DMF stabilized Li3N slurry for manufacturing self-prelithiatable lithium-ion capacitors

Li3N is an excellent zero-residue positive electrode pre-lithiation additive to offset the initial lithium loss in lithium-ion capacitors. However, Li3N has an intrinsic problem of poor compatibility with commonly used aprotic polar solvents in electrode manufacture procedure due to its high reactivity with commonly used solvents like N-methy-2-pyrrolidone (NMP) and etc. It is the Valley of Death between research and large-scale commercialization of Li-ion capacitors using Li3N as prelithiation agent. In this work, Li3N containing electrode is prepared by a commercially adoptable route for the first time, using N,N-dimethylformamide (DMF) to homogenate the electrode slurry. The DMF molecular stabilizing mechanism is confirmed via experiment analysis and DFT simulation, indicating that the dehydrogenation energy for DMF is obviously larger than other commonly used solvents such as NMP and etc. The soft package lithium-ion capacitors (LIC250) with only 12 wt% Li3N addition in AC positive electrode exhibits excellent rate capability, cyclic stability and ultrahigh specific energy. Its specific energy is 2.3 times higher than the Li3N-free devices, with energy retention as high as 90% after 10,000 cycles. (C) 2019 Science China Press. Published by Elsevier B.V. and Science China Press. All rights reserved.