Deep learning (DL) has indeed emerged as a powerful tool for rapidly and accurately predicting materials properties from big data, such as the design of current commercial Li-ion batteries. However, its practical utility for multivalent metal-ion batteries (MIBs), the most promising future solution of large-scale energy storage, is limited due to the scarce MIB data availability and poor DL model interpretability. Here, we develop an interpretable DL model as an effective and accurate method for learning electrode voltages of multivalent MIBs (divalent magnesium, calcium, zinc, and trivalent aluminum) at small dataset limits (150~500). Using the experimental results as validation, our model is much more accurate than machine-learning models which usually are better than DL in the small dataset regime. Besides the high accuracy, our feature-engineering-free DL model is explainable, which automatically extracts the atom covalent radius as the most important feature for the voltage learning by visualizing vectors from the layers of the neural network. The presented model potentially accelerates the design and optimization of multivalent MIB materials with fewer data and less domain-knowledge restriction, and is implemented into a publicly available online tool kit in http://batteries.2dmatpedia.org/ for the battery community.
Lithium-ion batteries (LIBs) are ubiquitous in everyday applications. However, Lithium (Li) is a limited resource on the planet and is therefore not sustainable. As an alternative to lithium, earth-abundant and cheaper multivalent metals such as aluminum (Al) and calcium (Ca) have been actively researched in battery systems. However, finding suitable intercalation hosts for multivalent-ion batteries is urgently needed. Open-tunneled oxides are a particular category of microparticles distinguished by the presence of integrated one-dimensional channels or nanopores. This work focuses on two prom…
Multivalent batteries are an energy storage technology with the potential to surpass lithium-ion batteries, however their performance has been limited by the low voltages and poor solid-state ionic mobility of available cathodes. A computational screening approach to identify high-performance multivalent intercalation cathodes among materials that do not contain the working ion of interest has been developed which greatly expands the search space that can be considered for materials discovery. This approach has been applied to magnesium cathodes as a proof of concept and four resulting candida…
Long-term durability is a major obstacle limiting the widespread use of lithium ion batteries (LIBs) in heavy-duty applications and others demanding extended lifetime. As one of the root causes of degradation and failure of battery performance, the electrode failure mechanisms are still unknown. Here, we reveal the fundamental fracture mechanisms of single-crystal silicon electrodes over extended lithiation/delithiation cycles, using electrochemical testing, microstructure characterization, fracture mechanics, and finite element analysis. Anisotropic lithium invasion causes crack initiation pe…
Slow ionic transport and high voltage drop (IR drop) of homogeneous porous electrodes are the critical causes of severe performance degradation of lithium-ion (Li-ion) batteries under high charging rates. Herein, we demonstrate that a bio-inspired vascularized porous electrode can simultaneously solve these two problems by introducing low tortuous channels and graded porosity. To optimize the vasculature structural parameters, we employ artificial neural networks (ANNs) to accelerate the computation of possible structures with high accuracy. Furthermore, an inverse-design searching library is …
We review recent ab initio molecular dynamics studies of electrode/electrolyte interfaces in lithium ion batteries. Our goals are to introduce experimentalists to simulation techniques applicable to models which are arguably most faithful to experimental conditions so far, and to emphasize to theorists that the inherently interdisciplinary nature of this subject requires bridging the gap between solid and liquid state perspectives. We consider liquid ethylene carbonate (EC) decomposition on lithium intercalated graphite, lithium metal, oxide-coated graphite, and spinel manganese oxide surfaces…
Machine learning (ML) techniques have rapidly found applications in many domains of materials chemistry and physics where large data sets are available. Aiming to accelerate the discovery of materials for battery applications, in this work, we develop a tool (http://se.cmich.edu/batteries) based on ML models to predict voltages of electrode materials for metal-ion batteries. To this end, we use deep neural network, support vector machine, and kernel ridge regression as ML algorithms in combination with data taken from the Materials Project Database, as well as feature vectors from properties o…
