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Lithium metal is a promising anode material for the development of advanced all-solid-state batteries (ASSBs) with high energy density. Among the various solid electrolytes, lithium phosphorus oxynitride glass electrolyte (LiPON) is notable for facilitating stable Li plating-stripping reactions in ASSBs employing Li metal. The aim of this study is to examine the Li/LiPON interface, with a specific emphasis on the reductive decomposition of LiPON near this interface. We employed time-of-flight elastic recoil detection analysis (TOF-ERDA) to assess changes in Li concentration around the Cu/LiPON interface immediately prior to the Li plating reaction. Our electrochemical measurements indicate that critical decomposition of LiPON occurs when the voltage at the Cu electrode is reduced to 0.1 V vs. Li/Li+ at 25 °C, resulting in the in situ formation of Li3P operating at 0.7 V vs. Li/Li+ as an anode material. The TOF-ERDA findings reveal that this decomposition reaction results in a layer with partial decomposition (ranging from 5 to 25% on average) extending up to approximately 30 nm from the Cu/LiPON interface. This insight is vital for enhancing the design and performance of ASSBs. [ABSTRACT FROM AUTHOR]

Micro energy sources as the nucleus of intelligent microdevices guarantee their full autonomy in the dimensions of time and space. However, the state‐of‐the‐art micro energy storage components, like all‐solid‐state thin‐film microbatteries (ASSTFBs), whose direct integration is impeded by the stereotyped vacuum‐based manufacturing technologies, for which an inevitable high‐temperature annealing step (> 500 °C) can exert catastrophic effects on the attached microdevices during the crystallization of manufactured insertion thin‐film cathodes, especially in flexible integration. Herein, a prototype construction is created to benchmark concrete feasibility for the low‐temperature manufacturing of ASSTFBs via a nonvacuum‐based spin‐coating electrode architecture. Results show that the spin‐coated LiFePO4 films enable low‐temperature (≈ 45 °C) manufacturing of ASSTFBs, by which it can deliver excellent cycling performance up to 1000 cycles. Importantly, this technology presents the versatility of integrating various cathode composites into ASSTFBs and is therefore generalized to the LiCoO2‐ and Li4Ti5O12‐based solid‐state chemistries. Furthermore, ASSTFBs with such compliant electrodes manifest outstanding flexibility without pronounced capacity degradation by successfully integrating on flexible temperature‐sensitive substrates. The spin‐coating protocol provides a general solution for excessive processing temperatures and ample opportunities for the development of on‐chip integratable and flexible ASSTFBs. [ABSTRACT FROM AUTHOR]

Lithium phosphorus-oxynitride (LiPON) films were deposited by the method of anodic evaporation of Li3PO4 in the nitrogen plasma of a low-pressure arc. A method for adjusting the degree of decomposition of vapors is proposed based on a change in the frequency of interaction of electrons with vapors at a constant heating power of the anode-crucible. The conditions ensuring the formation of films with a homogeneous microstructure and ionic conductivity (1–2) × 10−6 S/cm at a deposition rate of 8 nm/min have been determined. It is shown that the degree of vapor dissociation critically affects the morphology of the films and the magnitude of their ionic conductivity. The results of cyclic tests of LiPON films deposited by anodic evaporation in a low-pressure arc are presented. [ABSTRACT FROM AUTHOR]

Lithium phosphorus oxynitride (LiPON) is an amorphous solid-state lithium ion conductor displaying exemplary cyclability against lithium metal anodes. There is no definitive explanation for this stability due to the limited understanding of the structure of LiPON. Herein, we provide a structural model of RF-sputtered LiPON. Information about the short-range structure results from 1D and 2D solid-state NMR experiments. These results are compared with first principles chemical shielding calculations of Li-P-O/N crystals and ab initio molecular dynamics-generated amorphous LiPON models to unequivocally identify the glassy structure as primarily isolated phosphate monomers with N incorporated in both apical and as bridging sites in phosphate dimers. Structural results suggest LiPON's stability is a result of its glassy character. Free-standing LiPON films are produced that exhibit a high degree of flexibility, highlighting the unique mechanical properties of glassy materials.

Thin films of solid-state lithium-ion electrolytes show promise for use in small-sized autonomous power sources for micro- and nanoelectronic elements. The high rate of vacuum-plasma synthesis (~0.5 μm/h) of lithium phosphor-oxynitride (LiPON) films with an ionic conductivity of ~2·10−6 S/cm is achieved through anodic evaporation of Li3PO4 in a low-pressure arc. The microstructure and ionic conductivity of LiPON films are influenced by the proportion of free lithium in the vapor flow. This paper presents the results of a study on the plasma composition during anodic evaporation of Li3PO4 in a discharge with a self-heating hollow cathode and a crucible anode. A method is proposed for adjusting the free lithium concentration in the gas-vapor (Li3PO4 + N2/Ar) discharge plasma based on changing the frequency of collisions of electrons with Li3PO4 vapor in the anodic region of the discharge. It is demonstrated that an increase in the proportion of free lithium in the flow of deposited particles leads to an enhancement in the concentration and mobility of lithium ions in the deposited films and, subsequently, an improvement in the ionic conductivity of LiPON films.

