Mechanical rolling formation of interpenetrated lithium metal/lithium tin alloy foil for ultrahigh-rate battery anode

To achieve good rate capability of lithium metal anodes for high-energy-density batteries, one fundamental challenge is the slow lithium diffusion at the interface. Here we report an interpenetrated, three-dimensional lithium metal/lithium tin alloy nanocomposite foil realized by a simple calendering and folding process of lithium and tin foils, and spontaneous alloying reactions. The strong affinity between the metallic lithium and lithium tin alloy as mixed electronic and ionic conducting networks, and their abundant interfaces enable ultrafast charger diffusion across the entire electrode. We demonstrate that a lithium/lithium tin alloy foil electrode sustains stable lithium stripping/plating under 30mAcm(-2) and 5mAhcm(-2) with a very low overpotential of 20mV for 200 cycles in a commercial carbonate electrolyte. Cycled under 6C (6.6mAcm(-2)), a 1.0mAhcm(-2) LiNi0.6Co0.2Mn0.2O2 electrode maintains a substantial 74% of its capacity by pairing with such anode

Health diagnosis and recuperation of aged Li-ion batteries with data analytics and equivalent circuit modeling

Battery health assessment and recuperation play a crucial role in the utilization of second-life Li-ion batteries. However, due to ambiguous aging mechanisms and lack of correlations between the recovery effects and operational states, it is challenging to accurately estimate battery health and devise a clear strategy for cell rejuvenation. This paper presents aging and reconditioning experiments of 62 commercial high-energy type lithium iron phosphate (LFP) cells, which supplement existing datasets of high-power LFP cells. The relatively large-scale data allow us to use machine learning models to predict cycle life and identify important indicators of recoverable capacity. Considering cell-to-cell inconsistencies, an average test error of $16.84\% \pm 1.87\%$ (mean absolute percentage error) for cycle life prediction is achieved by gradient boosting regressor given information from the first 80 cycles. In addition, it is found that some of the recoverable lost capacity is attributed to the lateral lithium non-uniformity within the electrodes. An equivalent circuit model is built and experimentally validated to demonstrate how such non-uniformity can be accumulated, and how it can give rise to recoverable capacity loss. SHapley Additive exPlanations (SHAP) analysis also reveals that battery operation history significantly affects the capacity recovery.Comment: 20 pages, 5 figures, 1 tabl

A genetic variation map for chicken with 2.8 million single-nucleotide polymorphisms

We describe a genetic variation map for the chicken genome containing 2.8 million single-nucleotide polymorphisms ( SNPs). This map is based on a comparison of the sequences of three domestic chicken breeds ( a broiler, a layer and a Chinese silkie) with that of their wild ancestor, red jungle fowl. Subsequent experiments indicate that at least 90% of the variant sites are true SNPs, and at least 70% are common SNPs that segregate in many domestic breeds. Mean nucleotide diversity is about five SNPs per kilobase for almost every possible comparison between red jungle fowl and domestic lines, between two different domestic lines, and within domestic lines - in contrast to the notion that domestic animals are highly inbred relative to their wild ancestors. In fact, most of the SNPs originated before domestication, and there is little evidence of selective sweeps for adaptive alleles on length scales greater than 100 kilobases

Electrochemical energy storage devices for wearable technology : a rationale for materials selection and cell design

Compatible energy storage devices that are able to withstand various mechanical deformations, while delivering their intended functions, are required in wearable technologies. This imposes constraints on the structural designs, materials selection, and miniaturization of the cells. To date, extensive efforts have been dedicated towards developing electrochemical energy storage devices for wearables, with a focus on incorporation of shape-conformable materials into mechanically robust designs that can be worn on the human body. In this review, we highlight the quantified performances of reported wearable electrochemical energy storage devices, as well as their micro-sized counterparts under specific mechanical deformations, which can be used as the benchmark for future studies in this field. A general introduction to the wearable technology, the development of the selection and synthesis of active materials, cell design approaches and device fabrications are discussed. It is followed by challenges and outlook toward the practical use of electrochemical energy storage devices for wearable applications.ASTAR (Agency for Sci., Tech. and Research, S’pore

