Efficient Lithium-ion Batteries Research Articles

Investigation of the Effect of State-of-Charge and C-Rates on the Heat Loss and Efficiency of a Lithium-Ion Battery

To comprehend the thermal behaviour, performance and the dependency of the affecting parameters such as state-of-charge and C-rates on the heat loss, efficiency, heat flux and maximum temperature of a commercial pouch type lithium-ion battery under various working conditions, different loading were applied to the battery. The capacity of the battery is 13Ah, which has a lithium titanate oxide based anode from Altairnano. Surface temperatures and heat flux of the Lithium-ion battery cell were measured by means of isothermal battery calorimeter. Different charge and discharge current pulses with different C-rates at ten state of charge (SOC) levels from 10% to 90% SOC were applied to the battery by using Maccor automated test system. It was concluded that heat losses demonstrated approximately decreasing pattern from 10 % SOC to 90% SOC.

Phosphorus Decorated Electrospun Carbon Anodes for Highly Efficient Lithium and Sodium Ion Batteries

Electrospinning has recently attracted considerable attention as a powerful and versatile technique to produce efficient, specifically tailored and high-added value anodes for lithium ion batteries (LIBs) and sodium ion ones (SIBs) [1]. Carbon electrospun nanofibers (CNFs), obtained via polymer electrospinning and subsequent carbonization, provide faster intercalation kinetics with respect to commonly employed powder material thanks to the high surface to volume ratio and to the shorter diffusion paths for ions and electrons transport. They offer a large number of ions insertion sites and the charge-transfer resistance at the electrolyte/active material interface is therefore reduced [2]. Recently, red phosphorus has been considered as one of the most promising anode materials for LIBs and SIBs alternative to the C-based ones [3] but its widespread and easy application has been prevented due to its low conductivity and large volume expansion during cycling, leading to low cyclability and poor rate performances. For this reason, red phosphorus cannot be used alone, but it must be combined with other anode materials able to accommodate its expansion and to increase its conductivity. Here we suggest a simple double-step procedure to obtain high-capacity electrospun carbon nanofibers anodes and to enhance their electrochemical performances with the insertion of red phosphorus in the matrix. In particular, we propose a simple drop-casting method to confine micro- and nanosized amorphous red P within the carbon mat, thus obtaining an highly efficient, self-standing, binder- and collector-free anode. Red P insertion in the CNFs net has been demonstrated by SEM and TEM analysis and the resulting material has been used to manufacture anodes for LIBs and SIBs. The reversible specific capacity and the rate capability of the obtained composite anodes have been significantly improved with respect to the electrospun carbon mat alone. The outstanding electrochemical performances for both LIBs and SIBs can be accounted to the synergic action of high-capacity red P clusters with the fast transport properties of the carbon fiber mat, acting also as an accommodation-volume matrix for the significant phosphorus expansion during charging/discharging. [1] Wang, H. G., Yuan, S., Ma, D. L., Zhang, X. B. & Yan, J. M. Electrospun materials for lithium and sodium rechargeable batteries: from structure evolution to electrochemical performance. Energy Environ. Sci. 8, 1660–1681 (2015) [2] Kim, C. et al. Fabrication of electrospinning‐derived carbon nanofiber webs for the anode material of lithium‐ion secondary batteries. Adv. Funct. Mater. 16, 2393–2397 (2006) [3] Qian, J., Wu, X., Cao, Y., Ai, X. & Yang, H. High capacity and rate capability of amorphous phosphorus for sodium ion batteries. Angew. Chemie 125, 4731–4734 (2013)

Study on Li Metal Deposition, SEI Formation on Anodes and Cathode Potential Change during the Pre-Lithiation Process in a Cell Prepared with Laminated Porous Anodes and Cathodes