Thin film of lithium phosphorus oxynitride (LIPON) was successfully deposited by radio frequency (RF) magnetron sputtering technique using a Li3PO4 target. The optimal deposition parameters were determined for the thin films with the highest target-substrate distance. Characterization of deposited film was carried out by AFM, FTIR and Raman spectroscopy, which showed incorporation of nitrogen into the film as both doubly, Nd , and possibly triply, Nt, coordinated form. The ac impedance spectroscopy measurements revealed that the highest ionic conductivity of 1.1 µScm-1 was achieved at room temperature for the samples prepared at the optimum RF power and gas flow conditions.

Spinel‐type LiNi0.5Mn1.5O4 (LNMO) is one of the most promising 5 V‐class cathode materials for Li‐ion batteries that can achieve high energy density and low production costs. However, in liquid electrolyte cells, the high voltage causes continuous cell degradation through the oxidative decomposition of carbonate‐based liquid electrolytes. In contrast, some solid‐state electrolytes have a wide electrochemical stability range and can withstand the required oxidative potential. In this work, a thin‐film battery consisting of an LNMO cathode with a solid lithium phosphorus oxynitride (LiPON) electrolyte is tested and their interface before and after cycling is characterized. With Li metal as the anode, this system can deliver stable performance for 600 cycles with an average Coulombic efficiency >99%. Neutron depth profiling indicates a slight overlithiated layer at the interface prior to cycling, a result that is consistent with the excess charge capacity measured during the first cycle. Cryogenic electron microscopy further reveals intimate contact between LNMO and LiPON without noticeable structure and chemical composition evolution after extended cycling, demonstrating the superior stability of LiPON against a high voltage cathode. Consequently, design guidelines are proposed for interface engineering that can accelerate the commercialization of a high voltage cell with solid or liquid electrolytes. [ABSTRACT FROM AUTHOR]

Along with the soaring demands for all-solid-state thin-film lithium-ion batteries, the problem of their energy density rise becomes very acute. The solution to this problem can be found in development of 3D batteries. The present work deals with the development of a technology for a 3D solid-state lithium-ion battery (3D SSLIB) manufacturing by plasma-chemical etching and magnetron sputtering technique. The results on testing of experimental samples of 3D SSLIB are presented. It was found that submicron-scale steps appearing on the surface of a 3D structure formed on Si substrate by the Bosch process radically change the crystal structure of the upper functional layers. Such changes can lead to disruption of the layers' continuity, especially that of the down conductors. It is shown that surface polishing by liquid etching of the SiO2 layer and silicon reoxidation leads to surface smoothing, the replacement of the dendrite structure of functional layers by a block structure, and a significant improvement in the capacitive characteristics of the battery. [ABSTRACT FROM AUTHOR]

Amorphous lithium phosphorus oxynitride (LIPON) has emerged as a promising solid electrolyte for all‐solid‐state thin‐film lithium batteries. In this context, the use of theoretical modeling to characterize, understand, or screen material properties is becoming increasingly important to complement experimental analysis or elucidate features at atomistic level that are difficult to obtain through experimental studies. Density functional theory (DFT) is the method of choice for quantum mechanical material modeling at the atomistic scale. The current state of the art represents DFT values, such as the formation or migration energies relevant for bulk phase of materials, as absolute numbers. Estimating the accuracy or fluctuation range of the different density functionals is challenging. In order to investigate the thermodynamic and kinetic properties of LIPON by DFT, an approach to describe the fluctuation range caused by the choice of the exchange‐correlation (XC) functional is developed. Three different model systems were chosen to characterize various structural features of amorphous LIPON, which are distinguished by the cross‐linking of the POuN4‐u‐structural units. The uncertainty Ũ is introduced as a parameter describing the fluctuation range of energy values. The uncertainty approach does not determine the accuracy of DFT results, but rather a fluctuation range in the DFT results without the need for a reference value from a higher level of theory or experiment. The uncertainty was determined for both the thermodynamic Li‐vacancy formation energies and the kinetic Li‐vacancy migration energies in LIPON. We assume that the uncertainty approach can be applied to different material systems with different density functionals. [ABSTRACT FROM AUTHOR]

