Lower Cycle Life Research Articles

A bioinspired high-modulus mineral hydrogel binder for improving the cycling stability of microsized silicon particle-based lithium-ion battery

Silicon with high specific capacity is deemed an ideal anode material for lithium ion batteries, which, however suffers from low cycling life due to its dramatic volume changes. Water-soluble polymer binders recently gain increasing attention by providing an eco-friendly and low-cost way in improving the cycling stability of Si-based anodes. Herein, a novel bioinspired supramolecular mineral hydrogel binder consisting of polyacrylic acid (PAA) physically crosslinked with amorphous calcium carbonate (ACC) nanoparticles is designed for high-performance anodes made from low-cost microsized Si particles. Owing to its organic-inorganic hydrophilic nature, ACC-PAA hybrid binder exhibits the reported highest modulus (~ 22 GPa) for polymer binders in electrolyte, even higher than lithiated Si species (Li15Si4, ~ 12 GPa). Together with its excellent adhesion and electrochemical stability, ACC-PAA binder can effectively suppress the pulverization of Si particles and maintain the mechanical integrity of electrodes during cycling. Therefore, even with a low binder content, the anode still shows an initial discharge capacity of 2,973 mAh·g−1 and Coulombic efficiency of 81.5%, and retains 75% at a current density of 600 mA·g−1 after 100 cycles. The present organic-inorganic hybrid mineral binder may open a new approach for designing more effective polymer binders for Si-based lithium-ion batteries.

Ni@N-doped graphene nanosheets and CNTs hybrids modified separator as efficient polysulfide barrier for high-performance lithium sulfur batteries

Lithium-sulfur batteries (LSBs) have been regarded as one of the most promising energy storage systems to break through the upper limit of lithium-ion batteries. However, the rampant diffusions of soluble lithium polysulfides (LiPSs) in the electrolyte induced the shuttle effect between anode and cathode, resulting in low sulfur utilization, low energy efficiency and short cycling life. Herein, we prove the rational design and construction of Ni nanoparticles filled in vertically grown N-doped bamboo-like carbon nanotubes (CNTs) on graphene nanosheets (Ni@NG-CNTs) as efficient polysulfide barrier for high-performance LSBs. The unique design integrates graphene nanosheets and CNTs into hierarchical architectures with one-dimensional (1D) CNTs, two-dimensional (2D) ultrathin nanosheets and abundant carbon nanocages. This design provides large surface area for lithium polysulfides (LiPSs) adsorption, accelerates electron transport and enhances electrochemical redox of LiPSs. Benefiting from the unique structural features, the LSBs with the Ni@NG-CNTs as polysulfide barrier keep high reversible specific capacities of 309.1 and 265.0 mAh·g−1 at 5 and 10 C rates after 500 cycles. This work provides a new strategy for constructing self-assembled hybrids of CNTs and graphene nanosheets with abundant carbon nanocages for high-performance LSBs.

In-situ covalent bonding of polysulfides with electrode binders in operando for lithium–sulfur batteries

Dissolved polysulfides cause high self-discharge, low coulombic efficiency and short cycling life due to their shuttle effect in the charge/discharge cycles in lithium-sulfur (Li-S) batteries. Despite of various attempts (e.g., addition of metal oxides and chalcogenides in the cathode, immobilization of sulfur with various carbons, and confinement of sulfur within the cathode side with membranes) in solving this problem, it still remains a major challenge for Li-S batteries. Here, we demonstrate that chemically active binders can in situ bond to the polysulfides in the electrode. Besides the common binding functions of the cathode materials to the current collector, the covalent bonding between binders and polysulfides could bestow the higher capacity, stable cycling and high coulombic efficiency, even under the high loading of sulfur contents. Thus, this study provides an alternative and effective way in solving the shuttle effect of the dissolved lithium polysulfides for Li-S batteries.

