excellent long-term cycling performance and exhibits capacity (167.2 mAh/g in 0.2 C) close to the theoretical limit, and Coulombic efficiency remains at 99.2 %.

In Situ Construction of Elastic Solid-State Polymer Electrolyte with Fast Ionic Transport for Dendrite-Free Solid-State Lithium Metal Batteries.

Solid-state lithium metal batteries (LMBs) have been extensively investigated owing to their safer and higher energy density. In this work, we prepared a novel elastic solid-state polymer electrolyte based on an in situ-formed elastomer polymer matrix with ion-conductive plasticizer crystal embedded with Li6.5La3Zr1.5Ta0.5O12 (LLZTO) nanoparticles, denoted as LZT/SN-SPE. The unique structure of LZT/SN-SPE shows excellent elasticity and flexibility, good electrochemical oxidation tolerance, high ionic conductivity, and high Li+ transference number. The role of LLZTO filler in suppressing the side reactions between succinonitrile (SN) and the lithium metal anode and propelling the Li+ diffusion kinetics can be affirmed. The Li symmetric cells with LZT/SN-SPE cycled stably over 1100 h under a current density of 5 mA cm-2, and Li||LiFePO4 cells realized an excellent rate (92.40 mAh g-1 at 5 C) and long-term cycling performance (98.6% retention after 420 cycles at 1 C). Hence, it can provide a promising strategy for achieving high energy density solid-state LMBs.

Enhancing mechanical properties of composite solid electrolyte by ultra-high molecular weight polymers

Composite solid electrolytes combining the advantages of inorganic and polymer electrolytes are considered as one of the promising candidates for solid-state lithium metal batteries. Compared with ceramic-in-polymer electrolyte, polymer-in-ceramic electrolyte displays excellent mechanical strength to inhibit lithium dendrite. However, polymer-in-ceramic electrolyte faces the challenges of lack of flexibility and severely blocked Li+ transport. In this study, we prepared polymer-in-ceramic film utilizing ultra-high molecular weight polymers and ceramic particles to combine flexibility and mechanical strength. Meanwhile, the ionic conductivity of polymer-in-ceramic electrolytes was improved by adding excess lithium salt in polymer matrix to form polymer-in-salt structure. The obtained film shows high stiffness (10.5 MPa), acceptable ionic conductivity (0.18 mS cm−1) and high flexibility. As a result, the corresponding lithium symmetric cell stably cycles over 800 h and the corresponding LiFePO4 cell provides a discharge capacity of 147.7 mAh g−1 at 0.1 C without obvious capacity decay after 145 cycles.

A Highly Stable Practical Li Metal Anode via Interphase Regulation and Nucleation Induction

AbstractThe practical utilization of Li metal anodes has been significantly plagued by the challenges of uncontrollable dendritic Li growth and poor interphase instability. Here, the study reports a novel strategy to strengthen interphase and give highly efficient active seeds concurrently to stabilize Li metal via a highly lithiophilic In2O3 decorated porous scaffold. In situ configurated fast‐ion‐transport Li2O‐strengthened interphase layer cooperatively with highly efficient Li13In3 nucleation induction can endow the uniform Li nucleation/growth and high Li utilization efficiency. As a result, the achieved modified Li metal manifests high Coulombic efficiency, ultrahigh rate performance (5 mA cm−2), and ultra‐long lifespan cycling durability (7975 cycles). Importantly, the established Li|LiFePO4 cells exhibit long‐term cycling durability over 600 cycles at 1 C with an ultralow decay rate of ca. 0.017% per cycle. Moreover, the Li|LiCoO2 pouch cells with ultrahigh areal capacity of ca. 3.89 mAh cm−2 also exhibit extraordinarily prolonged cycling performance with excellent capacity retention despite extremely harsh cycling conditions of low negative‐to‐positive‐capacity (N/P) ratio of ca. 1.7 and lean electrolyte of ca. 4.9 g Ah−1. This work enlightens a facile and effective avenue toward highly stable Li metal anode toward reliable practicability.

A crown-ether-enabled eutectic electrolyte for ultra-high temperature lithium metal batteries

Lithium metal batteries (LMBs) are generally restricted to operating below 60 °C and not suitable for high-temperature applications due to their thermally susceptible carbonate electrolytes. Deep eutectic electrolytes (DEE) with strong supramolecular interactions are a new emerging type of liquid-state ionic conductors, and here we present a novel DEE—which is composed of 18-crown-6 ether (18C6) and lithium difluoro(oxalate)borate (LiDFOB)—to extend the working temperature up to 150 °C. Via combined physiochemical and theoretical characterizations, it is identified that such high thermotolerance is a result of specific solvation structure of Li(18C6)4DFOB with multiple Li–O interactions. Moreover, our newly developed DEE triggers the formation of a B/F-rich solid electrolyte interphase, contributing to superior thermal stability and enhanced compatibility with Li-metal anodes. Consequently, Li|DEE|LiFePO4 cell exhibits great tolerance to extremely high temperatures with a capacity reversibility of 83 % after 250 cycles at 120 °C. Even at 150 °C, the cell can retain 77 % of the initial capacity (105 mAh g−1) after 100 cycles. To our knowledge, the DEE is the first liquid electrolyte for LMBs working at unprecedented high-temperature. This work opens intriguing perspectives to design novel electrolytes for demanded performance of LMBs across a wide temperature range.