We fabricated and evaluated four types of Li batteries, in this case a LTO/liquid electrolyte/Li battery, a LTO/LiPON/Li all-solid-state battery, and LTO/LiPON + liquid electrolyte/Li batteries with and without a separator to investigate and clarify the effects of each interface. Through the present research, it was found that a conventional polymer-based separator increases the impedance in the middle frequency region, resulting in an increase in the total cell resistance. After replacing the polymer-based separator with a thin-film solid electrolyte, the cycleability and capacity of the cell were comparable to those of a conventional Li-ion battery with a polymer separator. The all-solid-state Li thin-film battery without a liquid electrolyte exhibits the lowest capacity due to the large interfacial resistance between the Li metal and the LiPON solid electrolyte. However, we found that the insertion of an Al 2 O 3 interlayer between the Li and LiPON improves the capacity. [ABSTRACT FROM AUTHOR]

A design of a fully solid-state thin-film lithium-ion battery prototype and results of its being tested are presented. It is shown that the specific features of its charge–discharge characteristics are associated with the change of the Fermi level in the electrodes and are due to changes in the concentration of lithium ions in the course of charge–discharge. The specific capacity characteristics of the prototype were determined and found to be comparable with the characteristics of commercial lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Along with the soaring demands for all-solid-state thin-film lithium-ion batteries, the problem of their energy density rise becomes very acute. The solution to this problem can be found in development of 3D batteries. The present work deals with the development of a technology for a 3D solid-state lithium-ion battery (3D SSLIB) manufacturing by plasma-chemical etching and magnetron sputtering technique. The results on testing of experimental samples of 3D SSLIB are presented. It was found that submicron-scale steps appearing on the surface of a 3D structure formed on Si substrate by the Bosch process radically change the crystal structure of the upper functional layers. Such changes can lead to disruption of the layers’ continuity, especially that of the down conductors. It is shown that surface polishing by liquid etching of the SiO2 layer and silicon reoxidation leads to surface smoothing, the replacement of the dendrite structure of functional layers by a block structure, and a significant improvement in the capacitive characteristics of the battery.

Transition metal fluoride (TMF) conversion-type cathodes promise up to 4 times higher gravimetric energy densities compared to those of common intercalation-type cathodes. However, TMF cathodes demonstrate sluggish kinetics, poor efficiencies, and incompatibility with many liquid electrolytes. In this work, coevaporated heterostructured iron and lithium fluoride (Fe-LiF) cathodes are investigated in thin-film solid-state batteries with a LiPON electrolyte and a lithium metal anode. The cells were cycled 2000 times at a cycling rate of 6C. They show a gradual improvement in voltaic efficiency (37-53%) and specific capacity (146-216 mAh/g) during cycling. After 2000 cycles, the cathode capacity reaches 480 mAh/g at a cycling rate of C/3.6, close to its theoretical capacity of 498 mAh/g, at room temperature conditions. This capacity gain is correlated with an observed electrochemically activated nanorestructuring of the cathode, characterized by cycling-induced coarsening (from 2.8 to 4.2 nm) of the metallic iron phase and its accumulation near the current collector interface, as well as lithium fluoride phase accumulation near the LiPON interface.

Thin films of solid-state lithium-ion electrolytes show promise for use in small-sized autonomous power sources for micro- and nanoelectronic elements. The high rate of vacuum-plasma synthesis (~0.5 μm/h) of lithium phosphor-oxynitride (LiPON) films with an ionic conductivity of ~2·10 -6 S/cm is achieved through anodic evaporation of Li 3 PO 4 in a low-pressure arc. The microstructure and ionic conductivity of LiPON films are influenced by the proportion of free lithium in the vapor flow. This paper presents the results of a study on the plasma composition during anodic evaporation of Li 3 PO 4 in a discharge with a self-heating hollow cathode and a crucible anode. A method is proposed for adjusting the free lithium concentration in the gas-vapor (Li 3 PO 4 + N 2 /Ar) discharge plasma based on changing the frequency of collisions of electrons with Li 3 PO 4 vapor in the anodic region of the discharge. It is demonstrated that an increase in the proportion of free lithium in the flow of deposited particles leads to an enhancement in the concentration and mobility of lithium ions in the deposited films and, subsequently, an improvement in the ionic conductivity of LiPON films.