Herein we report on a detailed investigation of the irreversible capacity in the first cycle of pyrolytic graphite electrodes in aluminum batteries employing 1-ethyl-3-methylimidazolium chloride:aluminum trichloride (EMIMCl:AlCl3) as electrolyte. The reaction mechanism, involving the intercalation of AlCl4 in graphite, has been fully characterized by correlating the micro/nanostructural modification to the electrochemical performance. To achieve this aim a combination of X-ray diffraction (XRD), small angle X-ray scattering (SAXS) and computed tomography (CT) has been used. The reported result…
Cycling efficiency and rate capability of porous copper-coated, amorphous silicon thin-film negative electrodes are compared to equivalent silicon thin-film electrodes in lithium-ion batteries. The presence of a copper layer coated on the active material plays a beneficial role in increasing the cycling efficiency and the rate capability of silicon thin-film electrodes. Between 3C and C/8 discharge rates, the available cell energy decreased by 8% and 18% for 40 nm copper-coated silicon and equivalent silicon thin-film electrodes, respectively. Copper-coated silicon thin-film electrodes also sh…
Stable and fast ionic conductors for magnesium cathode materials have the prospect of enabling high energy density batteries beyond current Lithium-ion technologies. So far, only a few candidate materials have been identified leading to data only being scarcely available to the community. Here, we present a systematic study, in the framework of Density Functional Theory, including the estimation of the diffusion barrier for 16 materials through employing Nudged Elastic Band (NEB) calculations. By introducing a path finder algorithm based on the idea of Voronoi tessellations, we show that an es…
The identification of alternatives to the Lithium-ion battery architecture remains a crucial priority in the diversification of energy storage technologies. Accompanied by the low reduction potential of $\mathrm{Ca^{2+}/Ca}$, -2.87 V vs. SHE, metal-anode-based rechargeable Calcium (Ca) batteries appear competitive in terms of energy densities. However, the development of Ca-batteries lacks high-energy density intercalation cathode materials. Using first-principles methodologies, we screen a large chemical space for potential Ca-based cathode chemistries, with composition of $\mathrm{Ca_iTM_jZ_…
Poor electrical conductivity and large volume expansion during repeated charge and discharge is what has characterized many battery electrode materials in current use. This has led to 2D materials, specifically multi-layered 2D systems, being considered as alternatives. Among these 2D multi-layered systems are the graphene-based van der Waals heterostructures with transition metal di-chalcogenides (TMDCs) as one of the layers. Thus in this study, graphene-Hafnium disulphide (Gr-HfS$_2$) system, has been investigated as a prototype Gr-TMDC system for application as battery electrode. Density fu…
Thick Li-ion battery electrodes with high ion transport rates could enable batteries that cost less and that have higher gravimetric and volumetric energy density, because they require fewer inactive cell-components. Finding ways to increase ion transport rates in thick electrodes would be especially valuable for electrodes made with graphite platelets, which have been shown to have tortuosities in the thru-plane direction about 3 times higher than in the in-plane direction. Here, we predict that bi-tortuous electrode structures (containing electrolyte-filled macro-pores embedded in micro-poro…
Density Functional Theory (DFT) calculations of electrode material properties in high energy density storage devices like lithium batteries have been standard practice for decades. In contrast, DFT modelling of explicit interfaces in batteries arguably lacks universally adopted methodology and needs further conceptual development. In this paper, we focus on solid-solid interfaces, which are ubiquitous not just in all-solid state batteries; liquid-electrolyte-based batteries often rely on thin, solid passivating films on electrode surfaces to function. We use metal anode calculations to illustr…
Charge lost per unit surface area of a silicon electrode due to the formation of solid-electrolyte-interphase (SEI) layer during initial lithiation was quantified, and the species that constitute this layer were identified. Coin cells made with Si thin-film electrodes were subjected to a combination of galvanostatic and potentiostatic lithiation and delithiation cycles to accurately measure the capacity lost to SEI-layer formation. While the planar geometry of amorphous thin films allows accurate calculation of surface area, creation of additional surface by cracking was prevented by minimizin…
