Galvanostatic Intermittent Titration Technique Research Articles

Industrial-scale Hard Carbon Designed to Regulate Electrochemical Polarization for Fast Sodium Storage.

Given the merits of abundant resource, low cost and high electrochemical activity, hard carbons have been regarded as one of the most commercializable anode material for sodium-ion batteries (SIBs). However, poor rate capability is one of the main obstacles that severely hinder its further development. In addition, the relationships between preparation method, material structure and electrochemical performance have not been clearly elaborated. Herein, a simple but effective strategy is proposed to accurately construct the multiple structural features in hard carbon via adjusting the components of precursors. Through detailed physical characterization of the hard carbons derived from different regulation steps, and further combined with in-situ Raman and galvanostatic intermittent titration technique (GITT) analysis, the network of multiple relationships between preparation method, microstructure, sodium storage behavior and electrochemical performance have been successfully established. Simultaneously, exceptional rate capability about 108.8 mAh g-1 at 8 A g-1 have been achieved from RHC sample with high reversible capacity and desirable initial Coulombic efficiency (ICE). Additionally, the practical applications can be extended to cylindrical batterywith excellent cycle behaviors. Such facile approach can provide guidance for large-scale production of high-performance hard carbons and provides the possibility of building practical SIBs with high energy density and durability.

Mixed polyanionic NaFe1.6V0.4(PO4)(SO4)2@CNT cathode for sodium-ion batteries: Electrochemical diffusion kinetics and distribution of relaxation time analysis at different temperatures

We report the electrochemical sodium-ion kinetics and distribution of relaxation time (DRT) analysis of a newly designed mixed polyanionic NaFe1.6V0.4(PO4)(SO4)2@CNT composite as a cathode. The specific capacity of 104 mAhg−1 is observed at 0.1 C with the average working voltage of ∼3 V. Intriguingly, a remarkable rate capability and reversibility are demonstrated up to very high current rate of 25 C. The long cycling test up to 10 C shows high capacity retention even after 2000 cycles. The detailed analysis of galvanostatic intermittent titration technique (GITT) and cyclic voltammetry (CV) data reveal the diffusion coefficient of 10−8–10−11 cm2s−1. We find excellent stability in the thermal testing between 25–55 °C temperatures and 80% capacity retention up to 100 cycles at 5 C. Further, we analyze the individual electrochemical processes in the time domain using the novel DRT technique at different temperatures. The ex-situ investigation shows the stable and reversible structure, morphology and electronic states of the long cycled cathode material. More importantly, we demonstrate relatively high specific energy of ≈155 Wh kg−1 (considering the total active material loading of both the electrodes) at 0.2 C for full cell battery having excellent rate capability up to 10 C and long cyclic stability at 1 C.

Rational design of germanium–copper based nanocomposite anodes for high-performance lithium-ion storage

The rising energy demand in the 21st century has necessitated a shift from fossil fuels to irregular renewable sources for carbon neutrality. Therefore, energy-storage systems are crucial for storing intermittently produced energy. Electric vehicles (EVs), which are expected to replace internal combustion engines, are in high demand for achieving carbon neutrality. The development of efficient secondary batteries (such as lithium-ion batteries; LIBs) is vital for increasing the energy-storage capacity and driving range of EVs. Currently, the most commercialized carbon-based anode material has a capacity of 372 mAh g-1. However, this capacity is insufficient to produce the high-capacity batteries required in the current market. Therefore, in this study, GeO2, which can store 8.4 lithium atoms in one molecule, was selected as the target material. To enhance its electrochemical properties, conductive Cu and C were introduced into GeO2. The composites were synthesized via high-energy ball milling, a simple and easy method to scale up. Three types of GeO2/Cu@C composites, GeO2/Cu@C (10, 20, and 30wt%), were prepared by varying the carbon content. Among them, GeO2/Cu@C (20wt%) exhibited an average reversible capacity of 660.6 mAh g-1 after 200 cycles, with a capacity retention of 75.4% at a current density of 0.1Ag-1. Even at a high current density of 0.5Ag-1, its average capacity and capacity retention were 672.3 mAh g-1 and 99.5%, respectively, after 100 cycles. Moreover, galvanostatic intermittent titration technique analysis revealed that the Li+ diffusion coefficient of GeO2/Cu@C (20wt%) was higher than those of the other electrodes. The full-cell with the NCM622 cathode exhibited a high energy density of 284.9Whkg-1. Therefore, the GeO2/Cu@C (20wt%) electrode is anticipated to be a potential anode for long-term LIB cycling.