Abstract Polycrystalline nickel ferrite (NiFe 2 O 4) thin films were fabricated by pulsed laser deposition (PLD) and coated with nanometer layer of lithium phosphorus oxynitride (LiPON) by radio frequency magnetron sputtering (RF sputtering). Physical characterizations demonstrated that NiFe 2 O 4 thin films were not destroyed by LiPON coating with 50 nm thickness. Discharge capacity of LiPON coated NiFe 2 O 4 thin film after 50 cycles at 5 μA cm−2 was 849 mAh g−1, much higher than the counterpart value of pristine NiFe 2 O 4 thin film (449 mAh g−1), while rate capability was also greatly enhanced. Ex situ TEM investigation confirmed the two-steps reaction mechanism between NiFe 2 O 4 and Li, which includes an irreversible decomposition reaction of NiFe 2 O 4 in the first discharge process and reversible reactions between NiO, Fe 2 O 3 and their nanosized metal particles afterward. The significant improvement on the electrochemical performance was ascribed to the amorphous LiPON layer on the surface, which suppressed the volume expansion of electrode, the formation of delaminated particles and generation of cracks on electrode surface, as proved by ex situ SEM and AFM results. The LiPON coating is an effective approach to enhance the electrochemical performance of conversion materials for lithium ion batteries. Highlights • Pristine and LiPON coated NiFe 2 O 4 thin films were fabricated. • LiPON coating benefits the electrochemical performance of NiFe 2 O 4 thin film. • Conversion mechanism was confirmed by ex situ TEM technique for the first time. • Ex situ SEM and AFM results explained the effect of LiPON coating. [ABSTRACT FROM AUTHOR]

Abstract Li-compensated LiPON (Li-LiPON) thin film solid electrolyte has been deposited by sputtering a sintered Li-rich Li 3.3 PO 4 target instead of the normally Li 3 PO 4 target, showing an improved Li ionic conductivity of 3.2 × 10−6 S/cm. All-solid-state thin film lithium batteries (TFLBs) with the structure of Si/SiO 2 /Ti/Au/LiCoO 2 /LiPON/Li have been fabricated by adopting Li-LiPON and normal LiPON (N-LiPON) electrolyte layers, respectively. The galvanostatic cycling tests show much better rate performance and higher capacity retention ratio of TFLB with Li-LiPON electrolyte. We suggested that the Li-LiPON solid electrolyte helps to reduce the space-charge layer effect induced by Li ionic defects. Highlights • Li-compensated LiPON electrolyte and all-solid-state thin film lithium batteries • Higher Li ionic conductivity was obtained in Li-compensated LiPON. • Better rate performance and higher capacity retention ratio in Li-compensated TFLB [ABSTRACT FROM AUTHOR]

Transparent lithium phosphorus oxynitride (LiPON) thin films were deposited by RF sputtering at room temperature for electrochromic (EC) applications. We carried out a basic study from single layer, double layers, and eventually to devices. The interactions between LiPON and bottom EC electrode during sputtering were highlighted. The effects of N 2 pressure on structural, morphological, chemical, and electrical properties of the LiPON films were investigated. The Li ionic conductivity of the films increased with decreasing N 2 pressure. The results of Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy indicated a probable increase of nitrogen content in the films with decreasing N 2 pressure. However, low pressure sputtering process induced the formation of a resistive layer between LiPON and bottom electrode. The electrochemical impedance measurements were conducted to evaluate the charge transfer processes across the interfaces. In the case of WO 3 electrode, the charge transfer resistance at the WO 3 /LiPON interface could be considerably high up to 5100 Ω cm 2 . For the NiO/LiPON interface, the highest value was 1400 Ω cm 2 . The high charge transfer resistance significantly hindered the ion transport, thus leading to irreversible Li insertion/extraction processes and lowered charge capacity in the electrode layers. The cycling reversibility and optical contrast for the complete EC device were compromised accordingly. The device using a 130 nm-thick LiPON ion conductor showed an optical modulation of 40% at 550 nm driven by −1.5 V (coloration) and 1 V (bleaching) with switching time of 30 s. [ABSTRACT FROM AUTHOR]

[Display omitted] • Assignment of 31P signals of LiPON thin films prepared by sputtering. • Observation of 31P-14N proximities using TRAPDOR experiments. • Probing 31P-31P proximities using dipolar recoupling techniques. • Quantification of the different P sites in LiPON thin films. Amorphous lithium phosphorus oxynitrides (LiPON), prepared by reactive magnetron sputtering, have become the electrolytes of choice for all-solid-state thin film microbatteries since its discovery in early 1990s. Nevertheless, there is still a lack of understanding of their atomic-level structure and its influence on ionic conductivity. Solid-state NMR spectroscopy represents a promising technique to determine the atomic-level structure of LiPON glasses but is challenging owing to its low sensitivity in the case of thin film materials. Recently, 31P solid-state NMR spectra of LiPON thin films were acquired under magic-angle spinning (MAS) conditions and assigned with the help of density functional theory (DFT) calculations of NMR parameters. However, the identification of the different P local environments in these materials is still a challenge owing to their amorphous structure and the lack of resolution of the 31P MAS NMR spectra. We show herein how the NMR observation of internuclear proximities helps to establish the nature of P sites in LiPON thin films. The 31P-14N proximities are probed by a transfer of population in double resonance (TRAPDOR) experiment, whereas 31P-31P proximities are observed using one-dimensional (1D) 31P double-quantum (DQ)-filtered and two-dimensional (2D) 31P homonuclear correlation spectra as well as dipolar dephasing experiments using DQ-DRENAR (DQ-based dipolar-recoupling effects nuclear alignment reduction) technique. The obtained NMR data further support the recently proposed assignment of 31P NMR signals of LiPON thin films. With the help of this assignment, the simulation of the quantitative 1D 31P NMR spectrum indicates that P O 4 3 - orthophosphate anions prevail in LiPON thin films and N atoms are mainly incorporated in [O 3 PNPO 3 ]5− dimeric anions. PO 3 N4− isolated tetrahedra and [O 3 POPO 3 ]4− anions are also present but in smaller amounts. [ABSTRACT FROM AUTHOR]

