All-solid-state Lithium-ion Batteries Research Articles

Regulating Ceramic-Polymer Interphase in Composite Solid Electrolytes

Exhibiting satisfactory safety and high energy density, all-solid-state lithium-ion batteries (ASSLBs) is considered as the next-generation energy storage device for green power. Composite solid electrolytes (CSEs) consisting of polymer matrix and active inorganic fillers have shown great potential for practical applications owing to desirable mechanical properties and improved ionic conductivity. However, mechanisms of how different active fillers enhance the ion transport in CSEs still remain inconclusive and comprehensive properties of CSEs need to be improved to meet the demand for high-performance ASSLBs. Our work focuses on the mechanism of Li ion transportation in CSEs and the interaction among polymer matrix, inorganic active fillers and Li-salts. Further, the specific insights into the improving mechanism are applied to the design of CSEs with ideal overall performance.First, NASICON-type (LATP) and garnet-type (LLZTO) inorganic solid electrolytes are utilized as active fillers to incorporate with poly (ethylene oxide) PEO matrix. The experimental and computational results shown that the high affinity between LATP and PEO facilitates unhindered interfacial Li+ transfer, so that LATP functions as bulk-active filler to provide additional inorganic ion pathway. Instead, anion-trapping LLZTO mainly improves the ion conductivity by dissociating lithium salt, making it an interface-active filler. Therefore, the as-prepared PEO-LATP CSEs achieve the highest ion conductivity with medium filler content (50wt%) due to the well-built synergistic ion transport tunnels. By contrast, PEO-LLZTO peak at low filler content (10wt%) attributed to the maximized interfacial interactions.Next, based on the above findings, surface defects are introduced to interface-active LLZTO to not only enhance the anion-trapping effect, but also serve as anchoring points for polymer chains, forming a firmly bonded polymer-ceramic interface. The as-prepared OV-LLZTO/PEO composite exhibits high mechanical strength, reduced interfacial resistance with electrodes as well as improved Li+ conductivity.Further, Li-salt combination in CESs is optimized to improve the electrode compatibility for higher energy density. With the interaction of interface-active LLZTO and main lithium salt, functional additive has access to more preferable coordination. As a result, robust inorganic-rich electrode/electrolyte interface with high ionic conductivity can be synergistically constructed. More importantly, stable and fast ion transport network is built inside the high-volt LCO cathode, thus high rate performance and high capacity retentions achieved in Li|PEO-LLZTO|LCO cells with charging cut-off of 4.2 V.To summarize, we have first revealed ion conduction mechanisms in CSEs, then optimization approaches such as surface defects introduction on the active fillers and Li-salt modification are employed to improve the critical properties of CSE (e.g. ionic conductivity, mechanical strength, interfacial contact and interfacial stability between electrode and electrolyte). These works jointly point out a new principle for the design of high-performance CSEs via regulating the ceramic-polymer interphases. Figure 1

Analysis of Ni-Rich Cathode Composite Electrode Performance According to the Conductive Additive Distribution for Application in Sulfide All-Solid-State Lithium-Ion Batteries

All-solid-state lithium-ion batteries (ASSLBs) represent a promising breakthrough in battery technology owing to their high energy density and exceptional stability. When crafting cathode electrodes for ASSLBs, the solid electrolyte/cathode material interface is physically hindered by the specific morphology of carbon additive materials. In this paper, we examine the distribution of conductive additives within the electrode and its impact on the electrochemical performance of composites incorporating either nano-sized carbon black (CB) or micron-sized carbon nanofibers (CNF) into Ni-rich (LiNi0.8Co0.1Mn0.1O2) cathode material based composites. When nano-sized CB is employed as a conductive additive, it enhances the electrical conductivity of the composite by adopting a uniform distribution. However, its positioning between the solid electrolyte and cathode material leads to an increase in interfacial resistance during charge and discharge cycles, resulting in decreased electrochemical performance. In contrast, using micron-sized CNF as a conductive additive results in a reduction in the composite’s electrical conductivity compared to CB. Nevertheless, due to the comparatively uninterrupted interfaces between the solid electrolyte and cathode materials, it exhibits superior electrochemical characteristics. Our findings are expected to aid the fabrication of electrochemical-enhanced cathode composite electrodes for ASSLBs.

