Improved Interface Construction on Anode and Cathode for Na-Ion Batteries Using Ultralow-Concentration Electrolyte...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Sodium-ion batteries (SIBs) offer a cost-effective alternative to lithium-ion batteries.
• Ultralow sodium salt electrolytes (0.3 M NaPF6) reduce cost but lead to defective interfaces and poor cycling.
• The organic-dominated interface, derived from solvent decomposition, hinders long-term SIB performance.

Purpose of the Study:

• To improve the cycling performance of SIBs using an ultralow concentration electrolyte.
• To investigate the effect of dual additives, NaDFOB and TMSB, on interfacial properties.
• To construct stable interface films on both anode and cathode.

Main Methods:

• Electrochemical testing of hard carbon/NaNi1/3Fe1/3Mn1/3O2 cells with dual additives.
• Utilizing sodium difluoro(oxalato)borate (NaDFOB) and tris(trimethylsilyl)borate (TMSB) as additives.
• Combining theoretical computation and experimental techniques to analyze interfacial mechanisms.

Main Results:

• Dual additives (NaDFOB and TMSB) significantly improved cycling stability.
• Capacity retention increased from 17% (baseline) to 79% (with NaDFOB) and 83% (with NaDFOB and TMSB) after 200 cycles.
• Effective interface films were constructed on electrodes in ultralow concentration electrolyte.

Conclusions:

• Dual additives are effective in enhancing SIB cycling performance in ultralow concentration electrolytes.
• The construction of stable interface films is crucial for improved electrochemical stability.
• This approach offers a promising strategy for developing cost-effective and high-performance SIBs.