Commercial NASICON-type electrolyte plates are coated with a thin film of LiPON to obtain a composite electrolyte system with high conductivity at room temperature that can be used in contact with metallic Lithium. The formation of the interface between the NASICON substrate and the LiPON coating is studied using an in-situ X-ray photoemission spectroscopy (XPS) surface science approach. The process of LiPON deposition induces changes in the surface chemical structure of the NASICON substrates as observed by XPS, including the partial reduction of Ti and the incorporation of N into the NASICON. The practical impact of the interface formation is studied by impedance spectroscopy, revealing a substantial increase of resistance for LiPON coated samples. [ABSTRACT FROM AUTHOR]

Model-type thin film all-solid-state batteries (ASSB) of the type Li/”LiPON”/Li 4 Ti 5 O 12 are characterized by impedance spectroscopy as function of the state of charge. Both the contact of Li 4 Ti 5 O 12 (LTO) to the substrate and current collector as well as the Li ion transport through the LTO thin film prove to be important factors for the rate limitation of the cell. The ionic charge transfer resistance between Li 4 Ti 5 O 12 and “LiPON” is proven to not be a rate limiting factor. The impedance measurements are interpreted in terms of the mechanism of phase change in the Li 4 Ti 5 O 12 thin film and the data indicate a solid solution mechanism of phase change. The resulting data are compared to recent results for the Li/”LiPON”/LiCoO 2 system, and several key similarities and differences are highlighted mostly involving the solid electrolyte/Li interface and the degradation thereof. The results are meant to improve the understanding of interfaces in ASSB in general rather than to advance high performance batteries. [ABSTRACT FROM AUTHOR]

The chemical instability of the glassy solid electrolyte LiPON against metallic lithium and the occurrence of side reactions at their interface is investigated by combining a surface science approach and quantum-mechanical calculations. Using an evolutionary structure search followed by a melt-quenching protocol, a model for the disordered structure of LiPON is generated and put into contact with lithium. Even the static optimization of a simple model interface suggests that the diffusion of lithium into LiPON is driven by a considerable driving force that could easily take place under experimental conditions. Calculated reaction energies indicate that the reduction and decomposition of LiPON is thermodynamically favorable. By monitoring the evolution of the LiPON core levels as a function of lithium exposure, the disruption of the LiPON network alongside the occurrence of new phases is observed. The direct comparison between UV photoelectron spectroscopy measurements and calculated electronic densities of states for increasing stages of lithiation univocally identifies the new phases as Li 2 O, Li 3 P and Li 3 N. These products are stable against Li metal and form a passivation layer which shields the electrolyte from further decomposition while allowing for the diffusion of Li ions. [ABSTRACT FROM AUTHOR]

Compact lithium phosphorous oxynitride (LiPON) thin films, as a solid-state electrolyte for all solid-state Li batteries and electrochromic (EC) devices, with the high ratio of the triply coordinated -N< (N) over the doubly coordinated -N= (N) structural units was deposited by a conventional reactive RF magnetron sputtering of a LiPO target at a low pure N pressure. The effect of heat treatment from 200 to 500 °C on the ionic conductivity and local structure of LiPON thin films were investigated by scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS) core level analysis. A dramatical improvement of ionic conductivity from 1.1 to 3.28 μS/cm and microstructure changes were happened on the LiPON thin films while annealed for 1 h at 300 °C, which was linked to structural differences with a highest ratio of -N< over -N= structural units. The work proves that a proper heat treatment on LiPON thin film can effectively improve its ionic conductivity and change its microstructure. [ABSTRACT FROM AUTHOR]

Relying on the combination of lithium phosphorous oxynitride (LiPON) as electrolyte and cobalt oxide (Co 3 O 4 ) as electrode material it is possible to fabricate symmetric all-solid-state micro-supercapacitors (ASTSCaps) on rigid and flexible substrates. Due to the nanoscale active layer dimensions, the excellent performance of the component materials and the high nominal voltage of 2 V, an exceptionally high volumetric energy and power densities of up to 8 (±2) mW h/cm 3 and 16 (±2) W/cm 3 , respectively, are obtained. These results are going far beyond the current state-of-the-art performance limits. The ASTSCaps are temperature stable up to 215 °C (for 1 V nominal voltage) and experience an endurance of more than 30,000 cycles. These ultra-thin all-solid-state micro-supercapacitors bring strong benefits for on-chip energy storage and open up interesting new avenues for autonomous and flexible electronic microsystems. [ABSTRACT FROM AUTHOR]