Approaching high rate All-Solid-State Lithium-Sulfur batteries via promoted sulfur conversion with nickel oxide nanoparticle electrocatalyst

All-solid-state lithium-sulfur battery (ASLSB) is deemed a promising next-generation energy storage device owing to its combination of high theoretical specific energy (2600 Wh kg−1) derived from the sulfur active material, and exceptional safety characteristics and the ability to suppress the polysulfide shuttle effect through the use of solid electrolyte (SE). However, the low electronic and ionic conductivity of sulfur, coupled with the poor solid–solid interfacial contact inherent in all-solid-state configuration, has resulted in poor electrochemical performance. Herein, NiO electrocatalyst supported on N-doped sites of super-p was synthesized and incorporated as a carbon additive in the composite cathode of the ASLSB. The direct growth of nanosized NiO electrocatalyst on the N-doped sites of super-p ensures facile electron transfer to the electrocatalyst surface, while maximizing the electrocatalyst’s surface area. As a result, the overpotential during charging and discharging of the ASLSB was significantly reduced, as assessed through galvanostatic intermittent titration technique and cyclic voltammetry, indicating enhanced redox conversion of sulfur. Furthermore, the Li6PS5Cl sulfide SE induces solid–solid conversion of sulfur, eliminating the dissolution issue of polysulfide intermediates and ensuring good cycle performance. The assembled ASLSB exhibits a high reversible capacity of 1845 mAh g−1 at 0.05C at room temperature and enhanced rate capability at high C-rates, operated at 60 °C. Even at a substantially high sulfur loading level of 6.65 mg cm−2, a maximum areal capacity of 9.48 mAh cm−2 was achieved at room temperature, highlighting the important role of electrocatalyst in realizing high performance ASLSBs.

Flexible free-standing Fe-CoP-NAs/CC nanoarrays for high-performance full lithium-ion batteries

In this study, a flexible, free-standing Fe-doped CoP nanoarrays electrode for superior lithium-ion storage has been successfully fabricated. The electrode combines the advantages of a Fe-doping and a flexible carbon cloth (CC) support, resulting in a high specific capacity (1356 mAh/g at 0.2 A/g) and excellent cycling stability (1138 mAh/g after 100 cycles). The cyclic voltammetry (CV) curves at different scan rates investigate the outstanding lithium storage behavior of Fe-CoP-NAs/CC which indicates a combined influence of diffusion behavior and capacitance behavior on the electrochemical process. The galvanostatic intermittent titration technique (GITT) analyzes the diffusion kinetics of Li+ which indicates the fast diffusion kinetics in the Fe-CoP/NAs/CC anode. The assembled Fe-CoP-NAs/CC//LiFePO4 battery exhibits a remarkable capacity of 325.2 mAh/g even at 5 A/g. And the battery also has good cycle stability, and still provides 498.1 mAh/g specific capacity after 200 cycles. Moreover, the Fe-CoP-NAs/CC//LiFePO4 soft-pack battery can continuously power the LEDs when it is bent at various angles which demonstrates its potential for use in wearable devices.

