Operando neutron imaging-guided gradient design of Li-ion solid conductor for high-mass-loading cathodes

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• High-mass-loading cathodes are essential for increasing energy density in all-solid-state batteries.
• Increased mass-loading typically leads to compromised electrochemical performance due to sluggish kinetics.

Purpose of the Study:

• To investigate ion transport limitations in high-mass-loading cathodes.
• To develop a strategy to overcome kinetic barriers and enhance battery performance.

Main Methods:

• Operando neutron imaging was used to visualize lithiation in a high-mass-loading NMC 811 cathode (33 mg/cm²).
• A gradient in catholyte concentration was engineered to match Li+ flux distribution.

Main Results:

• Neutron imaging revealed lithiation prioritization from the solid electrolyte membrane to the current collector.
• The engineered gradient design effectively addressed ion transfer limitations caused by catholyte distribution mismatch.
• A LiCoO2 cathode (100 mg/cm²) achieved an areal capacity of 10.4 mAh/cm² at 2.25 mA/cm².

Conclusions:

• Gradient engineering of catholyte concentration is an effective strategy to overcome kinetic barriers in high-mass-loading cathodes.
• This approach significantly enhances rate performance and battery energy density.
• The study provides critical insights into ion transport mechanisms in thick battery electrodes.