Metal-free aqueous batteries are promising candidates
for grid-scale
energy storage owing to their inherent safety, low cost, and cost
effectiveness. The battery chemistry based on fast NH4+ diffusion kinetics avoids unfavorable generation of inactive
metallic byproducts. However, their practical applications have been
impeded by electrolyte instability and the intrinsic drawbacks of
current electrodes. Herein, we propose an aqueous ammonium–iodine
battery by using a chaotropic electrolyte, 3,4,9,10-perylenetetracarboxylic
dianhydride (PTCDA) anode, and iodine composite (I2@CC)
cathode. Experimental investigations and theoretical calculations
reveal that the chaotropic electrolyte not only enhances electrolyte
stability through modulating the H-bond structure but also facilitates
the formation of a hydrophobic cationic sieve (HCS) on the anode,
which ensures the electrolyte/electrode stability and high reversibility
of the anode. Additionally, the Cl–-containing electrolyte
can support the consecutive I+/I0 reaction on
the cathode by forming [IClx]1–x interhalogen. The as-assembled aqueous ammonium–iodine
batteries (AIBs) based on NH4+ accommodation
at the anode and I+/I0 redox reaction at the
cathode can deliver superior electrochemical performance at room temperature
and low temperature (−20 °C). This study provides a strategic
insight into developing metal-free aqueous batteries with electrolyte
modulation.