Highly-pseudocapacitive origin and design principles of MoS2 for high-performance aqueous zinc-ion storage

Pseudocapacitive storage of Zn ²⁺ in nanostructured molybdenum disulfide (MoS ₂) is expected to break through the limitations of sulfide in monovalent or multivalent ions storage; however, the deficiency of theoretical guidance and experimental strategies that enable rational design of MoS ₂ as a kind of cathode material towards aqueous zinc-ion batteries. Herein, we firstly establish guiding theory in order to design pseudocapacitive MoS ₂-based cathode in the light of the first-principles calculation, and then propose a simple and effective one-pot template-free solvothermal method to synthesize 1T phase-dominated MoS ₂ cathode with low crystallinity. Through this method, MoS ₂ cathode delivers an exceptional reversible capacity of 233 mAhg ⁻¹ at 0.05 A g ⁻¹, especially at 0.1 A g ⁻¹, the stability can achieve >150 cycles, and maintains 84 % capacity retention after 2100 cycles at 5 A g ⁻¹. Experimental and theoretical analysis show that such extraordinary pseudocapacitive contribution determines by the synergistic effects in the activated and stable metallic phase, abundant lattice defects and larger interlayer spacing in the rag-like MoS ₂ cathode. The revealed origin of highly pseudocapacitive Zn ²⁺ storage and design principle for MoS ₂-based cathode facilitate the design of a variety of efficient cathodes.