Preparation of Lithium Oxide-Based Composite Cathode Lithium-Supplementing Material and Its Influence on the Electrochemical Performance of the Battery
During the first charge-discharge cycle of lithium-ion batteries,the formation of solid electrolyte interface(SEI)films on the negative electrode surface consumes some of the active lithium in the cathode material,resulting in irreversible capacity loss and subsequently reducing the energy density of lithium-ion batteries.To address this issue,lithium oxide(Li2O)is chosen as sacrificial lithium salt to compensate for the first irreversible capacity loss in lithium-ion batteries,aiming to improve the capacity and cycling performance of the battery.In order to investigate the prelithiation performance,the catalytic material LiMnO2 is ground and mixed with Li2O and conductive carbon black(SP)in certain mass ratios,iron phosphate(LiFePO4)is selected as the cathode,graphite is selected as the negative electrode,TCGG-Si is selected as the electrolyte,and a 2032 coin cell is assembled.The effect of the prelithiation additive(LiMnO2/Li2O/SP)on the electrochemical performance of the battery is studied through charge-discharge tests.The results show that when the mass fractions of LiMnO2,Li2O,and SP are 50％,45％,and 5％respectively,the first charge capacity of the LiMnO2/Li2O/SP composite material can reach 526.5 mAh·g-1 at a current density of 10 mA·g-1during charging to 4.3 V.The decomposition and release of active lithium in the first charge cycle are irreversible,with a Coulombic efficiency of only 14.63％in the first cycle.After the fourth cycle,the capacity is completely lost,indicating that LiMnO2/Li2O/SP composite material can be used as a prelithiation material added to the cathode material.When the composite material LiMnO2/Li2O/SP with a mass fraction of 3.6％is added to the iron phosphate half-cell,the first cycle charge capacity of the half-cell is 186.5 mAh·g-1.Compared to LiFePO4(166.8 mAh·g-1),the capacity is increased by 19.7 mAh·g-1,indicating that the prelithiation agent has played a role,and this excess capacity can be used for the formation of graphite SEI film.Adding LiMnO2/Li2O/SP to the iron phosphate-graphite full battery system as a cathode prelithiation agent not only compensates for the first-cycle irreversible capacity loss of the graphite negative electrode but also improves the cycling performance of the full battery.The first reversible capacity of the full battery is 158.2 mAh·g-1,and the reversible capacity after 100 cycles is 108.0 mAh·g-1.Compared to the situation without the additive,the first charge capacity of the full battery increases by 12.9 mAh·g-1,and the reversible capacity increases by 11.6 mAh·g-1 after 100 cycles,with a capacity retention rate increased by 13.90％.
NETL
NSTL
万方数据
维普
