Lithium metal is considered the ultimate choice for the next generation of anodes for lithium secondary batteries due to its high capacity (3860 mAhg-1) and associated low charging voltage. However, the electrodeposition solvation of lithium tends to be non-planar, with metallic dendrites, metal voids, and an unstable solid-state electrolyte phase (SEI).
Here,D**id Mitin from the University of Texas and Liu Wei from Sichuan UniversityThe correlation between external pressure and 10 MPa), solid electrolyte interface (SEI) structure morphology, and lithium metal deposition peeling behavior. To simulate an anode-free lithium-metal battery (AF-LMB), a commercial carbonate electrolyte is used"Empty"Copper current collectors were analyzed. Lower pressures promote organic-rich SEIs and macroscopically heterogeneous, filamentous lithium deposits interspersed with pores. Higher pressures promote F-rich inorganic SEIs, resulting in a more homogeneous and dense lithium film.
Excellent electrochemical performance at 1 mPa pressure: its half-cell has a capacity of 1 mA cm-2 -3 mAh cm-2 (175 m deposition stripping) was stable after 300 hours (50 cycles) with a cyclic coulometric efficiency (CE) of 998%。An AF-LMB battery with a high-load NMC622 cathode (21 mg cm-2) was cycled 200 times with a CE of 99 under conditions of C5 charge and C2 discharge (1C = 178 mA g-1).4%。
Figure 1DFT calculations
In summary, this work uses a layer of virgin graphene (pg@cu) coated directly on the current collector to demonstrate that enhanced metal wetting properties can directly replace higher pressures to stabilize the electrodeposition exfoliation behavior of lithium. The study shows that the graphene layer can achieve stable electrodeposition stripping of anode free lithium metal batteries (AF-LMB) at 1 MPa. The synergy between the PG layer and the 1 MPa low voltage enables the planar deposition of lithium throughout the long cycle, resulting in a Coulombic Efficiency (CE) of 99 for the half-cell8%, and achieved a stable cycle of the whole battery with a high capacity load.
In addition, density functional theory (DFT) shows the difference between the adsorption energy of solvated Li+ on different crystal planes of Cu (100), (110), and (111) and the adsorption energy of graphene lithiation delithiation, thus revealing the role of support surface energy in promoting SEI heterogeneity.
Figure 2Battery performance
interrelation between external pressure, sei structure, and electrodeposit morphology in an anode-free lithium metal battery,advanced energy materials2023 doi: 10.1002/aenm.202302261