Lithium–sulfur (Li–S) batteries hold great promise for next-generation energy storage owing to their high theoretical energy density and the abundance of sulfur. Realizing their practical potential, however, requires electrodes with high sulfur loading, high areal capacity, and operation under lean electrolyte conditions—requirements that exacerbate intrinsic challenges such as polysulfide shuttling, sluggish redox kinetics, and poor electrode integrity. MXenes, a rapidly emerging family of two-dimensional transition metal carbides, nitrides, and carbonitrides, offer a unique combination of high electrical conductivity, abundant surface terminations, tunable chemistry, and structural robustness, making them particularly suited for high-loading Li–S systems. In this review, we summarize the key physicochemical properties of MXenes and elucidate their interaction mechanisms with sulfur/polysulfides, tracing recent advances in MXene-based materials for Li–S batteries across their applications on sulfur hosts, separator modification and lithium anode protection, with emphasis on their role in enabling high sulfur utilization and long-term cycling stability. The discussion highlights how MXenes and their heterostructures enhance polysulfide adsorption, catalyze redox conversion, and maintain electrode integrity, while also promoting uniform lithium deposition. Finally, we provide perspectives on the challenges and opportunities in tailoring MXene composition, surface chemistry, and structural design to accelerate the development of practical, high-energy-density Li–S batteries.

The reversible storage of Zn²⁺ ions in Prussian blue analogues with typical aqueous solution was challenged by fast degradation and poor coulombic efficiency, while the mechanism is yet to be uncovered. This study correlates the performance of the nickel hexacyanoferrate to the dynamics of H₂O in the electrolyte and the associated phase stability of the electrode. It demonstrates severe Ni dissolution in conventional diluted aqueous electrolyte (1 _M ZnSO₄ or 1 _M Zn(TFSI)₂), leading to structure collapse with the formation of an electrochemical inert phase. This is regarded as the descriptor for the fast decay of nickel hexacyanoferrate in diluted aqueous electrolyte. However, a well-preserved open framework for zinc storage was obtained in concentrated aqueous electrolyte (1 _M Zn(TFSI)₂ + 21 _M LiTFSI) —the H₂O activity is highly suppressed by extensive coordination—thus, reversible capacity of 60.2 mAh g⁻¹ over 1600 cycles could be delivered.