In Li-ion batteries the electrochemical potential drives the redox reactions occurring at the interface between electrolyte and storage material, typically active particles for porous electrodes, allowing Li ions intercalation/extraction from electrodes. The limiting factor of the process is not solely related to the electrochemical affinity, but also to structural features as the morphology of the electrodes. In this note, the relevance of the electrodes architecture is investigated numerically, in terms of the electro-chemo-mechanical response of a battery cell with homogeneous electrodes an…
Conversion reaction is one of the most important chemical processes in energy storage such as lithium ion batteries. While it is generally assumed that the conversion reaction is initiated by ion intercalation into the electrode material, solid evidence of intercalation and the subsequent transition mechanism to conversion remain elusive. Here, using well-defined WO3 single crystalline thin films grown on Nb doped SrTiO3(001) as a model electrode, we elucidate the conversion reaction mechanisms during Li+, Na+ and Ca2+ insertion into WO3 by in situ transmission electron microscopy studies. Int…
A thick electrode with high areal capacity has been developed as a strategy for high-energy-density lithium-ion batteries, but thick electrodes have difficulties in manufacturing and limitations in ion transport. Here, we reported a new manufacturing approach for ultra-thick electrode with aligned structure, called structure electrode additive manufacturing or SEAM, which aligns active materials to the through-thicknesses direction of electrodes using shear flow and a designed printing path. The ultra-thick electrodes with high loading of active materials, low tortuous structure, and good stru…
Benefited from the advantages on environmental benign, easy purification, and high thermal stability, the recently synthesized two-dimensional (2D) material MoN2 shows great potential for clean and renewable energy applications. Here, through first-principles calculations, we show that the monolayered MoN2 is promising to be a high capacity electrode material for metal ion batteries. Firstly, identified by phonon dispersion and exfoliation energy calculations, MoN2 monolayer is proved to be structurally stable and could be exfoliated from its bulk counterpart in experiments. Secondly, all the …
Natural abundance, impressive chemical characteristics and economic feasibility have rekindled the appeal for rechargeable sodium (Na) batteries as a practical solution for the growing energy demand, environmental sustainability and energy independence. However, the scarcity of viable positive electrode materials remains a huge impediment to the actualization of this technology. In this paper, we explore honeycomb layered oxides adopting the composition Na$_2$Ni$_{2-x}$Co$_x$TeO$_6$ ($x = 0, 0.25$ and $0.50$) as feasible positive electrode (cathode) materials for rechargeable sodium batteries …
Identifying applicable anode materials is a significant task for Li- and Na-ion battery (LIB and NIB) technologies. We propose the GaN monolayer (2D GaN) can be a good anode candidate. The GaN monolayer manifests stable Li/Na adsorption and inherently low theoretical voltages. Most excitingly, both high storage capacity and extremely fast Li/Na diffusion can be simultaneously realized in the GaN monolayer. For Li, the storage capacity and diffusion barrier is 938 mA h g-1 and 80 meV , respectively. And the values for Na are 625 mA h g-1 and 22 meV. Comparing with known 2D anode materials with …
Recycling of beta-Li3PS4-based all-solid-state Li-ion batteries: Interactions of electrode materials and electrolyte in a dissolution-based separation process
The kinetic performance of graphite particles is difficult to deconvolute from half-cell experiments, where the influences of the working electrode porosity and the counter electrode contribute nonlinearly to the electrochemical re-sponse. Therefore, thin-layer electrodes of circa 1 μm thickness were prepared with standard, highly crystalline graphite particles to evaluate their rate capability. The performance was evaluated based on the different stage transitions. We found that the tran-sitions towards the dense stages 1 and 2 with LiC6 in-plane densi-ty are one of the main rate limitations …
Rechargeable Aluminium-organic batteries are an exciting emerging energy storage technology owing to their low cost and promising high performance, thanks to the ability to allow multiple-electron redox chemistry and multivalent Al-ion intercalation. In this work, we use a combination of Density Functional Theory (DFT) calculations and experimental methods to examine the mechanism behind the charge-discharge reaction of the organic dye 3,4,9,10-Perylenetetracarboxylic dianhydride (PTCDA) in the 1,3-ethylmethylimidazolium (EMIm$^+$) chloroaluminate electrolyte. We conclude that, contrary to pre…
