posted on 2021-07-01, 14:37authored byJie Yao, Chenglin Zhang, Guowei Yang, Mo Sha, Yulian Dong, Qun Fu, Yuhan Wu, Huaping Zhao, Minghong Wu, Yong Lei
Bismuth
(Bi) has been considered as a promising alloying-type anode
for potassium-ion batteries (PIBs), owing to its high theoretical
capacity and suitable working voltage plateaus. However, Bi suffers
from dramatic volume fluctuation and significant pulverization during
the discharge/charge processes, resulting in fast capacity decay.
Herein, we synthesize Bi nanoparticles confined in carbonaceous nanospheres
(denoted as Bi@C) for PIBs by first utilizing BiOCl nanoflakes as
a hard template and a Bi precursor. The construction of the loose
structure buffers the mechanical stresses resulting from the volume
expansion of Bi during the alloying reaction and avoids the fracture
of the electrode structure, thus improving the cycling performance.
Moreover, the carbonaceous layers increase the electronic conductivity
and disperse the Bi nanoparticles, enhancing the charge transportation
and ionic diffusion, which further promotes the rate capability of
Bi@C. It exhibits a superior capacity (389 mAh g–1 at 100 mA g–1 after 100 cycles), excellent cycling
stability (206 mAh g–1 at 500 mA g–1 over 1000 cycles), and an improved rate capability (182 mAh g–1 at 2.0 A g–1). This work provides
a new structuring strategy in alloying materials for boosting reversible
and stable potassium-ion storage.