Reducing Gases Triggered Cathode Surface Reconstruction for Stable Cathode-Electrolyte Interface in Practical All-Solid-State Lithium Batteries.

The interfacial compatibility between cathodes and sulfide solid-electrolytes (SEs) is a critical limiting factor of electrochemical performance in all-solid-state lithium-ion batteries (ASSLBs). This work presents a gas-solid interface reduction reaction (GSIRR), aiming to mitigate the reactivity of surface oxygen by inducing a surface reconstruction layer (SRL) . The application of a SRL, CoO/Li2 CO3 , onto LiCoO2 (LCO) cathode results in impressive outcomes, including high capacity (149.7 mAh g-1 ), remarkable cyclability (retention of 84.63% over 400 cycles at 0.2 C), outstanding rate capability (86.1 mAh g-1 at 2 C), and exceptional stability in high-loading cathode (28.97 and 23.45mg cm-2 ) within ASSLBs. Furthermore, the SRL CoO/Li2 CO3 enhances the interfacial stability between LCO and Li10 GeP2 S12 as well as Li3 PS4 SEs. Significantly, the experiments suggest that the GSIRR mechanism can be broadly applied, not only to LCO cathodes but also to LiNi0.8 Co0.1 Mn0.1 O2 cathodes and other reducing gases such as H2 S and CO, indicating its practical universality. This study highlights the significant influence of the surface chemistry of the oxide cathode on interfacial compatibility, and introduces a surface reconstruction strategy based on the GSIRR process as a promising avenue for designing enhanced ASSLBs.

The Effect of Conductive Additive Morphology and Crystallinity on the Electrochemical Performance of Ni-Rich Cathodes for Sulfide All-Solid-State Lithium-Ion Batteries

Sulfide electrolyte all-solid-state lithium-ion batteries (ASSLBs) that have inherently nonflammable properties have improved greatly over the past decade. However, determining both the stable and functional electrode components to pair with these solid electrolytes requires significant investigation. Solid electrolyte comprises 20–40% of the composite cathode electrode, which improves the ionic conductivity. However, this results in thick electrolyte that blocks the electron pathways in the electrode, significantly lowering the electrochemical performance. The application of conductive carbon material is required to overcome this issue, and, hence, determining the carbon properties that result in the most stable performance in the sulfide solid electrolyte is vital. This study analyzes the effect of the cathode conductive additive’s morphology on the electrochemical performance of sulfide electrolyte-based ASSLBs. Carbon black (CB) and carbon nanotubes (CNTs), which provide electron pathways at the nanoscale and sub-micron scale, and carbon nanofiber (CNF), which provides electron pathways at the tens-of-microns scale, are all tested individually as potential conductive additives. When the CNF, with its high crystallinity, is used as a conductive material, the electrochemical performance shows an excellent initial discharge capacity of 191.78 mAh/g and a 50-cycle capacity retention of 83.9%. Conversely, the CB and the CNTs, with their shorter pathways and significantly increased surface area, show a relatively low electrochemical performance. By using the CNF to provide excellent electrical conductivity to the electrode, the polarization is suppressed. Furthermore, the interfacial impedance across the charge transfer region is also reduced over 50 cycles compared with the CB and CNT composite cells. These findings stringently analyze and emphasize the importance of the morphology of the carbon conductive additives in the ASSLB cathode electrodes, with improvements in the electrochemical performance being realized through the application of long-form two-dimensional crystalline CNFs.

Electrothermal model of all‐solid‐state lithium battery with composite solid‐state electrolyte

AbstractFor secondary batteries, thermal runaway has become the main issue, and how to solve it is full of challenges. In this work, a universal thermal model for lithium ion batteries (LIBs) was proposed, which was validated by using commercially available 18650 batteries as well as testing the electrochemical parameters of a Poly(ethylene oxide)(PEO)–bis(trifluoromethane)sulfonimide lithium salt(LiTFSI)–Li2MnO3(LMO) (PLL) composite solid‐state electrolyte (CSSE), while a computational model was developed for all‐solid‐state LIBs (ASSLIBs) based on PLL CSSE. The simulation results show that the maximum temperature of ASSLIBs based on PLL CSSE and commercial standards are both significantly lower than the thermal runaway temperature of solid‐state electrolyte. However, as the temperature of the battery varies greatly under different operating conditions, it will cause great difficulties in the control of other ancillary components and even finally lead to certain safety issues. Therefore, from the perspective of performance and practical application, the CSSE should be improved toward improving the ionic conductivity at low temperatures to have more commercial prospects, and lower interfacial impedance and a higher lithium ion migration number would also be beneficial for optimizing the thermal behavior of ASSLIBs to achieve better commercial prospects.

