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From China:Xiaoliang Fang, Xiamen University: Construction of high energy density Lithium-sulfur battery based on water-based conductive ink with multi-component carbon material and hydrophilic polymer

Lithium-sulfur batteries have attracted much attention due to their high theoretical energy density. In recent years, researches on sulfur-bearing guest materials have rapidly promoted the performance improvement of lithium-sulfur batteries. However, low sulfur load makes it difficult for sulfur cathode to give full play to the advantage of high energy density of sulfur, which limits the practical application of lithium-sulfur batteries. Therefore, the preparation of positive electrode with high sulfur load is a key link in the construction of high energy density lithium-sulfur battery. The traditional slurry coating process using commercial zero-dimensional conductive additive (Super P) and commercial binder (PVDF or acrylonitrile polycopolymer LA132/133) is prone to electrode plate cracking and electron/ion transport path discontinuity during the preparation of the electrode, which makes it difficult to obtain high performance and high loading sulfur anode. However, in recent years, strategies such as self-supported electrode structure and natural binder developed for the positive electrode with high sulfur load have limited commercial application potential due to complex preparation process and high viscosity. How to develop an effective strategy to build lithium-sulfur batteries with high sulfur loading based on traditional slurry coating process is still facing challenges.


【 Content Introduction 】
In order to solve these problems, Our research team developed a water-based Conductive inks (WCI) for preparing high-sulfur positive electrodes. The water-based conductive ink is composed of multi-component carbon material and hydrophilic polymer (FIG. 1). It has the following advantages: 1) The integrated preparation process of conductive agent and binder is conducive to obtaining high-quality positive paste and anode sheet; 2) In addition to Super P, different dimensions of conductive agents such as multi-walled carbon nanotubes (CNT), carbon fiber grown in gas phase (VGCF) and ultra-thin graphite nanosheets can effectively improve the mechanical integrity, peel strength and electrical conductivity of the positive electrode with high sulfur load. 3) The introduction of partial lithium polyacrylic acid (PAA-Li) can significantly reduce the viscosity of natural adhesives (such as Xanthan gum, XG) and form a stable three-dimensional network structure with natural adhesives, which can further improve the sulfur loading capacity of the positive sulfur electrode and the ability to fix polysulfide intermediates. Based on this kind of WCI, we successfully prepared a high-loading sulfur anode using Super/S complex as the active substance, and realized the construction of 2.5Ah class flexible battery with energy density of 323 Wh kg-1. In addition, this strategy has good universality to the sulfur bearing guest materials reported in recent years. This research work is composed of multicomponent carbon nanomaterials and hydrophilic polymer binders for High-energy-density lithium-sulfur batteries “. Journal of Energy Storage Materials. Xin Qiao and Chaozhi Wang from Xiamen University and Dr. Zang Jun from Shandong Hongyun Nanotechnology Co., LTD are the co-first authors of this paper, and Professor Xiaoliang Fang from Xiamen University is the corresponding author of this paper.


[Research Content]
The authors conducted a series of characterization and electrochemical performance tests on the positive sulfur electrodes prepared by different methods (FIG. 1) (FIG. 2). Compared with the traditional slurry blending process, the stripping strength and conductivity of the positive sulfur electrode (5 mg cm-2) prepared by WCI-1 based on LA133 binder were significantly improved. In addition, by studying the influence of the composition of conductive agent on the stripping strength and conductivity of the anode sheet, it is found that VGCF can effectively improve the mechanical strength of the positive electrode sheet, and CNT and ultra-thin graphite nanosheet can form a THREE-DIMENSIONAL conductive network to greatly improve the conductivity of the positive electrode sheet.

Figure 1. (a) Schematic diagram of conventional sulfur cathode preparation; (b) Schematic diagram of preparation of WCI and corresponding sulfur anode; (C-J) physical map of conductive ink and SEM characterization of each conductive agent component.
厦门大学方晓亮课题组:基于多组分碳材料和亲水聚合物的水性导电油墨构建高能量密度锂硫电池
Figure 2. (A-E) Positive electrode characterization of sulfur prepared by WCI-1 based on LA133 as binder; (F-H) Sulfur cathode characterization diagram prepared by traditional slurry blending process; (i-j) The influence of different components of conductive agent on the stripping strength and conductivity of positive electrode; Electrochemical characterization of (K-N) sulfur cathode prepared by different methods.


