Facile Dual-Protection Layer and Advanced Electrolyte Enhancing Performances of Cobalt-free/Nickel-rich Cathodes in Lithium-Ion Batteries

Abstract

Despite cobalt (Co)-free/nickel (Ni)-rich layered oxides being considered as one of the promising cathode materials due to their high specific capacity, their highly reactive surface still hinders practical application. Herein, a polyimide/polyvinylpyrrolidone (PI/PVP, denoted as PP) coating layer is demonstrated as dual protection for the LiNi 0.96 Mg 0.02 Ti 0.02 O 2 (NMT) cathode material to suppress surface contamination against moist air and to prevent unwanted interfacial side reactions during cycling. The PP-coated NMT (PP@NMT) preserves a relatively clean surface with the bare generation of lithium residues, structural degradation, and gas evolution even after exposure to air with ∼30% humidity for 2 weeks compared to the bare NMT. In addition, the exposed PP@ NMT significantly enhances the electrochemical performance of graphite||NMT cells by preventing byproducts and structural distortion. Moreover, the exposed PP@NMT achieves a high capacity retention of 86.7% after 500 cycles using an advanced localized high-concentration electrolyte. This work demonstrates promising protection of Co-free/Ni-rich layered cathodes for their practical usage even after exposure to moist air.

Design of high‐performance and sustainable Co‐free Ni‐rich cathodes for next‐generation lithium‐ion batteries

“…Therefore, LiNi 0.9 Mn 0.05 Al 0.05 O 2 exhibits discharge capacity of 158 mAh g −1 after 500 cycles at 1.0 C with 80% capacity retention in the optimized electrolyte. 129 Then, Kim et al 33 prepared a Co-free Ni-rich LIB with superior cycle performance using a polyimide/polyvinylpyrrolidone (PP) surface-coated NMT combined with advanced localized high-concentration electrolyte (LHCE) modification. The LHCE consists of an electrolyte of LiFSI, 1,2-dimethoxyethane, TTE, and FEC in a molar ratio of 1:1.1:3:0.2, aiming to enhance the performance of graphite||NMT battery.…”

“…[30][31][32] It is worth noting that Ni-rich layered cathodes can provide higher reversible capacity. 4,33 Eliminating Co and increasing Ni content is a feasible approach to raise the energy density and reduce the price of LIBs. 4 Herein, we highlight the adverse roles of Co in Ni-rich layered cathodes and then summarize the recent challenges and advanced design strategies of Cofree Ni-rich layered cathodes.…”

“…On the other hand, when compared to industrial anode materials displaying high‐energy density, such as graphite (372 mAh g −1 ) and, in particular, silicon–carbon anodes (over 600 mAh g −1 ), the reversible capacity of commercial cathode materials are unqualified 30–32 . It is worth noting that Ni‐rich layered cathodes can provide higher reversible capacity 4,33 . Eliminating Co and increasing Ni content is a feasible approach to raise the energy density and reduce the price of LIBs 4 .…”

Booster Adhesion of Crystalline Poly(vinylidene fluoride) Binder by Heat Treatment for Ni‐rich Layered Oxide Cathode in Lithium‐ion Batteries

“…Replacing Co with Ni in LiCoO 2 results in a higher energy density and lower cost. [3][4][5] The use of metal ions other than Co, such as Ni, Mn, and Al, is being actively pursued to further increase the energy density and stability of the batteries. Esepcially, the recent commerialization of Ni-rich materials as cathode active materials for LIBs is a significant step towards improving the energy density and competitiveness of LIBs.…”

“…Ni‐rich layered oxide cathode is one of the top candidate for high energy density LIBs. Replacing Co with Ni in LiCoO 2 results in a higher energy density and lower cost [3–5] . The use of metal ions other than Co, such as Ni, Mn, and Al, is being actively pursued to further increase the energy density and stability of the batteries.…”