Maintaining the sustainability
of society demands the
strategic
use of multipurpose rechargeable batteries. One promising option is
K-ion batteries (KIBs), which are suitable as large stationary storage
batteries and store renewable energy because of their abundant K resources.
Herein, the anode properties of different binary antimonide (MSb
x
; M: metal)
electrodes were investigated for KIBs in an ionic-liquid electrolyte.
The results indicated that although Sb and SnSb electrodes exhibited
a high initial reversible capacity, their cycle stability was poor.
In contrast, rare-earth antimonide (LaSb, SmSb, and YSb) electrodes
showed extremely long cycle stability over 500 cycles with a capacity
approximately one-third that of the Sb electrode. Interestingly, rare-earth
antimonides possess seamless alloying and dealloying with K without
undergoing phase separation into rare-earth and Sb phases. Additionally,
other MSb
x
electrodes,
such as FeSb2, FeSb, and AlSb, exhibited relatively higher
reversible capacity and cycle stability when M was
K-inactive. These electrodes possessed moderate Mohs hardness and
low electrical resistance and caused MSb
x
phase separation into M and Sb
phases. Notably, the stiff M phase effectively withstood
the compressive stress produced by Sb and provided a supporting skeleton.
Our study will provide insight into the physicochemical properties
of M alloyed with Sb to achieve excellent cycle stability
in KIBs and reveal that the same active material demonstrated different
anode properties than Na-ion batteries.