The pre-doping of Li+ ions (pre-lithiation) in graphite anodes, which is needed to improve the initial charging/discharging efficiency of lithium ion batteries, was examined from the viewpoints of lithium metal deposition, surface electrolyte interface (SEI) formation and electrode potential changes in the cathode during the pre-lithiation. Using a cell composed of pre-laminated, through-holed anodes and cathodes, the anodes were pre-lithiated with the perpendicular pre-doping method, as explained in this work, which can effectively enhance the pre-lithiation process in laminated cells. In the pre-lithiation system, Li deposition was not observed on the anode surfaces during pre-lithiation, and the thickness of the SEI layers formed on the anodes did not increase. Moreover, the SEI layer has the same composition as that formed by the electrochemical lithiation (charging) process, even when the pre-lithiation of the anodes is accelerated by through-holes formed on the anode and cathode electrodes. In addition, the electrode potential of cathodes inserted between pre-lithiated anodes does not change during the pre-lithiation process, and the capacity of the cathodes does not degrade upon pre-lithiation. The perpendicular pre-doping method examined in this study is found to be applicable to the production process of lithium ion batteries with high charging/discharging efficiency.

Development of an Electro-Thermal Model for Electric Vehicles Using a Design of Experiments Approach

An accurate and computationally efficient lithium-ion battery model is beneficial when developing state-of-charge (SOC) and state-of-health (SOH) algorithms for battery management systems (BMS). These models allow for software-in-the-loop (SIL) and hardware-in-the-loop (HIL) testing, where the battery pack is simulated in software. However, development of these battery models can be time-consuming, especially when trying to model the effects of temperature and SOC on the equivalent circuit model (ECM) parameters. Estimation of this relationship is often accomplished by carrying out many experiments, which can be costly and time consuming for BMS manufacturers. To address these issues, this paper makes two contributions to literature. First, a comprehensive battery model is developed, where the ECM parameter surface is generated using a design of experiments (DOE) approach. Second, replication runs are conducted to accurately estimate the measurement noise and determine which model parameters are significant. The technique is then compared with existing approaches from the literature, and it is shown that, by using the proposed method, the same degree of accuracy can be obtained while requiring significantly fewer experimental runs. This can be advantageous for BMS manufacturers that require a high-fidelity model but cannot afford to carry out many experiments.

A Lithium‐Ion Battery using a 3 D‐Array Nanostructured Graphene–Sulfur Cathode and a Silicon Oxide‐Based Anode

An efficient lithium-ion battery was assembled by using an enhanced sulfur-based cathode and a silicon oxide-based anode and proposed as an innovative energy-storage system. The sulfur-carbon composite, which exploits graphene carbon with a 3 D array (3DG-S), was synthesized by a reduction step through a microwave-assisted solvothermal technique and was fully characterized in terms of structure and morphology, thereby revealing suitable features for lithium-cell application. Electrochemical tests of the 3DG-S electrode in a lithium half-cell indicated a capacity ranging from 1200 to 1000 mAh g-1 at currents of C/10 and 1 C, respectively. Remarkably, the Li-alloyed anode, namely, Liy SiOx -C prepared by the sol-gel method and lithiated by surface treatment, showed suitable performance in a lithium half-cell by using an electrolyte designed for lithium-sulfur batteries. The Liy SiOx -C/3DG-S battery was found to exhibit very promising properties with a capacity of approximately 460 mAh gS-1 delivered at an average voltage of approximately 1.5 V over 200 cycles, suggesting that the characterized materials would be suitable candidates for low-cost and high-energy-storage applications.

N-Doped graphene with anchored ZnFe2O4 nanostructures as an anode for lithium ion batteries with enhanced reversible capacity and cyclic performance

The challenges in developing more efficient lithium ion (Li-ion) batteries as a power source have been the subject of tremendous research due to the increase in demand for high-power unplugged electronics.

Designing BN sheets of X-G//(h-BN)<SUB align="right">n//X-G (X = B, N) and GO/h-BN/GO structures for based anodes material to improve the performance of lithium-ion batteries

We have investigated theoretically the efficiency of lithium-ion batteries (LIBs), aiming to remove some problems such as fire and explosion of the LIBs in view point of based anode materials. Nano-boron nitride compounds have displayed great potential as anode materials for LIBs due to their unique structural, mechanical, and electrical properties. The measured reversible lithium ion capacities of graphene/(h-BN)n/graphene(G/h-BN/G) based anodes are considerably improved compared to the conventional graphite(G)-based anodes. In this study boron nitride sheet has been localised inside the graphene as an option to enhance electrochemical ratio. Additionally, we have found that the structure of G/h-BN/G can be provide a suitable strategy for improving the performance of B-N-G based anodes because of its assembling into free-standing electrodes without any binder or current collector, which will lead to increased specific energy density for the overall battery design. In addition the modification of BN sheets and designing of X-G/h-BN/X-G structures (X = B and N) provides an extra strategy to improve the performance of LIBs. This study will help to create better anode materials which can replace graphite for higher capacity and better cycling performance in LIBs.

