1. Introduction
Nowadays, the depletion shortage of non-renewable natural fossil resources and environmental damages has led to the development of battery storage energy. Therein, energy storage through electrochemical cells has been considered the most satisfactory solution due to its high energy density, high power density, flexibility, and simplicity of maintenance. Moreover, as shown as the state-of-the-art technology for various applications, LIBs are required to show lightweight, long lifespans, high specific capacity, and good retention capacity. [1-4]
In recent years, the silicon-based anode has attracted more attention because of its superior theoretical capacity of 3579 mAh.g-1. [5] However, the formation of LixSiy alloy makes the silicon anode suffers a high-volume expansion (over 280%), which leads to concerns related to the safety and disconnection of electric contact, and then a severe decrease of capacity after the first cycles. Therefore, silica materials have been alternatives to develop silicon-based anodes owing to less volume expansion and high capacity of 635.7 mAh.g-1 for LIBs. [6-7]
Although those materials overcome the weakness of silicon anode, their low conductivity is one of the main reasons to prevent commercialization. As a solution, a hybrid composite SiO2/C was used to enhance battery performance. In detail, the hard carbon in the SiO2 structure enhances the ionic and electronic conduction and the kinetic migration of Li+ inside the materials by creating a linking network to boost electrons movements to convert SiO2 into Si and co-products faster. [8-10] Nevertheless, SiO2/C based as an anode suffers from significant active lithium loss, which leads to low initial Coulombic efficiency in Li-ion batteries. This phenomenon is caused by some Li+ ions trapped in an anode structure. In detail, the irreversible reaction and volume expansion create cracks inside the electrode, which need a large amount of the electrolyte. As a result, the thickness of the SEI layer increases after the first cycle, causing a significant amount of Li+ ions to be trapped inside the electrode by the SEI layer. [11-12]
To deal with this challenge, the pre-lithiation process was used to compensate for the active lithium loss of the anode to enhance the practical battery performance. [13-17] In this research, the two common pre-lithiation methods were used, which include the direct contact method (CM) using lithium foil and the half-cell electrochemical method (EM). [18-22] These techniques were applied for the composite anode SiO2/C, before matching in the full-cell with NMC622, cathode. In CM, the time for anode directly contacted with lithium was investigated. Meanwhile, regarding the electrochemical method, the anode was assembled in half-cell and pre-lithiated at various cycles to activate prior to the full-cell assembly. This study hopefully brings new insights into selecting an appropriate approach to successfully construct a high-performance lithium full-cell with silica/carbon-based anode.