Redox reactions of the Li + insertion/extraction from one to two interlayers of graphene (Gr) on area-defined single-crystalline SiC substrates are investigated using lithium phosphorus oxynitride glass (LiPON) as the solid-state electrolyte. Unlike an organic liquid electrolyte, this glassy electrolyte does not induce a reduction current and excludes the desolvation reaction of Li + . Gr electrodes with less than two Gr layers show a single reduction peak and one or two oxidation peaks below +0.21 V (vs Li + /Li), differing distinctly from those of graphite and multilayer Gr, which display multiple peaks (multiple stage transitions). However, this finding aligns with the conventional understanding that graphite stage structure transitions proceed with stepwise increases or decreases in the number of Gr layers between adjacent Li-inserted interlayers. Cyclic voltammetry measurements indicate the presence of surface capacity due to Li + adsorption/desorption at the LiPON/Gr interface. Moreover, Li + insertion and extraction induce different charge transfer resistances at the level of a single interlayer. These sensitive measurements are achieved using high-quality epitaxial Gr and LiPON electrolyte, which prevent the formation of a solid electrolyte interphase and the desolvation reaction of Li + . Similar measurements using bilayer Gr produced by chemical vapor deposition coupled with a Gr transfer method and an ethylene carbonate/dimethyl carbonate liquid electrolyte are not reliable. Thus, the proposed method is effective for electrochemical measurement of Gr electrodes with a controlled number of layers.

Amorphous lithium phosphorus oxynitride (LiPON) films of various thicknesses were prepared by radio frequency (RF) magnetron sputtering as an electrolyte layer for inorganic all-solid-state electrochromic devices.The ionic conductivity of LiPON films measured by electrochemical impedance spectroscopy was all approximately 10−6 S/cm, and the average optical transmittance characterized by UV–Vis spectroscopy was over 80%, indicating that the prepared LiPON films were suitable for electrochromic applications. Monoclinic electrochromic devices (ECDs) (ITO/NiO x /LiPON/WO 3 /ITO) with different LiPON thicknesses were fabricated and studied. It was found that the electro-optical properties of the ECDs could be significantly affected by the thickness and surface roughness of LiPON films. The ECDs demonstrated the best combination of optical contrast (68.4% at 560 nm), switching time (27s), and cycling stability (optical modulation degradation of 6.93% for 200 cycles) when the LiPON thickness was 450 nm. The above results not only shed lights on improving the interfacial properties of solid electrolytes, but also give directions for the performance enhancement of inorganic all-solid electrochromic devices. • ITO/NiO x /LiPON/WO 3 /ITO all-solid-state ECDs with different LiPON thicknesses were fabricated and studied. • The mechanism of solid electrolyte thickness affecting interfacial properties is discussed. • This mechanism relies on the effect of electrolyte surface roughness on interfacial contact properties. • The electro-optical properties and cycling stability of the ECDs are be deeply dependent on the electrolyte thickness. [ABSTRACT FROM AUTHOR]

This paper presents tests to characterize the mechanical resistance of the multilayers set which forms an all-solid-state lithium-ion micro battery. The system under investigation consists in five layers that were deposited successively onto a crystalline silicon substrate (100): Ti, TiOS, LiPON, aSi, Ti. The layer thicknesses are between 65 nm (amorphous silicon layer aSi) and 1400 nm (LiPON, TiOS). First, simple water immersion experiments allow internal stress to be put into evidence in the two external layers (aSi and Ti), basically a strong compressive stress in the aSi layer (at least −0.8 GPa). Afterwards, well-controlled 4-point bending tests lead to delamination of the weakest parts of the multilayer, which are the TiOS-LiPON and LiPON-aSi interfaces. The TiOS-LiPON interface is the weakest, with an adhesion energy around 2.5 J/m 2 . The TiOS layer exhibits a rather low cohesion energy, scarcely higher than 2.5 J/m 2 . The brittle character of LiPON clearly appears. By using samples of another kind (-Ti-TiOS-Ti on Si), local adhesion flaws are identified between the TiOS and underlying Ti layer. In our experiment, these local adhesion flaws lead to characteristic phenomena (formation of comet-shaped scales), which are explained in the framework of a simple mechanical model. [ABSTRACT FROM AUTHOR]

