Development of a battery modification system for reduction of SEI formation time
There is considerable interest and demand in lithium-ion batteries for electric and hybrid vehicles, satellite, defense, and military applications besides the need in portable devices such as laptops, cell phones, watches, etc. Battery performance – energy capacity, lifetime and safety, depends largely on the formation and development of the solid electrolyte interface (SEI) layer. To develop and increase quality, each battery produced must go through initial charge/discharge cycles and shelf time to form the SEI layer, which is time consuming. Standard constant current/constant voltage (CC/CV) charging practices are safer, but take longer and do not fully utilize active materials. In an effort to reduce the maturation time, we have initiated a pulsed charging protocol to identify specific pulsing parameters to optimize SEI formation time, assembled split-cell batteries to charge and discharge with both CC/CV and pulsed methods, and carried out electrochemical impedance spectroscopy (EIS). The pulse protocol was explored through the use of two separate sets of pulsing charge parameters, with all rest and discharge parameters held constant and used as a control for the experiment. The results showed a high degree of complexity and unpredictability. Further testing is under way, with employment of various optical and morphological techniques in an attempt to correlate the changes in the impedance spectra to actual changes in the SEI development. The system developments and testing of the modified protocols will be presented in this thesis report.
"Development of a battery modification system for reduction of SEI formation time"
ETD Collection for Tennessee State University.