In Situ and Low-Cost Improvement of the Lithium Anode Interface in Garnet-Type Solid-State Electrolytes.

In recent years, the development of electric vehicles and environmental concerns have made necessary improvements in the energy density and safety of lithium-ion batteries. Therefore, the development of all-solid-state lithium-ion batteries (ASSLIBs) has become imperative. One advantage of ASSLIBs is their potential for downsizing with the use of lithium metal as the anode. However, in this study, a garnet-type solid electrolyte (Li6.75La3Zr1.75Ta0.25O12) was used, which has low reactivity with lithium metal. Thus, interface modification using CaCl2 was employed to form a Li-Ca-Cl composite anode. The interfacial resistance was remarkably reduced to 7 Ω cm2, and the symmetric cell exhibited stable cycling for 1200 h at room temperature and a current density of 0.1 mA cm-2. The voltage ranged from ±15 to ±16 mV. The full cell demonstrated a high initial discharge capacity of 149.2 mA h g-1 and a Coulombic efficiency of 98.0% while maintaining a discharge capacity retention of 91.3% after 100 cycles. These findings lay a solid foundation for future commercial applications as interface modification was achieved through a simple spin-coating process using low-cost CaCl2 (0.7 USD g-1).

Enhanced electrochemistry stability of oxygen doped Li6PS5Cl argyrodite solid electrolyte by liquid-phase synthesis

The argyrodite solid electrolyte Li6PS5Cl is one of the promising candidates due to its high Li-ion conductivity for the application of all-solid-state lithium-ion batteries (ASSLIBs). Unfortunately, Li6PS5Cl argyrodite exhibits low stability against lithium metal anodes and oxide cathodes. One way to improve stability is by oxygen doping into Li6PS5Cl argyrodite. In this work, Li6PS5–2.5xO2.5xCl (x = 0, 0.05, and 0.10) solid electrolytes with oxygen doping were successfully synthesized using liquid-phase synthesis for the first time. Therefore, the solid electrolyte with x = 0.05 exhibits high ionic conductivity with enhanced electrochemical stability against lithium metal and oxide cathodes. Argyrodites with x = 0.05 and x = 0.10 show superior capacity retention and higher Coulomb efficiency compared to x = 0. Moreover, the solid electrolytes also demonstrate better stability during Li symmetrical cell measurements. This experiment provides a controllable amount of oxygen doping into the Li6PS5Cl argyrodite solid electrolyte system in order to achieve high performance of ASSLIBs through liquid-phase synthesis.

Motif-Based Exploration of Halide Classes of Li5M10.5M20.5X8 Conductors Using the DFT Method: Toward High Li-Ion Conductivity and Improved Stability.

The development of all-solid-state lithium-ion batteries (ASSLIBs) is highly dependent on solid-state electrolyte (SSEs) performance. However, current SSEs cannot satisfactorily meet the requirements for high interfacial stability and Li-ion conductivity, especially under high-voltage cycling conditions. To overcome the intractable problems, we theoretically develop the chemistry of structural units to build a series of MX6-unit mixed framework Li5M10.5M20.5X8 (total 184 halides) for use as SSEs and recommend six halide candidates that combine the (electro)chemical stability with a low Li-ion migration barrier. Among them, three Li5M10.5M20.5F8 compounds (M1 = Ca and Mg; M2 = Ti and Zr) exhibit expansive electrochemical windows with a high cathodic limit (6.3 V vs μLi) and three-dimensional Li diffusion associated with moderate Li-migration barriers. To discuss their stability and compatibility (and in turn as a reference for experiments), the energy above the convex hull, the electrochemical stability window, the predicted (electro)reaction products, and the calculated reaction energies of Li5M10.5M20.5X8 in combination with Li-metal and several cathodes are tabulated. We stress that the importance of the cation-mixed effect and specific moieties for the halide anion leads to a design principle for a halide class of Li-ion SSEs. We provide insight into selecting the optimal halide anion and cations and open a new avenue of broad compositional spaces for stable Li-ion SSEs.

