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Among the solid electrolytes studied for all-solid-state sodium batteries (ASSBs), Na3SbS4 (NAS) appears particularly promising due to its unique combination of high ionic conductivity and compatib...

Accurate and reliable state of charge (SoC) estimation becomes increasingly important to provide a stable and efficient environment for Lithium-ion batteries (LiBs) powered devices. Most data-driven SoC models are built for a fixed ambient temperature, which neglect the high sensitivity of LiBs to temperature and may cause severe prediction errors. Nevertheless, a systematic evaluation of the impact of temperature on SoC estimation and ways for a prompt adjustment of the estimation model to new temperatures using limited data has been hardly discussed. To solve these challenges, a novel SoC estimation method is proposed by exploiting temporal dynamics of measurements and transferring consistent estimation ability among different temperatures. First, temporal dynamics, which is presented by correlations between the past fluctuation and the future motion, are extracted using canonical variate analysis. Next, two models, including a reference SoC estimation model and an estimation ability monitoring model, are developed with temporal dynamics. The monitoring model provides a path to quantitatively evaluate the influences of temperature on SoC estimation ability. After that, once the inability of the reference SoC estimation model is detected, consistent temporal dynamics between temperatures are selected for transfer learning. Finally, the efficacy of the proposed method is verified through a benchmark. Our proposed method not only reduces prediction errors at fixed temperatures (e.g., reduced by 24.35 $\%$ at –20 $^{\circ }$ C, 49.82 $\%$ at 25 $^{\circ }$ C) but also improves prediction accuracies at new temperatures.

Dendrite growth under large current density is the key intrinsic issue impeding a wider application of Li metal anodes. Previous studies mainly focused on avoiding dendrite growth by building an additional interface layer or surface modification. However, the mechanism and factors affecting dendrite growth for Li metal anodes are still unclear. Herein, we analyze the causes for dendrite growth, which leads us to suggest three-dimensional (3D) metal anodes as a promising approach to overcome the dendrite issues. A 3D composite Li anode was prepared from renewable carbonized wood doped with Sn to demonstrate its superior electrochemical performance compared with Li foils. The anode was cycled at various current densities from 0.1 to 10 mA cm-2 for five cycles at each current density, displaying low overpotential compared with conventional Li foils. Long galvanostatic cycling at 1 mA cm-2 for 1000 h and at 2 mA cm-2 for 500 h was achieved without dendrite growth. Further analysis reveals that the 3D structure facilitates surface diffusion by increasing the surface area from 5.23 × 10-3 m2 g-1 (Li foil) to 2.64 m2 g-1 and by creating nanoscale separation walls. The tin alloying effectively prevents non-uniform lithium plating by creating abundant nucleation centers. Additionally, suitable alloying elements for a wider range of 3D Li anodes have been identified from density functional theory calculations.

State-of-the-art oxides and sulfides with high Li-ion conductivity and good electrochemical stability are among the most promising candidates for solid-state electrolytes in secondary batteries. Yet emerging halides offer promising alternatives because of their intrinsic low Li+ migration energy barriers, high electrochemical oxidative stability, and beneficial mechanical properties. Mechanochemical synthesis has enabled the characterization of LiAlX4 compounds to be extended and the iodide, LiAlI4, to be synthesized for the first time (monoclinic P21/c, Z = 4; a = 8.0846(1) Å; b = 7.4369(1) Å; c = 14.8890(2) Å; β = 93.0457(8)°). Of the tetrahaloaluminates, LiAlBr4 exhibited the highest ionic conductivity at room temperature (0.033 mS cm–1), while LiAlCl4 showed a conductivity of 0.17 mS cm–1 at 333 K, coupled with the highest thermal and oxidative stability. Modeling of the diffusion pathways suggests that the Li-ion transport mechanism in each tetrahaloaluminate is closely related and mediated by both halide polarizability and concerted complex anion motions.