Graphene-wrapped CoNi-layered double hydroxide microspheres as a new anode material for lithium-ion batteries.

High-performance electrode materials that can be easily prepared are imperative for obtaining highly efficient lithium-ion batteries (LIBs). In this study, graphene-wrapped CoNi-layered double hydroxide (LDH) microspheres were first fabricated and used as an anode material for LIBs. The composite electrode with a mass ratio of 2.5 : 1 (CoNi-LDH/graphene) showed a high reversible specific capacity of 1428.0 mA h g-1 at 0.05 A g-1, excellent rate performances (977.5, 670.8 and 328.1 mA h g-1 at 0.5, 2 and 10 A g-1, respectively) and long-cycling performance (75% retention at 10 A g-1 after 10 000 cycles). The excellent electrochemical performances could be due to the following reasons: CoNi-LDHs had high chemical reactivity, and the graphene shell improved the electrical conductivity of CoNi-LDHs, which facilitated charge transfer; the graphene shell also suppressed the volume expansion of metal hydroxides during charge-discharge cycling and enhanced the cycle stability of the electrode. More importantly, this is a significant study to directly use LDHs as a potential electrode for LIBs, which can promote applications of electro-active LDHs in energy storage and conversion fields.

Li3V(MoO4)3 as a novel electrode material with good lithium storage properties and improved initial coulombic efficiency

It is of great significance to discover new negative electrode materials featuring a low operating voltage, high capacity and improved initial coulombic efficiency for lithium ion batteries. This is the first report on the use of orthorhombic Li3V(MoO4)3 as a promising anode material that exhibits natural advantages over reported traditional metal oxides. High-crystalline Li3V(MoO4)3 nanoparticles decorated with carbon are synthesized by a facile mechanochemical route followed by low-temperature (480°C) calcination. The lithium storage ability of the prepared Li3V(MoO4)3 anode is fully tapped at 3.0–0.01V vs. Li+/Li, displaying a lower voltage plateau than the conversion-type metal oxides. It delivers a high reversible specific capacity of 999 mAh g−1 at 50mAg−1 and a high coulombic efficiency of 82.6%. Moreover, it maintains a capacity retention of 92% after 75 cycles at 500mAg−1. The GITT-determined Li+ diffusion coefficient ranges from 10−10 to 10–13cm2s−1 along with the voltage. The lithium storage mechanism indicates that Li3V(MoO4)3 can be considered a pre-lithiated material. In-situ XRD testing during the first cycle reflects the conversion reaction of Li3V(MoO4)3. These insights will benefit the discovery of novel anode materials for lithium-ion batteries.

Excess Li-Ion Storage on Reconstructed Surfaces of Nanocrystals To Boost Battery Performance.

Because of their enhanced kinetic properties, nanocrystallites have received much attention as potential electrode materials for energy storage. However, because of the large specific surface areas of nanocrystallites, they usually suffer from decreased energy density, cycling stability, and effective electrode capacity. In this work, we report a size-dependent excess capacity beyond theoretical value (170 mA h g-1) by introducing extra lithium storage at the reconstructed surface in nanosized LiFePO4 (LFP) cathode materials (186 and 207 mA h g-1 in samples with mean particle sizes of 83 and 42 nm, respectively). Moreover, this LFP composite also shows excellent cycling stability and high rate performance. Our multimodal experimental characterizations and ab initio calculations reveal that the surface extra lithium storage is mainly attributed to the charge passivation of Fe by the surface C-O-Fe bonds, which can enhance binding energy for surface lithium by compensating surface Fe truncated symmetry to create two types of extra positions for Li-ion storage at the reconstructed surfaces. Such surface reconstruction nanotechnology for excess Li-ion storage makes full use of the large specific surface area of the nanocrystallites, which can maintain the fast Li-ion transport and greatly enhance the capacity. This discovery and nanotechnology can be used for the design of high-capacity and efficient lithium ion batteries.

