Designing in-Situ Formed Interphases Enables Highly Reversible Cobalt-Free LiNiO2 Cathode for Lithium Metal/Ion Batteries

Abstract

Cathode materials control both the energy density and cost of lithium metal/ion batteries. The cobalt-free LiNiO2 with relatively low cost and extremely high theoretical energy density (~ 1050 Wh kg-1) is one of the most promising cathode materials for high-energy batteries. However, the continuous Ni dissolution, structural disordering, particle cracking and unstable cathode-electrolyte interphase (CEI) during cycling hinder its practical applications. Herein, we surmount these challenges by forming a robust F- and B-rich CEI on LiNiO2 using a high-fluorinated electrolyte with LiDFOB additive. The optimized CEI is able to protect the integrity of particle structure, decrease the dissolution of Ni and suppress the irreversible structure transformation. The LiNiO2 cathode maintains an unprecedentedly high capacity retention of >80% after 400 deep cycles at a high charge cut-off voltage of 4.4 V (vs. Li/Li+). In addition, the reduction of fluorinated electrolytes with LiDFOB additive forms an F, B-rich solid electrolyte interphase (SEI) on the Li metal/graphite anodes, enhancing the Coulombic efficiency to >99% for Li plating/stripping and >99.99 % for the lithiation/delithiation of graphite. This work sheds light on the designing interfacial chemistry for high-energy cathodes, and the design principle is also applicable for other alkali metal ion cathodes. Figure 1