Nano-HxMoO3 cathodes with fast kinetics and long cycle stability via H+ pre-intercalation and nano-engineering for aqueous zinc-ion batteries

Aqueous zinc-ion batteries (AZIBs) have gained significant attention due to their high safety profile and potential for cost-effectiveness. However, the lack of rapid kinetic and durable cycling cathode materials has impeded the development of AZIBs. The present study suggests the implementation of synthesizing nano-HxMoO3 through a H+-based intercalation strategy in nano α-MoO3 to effectively address these concerns. The electrochemical kinetics of HxMoO3 exhibit significant improvement, as shown by data analyses of cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic intermittent titration technique. In addition, the results of the charge and discharge tests show that the HxMoO3 cathode has significantly less capacity degradation during the first discharge than MoO3 and a more stable structure. As a result, the HxMoO3 cathode demonstrated outstanding electrochemical performance, exhibiting discharge capacities of 215 and 158 mAh g−1 at current densities of 0.5 and 5 A g−1, as comparison the MoO3 cathode only have 189 and 142 mAh g−1. Moreover, the HxMoO3 cathode maintained 74% of its initial capacity after 100 cycles at a current density of 0.5 A g−1. Even after 2000 cycles at a current density of 5 A g−1, HxMoO3 maintains 44% of its original capacity, whereas MoO3 only retains 30%.

Facile Synthesis and Electrochemical Analysis of Zn-Doped V2O5 Anode Materials for High-Rate Li Storage

The surging demand for Li rechargeable batteries with high energy densities and rapid rate capability has propelled research on materials that can replace the conventional anode materials like graphite. Vanadium pentoxides (V2O5) have emerged as promising anode candidates owing to their excellent rate capability. Specifically, V2O5 allows the electrochemical prelithiation process, in which three Li-ions can be inserted to form Li3V2O5, followed by reversible insertion and extraction of two Li-ions. Nevertheless, the unsatisfactory Li-ion diffusion coefficients and electrical conductivities of these materials remain major drawbacks. Here, we propose a Zn-doped V2O5 anode, fabricated using a two-step sol–gel method, for high-rate Li-ion batteries. Zn was incorporated into V2O5 to enhance the Li-ion transport kinetics through the electrode. The crystal structure (orthorhombic) of Zn-doped V2O5 was identified by X-ray diffraction analysis, and the Zn doping was confirmed by X-ray photoelectron microscopy. The effect of Zn doping was thoroughly examined using various analytical methods, such as cyclic voltammetry and galvanostatic intermittent titration technique. The Zn-doped V2O5 electrode exhibited remarkable cycling durability, enduring for 1000 cycles, while retaining an enhanced capacity, even under a high rate of 2C.

Engineering P2W18 and GO synergistically supported octahedral Fe2O3 anode for lithium-ion batteries

By employing polyoxometalate (POMs) with high ion-conductivity and graphene oxide (GO) with high electron-conductivity, series of Fe2O3@P2W18-x@GO composites were successfully designed and fabricated to upgrade the performance of Fe2O3 anode for lithium-ion batteries (LIBs), where (NBu4)6[P2W18O62] (P2W18) clusters are uniformly confined in octahedral Fe2O3 framework. In the work, the galvanostatic intermittent titration technique (GITT), electrochemical impedance spectroscopy (EIS) and cyclic voltammogram (CV) under different scan rates were employed to explore the lithium storage contribution of P2W18 and GO to Fe2O3. Compared with 734.5 mAh g−1 of octahedral Fe2O3 at 30 cycles, the capacity of Fe2O3@P2W18-x (x =1, 2, 3) decreases rapidly to 255.5 mAh g−1, indicating that P2W18 alone has a negative effect on the electrochemical performance of Fe2O3, maybe due to the intense Li+ conductivity of P2W18. After coating GO, the Fe2O3@P2W18–2@GO anode shows relatively stable electrochemical performance with specific capacity of 642.1 mAh g−1 after 400 cycles at 0.1 A g−1, and a very long lifetime of 1000 cycles with ca. 375.4 mAh g−1 at 1.0 A g−1. Numerous repeated/controlled experiments indicate that both P2W18 and GO are indispensable for ameliorating the electrochemical performances of Fe2O3.