The structural, electronic and ion transport properties of an amorphous member of the LiPON family with non-trivial composition and cross-linking are studied by means of electronic structure calculations within Density Functional Theory. By a combination of an evolutionary algorithm followed by simulated annealing and alternatively by a rapid quenching protocol, structural models of disordered Li 5 P 4 O 8 N 3 are generated, which are characterized by a local demixing in Li-rich and Li-poor layers. These structures have a composition close to what is found experimentally in thin films and contain all the expected diversely coordinated atoms, namely triply- and doubly-coordinated nitrogens and bridging and non-bridging oxygens. The issue of ionic conductivity is addressed by calculating defect formation energies and migration barriers of neutral and charged point defects. Li + interstitials are energetically much preferred over vacancies, both when the lithium reservoir is metallic lithium and LiCoO 2 . The competitive formation of neutral Li interstitials when LiPON is contacted with metallic Li results in the chemical reduction of LiPON and the disruption of the network, as recently observed in experiments. [ABSTRACT FROM AUTHOR]

Laser physical vapor deposition is used to deposit thin films of lithium phosphorous oxynitride in nitrogen and lithium nickel manganese oxide in oxygen ambient on Si substrate. LIPON film is also deposited on LiNiMnO film that is deposited on Si. Graphene films consisting of graphene platelets are deposited on Si substrate from a suspension in isopropyl alcohol. Li-graphene films are obtained after Li adsorption by immersion in LiCl solution and further drying. Transient thermo reflectance signal is used to determine the cross-plane thermal conductivity of different layers and interface thermal conductance of the interfaces. The results show that LIPON film with lower thermal conductivity is a thermal barrier. The interface thermal conductance between LIPON and Au or Si is found to be very low. Thermal conductivity of LiNiMnO is found to be reasonably high so that it is not a barrier to thermal transport. Film with graphene platelets shows a higher value and Li adsorbed graphene film shows a much higher value of cross-plane thermal conductivity. The value of interface thermal conductance between graphene and Au or Si (100) substrate is also much lower. The implications of the results for the thermal transport in thin film Li batteries are discussed. [ABSTRACT FROM AUTHOR]

In this paper, the preparation and characteristics of all-solid-state thin film batteries (TFB) are described. In contrast to the state-of-the-art TFB preparation processes, only room temperature processes are used. The cathode is based on amorphous molybdenum(VI) oxide (MoO 3 ), for the electrolyte lithium phosphorus oxynitride (LiPON) is employed and lithium metal acts as anode active material. The cycling stability and rate performance were examined and are discussed. The material set shows a very high cycling stability and excellent rate capability. Performing 550 full cycles at a current density of 202.5 μA cm −2 (10C) a discharge capacity fade of around 15% could be observed. Furthermore, at higher current densities of 2 μA cm −2 (145C) about one third of the initial discharge capacity remained. Using the proposed technology a shift from inorganic rigid substrates, such as glass to flexible polymer substrates is enabled. The performance of the MoO 3 /LiPON/Li TFBs on glass and flexible polyimide substrates were tested and are discussed within this paper. [ABSTRACT FROM AUTHOR]

Thin film batteries (TFB) are discussed to be one of the future power sources for integrated circuits and miniaturized autonomous electrical devices. The open circuit voltage of a TFB is determined by the difference of the Fermi level positions of the two electrodes, which are electronically separated by an ionically conductive solid electrolyte. The stepwise deposition of one material on top of another combined with in-situ X-ray photoemission spectroscopy (XPS) offers the possibility to measure energy band alignments and band bending due to space charge layer formation at the electrode/electrolyte interfaces, allowing insights into the formation and the properties of the (electrochemical) interface. In this contribution we show results on in-situ XPS measurements of the interface formation between the cathodic interface between LiCoO 2 /LiPON and on the anodic interface between LiPON/Li. From these measurements an electronic energy band diagram of the full battery cell is determined. The contributions of dipole- and space charge layers to the formation of the electrified interfaces as well as the ionic contribution to the cell voltage is discussed. [ABSTRACT FROM AUTHOR]

Lithium ion-conducting glasses attract wide interest for electrochemical applications like efficient energy storage devices. This work presents a structural study on involved bonding units, based on X-ray photoelectron spectroscopy and infrared spectroscopy, of lithium phosphorus oxide and oxynitride amorphous thin films prepared by RF magnetron sputtering. A thorough consideration of the mid- and far-infrared spectral regions demonstrated structural changes at the phosphate units and the lithium ion environments triggered by nitrogen incorporation and post-deposition thermal treatment. It was found that films prepared by sputtering in pure nitrogen atmosphere have about 75 % of their nitrogen atoms in sites doubly coordinated with phosphorus (P-N=P), and the rest in triply coordinated sites. It was shown also that nitrogen incorporation favors the stability of lithium ions, while annealing enhances ionic conductivity of the oxynitride films. [ABSTRACT FROM AUTHOR]

