Stable layered P3/P2 Na0.66Co0.5Mn0.5O2 cathode materials for sodium-ion batteries

Abstract

Rechargeable sodium-ion batteries are promising next-generation energy storage devices due to the low cost and rich natural abundance of Na. However, it is still a great challenge to suppress phase changes of cathode materials in the high-voltage region. Unlike P-type single-phase composites, herein we present a facile strategy for preparing P3/P2-type biphasic layered Na_0.66Co_0.5Mn_0.5O₂, namely, integrating P2 into P3-layered materials. The crystalline structure of Na_0.66Co_0.5Mn_0.5O₂, which was investigated by ex situ X-ray diffraction, was well maintained over long cycling in a high-voltage range. Taking advantage of their structural stabilization, Na_0.66Co_0.5Mn_0.5O₂ cathode materials displayed remarkably steady discharge capacity at high rates. With outstanding structural flexibility and electrochemical performance, Na_0.66Co_0.5Mn_0.5O₂ would stimulate the development of sodium-ion batteries.