Query: lithium ion current collector

title: Systematic analysis of interfacial resistance between the cathode layer and the current collector in lithium ion batteries by electrochemical impedance spectroscopy
abstract: Lithium ion batteries are required to have high power density, that is to reduce impedance, for use in electric vehicles. This paper focuses on interfacial resistance between the cathode layer (CL) and the current collector (CC) observed at high frequencies, which is generally attributed to a resistance of surface film like SEI. To investigate the interfacial resistance systematically, different interfaces between the CL and the CC were prepared by controlling the press rate for the cathode preparation, or by introducing a carbon under coating layer (CUL) followed by electrochemical impedance spectroscopy (EIS) The interfacial resistance between the CL and the CC prepared with an insufficient press rate or without a CUL was extremely high for the entire cathode. From the cathode cross sectional observation, it was observed that this high interfacial resistance was caused by low contact rate at the interface. Using a pouch type symmetric cell, EIS revealed that the interfacial resistance is attributed to electric resistance, that is, contact resistance at the interface. Also, the other resistances were attributed to be the ionic resistance of the electrolyte and pores in the cathode, and the charge transfer resistance of the cathode. Furthermore, the effectiveness of the CUL was shown to decrease the cathode impedance.

title: Binder free carbon coated TiO2@graphene electrode by using copper foam as current collector as a high performance anode for lithium ion batteries
abstract: Anatase TiO2 is widely used in lithium ion batteries (LIBs) due to its excellent safety and excellent structural stability. However, due to the poor ion and electron transport and low specific capacity (335 mAh g 1) of TiO2, its application in LIBs is severely limited. For the first time, we report a binder free, carbon coated TiO2@graphene hybrid by using copper foam as current collector (TG CM) to enhance the ionic and electronic conductivity and increase the discharge specific capacity of the electrode material without adding conductive carbon (such as super P, etc. and a binder (such as polyvinylidene fluoride (PVDF) etc. When serving as an anode material for LIBs, TG CM displays excellent electrochemical performance in the voltage range of 0.01 3.0 V. Moreover, the TG CM hybrid delivers a high reversible discharge capacity of 687.8 mAh g 1 at 0.15 A g 1. The excellent electrochemical performance of the TG CM hybrid is attributed to the increased lithium ion diffusion rate due to the introduction of graphene and amorphous carbon layer, and the increased contact area between the active material and electrolyte, and small resistance with copper foam as the current collector without an additional binder (PVDF) and conductivity carbon (super P)

title: Stress relieved Si anode on a porous Cu current collector for high performance lithium ion batteries
abstract: To overcome the mechanical stress generated during the cycling process in lithium ion batteries, Si anode is fabricated on a porous Cu current collector with holes using sputtering deposition method. The porous Cu/Si shows superior high rate and cycling performance in lithium ion batteries compared to the Si anode on the flat Cu. The excellent high rate performance and stable cyclability of the porous Cu/Si can be predominantly attributed to the efficient relief of the stress generated by the volumetric expansion of the Si anode on the porous Cu current collector.

title: Bio inspired, nitrogen doped CNT graphene hybrid with amphiphilic properties as a porous current collector for lithium ion batteries
abstract: Carbon based materials have been proposed as current collectors for lithium ion batteries (LIBs) however few of them have successfully integrated sp2 carbon and reach in sp3 carbon into one monolithic structure: in a way that sp2 carbon is responsible for electron transfer and sp3 carbon is capable for a high loading of active materials. Here we report an in situ growth of a nitrogen doped carbon nanotube (NCNT) on a three dimensional (3D) graphene network. The proposed structure (NCNT 3DG) is a bio inspired nanomaterial with a design of a "natural forest" The in situ growth of NCNT on 3D graphene guarantees a fast electron transfer between NCNT and 3DG. The hydrophilic nature of NCNTs insures a high loading of the active materials, such as Li4Ti5O12 (LTO) The designed LTO NCNT 3DG electrode achieves an active materials loading of 74 wt% of the overall electrode mass, compared to about 20 wt% on traditional metal foil and 55 wt% on other reported carbon current collectors. Such a hybrid electrode delivers a higher specific capacity of 158 mAh g 1 at 5C. The specific capacity retains 94% after 2000 cycles at 10 C. The proposed NCNT 3DG current collector is a novel strategy for fast charging LIBs.

title: Characterisation of lithium ion battery anodes fabricated via in situ Cu6Sn5 growth on a copper current collector
abstract: Li ion batteries (LIBs) are favoured in many applications due to their high energy density and good cyclic performance. However, some safety concerns remain with respect to the risk of fires and explosions with LIBs. Carbon based anode materials in LIBs operate close to the Li metal reduction potential, therefore Li dendrites can grow during voltage fluctuations, causing short circuits which may lead to fires. The Cu6Sn5 anodes has the lithiation potential at about 0.4 V vs Li/Li+ and therefore less prone to Li metal plating. A new manufacturing method involving direct in situ formation of Cu6Sn5 on a Cu current collector via melt solid contact is proposed. This method combines the active material production and the anode fabrication into a single process. Lithiation and delithiation mechanisms of the anode produced are studied by in situ synchrotron X ray powder diffraction (XRPD) and ex situ high voltage transmission electron microscope (HV TEM) The in situ XRPD study shows a reversible two step reaction during cycling, and also reveals the differences in the reaction mechanisms at higher charge/discharge rates than those in published data.