Extending Lifespan of Lithium Metal Electrodes Via Surface Structure Regulation Strategies

Li metal is an ideal anode material for high-energy secondary batteries owing to its ultrahigh capacity (3860 mAh g- 1) and the lowest reduction potential (-3.04 V vs. S.H.E.). To achieve practical application of Li metal electrodes, two fundamental challenges need to be resolved: (1) accommodating the large change in electrode volume during cycling that creates significant mechanical instability and cracks in electrodes and their interfaces; (2) preventing the side reactions of Li metal towards the electrolyte that produce a solid electrolyte interphase (SEI) layer, which cannot withstand mechanical deformation and continuously break and repair during cycling, resulting in low Coulombic efficiency and short cycling life. To address the harmful problematic of instable interfaces of Li metal anodes, we have developed a series of protective structures to provide efficacious volume confinement of Li metal surfaces, with aim of stabilizing the SEI layers for high Coulombic efficiency and long lifespan of the Li metal anodes (Figure 1). In the first protective model, we have fabricated a porous Al2O3 layer as an inorganic “host” to accommodate the deposited Li, and in parallel, a reinforced SEI was in-situ formed across this porous layer by using an electrolyte additive (Figure 1a). Based on its synergetic effect, such a composite structure has enabled a Coulombic efficiency of Li plating/stripping as high as 97.5-98% in carbonate-based electrolyte [1]. In the second protective model, we have synthesized a 3D porous Cu current collector with in-situ formed Li2O as reinforcing agent (Figure 1b). On one hand, the 3D Cu structure could efficiently reduce the local current density with aim of hindering the growth of Li dendrite; on the other hand, the Li2O reinforcing agent could stabilize the structure by extending the cycling life of Li anodes for more than 150 cycles [2]. In the third protective model, we have realized the formation of 3D SEI layer across a carbonaceous porous structure (Figure 1c). Thanks to the rigid carbonaceous structure with related 3D SEI layer coating, the Li plating/stripping efficiency was higher than 98% for more than 300 cycles [3]. Recently, our group has developed a plasma modified Porous 3D Carbon paper was fabricated and explored to store Li metal and stabilize Li plating/stripping processes. Using a mesoplasma technic, a high-quality sponge carbon layer was deposited on the top of the 3D carbon paper. Based on this Sponge Carbon layer coated 3D Carbon Paper (SCCP) as a host, Li ions are intercalated in the graphitic carbon paper skeletons then followed by Li metal plating, leading to the entire Li metal deposition underneath the sponge carbon layer, meanwhile the sponge Carbon layer acts as a physical barrier to mechanically block dendrite growth towards the electrolyte. In corrosive carbonate electrolyte, the Coulombic efficiency of Li metal plating/stripping processes could achieve 98-99% at high capacity of 3-4 mAh cm-2. Dendrite-free surface was also observed on the protected Li foil in a Li-LiFePO4 coin cell after 1000 cycles (6 months cycling). These results demonstrate the ability of the SCCP structure to protect Li metal in high-energy density batteries for long-term operation. Peng, S. Wang, J. Zhou, Y. Jin, Y. Liu, Y. Qin, Cai Shen,* W. Han* and D. Wang,* J. Mater. Chem. A, 2016, 4, 2427-2432.Zhang, X. Xu, S. Wang, Z. Peng,* M. Liu, J. Zhou, C. Shen,* and D. Wang,* ACS Appl. Mater. Interfaces 2016, 8, 26801-26808.Zhang, Z. Peng,* J. Zheng, S. Wang, Z. Liu, Y. Bi, Y. Chen, G. Wu, H. Li, P. Cui, Z. Wen* and D. Wang*, J. Mater. Chem. A, 2017, 5, 9339-9349.Lu, Z. Zhang, X. Chen, Q. Chen, F. Ren, M. Wang, S. Wu,* Z. Peng,* D. Wang and J. Ye, J. Energy Storage Materials, http://dx.doi.org/10.1016/j.ensm.2017.09.011. Figure 1

Construction of 3D Carbon Nanostructure: Carbon Nanosheets Decorated Carbon Nanofiber As a Three-Dimensional Carbon Hybrid for High Performance Lithium-Sulfur Battery

