NASICON-type Solid Electrolyte Research Articles

Advancing High-Energy Solid-State Batteries with High-Entropy NASICON-type Solid Electrolytes

Advancing High-Energy Solid-State Batteries with High-Entropy NASICON-type Solid Electrolytes

Investigating the Influence of Sintering Temperature and Ascertaining Hopping Path in Sodium Superionic Conducting Electrolytes for Sodium-Ion Batteries

Recently, sodium super-ionic conducting (NASICON) type solid electrolytes have gained significant interest as potential candidates for next-generation batteries due to their exceptional properties such as high ionic conductivity, affordability, and remarkable chemical and electrochemical stability. Therefore, NASICON type solid electrolyte (Na3Zr2Si2PO12) is synthesized by solution assisted-solid state reaction (SA-SSR) method and sintered at three different temperatures, 1200 ℃, 1250 ℃ and 1300 ℃. Various experimental techniques are used to characterize and optimize the sintered electrolytes. The Rietveld refinement of X-ray diffraction pattern of prepared electrolytes revealed the monoclinic crystal structure having 3-dimension hopping channel for sodium ion migration through triangular bottleneck area. Complex impedance spectroscopy revealed, the highest bulk and grain boundary conductivity are found, 4.05 mS cm-1 and 0.31 mS cm-1, respectively, for the sample sintered at 1250 ℃. Using optimized electrolyte, sodium half-cell is demonstrated with Na3V2P3O12 (NVP) as cathode. The assembled cell delivers maximum discharge capacity 101.6 and 84.45 mAh g-1 at the current density 10 and 40 mA g-1, respectively with good capacity retention (~95.02%) upto 50 cycles. Figure 1

Ionic conductivity and microstructural characteristics of NASICON-type solid electrolyte Li1.3Al0.3Ti1.7(PO4)3 affected by synthesis and manufacturing processes for all solid-state battery

Ionic conductivity and microstructural characteristics of NASICON-type solid electrolyte Li1.3Al0.3Ti1.7(PO4)3 affected by synthesis and manufacturing processes for all solid-state battery

Co-doping strategies for advanced solid state electrolytes with lithium salt: a study on the structural and electrochemical properties of LATP

The commercialization of lithium-ion batteries has revolutionized the field of energy storage, yet their usage of organic electrolytes has led to significant safety concerns. Solid-state electrolytes have emerged as a promising solution to these issues, enabling the development of high-performance solid-state lithium batteries. The NASICON-type solid electrolyte Li1.3Al0.3Ti1.7P3O12 (LATP) has demonstrated excellent properties and significant potential. This study involves the solid-state synthesis of LATP electrolytes doped with Cobalt and Silicon. Furthermore, adding 8% LiBr into LATP-0.04 significantly enhanced ionic conductivity, reaching a value of 3.50 × 10−4 S cm−1. This can be linked to lithium salt filling vacant spaces between grains, resulting in a significant drop in grain boundary resistances. The electrochemical analysis through Linear Sweep Voltammetry (LSV) indicates that the investigated material demonstrates the capability to sustain stability and functionality even under the influence of elevated voltages, notably up to 5.45 V. These findings imply that optimal cobalt doping and Lithium salt contribute to superior ionic conductivity compared to pristine LATP.

Multi-scale characterization of submicronic NASICON-type solid electrolyte Li1.3Al0.3Ti1.7(PO4)3 degraded by spark plasma sintering

One of the most promising and developed disruptive technology of energy storage for the future is all solid-state batteries. The NASICON phase LATP (Li1.3Al0.3Ti1.7(PO4)3) is widely studied especially thanks to its high ionic conductivity and mechanical strength. However, high temperature densification is required to obtain a dense and conductive material. Here we explore the fast sintering by Spark Plasma Sintering (SPS) of submicronic LATP particles, and the impact of the heating rate on the physico-chemical and transport properties of the pristine powder. High-speed rate for the sintering process induces particles’ growth, avoiding any reduction of titanium. The impurity AlPO4 plays a major role on the conductivity, depending on its content but also on its distribution within the composite, either as a coating (surface modification) or as crystalline particles within the grain boundaries. An intimate understanding of the ceramic composites was achieved using combination of advanced characterization techniques to get a multi-scale description of the material, from the pristine to the sintered states, from the surface to the bulk, and from the atomic long range to the local scales. Sharing these fundamental results is essential, with among other motivations, the spreading of our interpretation of complex spectroscopic results (Electronic Spin Resonance (ESR) spectroscopy, solid-state Nuclear Magnetic Resonance (NMR) spectroscopy and X-ray Photoelectron Spectroscopy (XPS)), key for characterization of reactivities at interfaces in this work and in others.

