Electrochemical Lithium Insertion Research Articles

Accelerating the reaction rates of nucleation growth and solid-state diffusion in electrochemical lithium insertion into MgMn2O4 by controlling the particle size

Accelerating the reaction rates of nucleation growth and solid-state diffusion in electrochemical lithium insertion into MgMn2O4 by controlling the particle size

Relaxation Analysis of Silicon Monoxide-Graphite Composite Anode

Relaxation analysis based on X-ray diffraction has been carried out on SiO-graphite composite anode of the lithium-ion battery, focusing on the lithium migration during the relaxation accompanied by the stage change of lithium graphite intercalation compound (Li-GIC). After the termination of electrochemical lithium insertion, XRD peaks of Li-GIC change from stage I into stage II during the relaxation. Due to the slower reaction for lithiation of SiO in comparison with the intercalation of Li-GIC, lithium migration from Li-GIC toward SiO to change the Li-GIC from stages I into II toward the equilibrium lithium distribution. The stage change is more apparent for higher current density at the charging, presumably due to the core–shell model of lithium concentration of SiO after charging.

Influence of Cation Substitution on Cycling Stability and Fe-Cation Migration in Li3Fe3-xMxTe2O12 (M = Al, In) Cathode Materials.

Li3Fe3Te2O12 adopts a crystal structure, described in space group Pnnm, related to that of LiSbO3, in which Te6+, Fe3+, and Li+ cations reside in a partially ordered configuration within an hcp array of oxide ions. Chemical or electrochemical insertion of lithium is accompanied by a fully reversible migration of some of the Fe cations with an initial capacity of 120 mA h g-1 (2.85 Li per formula unit). Long-term cycling stability is limited by the facile reduction of Te6+ to elemental Te, which leads to cathode decomposition. Partial substitution of Fe by In suppresses Te6+ reduction, such that Li3Fe2InTe2O12 shows no sign of this cathode decomposition pathway, even after 100 cycles. In contrast, Al-for-Fe substitution is chemically limited to Li3Fe2.6Al0.4Te2O12 and appears to have almost no influence on cathode longevity. These features of the Li3Fe3-xMxTe2O12 system are discussed on the basis of a detailed structural analysis performed using neutron and synchrotron X-ray diffraction.

Fast and Durable Lithium Storage Enabled By Tuning Entropy in Wadsley-Roth Phase Titanium Niobium Oxides

To date, Wadsley−Roth phase materials are one of the most promising intercalation-type hosts for fast lithium transport because of the unique crystalline diffusion channels. However, the volume expansion as well as sluggish ion/electron transport kinetics retards its application in grid scale. In recent years, various strategies have been suggested to further improve the overall performance of micro-sized Wadsley-Roth phase materials, such as oxygen vacancy creation or cation substitution.Lately, entropy tuning has received considerable interest due to the favorable entropy-dominated phase-stabilization and ionic conductivity boosting effects.[1,2] However, it has only been applied in a few materials and the understanding of its function is still limited. It has been suggested that entropy-stabilized Wadsley−Roth shear phases with a more ordered structure would be stable upon electrochemical lithium (de-)insertion without a phase transition, while a more disordered structure would compromise the stability of the active material.[3] Therefore, suitable entropy tuning in entropy-stabilized Wadsley−Roth phase materials remains challenging and detailed knowledge about its effect on crystal structure and lithium storage is still lacking.Here, we have successfully realized entropy-stabilized Wadsley-Roth phase Fe0.4Ti1.6Nb10O28.8 (FTNO) in which the increased entropy, due to iron substitution, leads to a reduced grain size, and therefore, a shortened Li+ diffusion channel length.[4] Secondly, the diffusion coefficient and the reaction rate constant are enhanced leading to a reduced overpotential and an improved rate performance. Benefiting from this, the micro-sized FTNO electrode exhibits an enhanced rate ability of 73.7 mAh·g-1 at 50 C as compared to 37.9 mAh·g-1 for its TNO counterpart. Thirdly, the increased entropy results in an extended cycling durability of FTNO electrode which can deliver a specific capacity of 130.0 mAh g-1 after 6000 cycles at high rate of 10 C. Operando XRD analysis demonstrates a suppression of the a-axis deformation during the first stage of the lithiation process. The mechanism is revealed by DFT calculations and found that Fe-O bond lengths undergo less changes than Ti-O during lithiation. Finally, the potential practical application of FTNO anodes has been demonstrated by successfully constructing fast charging and stable LiFePO4‖FTNO full cells.Our results demonstrate the effectiveness of tuning entropy by iron substitution to stabilize the Wadsley-Roth phase with fast charging ability, which can be extended to other intercalation electrodes for enhanced battery applications.[1] Y. Zeng et al., Science 2022, 378, 1320-1324.[2] R. Zhang et al., Nature 2022, 610, 67-73.[3] A. A. Voskanyan et al., Chem. Mater. 2020, 32, 5301-5308[4] J. Zheng et al., Small, smll.202301967R1, accepted.

