# In Situ Modification of Sulfur-Based Cathode Electrolyte Interphases for Boosting Zinc/Graphite Dual-Ion Batteries via Vinylene Carbonate Additive and Dipropylene Glycol Methyl Ether/Water Mixed Solvent

## TL;DR

This paper introduces a low-cost electrolyte modification that improves the performance and stability of zinc/graphite dual-ion batteries.

## Contribution

A novel electrolyte formulation using vinylene carbonate and a mixed solvent enhances graphite cathode stability and capacity retention.

## Key findings

- A sulfur-rich cathode electrolyte interface forms on graphite with vinylene carbonate additive.
- Nanosized sulfide particles are generated in the graphite lattice, improving anion storage.
- The modified battery achieves 84.2% capacity retention after 500 cycles at 100 mA g–1.

## Abstract

Dual-ion batteries
(DIBs) have been extensively explored due to
their low material costs, high power density, and eco-friendly characteristics.
However, the graphite cathode often leads to structural damage and
instability at the electrode/electrolyte interface, severely diminishing
its electrochemical performance. This work presents a cost-effective
approach from the perspective of electrolyte optimization to overcome
these challenges. By incorporating a moderate amount (5 wt %) of vinylene
carbonate (VC) as an additive into a mixed solvent of dipropylene
glycol methyl ether (DPM) and water, significant improvements in electrochemical
performance are achieved, primarily due to the formation of a sulfur-rich
cathode electrolyte interface (CEI) on the graphite surface and the
electrolyte additive fostering the generation of nanosized sulfide
particles in the graphite lattice, which provide active storage sites
for anions. In the graphite-Zn DIB, a high discharge-specific capacity
of 140 mAh g–1 was achieved at 100 mA g–1, and after 500 cycles, the capacity retention rate is 84.2%, which
is much higher than that of the battery without VC. This work demonstrates
the potential of a cost-effective electrolyte in optimizing the composition
of the graphite cathode CEI and promoting the formation of inorganic
nanoparticle hosts on the graphite cathode surface for enhancing the
performance of DIBs.