Among the emerging energy storage methods, lithium-sulfur battery (LiS) has drawn plenty of attentions due to its high theoretical energy density (2600 Wh kg-1),1 economical cost and environmental benignity. Nevertheless, the insulating nature of sulfur and notorious polysulfides shuttling result in a low sulfur utilization and short cycling life.2 To address these problems, carbon material has been confirmed as an ideal sulfur host to promote LiS’s performance because of their low cost, high conductivity and controllable structure such as carbon spheres, carbon nanotube/fibers and carbon nanosheets. For example, one-dimensional carbon nanotube can increase the sulfur utilization by providing better electrical conductivity. However, its “open-to-electrolyte” structures cannot effectively prevent shuttling effect.3 As for zero-dimension carbon materials, core/yolk shell carbon spheres in particular, are less capable of establishing conductive networks, which in turns, compromise the sulfur utilization and rate capability.4 Thus, it is of great necessity to develop three-dimensional (3D) carbon materials with multiple functions in order to achieve high-performance lithium-sulfur batteries. Along this line, we prepared a three-dimensional carbon nanosheets modified carbon nanofiber (3DCNF) as high porosity sulfur host. After decorated with vertically aligned carbon nanosheets, the surface area of pristine carbon nanofiber was dramatically increased from 30 m2/g to 500 m2/g due to the expanded dimension. Although both 1D nanofiber and 2D nanosheets cannot effectively prevent polysulfides shuttling by themselves, the delicate combination of them endows new functions, where 3D carbon hybrid is capable of accommodating sulfur expansion and deterring polysulfides dissolution by the hierarchical porous structure and interconnected carbon nanosheets. At the same time, the 3D porous carbon nanofiber can also form conductive network that allows rapid electron transfer. With the structural advantages, the 3DCNF and sulfur composite delivered a capacity as high as 1266, 977 mAh/g at 0.1 and 0.5 C, respectively. After 500 cycles at 0.5 C, it still retains a capacity of 607 mAh/g (0.07% capacity fading per cycle), exhibiting excellent cycling capability. Reference M. K. Song, E. J. Cairns and Y. Zhang, Nanoscale, 2013, 5, 2186-2204.Y. Yang, G. Zheng and Y. Cui, Chem. Soc. Rev., 2013, 42, 3018-3032.X. Liang, Z. Wen, Y. Liu, H. Zhang, J. Jin, M. Wu and X. Wu, J. Power Sources, 2012, 206, 409-413.Y. J. Hong, J.-K. Lee and Y. Chan Kang, J. Mater. Chem. A, 2017, 5, 988-995. Figure 1

What are the tradeoffs between battery energy storage cycle life and calendar life in the energy arbitrage application?

This paper develops a method and framework for analyzing the tradeoffs between the calendar life and cycle life of battery energy storage used for energy arbitrage in a wholesale electricity market. We implement a linear program to analyze the revenue potential of a battery system participating in the Electric Reliability Council of Texas (ERCOT) electricity market during 2002–2015, and show how the number of charge-discharge cycles performed in a year affects annual revenue potential. Then, we calculate the potential present worth (or the sum of discounted yearly revenues) of battery systems of various discharge durations and roundtrip efficiencies as a function of their calendar life and cycle life, and show how increasing calendar life and cycle life affects present worth. We show that increasing calendar life provides a greater benefit than increasing cycle life for lithium-ion, sodium-sulfur, and vanadium-redox flow batteries, which counters conventional notions about the importance of battery cycle life. However, we find that increasing the cycle life of lead-acid batteries provides a greater benefit than increasing calendar life, because lead-acid batteries have a lower cycle life than other technologies.

Structural Dependence of the Sulfur Reduction Mechanism in Carbon-Based Cathodes for Lithium–Sulfur Batteries

Lithium–sulfur batteries constitute a promising energy storage technology due to their high theoretical specific capacity and energy density. However, their commercialization has been hindered due to the low cycling life of the devices caused by long chain polysulfide shuttling between electrodes, the low conductivity of sulfur, and the volumetric expansion upon sulfur reduction. Nanostructured porous carbon cathodes have been the object of extensive research due to their proven capacity to overcome the aforementioned issues, though there is still a limited understanding of the physical–chemical behavior leading to high electrochemical performances. Herein, quantum chemical calculations are used to study the effect of the structure of porous carbon cathodes on the sulfur reactivity in lithium–sulfur batteries. Ab initio molecular dynamics (AIMD) simulations are initially employed to evaluate sulfur reduction mechanisms and kinetics in a confined environment. A porous cathode architecture is modeled throug...