High Conductivity and Rate Capability of NaNb13O33 Wadsley–Roth Phase as a Fast‐Charging Li‐Ion Anode

AbstractThe synthesis and electrochemical insertion of lithium into the Wadsley–Roth NaNb13O33 phase is studied. Lithium intercalation to form LixNaNb13O33 reaches a value of up to x~15, between 3.0 and 1.0 V vs. Li+/Li at a slow cycling rate, a capacity of 233 mAh g−1. Within this voltage window, two sharp peaks and one broad peak are observed in the differential capacity plots of lithium intercalation suggesting multiple two‐phase regions. High Li‐ion conductivity and rate capability was demonstrated. The lithium diffusion constant is about an order of magnitude greater than TiNb2O7. The average voltage is about 1.6 V and its high‐rate capability makes NaNb13O33 potentially useful as an anode in a fast‐charge Li‐ion battery application.

Electrochemical Lithium Insertion into TiO2 Anatase ALD Thin Films for Li‐Ion Microbatteries: An Atomic‐Scale Picture Provided by Raman Spectroscopy

AbstractElectrochemical lithium (de)intercalation in an atomic layer deposited (ALD) TiO2 anatase thin film deposited on a planar Si /Al2O3/Pt substrate is investigated by Raman spectroscopy. An initial discharge capacity of 63 µAh cm−2 µm−1 (0.5 Li+ mole−1) is reached at C/10 rate, which increases up to 77 µAh cm−2 µm−1 upon further cycles. An excellent capacity retention is achieved over at least 100 cycles, showing the good adherence of the ALD thin film. Raman spectra of LixTiO2 (0 ≤ x ≤ 0.5) thin film electrodes point to the nucleation of the orthorhombic lithiated titanate (LT) Li0.5TiO2 phase from x = 0.1. This LT phase coexists with tetragonal TiO2 in the 0.1 ≤ x ≤ 0.4 composition domain to be pure for x = 0.5. A fully reversible transformation from orthorhombic LT to tetragonal TiO2 is observed upon the charge. The high quality of the Raman spectra allows identifying for the first time 12 modes in the 100–800 cm−1 region for the electrochemically formed LT phase. Furthermore, an appropriate Raman spectra analysis allows a reliable and quantitative determination of the thin film composition during discharge and charge. These results illustrate Raman spectroscopy is a powerful probe to scrutinize the Li insertion/extraction mechanism in TiO2 thin films.

A near dimensionally invariable high-capacity positive electrode material.

