A Functionality-Graded Cathode Electrolyte Interphase Enables Ultra-Long Cycling Stability in Aqueous Zn-Mn Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• The rational design of cathode electrolyte interphases (CEI) is crucial for improving the kinetics and stability of zinc-manganese batteries.
• However, the design principles and formation mechanisms of CEI are not yet fully understood.

Purpose of the Study:

• To develop an in situ strategy for constructing a functionality-graded hierarchical CEI on a carbon-coated Cu-MnO2 cathode using an electrolyte additive.
• To investigate the formation mechanism and impact of this engineered CEI on battery performance.

Main Methods:

• Utilized theoretical calculations to guide the electrolyte additive-driven in situ construction of CEI.
• Employed trace KH2PO4 as an electrolyte additive to form a hierarchical CEI.
• Characterized the CEI structure and composition, and evaluated battery performance through cycling tests.

Main Results:

• Successfully constructed a hierarchical CEI with distinct inner inorganic, intermediate organic phosphate ester, and outer hydrated layers.
• The engineered CEI effectively regulated the interfacial water environment, mitigated volume stress, and promoted charge carrier transport.
• The zinc-manganese battery achieved exceptional cycling stability, with 100,000 cycles at 5.0 A g-1, a nearly 10-fold improvement over conventional systems.

Conclusions:

• The in situ strategy using KH2PO4 is a universal approach for interfacial engineering in aqueous batteries.
• This method provides new insights into regulating CEI formation and reaction kinetics through electrolyte engineering.
• Achieved durable energy storage performance in zinc-manganese batteries via rational CEI design.