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 Na0.66Co0.5Mn0.5O2, namely, integrating P2 into P3-layered materials. The crystalline structure of Na0.66Co0.5Mn0.5O2, 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, Na0.66Co0.5Mn0.5O2 cathode materials displayed remarkably steady discharge capacity at high rates. With outstanding structural flexibility and electrochemical performance, Na0.66Co0.5Mn0.5O2 would stimulate the development of sodium-ion batteries.