Stabilization the interface of NASICON-type solid electrolyte and Li metal by Al interlayer

Solid-state lithium-ion batteries with intrinsic safety and stable performance have emerged as alternative to liquid electrolyte-based systems. NASICON-type Li1.3Al0.3Ti1.7(PO4)3 (LATP) with high ionic conductivity is a promising solid electrolyte to be commercialized. However, the incompatibility of LATP with Li metal hinders its application in high energy density solid-state systems. Herein, we apply a 60 nm thick protective Al layer by PVD to construct a stable interface with metallic Li. The Al-coated LATP enables better electrochemical performance in a symmetric cell than bare LATP. Al-coated LATP is stable at 0.1 mA cm−2 for 100 cycles without building up polarization. The overpotential and the interfacial resistance are significantly reduced as direct contact between Li and LATP is avoided. The Al coating inhibits the reduction of Ti4+ to Ti3+ of LATP pellet during cycling. This work resolves the prominent limitations of LATP and strengthens the interfacial connectivity in solid-state system, pointing an environmental friendly and low cost modification strategy to improve the solid-state lithium-ion batteries.

Correlation between the particle size of Li1.3Al0.3Ti1.7(PO4)3 solid electrolyte and lithium-ion transport in composite cathodes for all-solid-state lithium-ion batteries

Solid electrolytes (SEs) are key materials for all-solid-state lithium-ion batteries (ASSLBs), and are being studied for various applications. Li1.3Al0.3Ti1.7(PO4)3 (LATP), a NASICON-type SE, is noteworthy due to its wide voltage range for cathode operation and economic feasibility. However, fabricating well-contacted interparticle interfaces in composite cathodes using LATP is challenging because of its high grain-boundary resistance. To address this issue, we investigated the correlation between lithium-ion transport in composite cathodes and the particle size of LATP. We successfully synthesized two LATPs with different size distributions and prepared composite cathodes. Performance evaluation and various advanced analyses of composite cathodes were conducted, the results revealed that LATP with a smaller particle-size distribution formed more a uniform Li+ transfer network in the composite cathode than the larger particles, which contributed to the stable and fast electrochemical characteristics of the ASSLB. Additionally, we also observed real-time structural changes during electrochemical reactions in composite cathodes through in situ X-ray diffraction analysis. The results of our comprehensive analysis are expected to provide valuable insights into the reaction mechanisms of LATP-based ASSLBs, as they have not been extensively explored before.

(Invited) Electrolytes for Next-Generation Sodium Metal Batteries

Developing reliable and cost-effective electrical energy storage systems (EESs) for portable electronics, electric vehicles, and grid storage applications is vital. Na-ion batteries are the most promising alternative technology owing to their natural abundance and low sodium cost.[1] Solid-state batteries (SSBs) have garnered extensive attention for their ability to suppress the safety hazards of organic liquid electrolytes by replacing them with solid electrolytes.[2] Among the various solid electrolytes being explored, our group mainly focuses on NASICON (Sodium superionic conductor) type silicate and solid polymer electrolytes. Sodium silicates are a class of materials with composition, NaxMxSixOx (M = rare-earth metals, x = integer (1-10)).[3] They have the advantage of low sintering temperature (~1050 °C) and 3D framework structure containing MO6 octahedra and SiO4 tetrahedra providing facile ionic movement.[4] Solid polymer electrolytes (SPE) are known for their flexibility and electrode compatibility. Highly conductive, filler-free composite solid polymer electrolyte films were prepared using poly(vinylidene fluoride), poly(vinyl pyrrolidone) (PVP), and NaPF6.[5] PVP binder played an essential role in improving Na ion conductivity and excellent plating−stripping performance. This talk will present an overview of these solid electrolytes for next-generation sodium metal batteries.