Achieving rapid sodiation/desodiation kinetics in NASICON-structured Na3MnTi(PO4)3 via Cr doping

Na3MnTi(PO4)3 is one of the most promising cathode candidates for sodium-ion batteries owing to its low cost, high operating voltage, and large reversible capacity. However, its electrochemical performance is significantly impeded by its deteriorative structure and sluggish Na+ diffusion kinetics. Herein, Cr-doping is introduced to tailor the structure of Na3MnTi(PO4)3, which helps to lengthen the Na2-O bond and expand the Na ion diffusion channels. X-ray diffraction, cyclic voltammetry, galvanostatic intermittent titration technique, and first principle calculations confirm the broadened diffusion channel for Na+ and facilitated Na+ diffusion rate after Cr-doping. As a result, the Na3.1MnTi0.9Cr0.1(PO4)3 electrode exhibits superior electrochemical performance with high discharge capacity (167.5 mAh g–1 at 0.1 C), outstanding rate capability (127.5 mAh g–1 at 10 C), and remarkable cyclability (70.56 % retention after 1400 cycles at 5 C). We believe that the results are useful for the design of high-performance NASICON-structured cathode materials for practical sodium-ion batteries.

Determination of phase boundaries and diffusion coefficients of copper in spinel CuCr2Se4 and delafossite CuCrSe2 by galvanostatic intermittent titration technique (GITT)

Determination of phase boundaries and diffusion coefficients of copper in spinel CuCr2Se4 and delafossite CuCrSe2 by galvanostatic intermittent titration technique (GITT)

Machine learning-assisted measurement of lithium transport using operando optical microscopy

Diffusion coefficients of electrode materials are often determined using galvanostatic (GITT) or potentiostatic intermittent titration technique (PITT), electrochemical impedance spectroscopy (EIS) or cyclic voltammetry (CV). However, these methods require special care as for each, their formal derivations use quite restrictive assumptions. As an alternative, a machine learning model is developed to extend a previously proposed optical method of studying lithium transport by operando microscopy. The herein reported model enables the measurement of concentration-dependent diffusion coefficients. For this purpose, a python code is developed that determines concentration profiles from RGB images using support vector regression (SVR), a flexible machine learning tool. To evaluate the diffusion coefficient, an inverse Boltzmann-Matano concept is applied. Representing the diffusion coefficient with generalized Redlich-Kister polynomials, concentration profiles are predicted and fit to the measured data. The method is demonstrated here on the example of delithiation of LiMn2O4, but it can, in-principle, be extended to any other battery material showing significant optical response on lithiation, which most of them do.

A green aqueous binder to enhance the electrochemical performance of Li-rich disordered rock salt cathode material

Li-rich disordered rock-salt oxides (DRX) are considered an attractive cathode material in the future battery field due to their excellent energy density and specific capacity. Nevertheless, anionic redox provides high capacity while causing O2 over-oxidation to O2, resulting in voltage hysteresis and capacity decay. Herein, the crystal structure of Li1.3Mn0.4Ti0.3O1.7F0.3 (LMTOF) cathode is stabilized by using sodium carboxymethylcellulose (CMC) binders replacing traditional polyvinylidene difluoride (PVDF) binders. The electrochemical impedance spectroscopy (EIS) and galvanostatic intermittent titration technique (GITT) reveal that the CMC-based LMTOF electrode has higher electronic conductivity and lithium-ion diffusion kinetics. Moreover, CMC has been demonstrated to improve the O2– reversibility, reduce the amounts of byproducts from electrolyte decomposition and suppress transition metal dissolution by Na+/Li+ exchange reaction. Furthermore, the CMC-based LMTOF electrode also exhibits less volume change upon lithiation/delithiation processes compared to the PVDF-based electrode, resulting in enhanced structural stability during cycling. Benefiting from these features, the CMC binders can effectively improve the cycling life and rate performance of the LMTOF cathode, and the CMC-based LMTOF electrode shows good capacity retention of 94.5 % after 30 cycles at 20 mA/g and 66.7 % after 100 cycles at 200 mA/g. This finding indicates that CMC as a binder can efficiently stabilize the structure and improve the electrochemical performance of Li-rich disordered rock-salt oxides cathode, making it possible for practical Li-ion battery applications.

