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Pre-lithiation technology is essential to improve the initial coulombic efficiency (ICE) and cycling stability of high SiO x content cells. Different amounts of pre-lithiation significantly affect the electrochemical performance of cells. In this study, three groups of LiNi 0.8 Co 0.1 Mn 0.1 O 2 || SiO x /Graphite pouch cells (SiO x , 45 wt%) with different pre-lithiation amounts are fabricated using an electrochemical pre-lithium method. The effects of pre-lithiation amounts on the capacity and cycling stability are comprehensively investigated by non-destructive tests and post-mortem analysis. The results show that increasing the amounts of pre-lithiation can substantially improve the capacity of the cells, but may also accelerate their aging. Further studies reveal that the cycling stability of SiOx/Graphite anode is strongly affected by the amounts of pre-lithiation, whereas the effect on the cathode is negligible. Moreover, titration gas chromatography (TGC) experiments are used to quantify the lithium loss in SiO x /Graphite anode. The accelerated formation of SEI and trapped lithiated active materials as well as lithium dendrites caused by over-lithiation at SiO x /Graphite anode are responsible for the rapid degradation of pouch cells with high pre-lithiation amounts. This work demonstrates the complex relationship between pre-lithiation amounts and electrochemical performance, which needs to be carefully measured in SiO x -based cells. [Display omitted] • NCM811||SiO x /Graphite pouch cells with different pre-lithiation amounts are evaluated. • Both ICE and cycle stability is greatly influenced by the pre-lithiation amount. • The amounts of pre-lithiation have little effect on the aging of the cathode. • High pre-lithiation amounts can accelerate anode aging. • Titration gas chromatography is used to quantify the lithium loss in anode. [ABSTRACT FROM AUTHOR]

Potassium-ion batteries (PIBs) are in the spotlight as a possible alternative to lithium-ion batteries. Graphitic carbons are promising anode materials for PIBs due to their low-plateau potential that is beneficial for the realization of high-voltage full cells. However, inferior cycling stability hinders their practical application. Herein, highly graphitized carbon nanofibers (HG-CNFs) as a free-standing electrode are served as the anode for PIBs. The HG-CNFs exhibits a reversible capacity of 200 mAh g−1 at the plateau potential below 0.2 V (76% of total capacity) and superior rate performance with a depotassiation capacity of 226 mAh g−1 at 35 C. Moreover, the capacity decay of HG-CNFs is less than 0.008% per cycle during 400 cycles, which is superior to those of most other graphitic carbons. The excellent electrochemical performance of HG-CNFs is attributed to its merits of free-standing fibrous networks and graphitic structure with rational defects that alleviate the volume expansion incurred by K+ intercalation. • Highly graphitized carbon nanofibers as a free-standing electrode was prepared. • The interconnected networks improve the integrity and buffer the volume expansion. • The HG-CNFs exhibits a capacity of 200 mAh g−1 at the plateau potential below 0.2 V. • The HG-CNFs shows outstanding cycling performance in K-ion half-cells. [ABSTRACT FROM AUTHOR]