Delivering inherently stable lithium-ion batteries is a key challenge. Electrochemical lithium insertion and extraction often severely alters the electrode crystal chemistry, and this contributes to degradation with electrochemical cycling. Moreover, electrodes do not act in isolation, and this can be difficult to manage, especially in all-solid-state batteries. Therefore, discovering materials that can reversibly insert and extract large quantities of the charge carrier (Li+), that is, high capacity, with inherent stability during electrochemical cycles is necessary. Here lithium-excess vanadium oxides with a disordered rocksalt structure are examined as high-capacity and long-life positive electrode materials. Nanosized Li8/7Ti2/7V4/7O2 in optimized liquid electrolytes deliver a large reversible capacity of over 300 mAh g-1 with two-electron V3+/V5+ cationic redox, reaching 750 Wh kg-1 versus metallic lithium. Critically, highly reversible Li storage and no capacity fading for 400 cycles were observed in all-solid-state batteries with a sulfide-based solid electrolyte. Operando synchrotron X-ray diffraction combined with high-precision dilatometry reveals excellent reversibility and a near dimensionally invariable character during electrochemical cycling, which is associated with reversible vanadium migration on lithiation and delithiation. This work demonstrates an example of an electrode/electrolyte couple that produces high-capacity and long-life batteries enabled by multi-electron transition metal redox with a structure that is near invariant during cycling.

(Digital Presentation) Do Silicon-Based Composite Electrodes for Li-Ion Batteries Need High Molecular Weight Polymeric Binder to Well Perform?

Among all potential active materials for the anodes of Li-ion batteries, silicon is considered as one of the most promising candidate because of its high specific and volumetric capacities, about 3600 mAh.g-1 and 2200 mAh.cm-3 respectively,1 as well as its low operation voltage (0.4 versus Li/Li+), abundant resources (the second largest in the earth’s crust), and environmental benignity (non-toxic). However, during the lithiation (formation of LixSi, x ~ 3.75) the silicon undergoes an expansion of about 280% of its initial volume2 which induces numerous damages to the electrode. The silicon micrometer particles tend to be pulverized when the size of the particles are upper than 150 nm.3 However, nanosizing the materials leads to more electrolyte degradation due to a higher specific surface developed and requires more binder and eventually more conducting additive in the electrode formulation. The pulverized Si particles are scattered and become electrically isolated and the adhesion of the Si electrode to the current collector are also damaged by these volume variations4. This effects drastically reduces the electrochemical performance and lifetime of the Si electrode. As a result, these challenges have seriously restricted the commercialization of Si anodes in high energy LIBs.5 To deal with these problems many researches are developing advanced binders. This later has a crucial role since it reinforces the mechanical strength of the electrode and thus helps to preserve the electrode architecture upon cycling against the large Si volume change.6 It is generally accepted that binders of very high molar masses (polymers) are necessary to allow cycling of silicon-based electrodes, as they favor the formation of more robust molecular bridges and therefore are a priori more capable of maintaining particle-to-particle contacts and therefore cohesion in the electrode. Quite surprisingly, we have discovered that it is possible to obtain good cyclability of silicon-based electrodes by using an organic binder of low molar mass (molecule). This calls into question the understanding of the mechanism by which the binder operates in silicon-based electrodes.This low molecular weight binder is a natural polyphenol, namely tannic acid. Here we will highlight that Silicon-based composite electrodes of high areal capacity (~7 mAh.cm-2) when prepared with tannic acid as small binder show a stable cycling like the one obtained with one state-of-the-art binder such as carboxymethyl cellulose. We will report in-depth characterization of the interactions between tannic acid and the silicon particles surface as well as of the rheological behavior of the electrode slurries and the electrodes properties and electrochemical performances.References(1) Obrovac, M. N.; Chevrier, V. L. Alloy Negative Electrodes for Li-Ion Batteries. Chem. Rev. 2014, 114 (23), 11444–11502.(2) Jung, S. C.; Choi, J. W.; Han, Y.-K. Anisotropic Volume Expansion of Crystalline Silicon during Electrochemical Lithium Insertion: An Atomic Level Rationale. Nano Lett. 2012, 12 (10), 5342–5347.(3) Liu, X. H.; Zhong, L.; Huang, S.; Mao, S. X.; Zhu, T.; Huang, J. Y. Size-Dependent Fracture of Silicon Nanoparticles During Lithiation. ACS Nano 2012, 6 (2), 1522–1531.(4) Hernandez, C. R.; Etiemble, A.; Douillard, T.; Mazouzi, D.; Karkar, Z.; Maire, E.; Guyomard, D.; Lestriez, B.; Roué, L. A Facile and Very Effective Method to Enhance the Mechanical Strength and the Cyclability of Si-Based Electrodes for Li-Ion Batteries. Adv. Energy Mater. 2018, 8 (6), 1701787.(5) Ko, M.; Chae, S.; Cho, J. Challenges in Accommodating Volume Change of Si Anodes for Li-Ion Batteries. ChemElectroChem 2015, 2 (11), 1645–1651.(6) Eshetu, G. G.; Figgemeier, E. Confronting the Challenges of Next-Generation Silicon Anode-Based Lithium-Ion Batteries: Role of Designer Electrolyte Additives and Polymeric Binders. ChemSusChem 2019, 12 (12), 2515–2539.