In situ construction of Sn-based metal–organic frameworks on MXene achieving fast electron transfer for rapid lithium storage

Due to the poor electron transfer characteristics of metal–organic frameworks (MOFs), they always exhibit subpar kinetic performance in Li-ion storage. To address this issue, herein we innovatively devised an in-situ growth technique to enable the construction of Sn-based MOFs on MXene (MXene@Sn-MOF), thereby enhancing its electron transfer capabilities. According to this optimization, the resulting MXene@Sn-MOF composite exhibits excellent Li-ion storage performance, with a remarkable reversible storage capacity of 1009 mAh/g at 0.1 A/g after 100 cycles. It is worth noting that even at a high current density of 2 A/g, the MXene@Sn-MOF composite still maintains a reversible specific capacity of 540 mAh/g after 500 cycles, demonstrating exceptional rate performance and cycling stability. Continuous electrochemical impedance spectroscopy and galvanostatic intermittent titration technique measurements reveal a significant reduction in electron transfer impedance at various states of charge with the introduction of MXene, accompanied by enhanced ion diffusion capabilities, further confirming the beneficial role of MXene in augmenting the Li-ion storage capacity of Sn-based MOFs. We believe that our work provides a promising avenue for the design of anodes with enhanced fast electron transfer ability for Li-ion storage.

Improved plating/stripping in anode-free lithium metal batteries through electrodeposition of lithiophilic zinc thin films

The new concept of anode-free Li batteries (AFLBs) with no excess lithium, while retaining numerous strengths, does come with certain challenges, such as high capacity loss and low coulombic efficiency. These challenges can be addressed through the utilization of modified lithiophilic current collectors to enhance the electrochemical performances. Herein, we investigated the surface modification of the Cu current collector by zinc electrodeposition to provide a lithiophilic thin layer. This process aims to facilitate a smoother plating/stripping process, leading to a uniform and dendrite-free lithium deposition on the LixZny phase formed at the first stages of plating. The zinc-modified current collectors improved cell's performances, including smooth and dense lithium deposition, reduced overpotential at various applied current densities (44.5 mV to 16.8 mV @0.25 mA cm−2), prolonged cycling stability for about 300 cycles and provided high coulombic efficiency of 95 % when compared to bare Cu electrodes. These improvements are attributed to a favorable lithium alloying reaction on the Zn-coated surface. Galvanostatic Intermittent Titration Technique (GITT) and Electrochemical Impedance Spectroscopy (EIS) revealed high diffusion coefficients for lithium (ranging from 10−9 to 10−6 cm² s-1), despite of the solid-state Li diffusion in the Zn film coating. We anticipate that implementing this modified current collector in a half-cell configuration could lead to the realization of a high-performance, anode-free lithium battery. This holistic approach proposes a scalable and cost-effective technique for boosting the performance of AFLBs.