(Digital Presentation) Electrochemical Impedance Analysis of Three-Electrode Cell with Solid Electrolyte/Liquid Electrolyte Interface

Mechanical contact loss at the solid electrolyte/electrode interface in all-solid-state batteries, a type of next-generation battery, has been reported as a major issue for ion transport in all-solid-state batteries[1]. To improve this contact problem, it has been proposed to add a small amount of liquid electrolyte to the solid electrolyte/electrode interface[2]. However, the reported ion transport analysis at the solid electrolyte/liquid electrolyte interface is limited in semi-solid-state system using symmetrical cells with lithium metal as the working electrode[3]. In this study, charge transfer reactions at the solid electrolyte/liquid electrolyte interface were analyzed by impedance (EIS) measurements in a three-electrode cell with a solid/liquid electrolyte interface using a composite electrode containing a cathode active material as the working electrode.A composite electrode prepared by mixing LiCoO2:acetylene black:polyvinylidene fluoride in a weight ratio of 8:1:1, coating Al foil, drying and pressing was used as the working electrode, while lithium metal was used as the counter and reference electrodes. A NASICON-type solid electrolyte Li1+x+y Al x (Ti2−y Ge y )P3−z Si z O12 was constructed between the working electrode and the counter electrode, and a three-electrode cell prepared by filling the liquid electrolyte 1 M LiClO4/PC between the solid electrolyte and both electrodes. The reference electrode was placed between the solid electrolyte and the counter electrode, as the solid electrolyte/liquid electrolyte interface charge transfer is not observed in EIS measurements when the reference electrode is placed between the working electrode and the solid electrolyte. After two cycles of constant current charge/discharge measurements (current rate: 0.1 C rate, cut-off potential: 3.2 V - 4.2 V vs. Li/Li+), the solid electrolyte/liquid electrolyte interface charge transfer was analyzed by performing EIS measurements. To identify the semicircle associated with the solid electrolyte/liquid electrolyte interface resistance, measurements were also performed in a cell without a solid electrolyte and the resistance components corresponding to each semicircle were assigned.The temperature dependence of the observed semicircles was analyzed. A comparison of the activation energies calculated from the slopes of the Arrhenius plots confirmed a particularly large activation barrier at the solid electrolyte/liquid electrolyte interface and the working electrode/liquid electrolyte interface charge transfer.[1] R. Koerver, I. Aygun, T. Leichtweiss, C. Dietrich, W. Zhang, J.O. Binder, P. Hartmann, W.G. Zeier and J. Janek, Chem. Mater., 29, 5574-5582 (2017).[2] C. Wanga, Q. Suna, Y. Liua, Y. Zhaoa, X. Lia, X. Lina, M.N. Banisa, M. Lia, W. Lia, K.R. Adaira, D. Wanga, J. Lianga, R. Lia, L. Zhangb, R. Yangb, S. Lub and X. Suna, Nano Energy, 48, 35-43 (2018).[3] T. Abe, H. Fukuda, Y. Iriyama, Z. Ogumi, J. Electrochem. Soc., 151, A1120-A1123 (2004).

Doped Nasicon-Type Solid Electrolytes for Sodium-Ion Batteries from Scalable Spray-Flame Synthesis

