Structure and Interface Design Enable Stable Li-Rich Cathode.

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Li-rich layered-oxide cathodes offer high theoretical energy density for Li-ion batteries.
• O3-structured cathodes face challenges like low initial Coulombic efficiency, voltage fade, and poor stability due to oxygen release and metal migration.

Purpose of the Study:

• To overcome the limitations of O3-structured cathodes in Li-rich layered oxides.
• To enhance the stability and performance of high-energy Li-ion batteries.

Main Methods:

• Utilized a stable O2-structured Li$_{1.2}$Ni$_{0.13}$Co$_{0.13}$Mn$_{0.54}$O$_{2}$ (O2-LR-NCM) cathode material.
• Employed an all-fluorinated electrolyte.
• Investigated the in situ formation of a fluorinated cathode-electrolyte interphase (CEI).

Main Results:

• The O2-LR-NCM structure effectively restricted transition metal migration.
• The fluorinated CEI suppressed structural transitions and oxygen release, safeguarding transition metal redox couples.
• Achieved a high initial Coulombic efficiency of 99.82%, cycling efficiency >99.9%, reversible capacity of 278 mAh/g, and 83.3% capacity retention after 100 cycles.

Conclusions:

• The synergistic design of the O2-structured cathode and all-fluorinated electrolyte significantly improves the stability and electrochemical performance of Li-rich layered oxides.
• This approach offers a promising strategy for developing next-generation high-energy Li-ion batteries.