All inorganic solid-state thin-film electrochromic devices based on lithium ion (Li + ) insertion and using lithium phosphorus oxynitride (LiPON) as the ion conductor were fabricated by physical vapor deposition technology. Multilayer architecture consisting of TCO/V 2 O 5 /LiPON/Li x WO 3 /TCO was deposited by RF sputtering technology on glass substrate. Electro-optical characterization carried out on complete devices highlighted transmittance changes as large as 40% at 600 nm wavelength upon ±1.5 V voltage application, with coloring and bleaching time of 30 s. Several hundreds of bleaching/coloration cycles have been carried out with almost no performance degradation. The effect of the multilayer architecture was investigated. The results showed interactions between the depositing and the deposited layers, which influences the total amount of injected charges and hence the device performance. In particular, it has been observed a reversibly inserted Li + charge capacity during LiPON deposition and a charge capacity extraction during deposition in presence of lithiated layers. The described phenomena should be considered in order to achieve the charge balance between the electrodes for optimum device performance. [ABSTRACT FROM AUTHOR]

Transparent amorphous lithium phosphorus oxynitride (LiPON) thin films with different thickness have been prepared by RF magnetron sputtering at a growth rate of 14 nm/min. The mean ionic conductivity of as-deposited LiPON films determined by impedance spectroscopy was 4.9 μS/cm at 22 °C with the activation energy of 0.55 eV. The electronic partial conductivity was measured to be 1.6 × 10 − 6 μS/cm by recording the current–time curves at a constant voltage. The optical transmission of LiPON films were measured by UV–Vis/IR spectroscopy. The prepared LiPON films on silica glass substrate showed transmission higher than 80% in the visible light range. The complex refractive index and bandgap (~ 2.94 eV) were estimated by fitting the transmission data with the Tauc–Lorentz dielectric function model. The local structure of the film was investigated by X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Both methods confirmed the incorporation of nitrogen in the matrix. Nitrogen is present in two different chemical environments, corresponding to P − N < P P and P N P. Inductively coupled plasma-optical emission spectrometry (ICP-OES) and Rutherford backscattering spectrometry (RBS) measurements showed that the composition of the LiPON film was Li 3.13 PO 1.69 N 1.39 . The high nitrogen content and low oxygen content appears to be responsible for the specific electrical and optical properties of the LiPON films. [ABSTRACT FROM AUTHOR]

Thin film technology is applied in different fields of Li-ion battery research and development, such as the fabrication of thin film cells and model electrodes. Data obtained by surface and interface analysis of thin films provides important insights into fundamental processes such as charge compensation mechanism or interface formation. In this overview, we present the analysis of LiCoO2 and LiPON thin films using photoemission. It includes data obtained directly after preparation, after exposure to molecular species and/or after electrode-electrolyte interface formation. Information both on electronic structure and surface chemistry of the films is deduced fromcore level spectra, valence band spectra, Fermi level position and work function. Next to PES analysis of our films, we address composition, structure and functionality in more general terms in relation to literature. [ABSTRACT FROM AUTHOR]

Lithium phosphorus oxynitride (LiPON) is an amorphous solid lithium ion conductor commonly used in all solid state thin film batteries (TFBs) with LiCoO 2 as cathode- and lithium as anode-material. TFBs exceed conventional Li ion batteries with respect to lifetime and safety but may suffer from high ion transfer resistances and interface reactions between the electrodes and the electrolyte. In this contribution we study interface layer formation between LiPON and metallic lithium using an in-situ X-ray photoemission spectroscopy (XPS) surface science approach. [ABSTRACT FROM AUTHOR]

We report on the preparation of Li + conducting lithium phosphorus oxynitride (LiPON) layers by ion beam sputtering, resulting in ultra-thin layers with a thickness down to only 12 nm. The morphology of the layers is studied by transmission electron microscopy, whereas homogeneity and excellent interface quality is observed. The ion conducting properties of the layers are studied as a function of temperature and layer thickness, using electrochemical impedance spectroscopy. In these measurements, a specific ionic conductivity at room temperature of around 2 · 10 −7 S cm −1 is found that results in a maximum conductance of 0.2 S cm −2 , thanks to their ultra-small thickness. To demonstrate the applicability of the thin films as functional solid state electrolyte, Ag/LiPON/Pt triple layers are studied, serving as models for all solid state batteries. The functionality of these model batteries is measured by cyclic voltammetry of up to 100 charge–discharge cycles, and their morphology after cycling is investigated by transmission electron microscopy. For the first time, these investigations give insight into the morphology of this kind of model cell after intensive cycling. In particular, they allow determining the specific lithium storage capacity of the interface reaction layer between Ag and LiPON, which is found to be around 12 μAh cm −2 μm −1 . [ABSTRACT FROM AUTHOR]