Differential pulse effects of solid electrolyte interface formation for improving performance on high-power lithium ion battery

Forward and reverse differential-pulse effects applied in the formation of a solid electrolyte interface to enhance the performance of lithium batteries

“…In this study, we developed two new FRDP methods that avoided ionic transfer polarization affecting the reaction kinetics during SEI formation, and thereby shortened the charging period. Based on previous results, we set the duration to appropriately 1.6 ms and the charging time to 0.4 ms [4]. In the case of the control batteries, the charging was performed as follows: the batteries were CC charged at 0.1C for 10 min and then subjected to CC charging at 0.2C up to 4.2 V, the charged voltage was maintained at 4.2 V until the current was below 0.01C The batteries were then discharged at a 0.2C constant-current rate to 2.75 V. All the charging programs used and the code names of batteries are listed in Table 1.…”

“…In the FRDP1 battery, a slow (0.2C) FP charging was used for SEI formation, with the results indicating that PEO cannot significantly support ionic diffusion on an interface, where the impedance of the interface between the SEI and the anode's surface is high, compared with interfaces that are formed more rapidly (0.5C), i.e. by forward charging [4]. These results indicate that, previously unappreciated FP and RP charging, effectively counter forward charging and disrupt the reactiondynamics and the equilibrium of Li + /electron transfer.…”

“…Previous results [4,20] have indicated that DP charging affects the formation and the composition of the SEI layer in distinct and dynamic ways; however, the dynamic electrochemical equilibrium of both Li + diffusion and the electron transfer must be re-examined because Li + diffusion is extremely slow compared with electron conduction. We conducted this study to determine whether balanced SEI formation on the anode surface can be achieved by further refining the DP protocol.…”

“…However, ensuring the formation of the organic compounds is challenging because the electrochemical reaction of the cyclic carbonates undergoes substantial mutations. Zhang et al, demonstrated that a twoelectron pathway is used for the electrochemical decomposition of EC and a one-electron pathway is used for the decomposition of PC because the electron-donating group, -CH 3 , augments the electron density within the cyclic structure [1] and thereby restricts the flow of electrons and generates an organic compound [1,4]. Research conducted using electrochemical impedance spectroscopy (EIS) has revealed that the SEI is formed in two early stages [5]: in the first stage, a porous, highly resistive, and dimensionally unstable SEI layer grows before Li ions intercalate into graphite, whereas the second stage occurs concurrently with the intercalation of Li ions and generates a highly elaborate and conductive organic SEI layer.…”

Investigation into State-of-Health Impedance Diagnostic for 26650 4P1S Battery Packs

“…4,5 The impedance associated with the SEI is in the 100-1000 Hz range of the electrochemical impedance spectrum for lithium batteries. [6][7][8][9][10][11][12] A C rate is defined as the rate at which a battery is discharged relative to its theoretical maximum capacity. For our work, 1 C = 2.6 AH.…”