title: Interface modification of an Al current collector for ultrafast lithium ion batteries
abstract: The ability to provide a reasonable design and a practical modification of the interfacial structure in lithium ion batteries (LIBs) is a key technology to enhance electrochemical kinetics and to improve ultrafast cycling performances. However, in recent years, despite considerable structural engineering efforts focused on active materials, in practice, ultrafast LIB performances still are characterized by low ultrafast cycling capacity and poor stability at the current density above 6 C. To solve these problems, in the present study, we propose a unique interface modification of the Al foil having crater porous interface using the electrochemical etching process. The cathode fabricated with a crater porous interface of the Al foil exhibits a remarkably enhanced ultrafast storage performance, such as high ultrafast cycling capacity (91.0 mAh g 1 at 10 C) and superb ultrafast cycling stability (76.2 mAh g 1 with the capacity retention of 84.8% at 10 C after 250 cycles) as compared to those of the cathode fabricated with the bare Al foil and commercial etched Al foil. These improved electrochemical performances can be explained by the combined effects of improved electrical conductivity related to fast charge transport and increased interface contact area between the active material and the current collector related to enhanced interface adhesion during ultrafast cycling performance.

title: A Novel and Generalized Lithium Ion Battery Configuration utilizing Al Foil as Both Anode and Current Collector for Enhanced Energy Density.
abstract: A novel battery configuration based on an aluminum foil anode and a conventional cathode is developed. The aluminum foil plays a dual role as both the active anode material and the current collector, which enhances the energy density of the packaged battery, and reduces the production cost. This generalized battery configuration has high potential for application in next generation lithium ion batteries.

title: 3D cathode design with foam like aluminum current collector for high energy density lithium ion batteries
abstract: Increasing the area specific capacity and reducing the inactive/active material ratio of cathodes and anodes is considered to be a promising approach to improve the energy density of lithium ion batteries. In principle, this can be achieved by increasing the thickness and the active material mass loading of the electrodes. However, the fabrication of thick electrodes with good electrochemical performance is challenging regarding the drying process, mechanical stability, electronic conductivity, etc. The application of Al foams as current collector provides a 3D electronic conductive network, which can host high loadings of active material combined with high mechanical stability. Herein, we demonstrate a slurry infiltration process capable to fabricate cathodes with high active material loading. A variety of LiNi1/3Mn1/3Co1/3O2 (NMC111) based cathodes with thicknesses up to 260 mm and area specific capacities high as 7 mAh cm 2 are investigated comprehensively. The electrodes exhibit good cycle life and rate capability performance due to the unique 3D current collector concept. Even at the 2.0C discharge rate, an area specific capacity of 2.3 mAh cm 2 is obtained, which is high in comparison to conventional Al foil concepts. The design freedom of the presented approach is illustrated by the fabrication of cathodes optimized for high rate capability.

title: First Principles Study on the Adsorption and Dissociation of Impurities on Copper Current Collector in Electrolyte for Lithium Ion Batteries
abstract: The copper current collector is an important component for lithium ion batteries and its stability in electrolyte impacts their performance. The decomposition of LiPF6 in the electrolyte of lithium ion batteries produces the reactive PF6, which reacts with the residual water and generates HF. In this paper, the adsorption and dissociation of H2O, HF, and PF5 on the Cu(111) surface were studied using a first principles method based on the density functional theory. The stable configurations of HF, H2O, and PF5 adsorbed on Cu(111) and the geometric parameters of the admolecules were confirmed after structure optimization. The results showed that PF5 can promote the dissociation reaction of HF. Meanwhile, PF5 also promoted the physical adsorption of H2O on the Cu(111) surface. The CuF2 molecule was identified by determining the bond length and the bond angle of the reaction product. The energy barriers of HF dissociation on clean and O atom preadsorbed Cu(111) surfaces revealed that the preadsorbed O atom can promote the dissociation of HF significantly.

title: Nano porous copper metal current collector for lithium ion batteries
abstract: A low cost and scalable ultrasonic synthetic method to produce copper metal current collector with uniform nanopores on the surface is achieved for the first time. A layer of silicon active material was sputtered on the surface of as prepared metal current collector (vs. metal lithium) as an innovative current collecting material for lithium ion battery. The assembled battery with this current collector showed an areal capacity of 2.2 mAh/cm2, comparable to that of commercially available lithium ion batteries. Due to the nano porous structure of current collector, the silicon active material electrochemical capacity retention and cycling stability also improved significantly.