Insights into morphological evolution and cycling behaviour of lithium metal anode under mechanical pressure

Dendritic Li formation is one of the critical reasons for the failure of Li batteries. In order to improve the lithium metal anode performance, a better understanding of the growth mechanisms of Li dendrites is necessary. Due to the malleable nature of lithium metal, mechanical pressure should play an important role in determining the morphology and cycling behaviour of Li anode. Here we investigated the effect of an applied external pressure on the electrochemical deposition of lithium metal. Instead of a highly porous, wire-like Li growth in the absence of pressure, a much more compact Li deposition can be achieved when a pressure is applied to the batteries in the charge/discharge processes. The improved Li deposition/stripping behaviour in the pressed cells yields a 5% higher Coulombic efficiency (~90%) and more than 5-fold longer cycling life than the cells without pressure at a current density of 2 mA/cm2. The use of pressure in shaping Li metal is an effective approach to address the Li metal problem and advance Li technologies in the future. ?? 201

Phase Transformations in TiS₂ during K Intercalation

The electrochemical performances of TiS₂ in potassium ion batteries (KIBs) are poor due to the large size of K ions, which induces irreversible structural changes and poor kinetics. To obtain detailed insights into the kinetics of phase changes, we investigated the electrochemical properties, phase transformations, and stability of potassium-intercalated TiS₂ (K_<i>x</i>TiS₂, 0 ≤ <i>x</i> ≤ 0.88). In situ XRD reveals staged transitions corresponding to distinct crystalline phases during K ion intercalation, which are distinct from those of Li and Na ions. Electrochemical (cyclic voltammetry and galvanostatic charge/discharge) studies show that the phase transitions among various intercalated stages slow down the kinetics of the discharge/charge in bulk TiS₂ hosts. By chemically prepotassiating the bulk TiS₂ (K_0.25TiS₂) to reduce the domain size of the crystal, these phase transitions are bypassed and more facile ion insertion kinetics can be obtained, which leads to improved Coulombic efficiency, rate capability, and cycling stability

<i>In Situ</i> Observation and Electrochemical Study of Encapsulated Sulfur Nanoparticles by MoS₂ Flakes

Sulfur is an attractive cathode material for next-generation lithium batteries due to its high theoretical capacity and low cost. However, dissolution of its lithiated product (lithium polysulfides) into the electrolyte limits the practical application of lithium sulfur batteries. Here we demonstrate that sulfur particles can be hermetically encapsulated by leveraging on the unique properties of two-dimensional materials such as molybdenum disulfide (MoS₂). The high flexibility and strong van der Waals force in MoS₂ nanoflakes allows effective encapsulation of the sulfur particles and prevent its sublimation during <i>in situ</i> TEM studies. We observe that the lithium diffusivities in the encapsulated sulfur particles are in the order of 10^–17 m² s^–1. Composite electrodes made from the MoS₂-encapsulated sulfur spheres show outstanding electrochemical performance, with an initial capacity of 1660 mAh g^–1 and long cycle life of more than 1000 cycles

A Genetic Variation Map for Chicken with 2.8 Million Single-Nucleotide Polymorphisms

We describe a genetic variation map for the chicken genome containing 2.8 million single-nucleotide polymorphisms (SNPs). This map is based on a comparison of the sequences of three domestic chicken breeds (a broiler, a layer and a Chinese silkie) with that of their wild ancestor, red jungle fowl. Subsequent experiments indicate that at least 90% of the variant sites are true SNPs, and at least 70% are common SNPs that segregate in many domestic breeds. Mean nucleotide diversity is about five SNPs per kilobase for almost every possible comparison between red jungle fowl and domestic lines, between two different domestic lines, and within domestic lines—in contrast to the notion that domestic animals are highly inbred relative to their wild ancestors. In fact, most of the SNPs originated before domestication, and there is little evidence of selective sweeps for adaptive alleles on length scales greater than 100 kilobases.This article is from Nature 432 (2004): 717, doi:10.1038/nature03156.</p