Dynamics of changes in the kinetic parameters of germanium nanowires during lithiation/delithiation in a wide temperature range

• Electrochemical behavior of Ge nanowires in the temperature range from –40 to +20 o C is studied. • Formation of SEI on germanium nanowires was confirmed by IR spectra. • The activation energies of Rs, R SEI , and Rct are of 21.8, 24.1, and 36.5 kJ/mol, respectively. Electrochemical impedance spectroscopy was used to study electrochemical lithium insertion into the electrodes based on germanium nanowires in a temperature range of +20 to −40 °C. Since such electrodes have a regular structure and do not contain binders and conductive additives, they are described by a relatively simple equivalent circuit including the electrolyte resistance (R s ), the resistance of the solid electrolyte film (R SEI ) on the surface of germanium nanowires, the capacitance of the solid electrolyte film (C SEI ), the charge transfer resistance (R ct ), a constant phase element (CPE), reflecting the capacitance of the double layer, and the Warburg impedance (W), reflecting the diffusion of lithium in germanium. It is characteristic of the R SEI and R ct values to grow with an increase in the lithiation degree from 0.3 to 0.9, respectively, by 28% and 16%. A decrease in temperature leads to an increase in the values of R s, R SEI , and R ct in accordance with the Arrhenius law with activation energies of 21.8, 24.1, and 36.5 kJ/mol, respectively. At the same time, the SEI capacity is independent of temperature.

Electrochemical lithium and sodium insertion studies in 3D metal oxy-phosphate framework MoWO3(PO4)2 for battery applications

Electrochemical lithium and sodium insertion studies in 3D metal oxy-phosphate framework MoWO3(PO4)2 for battery applications

Si-TiN alloy anode materials prepared by reactive N2 gas milling: thermal stability and electrochemistry in Li-cells

Si-TiN alloys were synthesized through a novel N2 gas milling method and a conventional inert gas milling approach. Thermal stability of these two kinds of Si-TiN alloys and their electrochemistry as negative electrodes in Li-ion cells were evaluated before and after heating. Si70(TiN)30 prepared by N2 gas milling was found to have high temperature tolerance, evidenced by low crystallization and fine grain structure after heat treatment. The Si70(TiN)30 (N2) alloy after heat treatment shows resistance to Li15Si4 formation during electrochemical lithium insertion, which is presumably due to its fine grain structure. Si70(TiN)30 (N2) was further modified by carbon coating at 800°C, resulting in a high capacity retention after 50 cycles of 94%, while achieving a large reversible volumetric capacity of 1490 Ah/L.

Structural Evolution of Layered Manganese Oxysulfides during Reversible Electrochemical Lithium Insertion and Copper Extrusion.