We introduce a family of ‘spatial’ random cycle Huang–Yang–Luttinger (HYL)-type models in which the counter-term only affects cycles longer than some cut-off that diverges in the thermodynamic limit. Here, spatial refers to the Poisson reference process of random cycle weights. We derive large deviation principles and explicit pressure expressions for these models, and use the zeroes of the rate functions to study Bose–Einstein condensation. The main focus is a large deviation analysis for the diverging counter term where we identify three different regimes depending on the scale of divergence with respect to the main large deviation scale. Our analysis derives explicit bounds in critical regimes using the Poisson nature of the random cycle distributions.

Solid-state fast ionic conductors are of great interest due to their application potential enabling the development of safer high-performance energy and conversion systems ranging from batteries th...

In this paper, we study various models for random combinatorial partitions using large deviation analysis for diverging scale of the reference process. Scaling limits of similar models have been studied recently \cite{FSa,FSb} going back to \cite{Ver96}. After studying the reference model, we provide a complete analysis of two mean field models, one of which is well-know \cite{BCMP05} and the other one is the cycle mean field model. Both models show critical behaviour despite their rate functions having unique minimiser. The main focus is then a model with negative counter term, the probabilistic version of the so-called \emph{Huang-Yang-Luttinger} (HYL) model \cite{BLP}. Criticality in this model is the existence of a critical parameter for which two simultaneous minimiser exists. At criticality an order parameter is introduced as the double limits for the density of cycles with diverging length, and as such it extends recent work \cite{AD21}., 40 pages, 7 figures, appendix with three parts. arXiv admin note: substantial text overlap with arXiv:1809.03387

The superior energy density renders hybrid Li-air batteries (HLABs) promising candidate energy storage systems to enhance the sustainability of power grids. Nevertheless, HLABs operated at ambient ...

Developing inexpensive, noble metal-free, efficient, stable, and bifunctional electrocatalysts has attracted significant research interest in electrocatalysis and air battery-based energy storage d...

Crystallisation, by which we mean the formation of solids precipitating from a solution, is the central theme of the present mini-workshop. Participants discussed different approaches towards a rigorous mathematical understanding of crystallisation as well as detecting, modelling and establishing properties of crystalline and quasicrystalline structures.

High density charge (energy) storage under supercapacitive mode requires an electrode which would deliver larger space for charge accumulation and offer larger electrochemical potential difference at an electrode–electrolyte interface. Porous carbon has been a preferred electrode for commercial supercapacitors; however, the charge storability is much lower to the state-of-the-art charge storage devices such as lithium ion batteries. We show that one of the primary limiting factors is the voids in porous carbon, which do not contribute to the capacitance as their sizes are much larger than the size of the solvated/unsolvated ions in the electrolyte. We activate these voids by filling them with a flower-shaped 3D hierarchical pseudocapacitive material (MnCo2O4) by assuming that flower-shaped fillers would provide additional easily accessible surface for charge adsorption. Less than 10wt.% MnCo2O4 in these voids through a simple wet impregnation results in five-fold increase in charge storability of porous carbon from palm kernel shells. Laboratory prototypes of electrochemical double layer capacitors are fabricated using the void-filled-carbon electrodes, which show five-fold higher specific energy than that of pure carbon and are cycled over 5000 times with >95% capacitance retention. The present strategy of activating the voids by hierarchical 3D nanostructures could be applied to build high performance energy storage devices.

The application of lithium metal anodes is hindered by safety issues originating from unwanted Li dendritic growth. To address this issue, designing 3D porous Cu current collectors is an effective strategy to modify Li deposition behaviour. However, known fabrication processes for these porous collectors are usually complicated, expensive and non-scalable. There is also lack of investigation into their mechanical strength, which is an important factor for practical applications. Herein, we develop a simple, low-cost and scalable process to fabricate a robust Cu porous framework via extrusion 3D-printing. The 3D-printed Cu framework (3DP-Cu) can well maintain as-built microchannels between filaments even under a high compressive pressure of ∼1.4 MPa, enabling it to host massive Li deposition, prevent Li dendrite growth and mitigate large volume changes during charging/discharging. Therefore, 3DP-Cu achieves a significantly high areal capacity of 20 mA h cm−2 with uniformly plated Li at a rate of 1 mA cm−2. Moreover, stable Li plating/stripping behaviour is obtained in symmetric cells even at a high rate of 10 mA cm−2, owing to the great ability to dissipate high local current densities efficiently by the porous network within filaments. Importantly, robocasting enables structural designs in any desired configurations and dimensions, thereby inspiring the fabrication of customized batteries.