Composite Solid Electrolyte Composed of 3D Ceramic Ion Transport Channel and in-Situ Formed Polymer Matrix

Rechargeable lithium-ion batteries (LIBs) with high energy density and excellent cycling performance have been widely used as portable power supplies for consumer electronics. In recent years, LIBs have expanded their applications to electric vehicles (EVs) and large energy storage systems (ESSs). Existing LIBs use liquid electrolytes, which have safety issues such as inflammability, leakage, and explosion. All-solid-state lithium-ion batteries (ASSLIBs) using various solid electrolytes, such as inorganic electrolytes and polymer electrolytes, have been extensively studied to alleviate safety issues and improve energy density. In addition, composite solid electrolytes (CSEs), which combine the advantages of ceramic and polymer electrolytes, are of particular interest. However, CSE based on a polymer matrix has low ionic conductivity at room temperature, making it difficult to use as an electrolyte for high-performance ASSLIB. In this study, we designed a highly efficient 3D LAGP framework for lithium ion transport that enhances the overall conductivity of CSE. This stiffer 3D LAGP structure also inhibits the growth of Li dendrites. The polymer component of CSE is manufactured using thermal polymerization of vinyl ethylene carbonate (VEC). In addition, excellent electrode-electrolyte interface properties were achieved using in-situ thermal polymerization technology. The optimized CSE exhibited high ionic conductivity of 0.79 mS cm-1 and excellent potential stability up to 5.09 V vs. Li/Li+ at 30 °C. The Li/CSE/NCM811 cells showed excellent rate performance and cycling potential. Therefore, a CSE composed of a 3D LAGP framework and a VEC-based polymer can be used as a potential electrolyte for ASSLIBs.

(Best Student Presentation) The Synthesis of Zr-Doped Li3-Xin1-XZrxCl6 with Ultrahigh Ionic Conductivity for All Solid State Lithium-Ion Batteries

All-solid-state lithium-ion batteries (ASSLBs) are an important milestone for the future of energy storage because of their capability of impressive energy density and outstanding safety. However, oxide and sulfide solid-state electrolytes (SSEs) suffer from either low ionic conductivity or poor chemical stability. In contrast, halide-based SSEs, are promising as candidate materials owing to high conductivity, good stability, and broad cathode compatibility. Element doping is an effective and common approach to further improve the electrochemical properties of SSEs. For this aspect, a serious of Li3-xIn1-xZrxCl6 were synthesised to explore the influences of zircounium dopant on Li3InCl6 . The synthesized Li2.75In0.75Zr0.25Cl6 exhibited Li ionic conductivity of 5.82 × 10–3 S·cm–1 at room temperature, which is the highest among reported halide SSEs. The ASSLB formed with Li2CoO2-Li2.75In0.75Zr0.25Cl6-Li/In delivers a high initial capacity of 129.3 mAh·g-1. Conclusively, this work provides an effective approach for the development of halide SSEs with improved stability and conductivity. The compelling results provide further possibilities and capabilities in future SSE research.

Investigation of Sulfide-Based Solid Electrolytes (SSE) Sensitivity Towards Humidity