Two-dimensional (2D) materials can have an excellent capability to handle high rates of charge in ion batteries since metal ions need not diffuse in a 3D lattice structure. However graphene, which is the most important 2D material, is known to have no Li capacity. Herein, adsorption of Li, as well as Na, K, and Ca on Ti$_3$C$_2$, one representative MXene, is predicted by first-principles density functional calculations. In our study, we observed that these alkali ions exhibit different adsorption energy depending on the coverage. The adsorption energies of Na, K and Ca decrease as coverage inc…
It is shown that continuously occurring electrolyte-reduction reaction on freshly-exposed electrode surfaces during lithiation/delithiation cycles causes the lowering of cycling efficiency, and hence, capacity fade in well-cycled silicon anodes in lithium-ion batteries. Using galvanostatic lithiation/delithiation data from multiple cycles on a Li/Si half-cell, a methodology to separate the charge due to the main reaction (lithiation/delithiation of Si) from the side-reaction (electrolyte-reduction) is presented. The rate of this parasitic side reaction is estimated on well-cycled amorphous sil…
Wearable electronic devices and gadgets raise the need for flexible, thin and lightweight batteries. In this article we present for the first time, a unique, single-step method for the preparation of a membrane-electrode assembly for flexible-batteries application. Concurrent electrophoretic deposition (EPD) of positive and negative battery electrodes (LFP and LTO) on opposite sides of a commercial nanoporous membrane (Celgard 2325) results in the formation of a three-layer-battery structure. The cell comprising this electrophoretically deposited structure ran for more than 150 cycles with 125…
Spatially-resolved neutron powder diffraction with gauge volume 2x2x20 mm3 has been applied to probe the lithium concentration in the graphite anode of different Li-ion cells of 18650-type in situ in charged state. Structural studies performed in combination with electrochemical measurements and X-ray computed tomography under real cell operating conditions unambiguously revealed non-homogeneity of lithium distribution in the graphite anode. Deviations from a homogeneous behaviour have been found in both radial and axial directions of 18650-type cells and were discussed in the frame of cell ge…
A significant problem associated with batteries is the rapid reduction of charge-storage capacity with increasing charge/discharge rate. For example, improving this rate-performance is required for fast-charging of car batteries. Rate-performance is related to the timescales associated with charge or ionic motion in both electrode and electrolyte. However, no quantitative model exists which can be used to fit experimental data to give insights into the dominant rate-limiting processes in a given electrode-electrolyte system. Here we develop an equation which can be used to fit capacity versus …
Li-O$_2$ batteries (LOB) performance degradation ultimately occurs through the accumulation of discharge products and irreversible clogging of the porous electrode during the cycling. Electrode binder degradation in the presence of reduced oxygen species can result in additional coating of the conductive surface, exacerbating capacity fading. Herein, we establish a facile method to fabricate free-standing, binder-free electrodes for LOBs in which multi-wall carbon nanotubes (MWCNT) form cross-linked networks exhibiting high porosity, conductivity, and flexibility. These electrodes demonstrate …
Passivating lithium ion battery electrode surfaces to prevent electrolyte decomposition is critical for battery operations. Recent work on conformal atomic layer deposition (ALD) coating of anodes and cathodes has shown significant technological promise. ALD further provides well-characterized model platforms for understanding electrolyte decomposition initiated by electron tunneling through a passivating layer. First principles calculations reveal two regimes of electron transfer to adsorbed ethylene carbonate molecules (EC, a main component of commercial electrolyte) depending on whether the…
Influence of Electrode Thickness and Electrolyte Composition on SEI Formation and Cycle Stability in Binder-Free Hard Carbon Anodes for Na-Ion Batteries
Université de Haute-Alsace（阿尔萨斯大学）；Institut de Science des Matériaux de Mulhouse (IS2M)（穆尔豪斯材料科学研究所）；CNRS UMR 7361（法国国家科学研究中心联合研究实验室7361）；Université de Strasbourg（斯特拉斯堡大学）；Réseau sur le Stockage Electrochimique de l’Energie (RS2E)（电化学储能网络）；CNRS FR3459（法国国家科学研究中心自由研究基金3459）
本研究探讨了硬碳自支撑电极厚度、大孔率及电解液添加剂对钠离子电池SEI形成和循环稳定性的影响，发现FEC添加剂可改善稳定性，实现高达93%的初始库仑效率和328 mAh g-1的可逆容量。