The Influence of Surface Morphology of Copper Foils on the Efficiency of Lithium Ion Batteries

For the increasing demand of portable electronic devices and electric vehicles, lithium-ion batteries (LIBs) become a fast-growing and crucial technology because of high power density and light weight. To manufacture LIBs with good performance and appropriate cost, the components constituting LIBs should not only possess excellent quality and reliability but also be cost-effective. The current collector in the negative electrode of LIBs is an indispensable material, and the most commonly used material is copper foil with optimal quality. Currently, the mainstream copper foil adopted in LIBs is manufactured by rolling, since the rolled copper foil provides smooth surfaces on double sides (Rz < 1 μm), which ensure good capacity retention rate. However, the rolled copper foil is much more expensive than electrodeposited (ED) copper foil, especially for ultra-thin one (< 8 μm), since it requires more times of rolling and annealing. Consequently, the manufacture of thin ED copper foil with optimal properties is a critical issue to lower the cost of LIBs. Unfortunately, the ED copper foil produced by conventional method is not applicable in LIBs industry, and the main reason is that the surface roughness of the ED copper foil on both sides is remarkably different, which affects the capacity retention rate of LIBs [1]. In addition, the actual mechanism of how the surface morphology influencing the performance of LIBs has been not studied yet. In this work, we produced an 8 μm thick ED copper foil with different surface morphology by adding specific additives in the plating bath, including very low profile copper foil (Rz < 0.1 μm) or copper foil with pinholes on the surface, and comparing the performance of these ED copper foils with a conventional ED copper foil and a commercial rolled copper foil. The surface morphology and structure of each copper foil was examined by SEM, AFM, and XRD. Most importantly, carbon based material would be coated on these copper foils and then sealed in coin cells to examine the electrochemical behavior and efficiency of lithium ion coin cells. Accordingly, the relationship of the active carbon material and the surface morphology of the negative current collector was clarified. Reference : 1. Kazuo Kondo, Rohan N. Akolkar, Dale P. Barkey, Masayuki Yokoi, Copper Electrodeposition for Nanofabrication of Electronics Devices, p. 243, Springer-Verlag New York (2014).

Synthesis and Lithium Storage Properties of Zn, Co and Mg doped SnO2 Nano Materials

In this paper, we show that magnesium and cobalt doped SnO2 (Mg-SnO2 and Co-SnO2) nanostructures have profound influence on the discharge capacity and coulombic efficiency of lithium ion batteries (LIBs) employing pure SnO2 and zinc doped SnO2 (Zn-SnO2) as benchmark materials. The materials were synthesized via sol-gel technique. The structural, chemical and morphological characterization indicates that the Zn, Mg and Co dopants were effectively implanted into the SnO2 lattice and that Co doping significantly reduced the grain growth. The electrochemical performances of the nanoparticles were investigated using galvanostatic cycling, cyclic voltammetry and electrochemical impedance spectroscopy (EIS). The Co-SnO2 electrode delivered a reversible capacity of around 575mAhg−1 at the 50th cycle with capacity retention of ∼83% at 60mAg−1current rate. A capacity of ∼415mAhg−1 when cycling at 103mAg−1and >60% improvement in coulombic efficiency compared to the pure compound clearly demonstrate the superiority of Co-SnO2 electrodes. The improved electrochemical properties are attributed to the reduction in particle size of the material up to a few nanometers, which efficiently reduced the distance of lithium diffusion pathway and reduction in the volume change by alleviating the structural strain caused during the Li+ intake/outtake process. The EIS analyses of the electrodes corroborated the difference in electrochemical performances of the electrodes: the Co-SnO2 electrode showed the lowest resistance at different voltages during cycling among other electrodes.