All-solid-state lithium-ion batteries (ASSBs) represent a new generation of energy storage tools containing only solid components. They are of great interest to researchers and manufacturers thanks to their high energy density, which makes them promising candidates for electric transport applications. Among different types of solid-state electrolytes for lithium-ion batteries (LIBs), sulfide-based electrolytes (SSEs) have several advantages, such as high ionic conductivity and malleability [1, 2]. However, one of their main drawbacks is a high sensitivity towards air humidity [3]. Fast reaction of the SSEs with water results in the degradation of their structure and release of toxic gas (H2S) when exposed to even low concentrations of humidity. This factor leads to significant process cost and safety issues associated with mass production of ASSBs with sulfide-based SEs.The purpose of the present work is to study in details reactivity of SSEs towards humidity by following two main directions: The development of a flow-through setup that allows a better identification and highly precise quantification of gases (H2S or others) generated during reaction between water (humidity) and commercial SSEs: this flow-through setup intends to solve problems usually encountered when using closed-type setups, which are the most used setups in the literature[3, 4]. These problems include over-concentration of detected gases and low reproducibility of measurements;Physico-chemical and electrochemical characterizations of pristine and humidity exposed-SSEs in order to reveal the main factors affecting sensitivity towards humidity and to understand the degradation mechanisms. First, the efficiency of the flow-through gas analysis setup developed had been validated: H2S detection curves obtained for commercial SSE powders (Li6PS5Cl, Li6PS5Br, Li7P3S11, Li3PS4, Li10GeP2S12) in contact with humid Argon (30 to 200 ppm H2O in Ar) are highly reproducible (see example in Fig. 1 and Table 1). Measurements conducted at different humidity levels allowed accessing kinetics of water-induced degradation reactions involved. SSE powders characterizations using XRD, Raman, XPS, SEM, EIS, granulometry before and after exposure to humidity provided an insight into degradation-related phenomena taking place: morphology deterioration, loss of structure and conductive structural groups, drastic increase of ionic resistance. A relationship between the structure of SSE and its reactivity towards water was found and described.Refs[1] Energy Storage Mater. 2018, 14, 58–74 ; [2] Nano Energy 2021, 83, 105858 ; [3] Solid State Ion. 2011, 182 (1), 116–119 ; [4] Chem. Mater. 2020, 32 (6), 2664–2672. Figure 1

Operando Hard X-Ray Photoelectron Spectroscopy for Observing Interfacial Electrochemical Reactions in All-Solid-State Batteries

All-solid-state lithium-ion batteries (ASS-LIBs) have been attracting wide attention for their potential superior performance, such as high safety and long cycle life compared with the conventional lithium-ion batteries with liquid organic electrolytes. However, one of the critical problems of the ASS-LIBs for wide spread applications, especially for electric vehicles, is the large interfacial resistance across the electrode/solid electrolyte (SE)1. When an electrode and SE come into contact, some mobile ions are redistributed at the interface according to their potential difference2,3. In addition, the distribution of the mobile ions and electric potential are also changed during the battery operations. Therefore, dynamic observation of their distribution across the electrode/SE interface is essential to identify and control the origin of the interfacial resistance.Hard x-ray photoelectron spectroscopy (HAXPES) is capable of nondestructive analysis of the elemental composition, oxidation states and electronic structure of sample surfaces and interfaces including those buried with over layers at depth > 10 nm[4].In this study, we developed a laboratory-based operando HAXPES system equipped with a Cr-Kα source (5414.9 eV), which enables angle-resolved measurements of and bias applications to the sample transferred without air-exposure, and applied it to the charging/discharging reactions of a LiCoO2 (LCO) positive electrode deposited on a Li6.6La3Zr1.6Ta0.4O12 (LLZT) solid electrolyte in a half cell configuration. HAXPES measurements were performed while the LCO electrode was electrically grounded to a hemispherical analyzer.The galvanostatic charge/discharge potential profiles exhibited a characteristic plateau due to delithiation of a O3-LiCoO2 at ~3.9 V vs. Li+/Li5. In the Co 2p 3/2 region of the pristine cell, a sharp intense main peak and a broad satellite peak typical to a LCO were observed. At the charged states, however, the main peak was asymmetrically broadened to the higher binding energy. The main peak was deconvoluted into two peaks at 780 eV and ~781 eV, corresponding to Co3+ ions and Co4+ ions, respectively. The full width half maximums (FWHMs) of the Co4+ ions peak increased at charged states, while that of the Co3+ ions peak was remained unchanged. Furthermore, the relative areas of satellite peak decreased at the charged states. These results suggest that Co3+ ions were oxidized to the Co4+ ions by delithiation of the LCO electrode6,7. After the subsequent discharging, the component of higher binding energy of the main peaks decreased, and the satellite peak increased. In addition, the FWHMs of the Co4+ ions peak decreased, suggesting that the Co4+ ions were reduced by lithiation into the LCO electrode during discharging. Thus, the lithiation/delithiation of LCO was successfully observed by operando HAXPES.References N. Ohta, K. Takada, L. Zhang, R. Ma, M. Osada and T. Sasaki, Advanced Materials, 18, 2226 (2006) K. Yamamoto, Y. Iriyama, T. Asaka, T. Hirayama, H. Fujita, C. A. Fisher, K. Nonaka, Y. Sugita and Z. Ogumi, Angew Chem Int Ed Engl, 49, 4414 (2010) J. Haruyama, K. Sodeyama, L. Han, K. Takada and Y. Tateyama, Chemistry of Materials, 26, 4248 (2014) N. K. F. Curran Kalha, Prajna Bhatt, et al., Journal of Physics: Condensed Matter, 33, 233001 (2021) J. N. Reimers and J. R. Dahn, The Electrochemical Society, 139, 2091 (1992) L. Dahéron, R. Dedryvère, H. Martinez, M. Ménétrier, C. Denage, C. Delmas and D. Gonbeau, Chemistry of Materials (2008) H. Kiuchi, K. Hikima, K. Shimizu, R. Kanno, F. Toshiharu and E. Matsubara, Electrochemistry Communications, 118, 106790 (2020)