Inspired by the fast lithium superionic conductor Li10GeP2S12, a new class of quaternary fast sodium-ion conductors, Na9+xSnxP3−xS12, has recently been identified. Among these, Na11Sn2PS12 was the fastest sodium ion-conducting sulphide in spite of its moderately low migration barriers. The isostructural Na+-ion electrolytes Na9+xSnxSb3−xS12 found soon thereafter combined only slightly lower ionic conductivity with excellent air stability and processability in aqueous solutions. Here we apply density functional theory to comprehensively study the stability and homogeneity range of these disordered Na+ ion conductors: For Na9+xSnxP3−xS12 we explored the composition range 1.75 ≤ x ≤ 2.25 as well as x = 1 (Na10SnP2S12), x = 0 (Na3PS4) and x = 3 (Na4SnS4). For Na9+xSnxSb3−xS12 we extended the range of calculations to x = 0, 1, 3, and 1.625 ≤ x ≤ 2.375. In both cases we find that the lowest energy composition is the stoichiometric phase with x = 2 and clarify that these compositions are also stable against decomposition into Na4SnS4 and Na3PS4 (or Na3SbS4). Our ab initio molecular dynamics (AIMD) simulations show that despite the exceptionally high local mobility of Na on Na6 sites, the negligible Na6 concentration in the stable lowest energy structure rules out a previously supposed key role of Na6 in ionic conductivity at room temperature. On the other hand, an onset of PS4 (but not SnS4) orientational disorder is observed above 500 K in our high temperature AIMD studies and characterised by analysing van Hove correlation functions. This orientational disorder affects the relative Na site energies enabling Na6 site occupancy and lowers the barriers for Na+ migration and. As soon as the orientational disorder allows for a significant Na6 occupancy, it also significantly contributes to the Na+ ion transport.

Lithium metal is the ultimate solution for high-energy density batteries, but is currently plagued from commercialization by the safety issue due to the uncontrollable Li dendrite growth. It would be worse when plating a higher areal capacity of lithium operating under higher current densities. Herein, we develop a novel N-doped carbon framework by extrusion-based 3D-printing of Zn-MOF precursor, which possess a hierarchically porous structure and a large specific surface area. Such unique structural features simultaneously suppress the dendrite growth, accommodate massive Li deposition, stabilize Li/electrolyte interface, and dissipate high current densities. As a result, the 3D-printed N-doped carbon framework (3DP-NC) enables an ultrahigh areal capacity of 30 mAh cm−2 at the high rate of 10 mA cm−2 and a high average Coulombic efficiency of 97.9% after a long lifespan of ~2000 h at the rate of 1 mA cm−2. Moreover, the Li-plated 3DP-NC anode is capable of working properly under an ultrahigh rate of 20 mA cm−2 in symmetric cells with low overpotentials and manifesting a much-enhanced rate capability in full cells with a 3D-printed LiFePO4 cathode. The 3D-printing strategy demonstrated in the present work provides a promising new avenue for the fabrication of high-performance Li-metal batteries.

Organic carbonyl molecules have recently been investigated as redox-active electrode materials in rechargeable organic batteries (ROBs), and although redox-active polymers offer high specific energ...

The low energy density and narrow operating temperature window besides the relatively high cost of the vanadium redox-flow battery (VRB) severely hinder its commercial deployment. Herein, in conjun...