A Data-Driven Learning-Based Continuous-Time Estimation and Simulation Method for Energy Efficiency and Coulombic Efficiency of Lithium Ion Batteries

Lithium ion (Li-ion) batteries work as the basic energy storage components in modern railway systems, hence estimating and improving battery efficiency is a critical issue in optimizing the energy usage strategy. However, it is difficult to estimate the efficiency of lithium ion batteries accurately since it varies continuously under working conditions and is unmeasurable via experiments. This paper offers a learning-based simulation method that employs experimental data to estimate the continuous-time energy efficiency and coulombic efficiency of lithium ion batteries, taking lithium titanate batteries as an example. The state of charge (SOC) regions and discharge current rates are considered as the main variables that may affect the efficiencies. Over eight million empirical datasets are collected during a series of experiments performed to investigate the efficiency variation. A back propagation (BP) neural network efficiency estimation and simulation model is proposed to estimate the continuous-time energy efficiency and coulombic efficiency. The empirical data collected in the experiments are used to train the BP network model, which reveals a test error of 10−4. With the input of continuous SOC regions and discharge currents, continuous-time efficiency can be estimated by the trained BP network model. The estimated and simulated result is proven to be consistent with the experimental results.

Synergetic Effects of Inorganic Components in Solid Electrolyte Interphase on High Cycle Efficiency of Lithium Ion Batteries

The solid electrolyte interphase (SEI) is a passivation layer formed on an electrode surface that can enhance long-term electrode stability. The inorganic components formed in SEI layer, including lithium carbonate and lithium fluoride, play a critical role in terms of providing both mechanical and chemical protection as well as accommodating lithium ion transport. Although lithium carbonate and lithium fluoride have relatively low ionic conductivities, surprisingly, we find that a synthetic composite coating made of both components creates a defect-intensive interface, which significantly improves lithium transport. The synergetic effect of both inorganic components leads yields higher current efficiencies and cycling stability. We envision that the defect-intensive composite coating is a promising artificial SEI layer for the suppression of undesirable side reactions and improvement in the life of lithium ion batteries employing silicon negative electrodes.

Eco-friendly synthesis of rutile TiO2 nanostructures with controlled morphology for efficient lithium-ion batteries

An environmentally friendly, scalable, and template-free route based on a simple hydrothermal process has been developed for preparing the rutile TiO2 nanostructures by using titanium oxysulfate (TiOSO4) as the titanium precursor under an acidic condition. Notably, two kinds of TiO2 nanostructures with different morphologies are obtained only by simply adjusting the solvent. The as-prepared hierarchical TiO2 nanostructures are constructed by numerous nanobundles or nanoneedles, corresponding to water and ethylene glycol as the solvent, respectively, designed as H-TiO2 and E-TiO2. The nucleation and crystal growth of rutile TiO2 products can be dominated with the help of hydrochloric acid, resulting in a uniform size and controllable morphology. The achieved products can be applied as the excellent anode material for lithium-ion batteries. Benefiting from the large specific surface area, small particle size and loosely hierarchical nanostructure, E-TiO2 product exhibits superior electrochemical properties including high reversible capacity, long cycling performance and good rate capability. Significantly, it shows a high reversible capacity up to 190mAhg−1 after 200 cycles at a high current rate of 0.6C, and a stable capacity of 85.4mAhg−1 can also be delivered at an extremely high rate of 10C.

High Voltage Li-Ion Battery Using Exfoliated Graphite/Graphene Nanosheets Anode.

The achievement of a new generation of lithium-ion battery, suitable for a continuously growing consumer electronic and sustainable electric vehicle markets, requires the development of new, low-cost, and highly performing materials. Herein, we propose a new and efficient lithium-ion battery obtained by coupling exfoliated graphite/graphene nanosheets (EGNs) anode and high-voltage, spinel-structure cathode. The anode shows a capacity exceeding by 40% that ascribed to commercial graphite in lithium half-cell, at very high C-rate, due to its particular structure and morphology as demonstrated by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The Li-ion battery reveals excellent efficiency and cycle life, extending up to 150 cycles, as well as an estimated practical energy density of about 260 Wh kg(-1), that is, a value well exceeding the one associated with the present-state Li-ion battery.

Synergetic Effects of Inorganic Components in Solid Electrolyte Interphase on High Cycle Efficiency of Lithium Ion Batteries.