Nano Silicon Anode without Electrolyte Adding for Sulfide-Based All-Solid-State Lithium-Ion Batteries.

All-solid-state lithium-ion batteries (ASSLBs) employing silicon (Si) anode and sulfide electrolyte attract much attention, since they can achieve both high energy density and safety. For large-scale application, sheet-type Si anode matching sulfide based ASSLBs is preferred. Here, a LiAlO2 layer coated Si (Si@LiAlO2 ) is reported for sheet-type electrode. This electrode employs conventional slurry coating methods without adding any sulfide electrolyte. The effect of LiAlO2 coating on the electrochemical performance and morphology evolution of Si electrode is investigated. Since the high mechanical strength and ionic conductivity of LiAlO2 layer can sufficiently relieve the huge expansion of Si and promote the Li+ diffusion, the electrochemical performance is significantly enhanced. The Si@LiAlO2 electrodes deliver high coulombic efficiency exceeding 80% and hold considerable specific capacity of 1205mAhg-1 (150cycles, 0.33C). The Si@LiAlO2 | LiNi0.83 Co0.11 Mn0.06 O2 full-cells exhibit a high reversible capacity of 147mAhg-1 (0.28mAcm-2 ) and a considerable capacity retention of 80.2% (62cycles, 2.8mAcm-2 ). This work demonstrates promising practicability and provides a new route for the scalable preparation of Si electrode sheets for ASSLBs with extended lifespan.

One dimensional CeO2 nanorods/poly(ethylene oxide) solid composite electrolyte for all-solid-state lithium-ion batteries

The research of poly(ethylene oxide) (PEO)-based solid composite electrolyte with high ionic conductivity and excellent interfacial stability is the key to the development of all-solid-state lithium-ion batteries (ASSLIBs). Herein, uniform nanorod structured CeO2 fillers were controllably synthesized by electrospinning, which were subsequently filled into PEO polymer to prepare CeO2/PEO solid composite electrolyte. The addition of CeO2 nanorods can reduce both the glass transition temperature and the melting point of PEO polymer, and also interact with PEO and lithium bis(trifluoromethanesulphonyl)imide (LITFSI) by Lewis acid–base reaction. Therefore, the solid composite electrolyte exhibits a high ionic conductivity of 4.52 × 10−4 S/cm, a wide electrochemical stability window of about 4.8 V, and a good interfacial stability with Li at 55 °C. Moreover, the LiFePO4/Li ASSLIB divulges the discharging specific capacity of 165, 162, 156 and 146 mA⋅h/g at 0.2, 0.5, 1 and 2 C, respectively, and achieves the capacity retention of 90.3% after 150 cycles at 0.5 C. Consequently, one dimensional CeO2 nanorods can be considered as an alternative filler for polymeric solid electrolyte.

Origin of the Seriously Limited Anionic Redox Reaction of Li-Rich Cathodes in Sulfide All-Solid-State Batteries.

