15-Minute Full Charge! USTC & SES AI Crack the Code for Ultrafast Lithium Metal BatteriesIntroduction: The "Fast-Charging Paradox" of Lithium Metal

Lithium metal batteries (LMBs) are often hailed as the "Holy Grail" of next-gen energy storage due to their ultra-high energy density. However, they face a severe bottleneck: Ultrafast Charging. When forced to charge quickly (e.g., 10-15 minutes), lithium ions cannot deposit uniformly, leading to dendrite growth, SEI rupture, and eventually, short circuits or safety hazards.

Traditional electrolyte engineering faces a dilemma: enhancing solvation accelerates ion transport in the bulk liquid but often hinders electron transfer at the interface. To break this deadlock, a team led by Prof. Xiaodi Ren (USTC) and Dr. Kang Xu (SES AI) introduced a novel strategy based on "Molecular Orbital Engineering," published in Nature Energy.

Core Breakthrough: The "Planar Aligned Electron Channel" (PAEC)

The team designed a novel ether-based solvent molecule: 1-methoxy-3-(3-methoxypropoxy)propane (MTP).

The genius lies in its microscopic electron structure. In traditional solvents (like G2), the electron orbitals are often spatially disordered when coordinating with Li-ions, creating a "bumpy road" for electrons. In contrast, when MTP coordinates with Lithium ions, the lone-pair electron orbitals of the oxygen atoms form a unique "Co-Planar Aligned" structure.

This Planar Aligned Electron Channel (PAEC) acts like a molecular-level "highway," facilitating not just rapid ion transport but also accelerating the transfer of electrons from the electrode to the lithium ions.

Unveiling the Mechanism: Mastering the Stereoelectronic Effect

The research revealed a crucial insight: Interface kinetics are not just about "desolvation energy" but also about the spatial distribution of electron orbitals.

• The Sweet Spot: MTP achieves a perfect balance. It maintains strong Li-solvent coordination (good for bulk transport) while its PAEC structure enables efficient electron coupling (good for interface reaction).

• Rapid Kinetics: Transient cyclic voltammetry tests showed the MTP electrolyte achieves an interfacial exchange current density of 267.11 mA cm⁻², far surpassing traditional electrolytes. This means even under high-current charging, Li-ions can instantly gain electrons and deposit uniformly, preventing dendrites at the source.

Practical Performance: 400 Wh/kg Pouch Cells at 4C

This technology has moved beyond coin cells to industrial-grade practical applications. The team tested the electrolyte in 2Ah Li||NMC811 pouch cells under harsh conditions (lean electrolyte: 0.8 g/Ah). The results were record-breaking:

• Ultrafast Charging: <15 minutes to 100% charge, and <10 minutes to 80% charge (4C rate).

• High Energy & Power: The battery achieved an energy density of ~400 Wh kg⁻¹ and a charging power density of 1747.6 W kg⁻¹.

• Durability: Stable cycling for over 100 cycles under 4C ultrafast charging/discharging conditions with >80% capacity retention.

Conclusion

This study disrupts the traditional understanding that interface reactions are solely dominated by desolvation. By leveraging the "Stereoelectronic Effect" to create aligned electron channels, the MTP electrolyte resolves the conflict between ion conduction and charge transfer. This paves the way for practical, high-energy-density lithium metal batteries that can charge as fast as filling a gas tank.

Literature Information

Digen Ruan, et al., Molecularly aligned electron channel for ultrafast-charging practical lithium metal batteries, Nature Energy (2026). https://www.nature.com/articles/s41560-025-01961-z