The abundance of Sodium (Na), its low-cost, and low reduction potential provide a lucrative inexpensive, safe, and environmentally benign alternative to Lithium Ion Batteries (LIBs). The significant challenges in advancing Sodium Ion Battery (NIB) technologies lies in finding the better electrode materials. Experimental investigations revealed the real potency of Germanium (Ge) as suitable anode materials for NIBs. However, a systematic atomistic study is necessary to understand the fundamental aspects of capacity-voltage correlation, microstructural changes of Ge, as well as diffusion kinetic…
A diffuse-interface model for predicting the evolution of metallic negative electrodes and interfacial voids in solid-state batteries with homogeneous and polycrystalline solid electrolyte separators
Silicon is one of the most promising anode materials for Lithium-ion batteries. Silicon endures volume changes upon cycling, which leads to subsequent pulverization and capacity fading. These drawbacks lead to a poor lifespan and hamper the commercialization of silicon anodes. In this work, a hybrid nanostructured anode based on silicon nanoparticles (SiNPs) anchored on vertically aligned carbon nanotubes (VACNTs) with defined spacing to accommodate volumetric changes is synthesized on commercial macroscopic current collector. Achieving electrodes with good stability and excellent electrochemi…
Uncontrolled crystal growth during electroreduction of reactive metals in liquid electrolytes produces porous, low-density, mossy metal deposits that grow primarily along the surface normal vector to a planar electrode substrate. The moss-like deposits are fragile and cause premature failure of batteries by chemical, physical, and mechanical pathways. Here we use electroanalytical Rotating-Disk Electrode (RDE) studies in a three-electrode electrochemical cell to elucidate the fundamental origin of moss-like growth of metals. We report that competing Faradaic reactions occurring on the electrod…
This is the first quantitative analysis of mechanical reliability of all-solid state batteries. Mechanical degradation of the solid electrolyte (SE) is caused by intercalation-induced expansion of the electrode particles, within the constrain of a dense microstructure. A coupled electro-chemo-mechanical model was implemented to quantify the material properties that cause a SE to fracture. The treatment of microstructural details is essential to the understanding of stress-localization phenomena and fracture. A cohesive zone model is employed to simulate the evolution of damage. In the numerica…
Beyond Lithium-Ion Batteries: Are Effective Electrodes Possible for Alkaline and Other Alkali Elements? Exploring Ion Intercalation in Surface-Modified Few-Layer Graphene and Examining Layer Quantity and Stages
The capacity and stability of constituent electrodes determine the performance of Li-ion batteries. In this study, density functional theory is employed to explore the potential application of recently synthesized two dimensional phosphorene as electrode materials. Our results show that Li atoms can bind strongly with phosphorene monolayer and double layer with significant electron transfer. Besides, the structure of phosphorene is not much influenced by lithiation and the volume change is only 0.2\%. A semiconducting to metallic transition is observed after lithiation. The diffusion barrier i…
A porous electrode resulting from unregulated Li growth is the major cause of the low Coulombic efficiency and potential safety hazards of rechargeable Li metal batteries. Strategies aiming to achieve large granular Li deposits have been extensively explored; yet, the ideal Li deposits, which consist of large Li particles that are seamlessly packed on the electrode and can be reversibly deposited and stripped, have never been achieved. Here, by controlling the uniaxial stack pressure during battery operation, a dense Li deposition (99.49% electrode density) with an ideal columnar structure has…
In today's modeling and analysis of electrochemical cycling of Li- and Na-ion batteries, an assumption is often made regarding the interphase that forms between the active material and liquid electrolyte at low potentials, the so-called solid-electrolyte interphase (SEI). The SEI is generally assumed to act like an Ohmic resistor despite its complex chemical composition and porosity distribution. Here, one reports that this assumption does not hold for alkali-ion batteries. The SEI possesses a non-linear overpotential characteristic which saturates already at low current density of 0.1 mAcm-2 …
Metal fluoride and oxides can store multiple lithium-ions through conversion chemistry to enable high energy-density lithium-ion batteries. However, their practical applications have been hindered by an unusually large voltage hysteresis between charge and discharge voltage-profiles and the consequent low energy efficiency (< 80%). The physical origins of such hysteresis are rarely studied and poorly understood. Here we employ in situ X-ray absorption spectroscopy (XAS), transmission electron microscopy (TEM), density-functional-theory (DFT) calculations, and galvanostatic intermittent titrati…