The solid electrolyte interphase (SEI), a passivation layer formed on electrodes, is critical to battery performance and durability. The inorganic components in SEI, including lithium carbonate (Li2CO3) and lithium fluoride (LiF), provide both mechanical and chemical protection, meanwhile control lithium ion transport. Although both Li2CO3 and LiF have relatively low ionic conductivity, we found, surprisingly, that the contact between Li2CO3 and LiF can promote space charge accumulation along their interfaces, which generates a higher ionic carrier concentration and significantly improves lithium ion transport and reduces electron leakage. The synergetic effect of the two inorganic components leads to high current efficiency and long cycle stability.

ITO/MWCNT Nanocomposites as New Novel Anode Electrodes for Li-Ion Batteries

In this study, we present a new anode electrode consisting of Indium Tin Oxide and multiwall carbon nanotube based buckypapers for high efficient lithium ion batteries. Core/shell Indium Tin Oxide/Buckypapers were produced by vacuum filtration techniques followed by an rf magnetron sputtering. The nanosized indium tin oxide particles were uniformly anchored onto the surfaces of buckypapers with a mean grain sizes of 2-7 nm confirmed by the FESEM, TEM and XRD results. The as-prepared nanocomposite anode electrodes exhibited outstanding reversible capacity (859, 875 and 895 mA h g(-1) after 50 cycles) and no significant capacity fading is observed after 50 cycles. The unique nanocomposite architecture which integrates both electronic conductivity and buffering matrix design strategies, contributing to enhanced lithium storage performance.

Ultrasmall TiO2 nanoparticles embedded in nitrogen doped porous graphene for high rate and long life lithium ion batteries

Modifying TiO2 with nitrogen and porous N doped graphene to form mesoporous TiO2/N doped graphene nanostuctures has been successfully achieved by a two-step hydrothermal–calcining method with urea as an inhibitor and nitrogen source. Porous N doped graphene network hinders the agglomeration of TiO2 nanoparticles, and enhances the conductivity of TiO2 based electrode simultaneously, achieving the enhanced capacity and fast discharge and charge rate. As a anode material, such nanocomposite exhibits a capacity as high as 330.7 mAh g−1at a current rate of 0.5 C and a reversible capacity over 288.6 mAh g−1 accompanying a coulombic efficiency of 96.4% at a current rate of 30 C after 1000 cycles. The superior electrochemical performance is ascribed to the excellent rate performance and cycling stability, moreover, highly exciting from a fundamental point of view, the good electronic conductivity caused by N incorporated graphene sheets and the positive synergistic effect between ultrafined nanoparticles and porous N decorated graphene matrix. Additionally, the restriction to ultrasmall reaction domains with high specific surface area and mesoporous structure allowing for an almost diffusion less and nucleation-free “conversion” results in highly efficient lithium ion batteries with fast charge/discharge rate and a remarkably enhanced cycling performance.

Multi layered Si–CuO quantum dots wrapped by graphene for high-performance anode material in lithium-ion battery

Various approaches to improve the efficiency of Lithium ion batteries (LiB) by using Si have been suggested because Si has the highest known lithium capacity. Although Si is more than ten times higher capacity than existing graphite anodes, Si anodes have limited applications due to its high volume change during cycling. Here we demonstrated graphene/Si–CuO quantum dots (Gr/Si–CuO QD) layered structure as an efficient LiB anode which prevents large volume expansion of Si due to the presence of CuO–Cu3Si. By Electrophoresis Deposition technique, the multi-layer of graphene and Si–CuO QD has been successfully fabricated followed by annealing process to form Cu3Si interlayer as confirmed by High Resolution Transmission Electron Microscope-Energy Dispersive Spectroscopy, X-ray diffraction and Raman analyses. The annealed Gr/Si–CuO QD exhibit the initial gravimetric specific capacity of 2869mAhg−1 which is five times higher than that of annealed graphene at 0.5C. After 100 cycles at 1C rate the capacity retains ∼71% and the excellent rate capability even at high C rate reveals controlled volume expansion owing to the multi layered architecture and the Cu3Si inter layer. The layered structure of Gr/Si–CuO QD electrode could be applied in next generation micro power sources.