چكيده به لاتين
In this thesis, at first, the basic definitions of primary and secondary batteries such as lithium-ion battery, the components of this battery, including the types of anode, cathode and electrolyte, were mentioned. In the following, the advantages and disadvantages of graphite anode, which is one of the most common anodes in the production of this category of batteries, are stated. Then, the introduction of silicon anodes, which is one of the promising alternatives as lithium-ion battery anodes, along with the challenges faced by these anodes, has been discussed. Also, several solutions have been introduced to solve challenges such as the change in the volume of silicon during the entry and exit of lithium ions and, by nature, the crushing and pulverization of the silicon, which will lead to the disconnection of the active electrode material from the current collector and, subsequently, a sharp drop in capacity and a reduction in battery life. In addition, the low electrical conductivity of silicon, which is one of the problems of using it as an active material in the anode, has been investigated. In the following, a suitable research method including the comparison of two common types of binders, polyvinylidene fluoride and polyacrylonitrile, both of which are polymer binders, is reported in the preparation of slurry for silicon anode material in four different ratio compositions, and then, the optimal binder type has been introduced along with the appropriate ratio composition. One of the most important reasons for comparing these two binders is to compare the better adhesion of the slurry to the surface of the current collector. Since, the silicon is crushed after the volume change during the electrochemical cycle, and if the binders has good adhesion, the active material is less separated from the surface of the current collector and participates more in the capacity, which results in an increase in the cycle life. It should be noted that in this research, polyacrylonitrile (PAN) binder with a ratio of (70:20:10) achieved the best results and was used to prepare the anodic material slurry. Next, as mentioned, one of the challenges facing silicon is its poor conductivity, which can be slightly increased by adding a carbon-based material such as graphene.Also, due to its lamellar structure, graphene oxide creates a good space for changing the volume of silicon particles during the electrochemical cycle, and in the end, commercial silicon in combination with graphene oxide material in the form of composites (silicon/graphene oxide and silicon/graphene oxide reduced) was modified and their results were analyzed as anode active material in the battery with different electrochemical and morphological tests. Among these results, we can mention the achievement of 2068.59 mAh/g capacity for silicon/graphene oxide composite at 0.01 C rate and 87.39% Coulombic efficiency.