Li-rich layered oxide (LLO) cathode materials with mixed cationic and anionic redox reactions display much higher specific capacity than other traditional layered oxide materials. However, the practical specific capacity of LLO during the first cycle in sulfide all-solid-state lithium-ion batteries (ASSLBs) is extremely low. Herein, the capacity contribution of each redox reaction in LLO during the first charging process is qualitatively and quantitatively analyzed by comprehensive electrochemical and structural measurements. The results demonstrate that the cationic redox of the LiTMO2 (TM = Ni, Co, Mn) phase is almost complete, while the anionic redox of the Li2MnO3 phase is seriously limited due to the sluggish transport kinetics and severe LLO/Li6PS5Cl interface reaction at high voltage. Therefore, the poor intrinsic conductivity and interface stability during the anionic redox jointly restrict the capacity release or delithiation/lithiation degree of LLO during the first cycle in sulfide ASSLBs. This study reveals the origin of the seriously limited anionic redox reaction in LLO, providing valuable guidance for the bulk and interface design of high-energy-density ASSLBs.

Composition, structure and electrochemical performance of LiSiPSCl electrolyte with Li/Li-In anodes in all-solid-state batteries

The lithium silicon phosphor sulfo-chloride (LiSiPSCl) with a Li10GeP2S12-type structure is one of the most promising solid electrolytes (SEs) for all-solid-state lithium-ion batteries (ASSLIBs) due to its currently highest ionic conductivity at RT. In this work, three kinds of LiSiPSCl electrolytes, i.e. Li7.59(10)Si1.95(9)P1.65(7)S11.64(1)Cl0.36(1) (SE-450), Li7.67(12)Si1.90(1)P1.67(1)S11.61(2)Cl0.39(2) (SE-475) and Li7.58(5)Si1.75(4)P1.79(2)S11.54(4)Cl0.46(4) (SE-500), were prepared at 450 / 475 / 500 °C for 8 h through a solid-state method. The assembling of blocking / symmetrical / semi-blocking cells and ASSLIBs, and electrochemical measurements were carried out by coupling the three SEs with two kinds of anodes (Li metal and Li-In alloy) and one cathode of LiNbO3-coated LiNi0.8Co0.1Mn0.1O2 (NCM@LNO). Studies were focused on the relationship among chemical compositions, phase structures and electrochemical properties, as well as the electrolyte/electrode interfacial stability. Results show that LiSiPSCl electrolytes had favorable interfacial stability with Li-In anode and exhibited low polarization voltage (< 20 mV) and decomposition current (< 0.01 mA). The optimized NCM@LNO//SE-475//Li-In of ASSLIBs exhibited a stable long-term cycle performance with a capacity retention of 97.0% (128.4 mAh g−1) after 50 cycles and 81.1% (107.4 mAh g−1) after 100 cycles at 0.1 C. In addition, it exhibited a good rate performance while its capacity retention remained 99.3% (140.6 mAh g−1) after 39 cycles at 0.05 / 0.1 / 0.2 / 0.5 / 0.05 C.

Assembly of an elastic & sticky interfacial layer for sulfide-based all-solid-state batteries

All-solid-state lithium-ion batteries (ASSLBs) have recently attracted significant attention, however, two major degradation processes at the composite cathode interface in ASSLBs, including side electro-chemical reactions and morphological/structural degradation, still hinder their development seriously. To overcome the above two challenges simultaneously, we propose and demonstrate a successful assembly of an elastic & sticky interfacial layer for ASSLBs by using advanced molecular layer deposition (MLD) technique. Our spectroscopic and mechanical characterization results show that the elastic and sticky Al-GL coating layer (Young’s modulus = 0.17 GPa, k = 3.300 N m−1) not only suppresses interfacial side reactions, but also enables single-crystal NCM811 particles to be in close contact with the sulfide electrolyte tightly during repeated cycles. Compared to the irreversible interfacial resistance (51.74 Ω cm−2) formed between bare NCM811 and solid electrolyte during the initial charge progress, the irreversible resistance becomes much less (11.77 Ω cm−2) after Al-GL modification. Therefore, it not only shows a capacity retention of 88.0% of the composite electrode, which is nearly 30 % higher than bare NCM811 (59.9 %) for 100 cycles at 0.2 C (1 C = 180 mA g−1) with a mass loading of 10.2 mg cm−2 at 30 °C. Furthermore, even with a mass loading of 20.4 mg cm−2 at 60 °C, the capacity retention of 80.0% is obtained after 1000 cycles at 1 C. This work highlights the critical role of elastic and sticky coatings in maintaining the electrochemical-mechanical integrity of composite cathode materials and provides a promising avenue for developing mechanically reliable cathode materials for ASSLBs.