Effects of cerium on the hydrogen absorption-desorption properties of rare earth-Mg-Ni hydrogen-absorbing alloys

Abstract The influence of Ce addition on the phase constitution, microstructure, hydrogen absorption/desorption properties and battery performances of newly developed rare earth (RE)-Mg-Ni hydrogen-absorbing superlattice alloys for negative electrode materials in Ni-metal hydride (MH) batteries were investigated. The partial substitution of RE (La and Nd) with Ce results in a higher discharge performance and a lower cycle life in the battery. The Ce addition greatly affects the phase constitution, which is mainly characterized by increased formation of the AB2 phase (A = RE or Mg and B = Ni or Al). The existence of the AB2 phase is found to accelerate alloy pulverization and oxidation when the alloys are used as negative electrode materials in Ni-MH model cells. The accelerated pulverization and oxidation are considered to be responsible for the observed higher discharge performance and lower cycle life in the batteries, respectively.

Preheating treatment of thermal barrier coatings by supersonic plasma jet

The low thermal cycling life is a big concern for plasma sprayed thermal barrier coatings (TBCs). This paper presents a novel and effective preheating treatment conducted by one supersonic plasma jet, which has been proven to significantly improve the anti-oxidation and thermal shock resistance of TBCs. After preheating treatment, the surface roughness (Ra) of metallic bond coat decreased by nearly 30%, while one dense oxide layer appeared on its surface. This oxide layer effectively suppressed the growth of thermally grown oxides (TGOs), resulted in the improvement of anti-oxidation of TBCs. The results of water-quenching test from 1100°C into room temperature showed that the thermal cycling life of preheated TBCs reached 846 cycles, approximately 126 cycles higher than their counterparts without preheating.

Thin Film Coatings on Multiwalled Carbon Nanotubes for Lithium-Oxygen Battery Cathodes: Eliminating the Carbon Surface

Energy storage is one of the biggest challenges in our way before switching to sustainable energy resources. Batteries can be a viable solution to this challenge if “better” batteries with higher energy density, improved stability and cheap price can be realized. Lithium-oxygen batteries have become popular recently as they can theoretically offer much higher energy densities compared the widely used Li-ion or Ni-Mh batteries. However, realizing Li-O2 batteries is no easy task, because of the electrolyte decomposition, cathode degradation and anode related problems which were intensively studied in recent years.1,2 These aforementioned problems come together to complicate the electrochemistry taking place inside the cell, consecutively over-potential, low cycling life and poor current rate responses are observed. In this study thin film coatings of TiO2 are fabricated using atomic layer deposition technique (ALD) on multiwalled carbon nanotubes (MWCNT) and these composites were used as cathode for Li-O2 battery. (Fig.1) Such a structure eliminates the direct interaction of carbon surface with electrolyte molecules and prevents the degradation of carbon cathode without sacrificing the high energy density carbon provides. TiO2 was chosen as the coating material, since in a recent study by Thotiyl et. al. a thin surface film of TiO2 was shown to increase the oxygen reduction and evolution reactions activity of the TiC cathodes.3 The electrochemical properties of the prepared composites and the comprehensive analysis of their effect on degradation mechanisms will be discussed in this presentation. References Thotiyl, M. M. O., Freunberger, S. A., Peng, Z., Bruce, P. G., J. Am. Chem. Soc. 2013, 135, 494.McCloskey, B. D., Speidel, A., Scheffler, R., Miller, D. C., Viswanathan, V., Hummelshøj, J. S., Nørskov, J. K., Luntz, A. C., J. Phys. Chem. Lett., 2012, 3, 997.Thotiyl, M. M. O., Freunberger, S. A., Peng Z., Chen, Y., Liu, Z., Bruce, P. G., Nat. Mater. 2013, 12, 1050. Figure 1

Effect of LaCoO<sub>3</sub> Additive on the Electrochemical Behavior of Zinc Anode in Alkaline Solution

The utilization of zinc anode for zinc-based battery is limited due to low cycling life, shape change and ZnO passivation on the electrode surface. The electrochemical behavior of zinc anode in the presence of the additives added to the electrodes or the electrolytes have been reported. In this work, LaCoO3 was used as an additive to improve the electrochemical properties of the zinc oxide anode. LaCoO3 synthesized by sol gel method (Schiff base complex) was added to zinc oxide powder (99.9%) with the weight ratio of 1:0.001, 1:0.002 and 1:0.003. The relative ZnO/LaCoO3 ratios were confirmed by particle induced x-ray emission (PIXE) technique.The electrochemical behavior of the ZnO/LaCoO3 electrodes in 6M KOH solution were investigated by voltammetry and electrochemical impedance spectroscopy (EIS). The cyclic voltammogram showed that ZnO/LaCoO3 gave higher anodic current and ZnO passivation delayed. The EIS spectra showed that charge transfer resistances of the ZnO/LaCoO3 anodes due to zinc oxidation were higher than that of ZnO electrode