Boosting Li ion kinetics in H–Co3O4@CNT electrode by synergic design of CNT coating and hollow structure

Although the term “synergy” is generally adopted to explain the performance improvement of lithium-ion batteries (LIBs), the interaction mechanism is ambiguous due to the great challenge in identifying the individual contribution of each factor. In this work, a carbon nanotube (CNT) wrapped hollow Co3O4 (H–Co3O4@CNT) anode material is fabricated to quantify the synergy kinetics contribution through galvanostatic intermittent titration technique (GITT) and cyclic voltammetry (CV) analyses. The H–Co3O4@CNT electrode delivers higher Li+ diffusion coefficients (DLi+) value of 10−9.44–10−8.78 cm2 s−1 and Li+ capacitive coefficients (CLi+) value of 10−8.34–10−7.68 cm2 s−1 than the other two electrodes during depth of discharge (DOD) process. Depending on the further individual DLi+ and CLi+ calculation of CNT coating, hollow structure and their synergy, it is proved that CNT coating plays a significant role in the overall kinetic performance of H–Co3O4@CNT electrode. However, the result also demonstrates that hollow structure does not always play a positive role in synergy kinetics contribution. This work provides a kinetics mechanism analysis and quantitative individual factor contribution strategy for design of advanced LIBs.

Deciphering the role of optimal P2/O3 phase fraction in enhanced cyclability and specific capacity of layered oxide cathodes

Poor cyclability and rate performance of layered oxide cathodes have impeded their deployment in Na+ batteries. Here, Mn-rich biphasic cathodes with tuned P2/O3 phase fractions were synthesized by varying Na in NaxMn0.60Ni0.30Cu0.10O2 (NMNC-x) (0.80 ≤ x ≤ 1.00) and the P2/O3 phases were confirmed using X-ray diffraction (XRD), X-ray photoelectron spectroscopy, and extended X-ray absorption fine structure spectroscopy. The Rietveld refinement of XRD data showed that the O3 phase fraction increased from 13 % to 89 % with increasing x from 0.80 to 1.00. The NMNC-0.90 sample (with 54 % O3 phase) demonstrated excellent rate performance (119 and 100 mAh/g at 1C and 3C, respectively) but poor cyclic stability (64 % capacity retention at 1C after 200 cycles). P2 dominant NMNC-0.80 showed exceptional rate performance (147 & 103 mAh/g at 0.1C & 3C, respectively) and O3 dominant NMNC-1.00 exhibited a high specific capacity (187 mAh/g at 0.1C). These cathodes showed excellent capacity retention of around 91 % at 1C after 200 cycles. Operando Synchrotron XRD results confirmed a reversible O3 ↔ P3 phase transformation at ∼3.4 V. Further, a significant mismatch in the levels of the strain developed in the P2 and O3 phases was observed in NMNC-0.90 sample during charge/discharge, explaining its poor cyclability. Na+ diffusion coefficients calculated from the galvanostatic intermittent titration technique were in the 10−12 − 10−10 cm2 s−1 range. This investigation shed light on the optimum P2/O3 phase fraction for designing biphasic cathodes with high specific capacity and cyclability.

Mitigation of charge heterogeneity by uniform in situ coating enables stable cycling of LiCoO2 at 4.6V

LiCoO2 is a predominant cathode for lithium-ion batteries of portable electronics owing to its merit of high volumetric energy density. Nevertheless, it experiences rapid capacity deterioration under high voltages, concomitant with structural degradation and numerous intragranular cracks. Coating has been recognized as an efficacious strategy to ameliorate the decline in cycling performance of LiCoO2 at high voltages. Hence, a systematic elucidation of the precise mechanisms underlying the mitigation of structural degradation via coating layers assumes paramount importance in the context of advancing the next generation of high-voltage LiCoO2. In this work, the intricate interrelation among lithium-ion diffusion coefficients, charge heterogeneity, and crack distribution is explicated through techniques inclusive of galvanostatic intermittent titration technique (GITT), finite element analysis (FEA), and X-ray computed tomography (XCT). A robustly stable lithium-ion-conducting coating material serves the function of curtailing the occurrence of surface passivation layers, achieved by diminishing side reactions between the LiCoO2 and the electrolyte; while a uniform coating ensures a homogeneous lithium-ion flux, thereby mitigating charge heterogeneity and the resultant mechanical strain as well as intragranular cracks. Both are important elements that collectively allow the coating to effectively protect the surface from structural degradation, thus achieving superior performances upon high-voltage charging.