Chemical speciation changes of an all-solid-state lithium-ion battery caused by roasting determined by sequential acid leaching

All-solid-state lithium-ion batteries (ASS-LIBs) are expected to replace current liquid-based LIBs in the near future owing to their high energy density and improved safety. It would be preferable if ASS-LIBs could be recycled by the current recycling processes used for liquid-based LIBs, but this possibility remains to be determined. Here, we subjected an ASS-LIB test cell containing an argyrodite-type solid electrolyte (Li6PS5Cl) and nickel–manganese–cobalt-type active material (Li(Ni0.5Mn0.3Co0.2)O2) to roasting, a treatment process commonly used for recycling of the valuable metals from liquid-based LIBs, and investigated the changes in chemical speciation. Roasting was performed at various temperatures (350–900 °C), for various times (60–360 min), and under various oxygen fugacity (air or O2) conditions. The chemical speciation of each metal element after roasting was determined by sequential elemental leaching tests and X-ray diffraction analysis. Li formed sulfates or phosphates over a wide temperature range. Ni and Co followed very complicated reaction paths owing to coexistence of S, P, and C, and they formed sulfides, phosphates, and complex oxides. The optimum conditions for minimizing formation of insoluble compounds, such as complex oxides, were a roasting temperature of 450–500 °C and a roasting time of 120 min. The results indicated that although ASS-LIBs can be treated by the same roasting processes as those used for current liquid-based LIBs, the optimal roasting conditions have narrow ranges. Thus, careful process control will be needed to achieve high extraction percentages of the valuable metals from ASS-LIBs.

Thermal Decomposition Assisted Construction of Nano-Li3 N Sites Interface Layer Enabling Homogeneous Li Deposition.

Lithium (Li) metal is a highly desirable anode for all-solid-state lithium-ion batteries (ASSLBs) due to its high theoretical capacity and being well matched with solid-state electrolytes. However, the practical applications of Li metal anode are hindered by the uneven Li metal plating/stripping behavior and poor contact between electrolyte and Li anode. Herein, a convenient and efficient strategy to construct the Li3 N-based interlayer between solid poly(ethylene oxide) (PEO) electrolyte and Li anode is proposed by in situ thermal decomposition of 2,2'-azobisisobutyronitrile (AIBN) additive. The evolved Li3 N nanoparticles are capable of combining LiF, cyano derivatives and PEO electrolyte to form a buffer layer of about 0.9 μm during the cell cycle, which can buffer Li+ concentration and homogenize Li deposition. The Li||Li symmetric cells with Li3 N-based interlayer show excellent cycle stability at 0.2 mA cm-2 , which is at least 4 times longer cycle life than that of PEO electrolytes without Li3 N layer. This work provides a convenient strategy for designing interface engineering between solid-state polymer electrolyte and Li anode.

Exploring the Possibility of Machine Learning for Predicting Ionic Conductivity of Solid-State Electrolytes.

Unlike conventional liquid electrolytes, solid-state electrolytes (SSEs) have gained increased attention in the domain of all-solid-state lithium-ion batteries (ASSBs) due to their safety features, higher energy/power density, better electrochemical stability, and a broader electrochemical window. SSEs, however, face several difficulties, such as poorer ionic conductivity, complicated interfaces, and unstable physical characteristics. Vast research is still needed to find compatible and appropriate SSEs with improved properties for ASSBs. Traditional trial-and-error procedures to find novel and sophisticated SSEs require vast resources and time. Machine learning (ML), which has emerged as an effective and trustworthy tool for screening new functional materials, was recently used to forecast new SSEs for ASSBs. In this study, we developed an ML-based architecture to predict ionic conductivity by utilizing the characteristics of activation energy, operating temperature, lattice parameters, and unit cell volume of various SSEs. Additionally, the feature set can identify distinct patterns in the data set that can be verified using a correlation map. Because they are more reliable, the ensemble-based predictor models can more precisely forecast ionic conductivity. The prediction can be strengthened even further, and the overfitting issue can be resolved by stacking numerous ensemble models. The data set was split into 70:30 ratios to train and test with eight predictor models. The maximum mean-squared error and mean absolute error in training and testing for the random forest regressor (RFR) model were obtained as 0.001 and 0.003, respectively.