26650 battery

Research on technologies to improve 26650 battery storage performance

In the past decade, the demand for high-energy-density materials has been growing to power emerging electric vehicles and mobile electronics, and high-performance rechargeable batteries have also attracted attention. To promote the commercialization of 26650 battery-sulfur batteries, researchers have reported a variety of strategies to improve the capacity utilization of sulfur and prevent the loss of polysulfide; however, it is still a huge challenge to increase the energy density of 26650 battery-sulfur batteries (Li-S) to practical application levels because the electronic and ionic conductivity of sulfur and 26650 battery sulfide in high-load electrodes that meet practical application levels is low. As a highly conductive active material that can replace sulfur, Li-Se batteries with selenium (Se) as the positive electrode material have better reaction activity; however, Se has a low mass specific capacity and is expensive, which limits the application range of Li-Se batteries. In order to achieve the complementary advantages of the electrochemical properties of S and Se, S-Se solid solution (SexSy) is considered to be a very promising 26650 battery storage material. A series of SexSy-based positive electrode materials have shown attractive energy storage advantages. However, similar to the S positive electrode, the soluble intermediates of the SexSy positive electrode can also cause rapid battery capacity decay. Inspired by the chemical adsorption mechanism of 26650 battery-sulfur batteries, some polar materials may also effectively inhibit the dissolution of polysulfide ions/polyselenium ions in the SexSy cathode. Recently, it has been reported that some metal oxides/nitrides/sulfides can be used as host materials to effectively solve the problem of polysulfide dissolution in 26650 battery-sulfur batteries; among them, CoS2 materials can be used as effective host materials for 26650 battery-sulfur batteries due to their unique physical and chemical properties. They can not only provide strong chemical adsorption for 26650 battery polysulfide, but also kinetically promote the reduction reaction of 26650 battery polysulfide. Recently, Professor Lou Xiongwen of Nanyang Technological University published an article entitled "A Freestanding Selenium Disulfide Cathode based on Cobalt Disulfide-Decorated Multichannel Carbon Fibers with Enhanced 26650 battery Storage Performance" in Angewandte Chemie-International Edition, reporting a CoS2 nanoparticle-modified lotus root-type carbon fiber network (CoS2@LRC) as a host material for SeS2 to improve the storage performance of 26650 battery. The overall electrode is composed of three-dimensional cross-linked multi-channel carbon fibers, which can not only accommodate a high content of SeS2 (70wt%), but also ensure the rapid transmission of electrons and ions, thereby achieving a high capacity utilization rate of 1015mAh/g at a current density of 0.2A/g. [Graphic Introduction] Figure 1. Schematic diagram of the synthesis process

a) Schematic diagram of the synthesis process of CoS2@LRC; b) Schematic diagram of the advantages of CoS2@LRC/SeS2 compared to LRC/SeS2. Figure 2. XRD, FESEM, TEM and TGA characterization

a, e, i) XRD spectra; b, c, f, g, j, k, l) FESEM characterization images; d, h, n, o, p) TEM characterization images; m) TGA curves; a-d) Co(Ac)2/PAN/PS; e-h) Co@LRC; i-p) CoS2@LRC. Figure 3. Characterization of CoS2@LRC/SeS2 electrode

a-c) FESEM characterization of CoS2@LRC/SeS2 electrode, the inside of Figure a is the photo of CoS2@LRC/SeS2 electrode, the inside of Figure b is the cross-sectional FESEM image of CoS2@LRC/SeS2 electrode; d) TGA curve of CoS2@LRC/SeS2 electrode; e) TEM image of CoS2@LRC/SeS2 electrode; f) Element mapping corresponding to the TEM image of CoS2@LRC/SeS2 electrode. Figure 4. Electrochemical performance test of CoS2@LRC/SeS2 electrode

a) Voltage distribution curve of CoS2@LRC/SeS2 electrode at a current density of 1A/g; b) Comparison of cycle performance of CoS2@LRC/SeS2 electrode and LRC/SeS2 electrode; c) Voltage distribution curve of CoS2@LRC/SeS2 electrode at different current densities; d) Rate performance of CoS2@LRC/SeS2 electrode at different current densities; d) Long cycle life of CoS2@LRC/SeS2 electrode at a current density of 5A/g. [Summary] This article reports a self-supporting CoS2@LRC/SeS2 electrode with good integration characteristics, which has a high content of electroactive SeS2, multifunctional CoS2 nanoparticles and a conductive LRC network structure. Specifically, SeS2 is more reactive than S; the conductive LRC network further ensures the capacity utilization and the CoS2 nanoparticles ensure good cycle stability. Due to the above advantages, the CoS2@LRC/SeS2 cathode material has a high discharge capacity, with a capacitance of up to 1015 mAh/g at a current density of 0.2 A/g (2.3 mg/cm2). It also has excellent rate performance and a long cycle life of more than 400 cycles.

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