Shortly Branched, Linear Dextrans as Efficient Binders for Silicon/Graphite Composite Electrodes in Li-Ion Batteries

Abstract

Dextran was evaluated as a binder material for graphite electrode, silicon electrode, and Si/graphite composite electrode in Li-ion cells. The performance was also compared with poly­(vinylidene fluoride) (PVDF) binder or lithium salt of poly­(acrylic acid) (LiPAA) binder. A graphite-rich Si/graphite composite electrode shows a reversible capacity of about 525 mAh g–1 at a C/5 rate and has an excellent cycling stability. An interface study using impedance spectroscopy, X-ray photoelectron spectroscopy, and postmortem scanning electron microscopy analysis shows that the superior performance is due to the formation of a solid–electrolyte interface (SEI) layer that completely covers the surfaces of silicon and graphite. This could be attributed to a strong interaction between dextran through the shortly branched one-dimensional structure and silicon surface as evidenced by attenuated total reflection–infrared spectroscopy. This along with its low cost and environmentally friendly nature makes it an attractive binder material for Si/graphite composite electrodes in Li-ion batteries.

Pilot-Plant Production of High-Performance Silicon Nanowires by Molten Salt Electrolysis of Silica

“…Silicon has been recognized as one of the most promising negative electrode material for the lithium-ion batteries (LIBs) of next generation because of its high specific capacity (10 times that of graphite). − The market share of silicon-based materials for LIBs has increased to 3–5% in the past three years because of the huge demand of electric vehicles. However, the large volume expansion of silicon (approximately 360%) during charge–discharge cycling leads to a rapid decline of the LIB capacity. − To solve this problem, one of the effective methods is preparing silicon of nanostructures, such as nanoparticles, nanotubes, and nanowires. − It is reported that the unique structure of silicon nanowires (SiNWs) can not only shorten radial Li-ion diffusion distance, but also enhance the structural robustness against volume variations, which makes SiNWs become a promising new negative electrode material for LIBs. − SiNWs can be prepared by various methods, such as chemical vapor deposition, , laser ablation, , thermal evaporation, and template method . In spite of their respective specific merits, all of these methods have their own shortcomings, such as the high cost because of the requirements of energy-consuming equipments, high-purity Si substrates, and noble metal catalysts.…”

Revealing the Role of Poly(vinylidene fluoride) Binder in Si/Graphite Composite Anode for Li-Ion Batteries

“…However, these binders are not perfect for Si/graphite composite electrodes, and to the best of our knowledge, very few binders have been designed specifically for Si/graphite composite electrodes. During our search for the ideal binders, we have been intrigued by the finding that the graphite-rich Si/graphite composite electrode with PVDF binder loses its capacity very quickly during cycling, and after five cycles, the capacity is even lower than that of the graphite-only electrode . We essentially want to address the question “How could a small amount of silicon cause such a catastrophic effect on a composite that is very rich in graphite which is known for its good affinity to PVDF?”…”

Recent Development on Binders for Silicon-Based Anodes in Lithium-Ion Batteries

“…随后, Jeong 等 [105] 利用天然黄原胶双螺旋超结构粘 化 学 学 报 综述 图 10 GG 与 LBG 粘结剂 Figure 10 GG and LBG binders (a) The chemical composition of guar gum (GG) and locust bean gum (LBG) [102] , (b) Schematic illustration of lithium-ion transfer in the GG binder [101] , (c) Electrochemical performance of SiNP anodes with different binders at 2100 mA•g -1 between 0.01 and 1.2 V [101] , (d) cycle performance with limited discharge capacity of 1000 mAh•g -1 at 1000 mA•g -1 [101] , (e) The symmetrical cycling performance of SiNPs with GG, LBG, Na-CMC and PVDF binders [102] 图 11 XG 粘结剂 [105] Figure 11 XG binder [105] (a) Chemical structure of XG binder, (b) Concept transfer from macroscopic to nanoscopic world and structural analogy of millipede to that of native-XG towards strong adhesion. A series of small legs in the millipede corresponds to multiple short side chains in native-XG (both colored in red 除以上粘结剂外, 研究人员还制备出新型耐高温粘 结剂结冷胶 [106] , 含有蛋白质以增加柔韧性的粘结剂卡 拉亚胶 [107] , 骨架构象能在锂化过程中转变的果胶 [108] , 从肠膜明串珠菌细菌中提取的天然多糖右旋糖酐 [109] , 模仿贻贝螺旋连接的儿茶酚共聚物 [110] 等粘结剂. [114,115] .…”