Due to the limited availability of raw materials, sodium-ion batteries (SiB) are a viable alternative to lithium-ion batteries. However, liquid-electrolyte-based SiBs have a comparably low energy density and suffer from safety issues similar to their lithium-ion-based counterparts. To address these issues, solid-state SiBs are a promising option and sodium super ionic conductors (NaSICON) are suitable solid electrolytes for such systems. They exhibit good mechanical properties and chemical stability, high ionic conductivity and compatibility with sodium metal based anodes enabling high energy density [1]. One of the best studied NaSICON materials is Na3Zr2Si2PO12 (NZSP) with a high ionic conductivity in the order of 10-4 –10-3 S·cm-1 at room temperature [2]. Conventional synthesis methods of this class of materials such as solid-state reaction and liquid-phase synthesis have several drawbacks due to time-consuming process steps such as milling, high temperature sintering, precipitation, washing and drying steps to obtain the final product.We present spray flame synthesis (SFS) as a new approach for the synthesis of nanosized NaSICON materials. Recent studies have shown that sintering of nanoparticular NZSP precursors offers several advantages: A high specific surface area, which increases the sintering activity, and short atomic diffusion paths, allowing high homogeneity and phase purity to be achieved at comparatively low sintering temperatures [3]. In SFS, metal salts dissolved in organic solvents are combusted resulting in fine metal oxide particles. They are characterized by transmission electron microscopy (TEM), X-Ray diffraction (XRD) and Raman-Spectroscopy for structural and morphological investigation. Elemental information is obtained via energy-dispersive X-Ray spectroscopy (EDX). Ionic conductivities of sintered NZSP pellets are measured by impedance spectroscopy.In our approach, nanoparticles with a median diameter of around 5–9 nm are obtained. The pristine particles consist of crystalline ZrO2, homogeneously covered with an amorphous layer consisting of the elements Na, Si, P and O. After a short annealing step for 1h at 1000°C, this mixture can be converted almost quantitatively into the desired rhombohedral NZSP phase. Moreover, aliovalent dopants were successfully added for the synthesis of Na3+2xAxZr2−xSi2PO12 with A = Mg or Ca. Pressed pellets sintered at 1100°C for 3h to a relative density of ~92% showed - for a material sintered for such a short period of time - a surprisingly high ionic conductivity of up to 7.9×10-4 S·cm-1 (Mg-doped).In conclusion, a novel approach for the preparation of NZSP allowing the phase formation at relatively low temperatures is demonstrated. Spray flame synthesis is an elegant and promising possibility for the scalable production of solid electrolytes, which also holds great potential, especially with regard to further improvement of ionic conductivity through targeted doping.[1] Zhang et al., ACS Appl. Energy Mater., 3 (2020) 7427; doi.org/10.1021/acsaem.0c00820[2] Narayanan et al., Solid State Ion., 331 (2019), 22; doi.org/10.1016/j.ssi.2018.12.003[3] Jalalian-Khakshour et al. J.Mater.Sci., 55, (2019) 2291; doi.org/10.1007/s10853-019-04162-8

Li1.4Al0.4Ti1.6(PO4)3 inorganic solid electrolyte for all-solid-state Li–CO2 batteries with MWCNT and Ru nanoparticle catalysts

The Li–CO2 battery has gathered considerable attention due to its high energy density and the possibility of utilizing carbon dioxide. However, their practical application is limited by kinetic and safety challenges. In this work, a highly stable and conductive NASICON-type solid electrolyte (Li1.4 Al0.4Ti1.6(PO4)3) is utilized to address the safety aspect. Additionally, a Ru catalyst is introduced to decrease polarization and improve battery performance. The LATP solid electrolyte synthesized through a solution-based method exhibited fine granularity and high uniformity. After sintering, a dense pellet without cracks and with no phase changes was produced. The LATP pellet exhibits an ionic conductivity of 9.2 × 10−4 S/cm. The fabricated Li–CO2 battery delivers a specific capacity of 6531 mAh/g at a current density of 150 mA/g and undergoes 50 cycles at a current supply of 50 mA/g with a cut-off capacity of 500 mAh/g. The MWCNT with Ru electrode - LATP electrolyte configuration demonstrates improved battery performance with 50-cycle life and low polarization of 1.3 V.

