Current Li-ion batteries struggle with fast charging, low temperatures, and thick electrodes due to challenges in managing mass transport and interfacial effects. These limitations restrict their use in demanding applications, especially in extreme conditions and setups without effective thermal management.
Engineers at the University of Michigan have developed a groundbreaking strategy enabling lithium-ion batteries to achieve extremely fast charging (up to 6C) at temperatures as low as −10°C while preserving high electrode loadings (> 3 mAh/cm²). This marks the first successful approach to combine fast charging, low-temperature operation, and energy density without compromise.
The approach combines 3D electrode architectures with an artificial solid-electrolyte interface (SEI) created through atomic layer deposition. This synergy improves mass transport and interfacial kinetics during fast charging and low temperatures, enabling thicker electrodes to access more capacity efficiently.
Graphite/NMC pouch cells were designed to separate the effects of electrolyte transport and interfacial impedance. When tested at a 6C-rate and −10°C, these integrated electrodes achieved over a 500% increase in accessible capacity and retained more than 97% of their capacity after 100 cycles, showcasing remarkable performance improvements in extreme conditions.
New energy-dense batteries work well in scorching sun and freezing cold
Previously, engineers enhanced battery charging by laser-drilling 40-micron pathways in the anode, allowing lithium ions to lodge faster and charge more uniformly, even deep within the electrode.
While the laser-drilled pathways improved room-temperature charging, cold charging remained inefficient. The team pinpointed the issue: a chemical layer forms on the electrode’s surface due to reactions with the electrolyte. In cold conditions, attempting fast charging through this layer causes lithium metal to accumulate on the anode, creating a “traffic jam” that disrupts efficiency.
The lithium plating blocks the electrode from charging, reducing the battery’s capacity. To address this, the team applied a 20-nanometer-thick glassy coating made of lithium borate-carbonate to prevent the surface layer from forming.
Combining surface coatings and 3D-structured graphite anodes effectively overcomes transport and interfacial challenges in extreme conditions, preventing harmful lithium plating.
This coating significantly improved cold charging, and when paired with the laser-drilled channels, the test cells charged 500% faster in subfreezing conditions.