The electrochemical lithiation and delithiation of the layered oxysulfide Sr2MnO2Cu4−δS3 has been investigated by using a combination of in situ powder X-ray diffraction and ex situ neutron powder diffraction, X-ray absorption and 7Li NMR spectroscopy, together with a range of electrochemical experiments. Sr2MnO2Cu4−δS3 consists of [Sr2MnO2] perovskite-type cationic layers alternating with highly defective antifluorite-type [Cu4−δS3] (δ ≈ 0.5) anionic layers. It undergoes a combined displacement/intercalation (CDI) mechanism on reaction with Li, where the inserted Li replaces Cu, forming Li4S3 slabs and Cu+ is reduced and extruded as metallic particles. For the initial 2–3% of the first discharge process, the vacant sites in the sulfide layer are filled by Li; Cu extrusion then accompanies further insertion of Li. Mn2.5+ is reduced to Mn2+ during the first half of the discharge. The overall charging process involves the removal of Li and re-insertion of Cu into the sulfide layers with re-oxidation of Mn2+ to Mn2.5+. However, due to the different diffusivities of Li and Cu, the processes operating on charge are quite different from those operating during the first discharge: charging to 2.75 V results in the removal of most of the Li, little reinsertion of Cu, and good capacity retention. A charge to 3.75 V is required to fully reinsert Cu, which results in significant changes to the sulfide sublattice during the following discharge and poor capacity retention. This detailed structure–property investigation will promote the design of new functional electrodes with improved device performance.

Changes in the spectroelectrochemical properties of copper(II) hexacyanoferrate(III) during electrochemical insertion of alkaline ions

In this work, the influence of the electrochemical insertion of different alkali ions, e.g., lithium, sodium, and potassium, on the electrochromic properties of copper(II) hexacyanoferrate(III) (CuHCF) was addressed. CuHCF was electrochemically synthesized on FTO substrates, and a nucleation and growth analysis was shown that follows a 3D progressive nucleation with diffusion-controlled growth, which was confirmed by SEM analysis. The spectroelectrochemical study demonstrated that spectral changes were centered into three regions: a green band (506 nm) associated with a charge transfer (FeIII → CuII), a violet band (413 nm) associated with d-d orbital transition for Cu+2 ions, and an ultraviolet band (354 nm) associated with a ligand-metal charge transfer (CN-→ FeIII). This electronic transfer, along with the calculated electrochromic efficiency averages, indicates a relationship between the ionic radius of insertion ions and the deformation generated in CuHCF. An increase in the ionic radius decreases the interatomic charge transfer, which produces a low electrochromic efficiency.

A comparison of high voltage outgassing of LiCoO2, LiNiO2, and Li2MnO3 layered Li-ion cathode materials

One method of increasing the energy density of Li-ion batteries is to access reversible Li intercalation in conventional layered transition metal oxide cathode materials at high potentials (4.3–5 V vs. Li/Li+), and thus allow more electrochemical capacity per volume of active material. This comes at the cost of increased interfacial reactivity and often results in capacity fade over many cycles. Tracing gas evolution during electrochemical lithium extraction and insertion provides a useful strategy to understand this high voltage reactivity. In this study, we examine outgassing during Li extraction in well-known layered oxides (LiCoO2, LCO; LiNiO2, LNO; and Li2MnO3, LMO). We highlight key differences in the outgassing of each material. Whereas negligible O2 release is found in LCO and LNO, even with voltage holds at 5 V vs. Li/Li+, O2 release is found to account for a large portion of the electrochemical capacity and persists over many cycles in LMO. CO2 outgassing is observed to varying extents, following the trend of LMO ≈ LNO > LCO, and is due to a combination of residual solid carbonate oxidation and electrolyte degradation. Taken together, these results show the importance of quantitative analysis in understanding the role of transition metal composition on the chemistry of conventional Li-ion battery materials.

(Invited) Study of Mechanical Behaviour of Si Anode upon Electrochemical Lithium Insertion

A battery is one of the representative electrochemical systems studied widely for energy storage applications. In particular, Li-ion batteries are becoming an essential component in mobile electronic devices and electric vehicles, as smaller, lighter, and longer energy storage is required. Silicon is considered as one of the most promising anode materials for Li-ion batteries because of its exceptional specific capacity, which is about ten times that of commercial graphite anodes. However, conventional Si anodes typically suffer from rapid capacity decay due to mechanical fracture caused by large volume changes (300%) during repeated electrochemical lithium insertion and extraction. It this talk, I will present the mechanical behaviour of various structure of single crystalline Si nanopillar upon electrochemical lithiation. Single crystalline Si nanopillar array fabricated by top-down process provides well defined dimension and crystalline orientation. The study of lithiated Si nanopillar exhibited interesting phenomena such as anisotropic expansion, size dependency of mechanical fracture, and temperature dependency [1-4]. Single crystalline Si plate various bending behaviour for the crystalline orientation and its large fracture resistance [5]. These studies will provide better understanding of mechanical behaviour of lithited Si anode for design of robust Si anode electrode. Acknowledgement The contents in this paper were published in references [1-5].