Aliovalent dual element co-assisted strategy to enhance ionic conductivity and stability of NASICON-type solid electrolyte for all-solid-state sodium batteries

The urgent need for high-performance sodium batteries has drawn great attention to the development of novel solid-state electrolyte systems. However, it is still a great challenge to obtain excellent ionic conductivity and interfacial stability performance for most solid-state electrolytes. In this study, a new NASICON-type solid-state electrolyte Na3.1+xZr2−xScxSi2.1P0.9O12 (donated as NZSSP, x = 0, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3) was successfully prepared by solid-phase method. Due to the aliovalent substitution of Sc3+/Si4+, the phase transition or unwanted rhombohedral phase is effectively suppressed, the Na+ transport channel bottlenecks are greatly enlarged, and the concentration of Na+ is largely increased, giving rise to the significant improvement of the ionic conductivity and stability of NZSSP solid-state electrolyte. The Na3.35Zr1.75Sc0.25Si2.1P0.9O12 solid-state electrolyte has an ultra-high ionic conductivity of 4.92 mS cm−1 at room temperature. Meanwhile, it shows an excellent sodium plating/stripping stability by the optimization of the Na+ transport channel. The critical current density of the Na//Na3.35Zr1.75Sc0.25Si2.1P0.9O12//Na symmetric battery is achieved up to 1.0 mA cm−2, and it can stably cycle for nearly 3000 h at 0.1 mA cm−2 or 1000 h at 0.5 mA cm−2 at room temperature. A detailed analysis of these aliovalent dual element substitution samples has been performed, and the mechanism of the conductivity enhancement is discussed systematically. This study can provide a feasible method to improve the ionic conductivity and electrochemical stability of NZSP materials and paves a way for the application of all-solid-state sodium batteries.

Rechargeable Solid-State Na-Metal Battery Operating at -20 °C.

Achieving satisfactory performance for a solid-state Na-metal battery (SSNMB) with an inorganic solid electrolyte (SE), especially under freezing temperatures, poses a challenge for stabilizing a Na-metal anode. Herein, this challenge is addressed by utilizing a Natrium super ionic conductor (NASICON) NASICON-type solid electrolyte, enabling the operation of a rechargeable SSNMB over a wide temperature range from -20 to 45 °C. The interfacial resistance at the Na metal/SE interface is only 0.4 Ω cm2 at 45 °C and remains below 110 Ω cm2 even at -20 °C. Remarkably, long-term Na-metal plating/stripping cycles lasting over 2000h at -20 °C are achieved with minimal polarization voltages at 0.1mA cm-2 . Further analysis reveals the formation of a uniform Na3- x Cax PO4 interphase layer at the interface, which significantly contributes to the exceptional interfacial performance observed. By employing a Na3 V1.5 Al0.5 (PO4 )3 cathode, the full battery system demonstrates excellent adaptability to low temperatures, exhibiting a capacity of 80mA h g-1 at -20 °C over 50 cycles and retaining a capacity of 108 mAh g-1 (88.5% of the capacity at 45 °C) at 0 °C over 275 cycles. This research significantly reduces the temperature threshold for SSNMB operation and paves the way toward solid-state batteries suitable for all-season applications.

NASICON-based all-solid-state Na–ion batteries: A perspective on manufacturing via tape-casting process

On the background of the urgent demand to realize a decarbonized society, energy storage technology plays a key role in shifting from social activities founded on the combustion of fossil fuels to those based on renewable energy resources. Toward this end, global deployment of large-scale rechargeable batteries supplying electricity to power grids is imperative, which requires widespread commercialization of high-performance and safe batteries at a low price relying on abundant and ubiquitous source materials and a cost-efficient manufacturing process. Along this line, the trend of the battery research field is currently located at a turning point: “from Li–ion to Na–ion” and “from liquid to solid electrolyte.” From the viewpoints of the distinguished oxide solid electrolyte, Na superionic conductor (NASICON), and the long-standing progress in ceramic processing, Na–ion all-solid-state batteries (Na-ASSBs) based on NASICON and its derivatives show great promise to realize an innovative and sustainable society in the future. At this moment, however, Na-ASSBs face multifaceted and formidable challenges to overcome for practical usage, mostly relating to interfacial matters in terms of interparticle and interlayer contacts. Here, we overview the recent research progress in NASICON-based solid electrolytes (SEs) from the aspects of synthetic techniques and sintering aids, particularly focusing on the tape-casting process and glass additive. We also provide insights into how to prepare electrode layers and incorporate them with an SE layer into an ASSB cell via tape casting, with the prospect of a high-capacity multilayer-stacked ASSB analogous to the multilayer ceramic capacitors (MLCCs). In addition, the feasibility of a Na metal anode in conjunction with the NASICON-type SEs and the tape-casting process toward an MLCC-type cell configuration is discussed. In the last section, we propose our ideas about future research directions in relevant fields to achieve a breakthrough for Na-ASSBs based on NASICON.

