Silicon-carbon materials have broad development prospects as negative electrode materials for lithium-ion batteries. In this paper, polyvinyl butyral (PVB)-based carbon-coated silicon (Si/C) composite materials were prepared using PVB-coated Si particles and then high-temperature carbonization methods. Furthermore, the PVB-based carbon-coated silicon/artificial graphite composite materials (Si/C-Gr) were prepared by using artificial graphite as conductive skeleton. And the electrochemical and battery performances of Si/C and Si/C-Gr composite materials as negative electrode materials of lithium-ion batteries were investigated in detail. The results showed that PVB-based carbon was uniformly coated on the surface of silicon particles, and the electrochemical performance and battery performance of the Si/C composite material was improved with the increasing proportion of PVB in the reaction feed. With the introduction of artificial graphite, the constructed ternary composite of Si/C-Gr as anode exhibited a further improved electrochemical performances, such as cycling stability, rate performance, and coulombic efficiency. Specially, the Si/C-Gr (1:30:0.7) composite anode has a discharge specific capacity of 1239.9 mAh/g in the first cycle and 922.9 mAh/g in the 100th cycles at a current density of 0.1 A/g. And the corresponding coulombic efficiency was 84.5% in the first cycle and maintained at around 98% after 100 cycles. The average discharge specific capacity was 1045.5, 796.08, 688.75, 507.09, and 479.11 mAh/g at the current rate of 0.1, 0.2, 0.4, 0.8, and 1 A/g, respectively. This is attributed to the addition of artificial graphite forming an effective conductive skeleton structure, which enhanced the structural stability of the composite material and improved the electronic conductivity of the electrode material. Also, PVB as functional coating polymer improved the dispersion of Si particles on the surface of graphite. All above reasons enabled the electrode materials to have good electrochemical performances.
Carbon-coated core-shell structure artificial graphite@plasma nano-silicon@carbon (AG@PNSi@C) composite, applying as lithium ion battery anode material , has been prepared via spray drying method. The plasma nano-silicon (<100 nm), which contained amorphous silicon , was synthesized by radio frequency induction plasma system with the high temperatures processing capability and high quench rates. The artificial graphite in the composite acts as the core which supports the particle and provides electroconductivity , while PNSi attached on the surface of the core, enhances the specific capacity of the composite. The as prepared composite shows superior performance as anode in lithium-ion batteries, regarding to the initial Coulombic efficiency and cycle life. The initial Coulombic efficiency of AG@PNSi@C electrode is 81.0% with a discharge capacity of 553 mAh g −1 and a recharge capacity of 448 mAh g −1 . During cycling, AG@PNSi@C exhibits excellent performance with a very low capacity fading that the discharge capacity maintains 498.2 mAh g −1 and 449.4 mAh g −1 after 250 cycles and 500 cycles. AG@PNSi@C also shows enhanced resistance against high current density . Besides the remarkable electrochemical performances , the facile and mass-producible synthesis process makes the AG@PNSi@C composite very promising for its application in lithium-ion batteries.
Huajun Zhao,Yunxian Qian,Guangfu Luo,Jian Chang,Chaoyang Wang,Jun Wang,Huaiyu Shao,Yonghong Deng
LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) cathode coupling with artificial graphite (AG) is a promising tendency for high-energy-density batteries . However, realization of long-term lifespan under current realistic conditions remains a “Gordian knot” for large-scale commercialization-oriented realm owing to the aggressive and highly reactive Ni 4+ sites on the delithiated cathodes and electrolyte exhaustion. Vinylene carbonate (VC) is commonly employed as the additive for graphite anode in carbonate electrolytes. However, VC has limited protection ability for NCM811/AG, especially for high-temperature cycling, showing conspicuous gas generation and large interfacial resistance . Herein, advanced carbonate-based electrolytes containing vinylene carbonate (VC) and phosphate compounds like triallyl phosphate (TPPC2) and tripropargyl phosphate (TPPC3) as electrolyte additives are reported to improve the performance of NCM811/AG pouch cells at elevated temperature. Theoretical calculations and comprehensive characterizations reveal that these two electrolytes well regulate the electrodes interface with more robust and homogenous films. Moreover, the TPPC2 and TPPC3 additives exhibit stronger tendency to eliminate the corrosive active oxygen ( 1 O 2 ) released from NCM811. These merits mitigate the electrolyte decomposition, decrease the gas generation, inhibit the dissolution of transition metals from cathode, and protect the structure stability of NCM811. Such outstanding electrochemical performance reveals promising prospects in the commercialized application of NCM811/AG batteries .
危险品化学品经营许可证（带存储）