Synthesis and Electrochemical Analysis of Li3Ti0.75(MoO4)3 Phase with Lyonsite Structure

Li3Ti0.75(MoO4)3 compound crystallizes in lyonsite type structure. The structure was prepared by the solid state reaction method. Electrochemical lithium insertion was performed into sample for the first time. Preliminary studies were carried out to analyze the sample as electrode material for Li-ion batteries. The electrochemical charge discharge curves shows insertion of 4.8Li is obtained in sample when discharged to 1.5 V and extraction of 3.3Li is observed during charge. A reversible capacity of 112 mA h/g is observed after 25 cycles.

Relaxation stage analysis of lithium inserted graphite

Relaxation analysis has been carried out on lithium graphite intercalation compound (Li-GIC) focusing on the variation of stage structure and graphene interlayer distances. X-ray diffraction coupled with the one-dimensional Rietveld analysis revealed that, after the termination of electrochemical lithium insertion, excessively formed stage I partly transforms into stage II during the relaxation process. In addition, the periodic stacking of defective lithium layers forming stage II orders the lithium occupation at the relaxation, which is more apparently observed for faster charged sample. Even after the lithium extraction, gradual stage changes from I to II accompanied by the ordering of lithium occupation in stage II have been observed at the relaxation process. Lithium ion is rather uniformly intercalated or deintercalated in the graphene interlayers, while Li-GIC turned into ordered stage structure to achieve the stable state at the relaxation time.

Dynamic Tuning of Gap Plasmon Resonances Using a Solid-State Electrochromic Device.

Plasmonic antennas and metasurfaces can effectively control light-matter interactions, and this facilitates a deterministic design of optical materials properties, including structural color. However, these optical properties are generally fixed after synthesis and fabrication, while many modern-day optics applications require active, low-power, and nonvolatile tuning. These needs have spurred broad research activities aimed at identifying materials and resonant structures capable of achieving large, dynamic changes in optical properties, especially in the challenging visible spectral range. In this work, we demonstrate dynamic tuning of polarization-dependent gap plasmon resonators that contain the electrochromic oxide WO3. Its refractive index in the visible changes continuously from n = 2.1 to 1.9 upon electrochemical lithium insertion and removal in a solid-state device. By incorporating WO3 into a gap plasmon resonator, the resonant wavelength can be shifted continuously and reversibly by up to 58 nm with less than 2 V electrochemical bias voltage. The resonator can remain in a tuned state for tens of minutes under open circuit conditions.