Impact of sintering temperature and ascertaining hopping bottlenecks for ions in sodium superionic conducting electrolyte for sodium-ion batteries

Recently, sodium super-ionic conducting (NASICON) type solid electrolytes have gained attention for next generation batteries because of their high ionic conductivity, low cost, excellent chemical and electrochemical stability. Therefore, in the present study, NASICON-type solid electrolyte Na3Zr2Si2PO12 is synthesized by solution assisted-solid state reaction (SA-SSR) route. The electrolytes are sintered at three different temperatures, 1200 °C, 1250 °C and 1300 °C. The sintered electrolytes are characterized by various experimental techniques. The Rietveld refinement of X-ray diffraction pattern of prepared electrolytes revealed the monoclinic crystal structure. The 3-dimension hopping channel for sodium ion migration through triangular bottleneck area is identified. From complex impedance spectroscopy measurement, the highest bulk and grain boundary conductivity are found, ∼4.05mScm−1 and ∼0.31mScm−1, respectively, for the sample sintered at 1250 °C. The optimized electrolyte shows wide electrochemical stability (∼6.5 V) which is suitable for high voltage battery application. Using optimized electrolyte, sodium half-cell is fabricated with sodium metal as anode, and Na3V2P3O12 (NVP) as cathode. The assembled cell delivers maximum discharge capacity ∼101.6 and ∼84.5mAhg−1 at the current density 10 and 40mAg−1, respectively with good capacity retention (∼95.02%) upto 50 cycles.

A high-quality dataset construction method for text mining in materials science

Numerous data and knowledge generated and stored as text in peer-reviewed scientific literature are important for materials research and development. Although text mining can automatically explore this information, the barriers of acquiring high-quality textual data prevent its general application in materials science. Herein, we systematically analyze the issues of textual DATA QUALITY and related research from the perspectives of data quality and quantity. Following this, we propose a pipeline to construct high-quality datasets for text mining in materials science. In this pipeline, we utilize the traceable automatic acquisition scheme of literature to ensure the traceability of textual data. Then, a data processing method driven by downstream tasks is used to generate high-quality pre-annotated corpora conditioned on the characteristics of material texts. On this basis, we define a general annotation scheme derived from materials science tetrahedron to complete high-quality annotation. Finally, a conditional data augmentation model incorporating material domain knowledge (cDA-DK) is constructed to augment the data quantity. Experimental results on datasets with various material systems demonstrate that our method can effectively improve the accuracy of downstream models and the F1-score towards the named entity recognition task in NASICON-type solid electrolyte material reaches 84%. This study provides an important insight into the general application of text mining in materials science, and is expected to advance the material design and discovery driven by data and knowledge bidirectionally.

Microstructural and mechanical characterization of Na1+xHf2Si2.3P0.7O10.85+0.5x and Na1+xZr2P3-xSixO12 NASICON-type solid electrolytes

NASICON-type solid electrolytes are promising materials for novel solid-state-batteries aiming toward high energy densities. Na1+xHf2Si2.3P0.7O10.85+0.5x with varying sodium content as well as Sc- or Mg-doped and undoped Na1+xZr2P3-xSixO12 were synthesized by solution-assisted solid-state reaction. Microstructural and mechanical characteristics as well as conductivities were investigated. The electrochemical and microstructural properties of all studied materials appear to be highly affected by the sodium content glassy phase and secondary phase formation as well as bloating. The mechanical properties of the specimens depend mainly on microstructural characteristics. Our findings indicate improved mechanical behavior is achieved when bloating and secondary phase formation are inhibited. However, possible influences of glassy phase content on the material properties need to be further investigated.

