A 5 molar concentrated electrolyte effectively stabilizes bismuth–potassium batteries due to its elevated resistance to electrochemical reduction.

0.62 K+ readily (de)intercalates in WS2 with well-defined voltage plateaus, an intrinsically safe operation potential, and ultrahigh reversibility.

Aqueous rechargeable batteries (ARBs) are provided with the merits of low cost, inherent security, environmental friendliness, and excellent electrochemical properties. Among various aqueous battery systems, aqueous ammonium‐ion batteries (AIBs) have shown great potential in low‐cost energy storage systems for future large‐scale smart grid applications due to their unique advantages including resource affordability and quite competitive electrochemical performance and received extensive research attention during recent years. Their unique battery chemistry also brings new insights and understanding into exploration of electrode and battery design. However, research on aqueous AIBs is still in its infancy and there are still many scientific issues in AIBs system worth exploring. In this paper, the latest developments in electrode materials, electrolytes, and battery chemistry in AIBs are reviewed in detail timely. Then further challenges and opportunities are pointed out.