Surface-Modified Graphite Anodes for High-Rate Long-Cycling in Sulfide All-Solid-State Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Sulfide-based all-solid-state lithium batteries (ASSLIBs) offer high power density but face limitations in fast-charging capabilities.
• Reactivity between lithiated graphite and sulfide electrolytes, along with side reactions, hinders ASSLIB performance.

Purpose of the Study:

• To address the limitations of graphite anodes in ASSLIBs for improved fast-charging performance.
• To develop a stable anode-electrolyte interface to enhance cycling stability and rate capability.

Main Methods:

• Synthesis of a lithium niobate-coated spherized natural graphite composite (LNO@SNG) using a scalable sol-gel method.
• Fabrication of full cells using a LiNi0.7Co0.2Mn0.1O2 cathode and the LNO@SNG anode with Li6PS5Cl electrolyte.
• Electrochemical testing to evaluate cycling stability, rate capability, and performance under various conditions.

Main Results:

• The LNO@SNG anode formed an electrochemically stable interface with the Li6PS5Cl electrolyte.
• Full cells demonstrated excellent cycling stability under low stack pressures (≤5 MPa) and high rates (up to 12C).
• Achieved 96.5% capacity retention after 600 cycles at 4 mA·cm-2 (6C), even with high cathode loading (30.57 mg·cm-2).

Conclusions:

• The surface-modified graphite anode effectively mitigates interfacial reactivity and side reactions.
• The LNO@SNG anode offers a promising combination of cost-effectiveness, interfacial stability, and superior rate capability.
• This development represents a significant advancement for the commercialization of ASSLIBs.