Due to the use of Super/S complex as the active substance, wCI-1 based on LA133 binder is difficult to prepare positive sulfur electrode with sulfur surface loading of more than 6 mg cm-2. XG and other natural adhesives are used as a binder for the positive electrode of high sulfur load by virtue of their rich polar functional groups and good mechanical strength. However, natural adhesive solution usually has high viscosity and it is difficult to prepare high solid electrode slurry. Therefore, the author introduced partial lithium PAA-Li to reduce the viscosity of the natural adhesive, and further improved the mechanical integrity and strength of the positive electrode with high sulfur load through hydrogen bonding between PAA-Li and the natural adhesive (Figure 3). Compared with WCI-1, the positive electrode with high loading sulfur prepared by USING XG/PAA-Li as binder has higher peel strength and conductivity.
厦门大学方晓亮课题组:基于多组分碳材料和亲水聚合物的水性导电油墨构建高能量密度锂硫电池
Figure 3. (a) Schematic diagram of XG/PAA-Li composite binder; (b) Physical image of WCI-2 prepared with XG/PAA-Li as binder; (c) Physical map of polysulfide adsorption of WCI; (D,e) Thermogravimetric diagram of XG/ PaA-Li composite binder; (F-i) Characterization of electrolyte wettability, SEM, stripping strength, and conductivity of high-loading sulfur cathode prepared by WCI-2.


The positive electrode with high loading sulfur prepared by WCI-2 showed good magnification and long cycle stability (FIG. 4). Under the condition of high sulfur load of 10.5 mg cm-2, the surface capacity of the battery remains 10.17 mAh cm-2 after 50 cycles. To verify the potential of this strategy, we fabricated a 2.5Ah soft pack battery based on Super/S composite, with an energy density of 323 Wh kg-1. In addition, WCI-2 can be applied with different types of sulfur-bearing guest materials with good universality (FIG. 5).
厦门大学方晓亮课题组:基于多组分碳材料和亲水聚合物的水性导电油墨构建高能量密度锂硫电池
Figure 4. (A-E) Comparison of the electrochemical performance of high-loading sulfur cathode prepared by WCI-1 and WCI-2.


厦门大学方晓亮课题组:基于多组分碳材料和亲水聚合物的水性导电油墨构建高能量密度锂硫电池
Figure 5. (A-c) WCI-2 soft battery schematic diagram and physical drawing; (D-C) Electrochemical performance of the soft pack cell; (f) Comparison of the performance of soft-pack batteries in the reported literature; (G-I) SEM characterization of different sulfur carrier materials; (J-L) Electrochemical performance of positive electrode with high sulfur load prepared by WCI-2 and different sulfur carrier materials.


【 conclusion 】
An integrated conductive/binder slurry prepared from multi-component carbon material (i.e., water-based conductive ink) can effectively improve the sulfur load, mechanical and electrochemical properties of the positive sulfur electrode. Partial lithium paA-Li combined with natural adhesive can further improve the electrochemical performance of the positive electrode with high sulfur load based on water-based conductive ink while ensuring the solid content of the positive slurry, which provides a new idea for the construction of high energy density lithium sulfur battery.


This work was supported by the National Key RESEARCH and Development Program of China, the National Natural Science Foundation of China, xiamen Youth Innovation Fund project and fujian Energy Materials Science and Technology Innovation Laboratory of China.

Xin Qiao, Chaozhi Wang, Jun Zang, Baofu Guo, Ying Zheng, Rongrong Zhang, Jingqin Cui, Xiaoliang Fang, Conductive inks composed of multicomponent carbon nanomaterials and hydrophilic polymer binders for high-energy-density lithium-sulfur batteries; Energy Storage Mater., 2022, DOI: 10.1016 / j. NSM. 2022.04.022


厦门大学方晓亮课题组:基于多组分碳材料和亲水聚合物的水性导电油墨构建高能量密度锂硫电池

The post From China:Xiaoliang Fang, Xiamen University: Construction of high energy density Lithium-sulfur battery based on water-based conductive ink with multi-component carbon material and hydrophilic polymer first appeared on 宽生实效营销.

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