In situ catalytic polymerization of LiNO3-containing PDOL electrolytes for high-energy quasi-solid-state lithium metal batteries

1,3-Dioxolane (DOL) can be induced to form polymer electrolytes by in situ ring opening polymerization at Lewis acid salts. However, the presence of ion–dipole interactions between NO3− and DOL suppresses this polymerization behavior. Herein, we report that the use of Sc(OTf)3 as an initiator can well disrupt this ion–dipole interaction. The in situ ring-opening polymerization of DOL is achieved to form a LiNO3-modified polyDOL-based electrolyte. New mechanism of Li migration in polymer electrolytes have been revealed by molecular dynamics modeling and constructed molecular interface models. It is found that the electrolyte interior is affected by the ion–dipole interactions of Li+ by NO3−, which made it easier for Li+ to be released from the polar ether-oxygen ligands on the polymer chain for rapid migration, thus exhibiting an ionic conductivity of 1.8 mS cm−1 and tLi+ of 0.78. In addition, NO3− preempts the binding sites around Li+, improves the coordination environment, and prioritizes the formation of a kinetically stable anion-derivative interface, which effectively mitigates the interfacial side reactions between the electrodes and the electrolytes. As a result, the assembled solid-state Li||LiFePO4 cell exhibits an impressive 152.3 mAh/g discharge capacity at 0.5C and maintains 80.3 % of the capacity after 450 cycles at 50 °C. This work not only opens a new avenue for designing high-performance gel polymer electrolytes for more metal-based batteries, but also provides valuable insights into understanding the ion migration mechanism.

Data-driven autoencoder neural network for onboard BMS Lithium-ion battery degradation prediction

An autoencoder based neural network architecture, CD-Net, is proposed to predict Lithium-ion battery capacity degradation as a function of operation time as part of a battery management system. CD-Net's generalization performance on various LIB cell chemistry is tested. The incorporation of cell chemistry in CD-Net leads to an improvement in the overall battery capacity prediction accuracy of >2 % for LiNiMnCoO2 cells, >5 % for LiNiCoAlO2 cells, and >12 % for LiFePO4 cells when compared to the similar ML models that do not incorporate cell chemistry information. A comparison of onboard battery health prediction using CD-Net against support vector regression, Bayesian regression, and Gaussian process regression-based approaches shows that CD-Net has higher computational efficiency with <2 % of relative remaining useful life (RUL) prediction error in a no-cell chemistry information setting. In summary, our work presents a chemistry-independent neural network model tailored specifically for onboard BMS applications, showcasing notable predictive capabilities in the context of Lithium-ion battery health assessment.

Dendrite‐Free Lithium Metal Batteries Enabled by Coordination Chemistry in Polymer‐Ceramic Modified Separators

AbstractIssues with lithium dendrite growth and dead lithium formation limit the practical application of lithium metal batteries, especially under high current conditions where uneven temperature distribution leads to serious safety concerns. Herein, In situ assembly of polydopamine (PDA) and aluminum nitride (AlN) coatings on polypropylene (PP) separator is introduced to address these challenges. The AlN particles are encapsulated by PDA, and the functional groups in PDA form Al‐O coordination bonds with Al3+, which promote uniform Li+ flux and reduce the migration barrier of Li+, thereby enabling dendrite‐free lithium deposition. In addition, the designed PDA@AlN@PP separator exhibits excellent electrolyte wettability, enhanced mechanical performance, and stable thermal resistance, providing a uniform thermal distribution and serving as a robust barrier against dendrite penetration. As a result, symmetric Li||Li cells (over 1800 h at 1 mA cm−2 and 1 mAh cm−2) and Li||Cu cells (over 600 cycles at 0.5 mA cm−2 and 0.5 mAh cm−2, coulombic efficiency over 98%) demonstrate outstanding long cycle performance and high coulombic efficiency. Moreover, the corresponding Li||LiFePO4 cells exhibit a high specific capacity of 91.3 mAh g−1 at 5 C. This work provides a new approach for designing functionalized separators for high‐performance lithium metal batteries.