In this article, we have reported a one-step scalable synthesis of MgCo2O4 nanostructures as efficient anode material for Li-ion batteries and investigated the role of post-synthesis calcination temperature (400, 600 and 800 °C) on its physiochemical properties and electrochemical performances. The XRD pattern of the calcinated sample at 400 °C (MC 400) indicates a pure phase of MgCo2O4. However, on increasing the calcination temperature to 600 °C (MC 600), an additional phase corresponding to MgO was detected and the corresponding XRD peak intensity further increased on increasing the calcination temperature to 800 °C (MC 800 °C). This was accompanied by a morphological transformation from flake and rod-like nanostructures, to an agglomerated dense flake-like morphology. Electrochemical studies revealed that the calcination temperature plays an important role in determining the electrochemical performance of the MgCo2O4 as anode material. In a half cell, the MC 600 showed the best electrochemical performance with high discharge capacity of 980 mA h g−1 (2nd discharge at 60 mA g−1) and a reversible discharge capacity of 886 mA h g−1 at the end of 50 cycles with high coulombic efficiency of 98%. Long term stability was carried out at 0.5C which showed a capacity retention of 358 mA h g−1 at the end of 500 cycles. The superior electrochemical performance of the MC600 can be attributed to the presence of the small amount of MgO, which is believed to provide the anode materials better structural stability during cycling. The claim was further supported by ex-situ TEM analysis of the anode material of a cycled cell (50 cycles).

We report a simple and scalable synthesis of MnCo2O4/MWCNT nanocomposite by a simple precipitation method and its application as a high capacity anode material for Li-ion batteries. X-ray diffraction analysis showed a pure phase of MnCo2O4 and morphological analysis revealed a uniform decoration of MnCo2O4 nanoparticles along MWCNT backbone. As an electrode material, MnCo2O4 showed a high initial discharge capacity of 1431 mA h g−1 with a capacity retention of 444 mA h g−1 at the end of 30 cycles. With a small addition of MWCNT to MnCo2O4, the stability of the composite increased with a reversible capacity of 871 mA h g−1 at the end of 30 cycles. The inclusion of MWCNT as a conductive matrix resulted in a significant improvement in rate capability and cyclic stability.

Metallic or ceramic micro/nanoporous materials have attracted particular attention due to some interesting structural and functional properties. There exist a variety of methods for producing porou...

Fast sodium ion conducting Na11Sn2PSe12 solid electrolyte was prepared by a mechanochemical method. This is the first tin based selenide prepared by room temperature ball milling instead of conventional synthesis in a sealed quartz tube under vacuum. Our approach is safe and easy to scale up. Samples were synthesized systematically using various intervals of ball milling and annealing time to maximise phase purity and ionic conductivity. The highest room temperature bulk ionic conductivity of the mechanochemically synthesized Na11Sn2PSe12 was 1.0 mS cm−1 observed for a sample prepared by ball milling for 15 h followed by 6 h annealing at 550 °C. This fast-ion conducting Na11Sn2PSe12 allowed to demonstrate the first Na–Se all-solid-state batteries Na/Na11Sn2PSe12/C–Se and Na3Sn/Na11Sn2PSe12/C–Se with specific initial discharge capacities of 430 mA h g−1 or 400 mA h g−1, respectively at a current density 0.08 mA cm−2. The Na3Sn/Na11Sn2PSe12/C–Se battery could be cycled 500 times with a capacity that decreased gradually to 50 mA h g−1.

