Synergistically Controlled Mechanism of Sodium Birnessite with a Larger Interlayer Distance for Fast Ion Intercalation toward Sodium-Ion Batteries

The high theoretical capacity of sodium birnessite cathode materials for sodium-ion batteries (SIBs) has been restricted due to drastic volume variation and fast capacity fading. The underlying reasons are the interlayer electrostatic interaction and the Mn 3+ Jahn–Teller effect. To overcome these two effects, herein, the synergistically controlled mechanism of sodium birnessite with a larger interlayer distance is achieved through enhancing the interlayer distance. Tetramethylammonium ions (TMA + ) as effective supporters stabilized the host structure, providing a fast and stable Na + transmission channel. The TMA + intercalated into sodium birnessite as a cathode material in sodium-ion batteries delivered a specific discharge capacity of 136 mAh g –1 at 2C and a Coulombic efficiency of 100% after 200 cycles. The result provides a stable charge-storage strategy of layered materials for high-rate capability using intercalation chemistry.