Rechargeable batteries with aqueous electrolytes

In recent years, rechargeable batteries (RB’s) have found important new applications in rapidly expanding markets, such as portable computers (laptops), telecommunication equipment (handies), camcorders and tools. The interest in electric vehicles has continued to stimulate research on RB’s having improved specific energy. Attention has been focussed on nonaqueous battery systems, in particular on lithium batteries. Small rechargeable lithium batteries, available on the market today, show specific energies of 100–120 Wh kg −1. The upper limit surpasses those of aqueous electrolyte counterparts (nickel–cadmium or nickel–metal hydride) by a factor of 1.5–2. Is there still a future for aqueous electrolyte battery systems? This paper reviews the present status of the various RB’s with aqueous electrolytes and analyses their outlook for the future. Traditionally, lead, cadmium and iron were used as active materials in the negative electrode. In recent years, research on rechargeable zinc electrodes has been intensified. The development of metal hydride negative electrodes has resulted in RB’s with improved specific energy (60–70 Wh kg −1, under some conditions even 80 Wh kg −1). Similar values can be reached with nickel–zinc batteries, the latter having, however, a considerably lower cycle life. Rechargeable zinc–air batteries, with bifunctional air electrodes, are capable of specific energies matching those of lithium batteries. Their cycle life is, however, up to now still totally unsatisfactory. Systems with ‘mechanical recharge’ of the highly porous zinc electrodes have been tested in electric vehicles. Although the specific energy during discharge exceeded 200 Wh kg −1, this system has not gained any large scale practical acceptance. All metal–air batteries suffer, in principle, from a poor energy efficiency ( η<50%). At present, it appears unlikely that alternative negative electrode materials, such as anthraquinone, polypyrrole, or specially passivated lithium, can be adapted to permit long-term cycling in aqueous electrolytes. Regarding positive electrodes, no alternatives to lead dioxide and nickel-oxy hydroxide are in sight. Manganese dioxide electrodes tend to rapidly loose capacity during cycling. So far, active materials such as bromine, chlorine and insertion electrodes based on carbon, have not, and will probably not in the near future, see commercial use. The main advantages of aqueous electrolyte systems are low cost and ability to withstand overcharge (due to the establishment of the socalled oxygen cycle). This simplifies charging equipment. Due to high electrolyte conductivity, relatively thick electrodes can be used. Lead–acid batteries, in particular maintenance-free or sealed types, will remain ‘work horses’ in SLI and stationary (standby) applications. Large stationary redox cells may possibly find use for the storage of solar energy. Of all the aqueous systems, the metal hydride batteries might have the brightest future. Chances are good that their specific energy can be further improved. Negative and positive electrodes are both of the ‘insertion type’, thus avoiding a dissolution–redeposition step. This results in excellent cycle life. As to electric cars, aqueous–electrolyte fuel cell systems might some day become power sources being capable to beat lithium batteries with respect to specific energy and driving range.

In situ Synchrotron X-ray Studies on Novel Mn Oxide Spinel Cathodes for Li-ion Batteries: Influence of Other Transition Elements

ABSTRACTPartial substitution of Mn in lithium manganese oxide spinel materials by Cu and Ni greatly affects the electrochemistry and the cycle life characteristics of the cathode. Substitution with either metal or a combination of both shortens the 4.2 V plateau associated with the conversion of Mn3+ to Mn4+. A higher voltage plateau associated with oxidation of the substituted transition element is also observed. These substituent also significantly alter the onset of Jahn Teller distortions in the 3 V plateau. Synchrotron based in situ x-ray absorption (XAS) is used to determine the exact nature of the oxidation state changes in order to explain the overall capacities at the different voltage plateaus. Synchrotron based in situ x-ray diffraction (XRD) studies on LiCu0.5Mn1.504 shows single phase behavior in the 4-5 V region and a good cycle life. Lower cycle life characteristics for LiNi0.5Mn1.504 and LiNi0.25Cu0.25Mn1.504 are accounted for on the basis of several phase coexistence in this potential region. In the 3 V plateau however, the LiCu0.5Mn1.504 shows onset of the Jahn Teller distortions, in contrast to the LiNi0.5Mn1.504 and LNi0.25Cu0.25WMn1.504.