Herein, electrochemistry-related aspects of safety of graphene-based non-aqueous electrochemical supercapacitors are elucidated by using MgO-decorated few-layer graphene (FLG) as an electrode material. MgO-decorated FLG (MgO/FLG) is chosen in this study because on the one hand it has good physical characteristics making it lucrative as an electrode material in graphene based aqueous and non-aqueous electrochemical supercapacitors and on the other hand in MgO/FLG, MgO is chemically bonded to FLG (through either oxygen-mediation (Mg–O–C) or direct bonding with carbon (Mg–C)) and thereby reduces the possibility of exothermic reactions upon charge–discharge cycling leading to an unsafe failure of the supercapacitor. As anticipated, coin cell supercapacitors fabricated with MgO/FLG symmetric electrodes and a non-aqueous BMIM BF4 electrolyte popped up exothermically (the temperature rise was in the range of 110–165 °C) during the initial charge cycles. Post-cycling X-ray photoelectron spectroscopic analysis of the electrode material revealed that the chemical bonding between MgO and FLG triggered highly exothermic reactions leading to the formation of products such as MgF2 and Mg(OH)2. This study elucidates that the heat production and the gaseous species release during charging–discharging cycles are serious safety concerns if the choice of the electrode material and non-aqueous electrolyte (BMIM BF4 and plausibly PF6 based electrolytes) combination is not properly made. On the other hand when MgO/FLG was used in combination with a 6 M KOH aqueous electrolyte in an aqueous supercapacitor, it delivered a discharge capacitance as high as 168 F g−1 at a current density of 0.5 A g−1. Even at the end of the 5000th cycle with a current rate of 3 A g−1, a discharge capacitance of 101 F g−1 corresponding to 95% retention was recorded.

The state of health (SOH) estimation plays an essential role in battery-powered applications to avoid unexpected breakdowns due to battery capacity fading. However, few studies have paid attention to the problem of uneven length of degrading cycles, simply employing manual operation or leaving to the automatic processing mechanism of advanced machine learning models, like long short-term memory (LSTM). As a result, this causes information loss and caps the full capability of the data-driven SOH estimation models. To address this challenge, this paper proposes an innovative cycle synchronization way to change the existing coordinate system using dynamic time warping, not only enabling the equal length inputs of the estimation model but also preserving all information. By exploiting the time information of the time series, the proposed method embeds the time index and the original measurements into a novel indicator to reflect the battery degradation status, which could have the same length over cycles. Adopting the LSTM as the basic estimation model, the cycle synchronization-based SOH model could significantly improve the prediction accuracy by more than 30% compared to the traditional LSTM., Comment: Accepted by IECON 2021

By informing accurate performance (e.g., capacity), health state management plays a significant role in safeguarding battery and its powered system. While most current approaches are primarily based on data-driven methods, lacking in-depth analysis of battery performance degradation mechanism may discount their performances. To fill in the research gap about data-driven battery performance degradation analysis, an invariant learning based method is proposed to investigate whether the battery performance degradation follows a fixed behavior. First, to unfold the hidden dynamics of cycling battery data, measurements are reconstructed in phase subspace. Next, a novel multi-stage division strategy is put forward to judge the existent of multiple degradation behaviors. Then the whole aging procedure is sequentially divided into several segments, among which cycling data with consistent degradation speed are assigned in the same stage. Simulations on a well-know benchmark verify the efficacy of the proposed multi-stages identification strategy. The proposed method not only enables insights into degradation mechanism from data perspective, but also will be helpful to related topics, such as stage of health., Comment: Accepted by IECON 2020 (The 46th Annual Conference of the IEEE Industrial Electronics Society)

Polymer‐based solid‐state electrolytes are shown to be highly promising for realizing low‐cost, high‐capacity, and safe Li batteries. One major challenge for polymer solid‐state batteries is the relatively high operating temperature (60–80 °C), which means operating such batteries will require significant ramp up time due to heating. On the other hand, as polymer electrolytes are poor thermal conductors, thermal variation across the polymer electrolyte can lead to nonuniformity in ionic conductivity. This can be highly detrimental to lithium deposition and may result in dendrite formation. Here, a polyethylene oxide‐based electrolyte with improved thermal responses is developed by incorporating 2D boron nitride (BN) nanoflakes. The results show that the BN additive also enhances ionic and mechanical properties of the electrolyte. More uniform Li stripping/deposition and reversible cathode reactions are achieved, which in turn enable all‐solid‐state lithium–sulfur cells with superior performances., A boron nitride (BN) incorporated solid polymer electrolyte is developed with improved ionic conductivity, thermal responses, and mechanical properties for the application of all‐solid‐state Li–S batteries. The thermal and current uniformity derived from BN additive leads to a uniform Li deposition and preferred S conversion. Thus, an all‐solid‐state Li–S battery is successfully demonstrated with outstanding electrochemical performances.