Regulating Na/NASCION electrolyte interface chemistry for stable solid-state Na metal batteries at room temperature

It is critical for solid-state alkaline metal batteries to solve the issues of large interfacial resistance and poor interfacial stability between the alkaline metal anode and the solid electrolyte. We tune the interface chemistry between Na metal and a NASICON-type solid electrolyte by a facile Cu2+-ion doping method. It is demonstrated that the Cu2+-ion incorporation into Na3Zr2Si2PO12 (NZSP) significantly reduces the interfacial resistance (Rinter) and boosts the interfacial stability during charge/discharge cyles at 25 °C. The optimal Na3.4Zr1.8Cu0.2Si2PO12 (NZSP-0.2Cu) realizes an increased critical current density of 0.5 mA cm−2 and an impressively low Rinter value of 19 Ω cm2 at 25 °C, which is only 1/35 of the undoped one (665 Ω cm2). Moreover, the symmetrical Na|NZSP-0.2Cu|Na cell maintains steady Na plating/stripping cycles for as long as 1450 h under 0.2 mA cm−2, clearly indicating the desired chemical compatibility at the Na metal anode interface. A self-formed dynamically stable Cu3PO4-dominant interphase layer at the Na metal/NZSP-0.2Cu interface is verified to explain for the outstanding interfacial performance. Furthermore, a room-temperature solid-state NaCrO2|NZSP-0.2Cu|Na metal battery is assembled, exhibiting excellent cycling performance at 5 C for 660 cycles with a capacity retention of 86.5% and an overall Coulombic efficiency of 99.5%.

Effect of TeO2 sintering aid on the microstructure and electrical properties of Li1.3Al0.3Ti1.7(PO4)3 solid electrolyte

NASICON-type solid electrolyte Li1.3Al0.3Ti1.7(PO4)3 (LATP) has become an excellent substitute for organic liquid electrolytes due to its high ionic conductivity and exceptional air stability. However, its application is limited by its poor sintering characteristics and high grain boundary resistance. In this study, TeO2 was introduced into LATP as a sintering aid to promote its sintering, and its properties were measured by XRD, SEM, XPS, EIS and dilatometry. The results show that the addition of TeO2 can form eutectic liquid phase in LATP ceramic pellets during sintering, thus effectively promoting particle sintering. Not only the grain size was greatly increased, but also grain boundary and pore defects were reduced. With the help of TeO2, the performance of LATP is greatly improved when sintered at only 750 °C, the relative density and total ionic conductivity reached 90.64% and 0.207 mS/cm, respectively. The highest total ionic conductivity of 0.279 mS/cm and the highest relative density of 93.81% were obtained when sintered at 800 ℃ and 950 ℃, respectively. However, due to the volatilization of Li and Te at high temperature, the relative density and total ionic conductivity of LATP with TeO2 added sintered at high temperature have only a small increase compared to that without addition. In conclusion, this study provides a feasible scheme for improving LATP performance.

Effect of cobalt addition to NASICON-type Li1.3Al0.3Ti1.7(PO4)3 (LATP) on its sintering behavior and electrical properties

Co ions as a sintering aid were electrostatically adsorbed on the surface of negatively-charged NASICON-type solid electrolyte Li1.3Al0.3Ti1.7(PO4)3 (LATP) particles using cobalt nitrate hexahydrate in an ethanol solvent. The Co element-modified LATP (Co-LATP) showed the maximum relative density of 80% at the firing temperature of 800 °C. This value was comparable to the relative density of LATP with no Co addition fired at 1000 °C. It was observed that the addition of Co promoted neck growth between the LATP particles. During the heating process, the cobalt ions diffuse into the LATP and form a reaction phase, such as LiCoPO4 (LCP), on the surface of the LATP. The electrical conductivity of Co-LATP fired at 800 °C increased from the Co addition amount of 0.0 to 0.5 wt%, demonstrating that the addition of cobalt contributed to the increase in the conductivity. The addition of an appropriate amount of Co ions to the LATP is effective in order to decrease the process temperature and increase the conductivity.