A Lithium-ion Battery Using Partially Lithiated Graphite Anode and Amphi-redox LiMn₂O₄ Cathode

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Cubic lithium manganese oxide (LMO) spinel has been utilized for energy storage in lithium-ion batteries (LIBs).
• Current LIB applications primarily use Li+ occupied (n-type) tetrahedral sites in LMO for delithiation/lithiation at ~4 V.

Purpose of the Study:

• To explore the potential of unoccupied (p-type) octahedral sites in LMO for enhanced lithium-ion battery energy storage.
• To achieve the full capacity of amphi-redox LMO by utilizing both n-type and p-type redox sites.

Main Methods:

• Investigated lithiation of unoccupied octahedral sites in LMO at ~3 V, a previously unused capacity in full-cell configurations.
• Employed graphene-wrapping of LMO nanoparticles (LMO@Gn) to ensure durable reversibility of the 3 V reaction.
• Utilized prelithiated graphite (Li_nC_6, n<1) as anodes to facilitate the lithiation of unoccupied octahedral sites in LMO.

Main Results:

• Successfully utilized unoccupied octahedral sites in LMO at ~3 V, delivering an additional ~100 mAh g_LMO^-1 capacity.
• Achieved the total capacity of amphi-redox LMO at ~200 mAh g_LMO^-1 by combining reactions at both 4 V and 3 V.
• Demonstrated durable reversibility for the 3 V reaction through graphene-wrapping of LMO nanoparticles.

Conclusions:

• The study demonstrates a novel approach to significantly enhance LMO capacity for LIBs by exploiting amphi-redox properties.
• Utilizing both n-type and p-type redox sites in LMO offers a pathway to doubling energy storage potential.
• Graphene-wrapping and prelithiated graphite anodes are effective strategies for realizing stable and high-capacity LMO-based LIBs.