In-Situ Characterization of the Li-Al System at Elevated Temperatures

We will describe our platform for ex- and in-situ characterization of lithium ion electrode and electrolyte materials over a wide range of temperatures, and our use of this platform to characterize phase formation and dissociation in the Li-Al system. Aluminum electrodes have been studied for use in lithium electrochemical cells for more than 40 years. Electrochemical insertion of lithium in to aluminum at very high temperatures (>400 °C) follows the equilibrium phase diagram; studies at e.g. room temperature only demonstrate the formation of LiAl. The formation of the other expected Li-Al phases, Li3Al2 and Li9Al4, is thought to be inhibited by slow diffusion of Li in LiAl. Aluminum is available in a wide variety of morphologies and manufacturing-induced microstructures and as such is a model test platform for deconvoluting the effects of microstructure, diffusion, and phase formation in metal alloy electrodes. Our core enabling technology is an adaptable high-temperature compatible cell design inspired by high-temperature compatible primary cell hardware and adapted from earlier work. Our double-ended glass-to-metal Conflat cells are compatible with low and high voltage electrode materials, adjustable (and commercially-relevant) electrode thicknesses and stack pressures, and can maintain ultra-high vacuum (<10-7 Pa) tight seals at temperatures up to 415 °C. Results from in-situ cycling of a Conflat cell with lithium and aluminum foil electrodes at 110 °C are presented in Fig. 1. Three voltage plateaus are evident, and the step changes between plateaus roughly correspond with the expected phase transition compositions (i.e. LiAl for Li/Al = 0 <–> 1, Li3Al2 for Li/Al = 1 <–> 1.5, Li9Al4 for Li/Al = 1.5 <-> 2.25). XRD patterns collected at room temperature (ex-situ) at three indicated compositions (x1, x2, x3) are also provided in Fig. 1. Patterns collected from samples cycled to 200 mV vs. Li metal on insertion (x1) and 150 mV vs. Li metal on removal (x3) indicate LiAl and Li3Al2 are present, as expected. However, the XRD pattern collected from the sample cycled to 40 mV vs. Li metal on removal (x2) indicates Li1.77Al, rather than Li9Al4, is present at a composition of Li/Al = 2.2. Li9Al4 has been detected in samples cycled in different conditions (temperature, current density, voltage limits, sample morphology etc.) The discrepancy between measured and expected phase composition at x2 (Li/Al = ~2.2 vs. ~1.8, respectively) is attributed to consumption of lithium in solid-electrolyte interphases (SEI). Li3Al2 (at composition x3, Li/Al = 1.8) has a similar discrepancy (expected composition of Li/Al = 1.5). Known phase transitions can therefore be used as guideposts to quantify SEI formation. XRD results shown in Fig. 1 and described above were collected by cooling and then disassembling Conflat cells and incorporating the lithiated electrode in a polypropylene encapsulated sample holder. A major advantage of Conflat cell technology is the ability to bolt-on new functionality without compromising cell performance. Conflat flanges incorporating x-ray transparent windows are now being incorporated in to our cells. We will present ex- and in-situ (variable temperature cycling, room temperature XRD, with and without cell disassembly) and in-operando (integrated variable temperature cycling and XRD, without cooling) results from aluminum thin films and (much thicker, but still thin) aluminum foils to map out phase formation as a function of temperature, sample morphology, and static and dynamic stress. This data, when coupled with insight in to Li diffusion rates and nucleation barriers for the various Li-Al phases, will enable a more complete understanding of ion mobility and phase formation and stability in the Li-Al and other metal alloy systems. Figure 1

Freestanding all-solid-state rechargeable lithium batteries with in-situ formed positive electrodes

Abstracts Freestanding all-solid-state rechargeable lithium batteries (Li/LiPON/LATP sheet/Au, SSB) operating at 2.3 V were developed. The electrochemical insertion of lithium into a white-colored Li+ conductive glass-ceramic solid electrolyte (LATP) sheet transformed the electrolyte into a blue-colored in-situ formed electrode, which provided a low-resistance electrode/solid electrolyte interface of ca. 100 Ω cm2. In addition, the interfacial resistances at both Li/LiPON and LiPON/LATP were less than 100 Ω cm2, and all the components in the SSB were combined with low-resistance interfaces. As a consequence, the resultant SSB delivered a clear redox peak at 100 mV s−1 in the cyclic voltammetry measurements at 25 °C. The reaction region of the in-situ formed electrode was limited around the Au/LATP interface at 25 °C, but this region expanded into the LATP sheet at higher temperatures. At 100 °C, the resultant SSB delivered ca. 300 μΑh cm−2 and a volumetric energy density of 53 Wh L−1. The electronic conductivity of the in-situ formed electrode appeared to control the reaction region, and thus a SSB using a carbon-LATP composite sheet delivered a larger discharge capacity at 25 °C than that of the SSB using only LATP operated at 100 °C. The use of conductive LATP sheets may be a possible solution for developing SSBs that can be rationally designed according to the operational environments of the IoTs.