Battery prelithiation enabled by lithium fixation on cathode

Li3N in the form of powder as the most appealing sacrificial salt has already been investigated for prelithiation, yet not been widely acknowledged due to its incompatibility with common solvents to a great extent. Herein, we report an unexpected way by depositing metal lithium directly on cathode surface and then fixing it by nitrogen gas to synthesize pure alpha-Li3N film with (001) plane perpendicular to surface. Moreover, its decomposition pathway along the direction from the surface to the inner cathode is revealed. After being used to compensate the lithium loss in LiFePO4/graphite full cell, discharge capacity at 120th cycle has raised by 30.7% with 1% Li3N coating. Apart from that, this kind of Li3N film has successfully served as the sole lithium source to fabricate full cell with TiS2 and graphite as electrodes, in which 142.4 mAh g(+1) of capacity can remain after 50 cycles. In short, the introducing/expelling of nitrogen for Li fixation/Li+ release is a facile strategy to realize battery prelithiation with easy preparation and high efficiency.