Ion Storage and Self-Healing Feature in All-Solid-State Battery
Researchers at the University of Western Ontario are making strides in the development of lithium-iron-chloride (LiFeCl) cathodes for all-solid-state batteries (ASSBs). This innovative material promises improvements in range, charging time, and safety compared to current lithium-ion batteries.
The new cathode material, LiFeCl, is created by mixing crushed lithium chloride and two different formulations of iron chloride. This unique composition allows lithium ions to move freely and find storage sites, a key factor in battery performance.
One of the standout features of LiFeCl is its self-healing property. During charging and discharging cycles, the material undergoes phase transitions, expanding by about 8% as it fills up with ions. This change in state, combined with the heat associated with charge/discharge, triggers a transition from brittle to ductile, enabling the material to fix any damage that may occur. As a result, LiFeCl retains over 90% of its capacity after 3,000 cycles when charged and discharged at a rate of 5 C.
Integration with a nickel-rich layered oxide increased the energy density of LiFeCl to 725.6 Wh/kg. In a test setup, it had an initial electrode energy density of 529.3 Wh/kg relative to a Li+/Li reference material, a figure similar to that of iron-phosphate cathodes.
Current advancements in the development and manufacturing of LiFeCl cathodes focus on enhancing compatibility and stability of solid electrolytes with lithium metal anodes, improving interfacial stability, and optimizing cathode materials to increase capacity retention and cycling life.
Research into iodide-chloride solid electrolytes, such as Li2ZrCl6-xIx, has been promising. These electrolytes exhibit high ionic conductivity, good mechanical deformability, and oxidative stability, enabling stable cycling over 6000 hours and high critical current densities (up to 6 mA cm⁻²).
Machine learning approaches are also being applied to the design of cathode materials, targeting improved capacity retention and stability. While not specific to LiFeCl cathodes, these data-driven strategies may accelerate the identification and optimization of novel cathode compositions suitable for ASSBs.
The integration of conductive additives, such as single-wall carbon nanotubes (SWCNTs), into cathodes is another noteworthy advancement. This improves electrical connectivity and reduces electrode resistance, potentially applicable to LiFeCl cathodes as well.
With these advancements, solid-state batteries are expected to take a significant step forward this year, offering a brighter future for electric vehicles and other applications requiring high-performance batteries.
- The unique self-healing property of the LiFeCl cathode, especially during charging and discharging cycles, makes it a promising material for all-solid-state batteries (ASSBs) due to its ability to overcome damage and retain over 90% of its capacity after 3,000 cycles.
- Collaborative efforts are being made in the research of iodide-chloride solid electrolytes, such as Li2ZrCl6-xIx, which exhibit high ionic conductivity, good mechanical deformability, and oxidative stability, potentially enhancing the compatibility and stability of solid electrolytes with lithium metal anodes for improved performance in ASSBs, including LiFeCl cathodes.
