Multi-stage constant-current charging protocol for a high-energy-density pouch cell based on a 622NCM/graphite...

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• High-energy-density lithium-ion cells (LICs) require efficient charging methods.
• Conventional constant-current (CC) charging can be time-consuming and may lead to degradation.
• Optimizing charging protocols is crucial for battery performance and lifespan.

Purpose of the Study:

• To introduce and evaluate a novel multi-stage-constant-current (MS-CC) charging protocol for LICs.
• To assess the charging speed, lithium plating, and capacity retention of the MS-CC protocol.
• To compare the MS-CC protocol against conventional 1.5C CC charging.

Main Methods:

• Developed and implemented a three-stage MS-CC charging protocol.
• Conducted twelve experimental groups under controlled conditions to avoid lithium plating.
• Performed cell dismantling to analyze lithium deposition and conducted cycling tests at various temperatures (10 °C, 25 °C, 50 °C).

Main Results:

• MS-CC charging significantly reduced charging time to under 36 minutes.
• MS-CC charging resulted in less lithium deposition compared to 1.5C CC charging.
• Capacity retention after 300 cycles at 25 °C was 99.5-100.0% for MS-CC, versus 95.7% for 1.5C CC.
• Specific MS-CC groups (2.0-1.5-0.9C and 1.8-1.5-0.9C) showed excellent capacity retention (99.6-99.9%) even after 510 cycles at 10 °C.

Conclusions:

• The MS-CC charging protocol offers a faster and more efficient method for charging LICs.
• MS-CC charging minimizes cell material damage and polarization, leading to superior capacity retention.
• This protocol presents a viable alternative to conventional CC charging for improved battery performance and longevity.