Dendrite-free potassium metal anode induced by in-situ phase transitions of MoS2

Potassium ion batteries (PIBs) are identified as an imperative alternative for next-generation energy storage devices due to its abundant reserves. Even potassium (K) metal is a promising anode for its high theoretical capacity and intrinsic low potential, however, it still suffers from uncontrollable dendrite growth. Herein, a dendrite-free K anode is obtained by plating K metal on MoS2-modified carbon cloth (MoS2/CC@K). Specifically, MoS2 undergoes a series of phase transitions from initial MoS2 to KxMoS2 and final K2S4 with gradual insertion of K, then K metal is uniformly deposited on K2S4 with further discharging. This phase transition significantly reduces the K nucleation energy barrier. The strong interaction between K and K2S4 interface induces K in uniformly depositing to suppress the formation of K dendrites. Owing to these merits, the symmetric MoS2/CC@K cells exhibit low voltage hysteresis and superior cycling stability. When paired with perylene-3,4,9,10-tetracarboxylic diimide (PTCDI) cathode, the full cells display superior rate capability and long lifespan (10,000 cycles). Additionally, this strategy is also performed on Li and Na metal anodes, the MoS2/CC substrate still expresses superior electrochemical performance. This work provides a new view to induce the uniformly deposition of K, Li and Na metals.