Tracking Sodium Cluster Dynamics in Hard Carbon with a Low Specific Surface Area for Sodium‐Ion Batteries

AbstractHere, the sodium storage mechanism in commercial grade hard carbon with a low surface area is comprehensively investigated using electrochemical impedance spectroscopy (EIS), the galvanostatic intermittent titration technique, and in situ Raman spectroscopy for fresh and cycled electrodes. The reversible shift of the carbon G‐band peak on Raman spectra and substantial change of the charge‐transfer resistance in the sloping region of the voltage profile indicates the intercalation of sodium ions into hard carbon, whereas the low‐voltage plateau is associated with the pore‐filling process. In situ Raman analysis at low frequencies reveals that the pore filling is progressed via formation of small sodium clusters in closed pores. Prolonged cycling demonstrates that intercalation is stable and consistent throughout multiple charge–discharge cycles. The transition from intercalation to pore filling strongly affects the diffusion behavior, leading to considerably slower diffusivity at low voltage. The EIS effectively differentiates the contribution of adsorption to charge storage. The gradual growth of the solid‐electrolyte interphase layer affects the rise of the interfacial resistance as cycling progresses. In combination with the slower diffusivity, the low‐voltage plateau region strictly impedes fast de/sodiation and eventually causes capacity fade.

Accurate Calculation of Solid-State Li+ Diffusion Coefficient and Kinetic Activation Energies for an Artificial Graphite Anode

The slow electrochemical reaction kinetics of artificial graphite is one of the limiting factors for safety of lithium-ion batteries, especially the lack of systematic research on activation energies of various kinetic processes. In this work, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic intermittent titration technique (GITT) were used to investigate key kinetic parameters of artificial graphite such as solid-state Li+ diffusion coefficient (D Li+) and activation energy. The results reveal the evaluation of the chemical diffusion coefficient of same material is independent of the technique and shows a similar value, with D Li+ ranging from 10−11 to 10−13 cm2·s−1. The activation energies measured by EIS and GITT for solid-state Li+ diffusion in graphite at 50% depth of discharge are 74.5 kJ·mol−1 and 66.8 kJ·mol−1, which are in the same order of magnitude as the activation energies of charge transfer resistance (59.5 kJ·mol−1), electrode/electrolyte interface membrane impedance (56.1 kJ·mol−1), and ohmic impedance (6.6 kJ·mol−1). It demonstrates that the solid-state Li+ diffusion, interface charge transfer process, and Li+ transmission through SEI membrane are significantly affected by temperature. This work provides a reliable parameter basis for establishing more accurate thermal-electrochemical coupling models and designing safer battery thermal management systems for lithium-ion batteries.

Method—AMIDR: A Complete Pulse Method for Measuring Cathode Solid-State Diffusivity

The Atlung Method for Intercalant Diffusion and Resistance (AMIDR) is a novel, high accuracy method for measuring solid state diffusivity and interface resistance related to the Atlung Method for Intercalant Diffusion (AMID) with several key differences. Most notably, AMIDR is designed to analyze the voltage response over time of “complete” pulses, pulses that last until an impedance steady state is reached. These differences allow for AMIDR to return diffusivity results with a higher degree of confidence than Galvanostatic Intermittent Titration Technique (GITT) and at a faster rate with higher state of charge (SOC) resolution than Electrochemical Impedance Spectroscopy (EIS). In this study, three different lithium transition metal oxides were studied. These active materials showed very similar kinetic behaviour that varied with dependence on the fraction of Ni atoms filling sites in the Li layer. AMIDR comes with a user-friendly python program complete with a user interface that is intended to assist other researchers in measuring active material diffusivity in a controlled, repeatable manner. This program, along with instruction on its use, the results of this study from raw data to the final key kinetic metrics, and a video summary of AMIDR design are available for download at https://github.com/MitchBall/AMIDR.