Efficient Ion Percolating Network for High-Performance All-Solid-State Cathodes

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• All-solid-state lithium batteries (ASSLBs) are hindered by low cathode loading and poor rate performance, limiting energy and power densities.
• Traditional goals of high ionic conductivity and low interfacial resistance are insufficient to overcome these limitations.
• The structure and connectivity of ion transport pathways within the cathode are critical for ASSLB performance.

Purpose of the Study:

• To investigate the impact of ion percolating network structure on ASSLB electrochemical performance.
• To develop a method for creating an efficient ion percolating network in solid-state cathodes.
• To demonstrate improved energy and power densities in ASSLBs through optimized cathode architecture.

Main Methods:

• Utilizing magnetic manipulation to achieve vertical alignment of Li_0.35La_0.55TiO₃ nanowires (LLTO NWs) in solid-state cathodes.
• Fabricating all-solid-state LiFePO₄/Li cells with poly(ethylene oxide) electrolyte.
• Evaluating electrochemical performance, including capacity retention at various C-rates and temperatures, and areal capacity.

Main Results:

• Vertically aligned LLTO NW cathodes exhibited doubled ionic conductivity compared to randomly distributed LLTO NW cathodes.
• All-solid-state LiFePO₄/Li cells achieved high capacities of 151 mAh g^-1 (2 C) and 100 mAh g^-1 (5 C) at 60 °C.
• A room-temperature capacity of 108 mAh g^-1 at 2 C and a high areal capacity of 3 mAh cm^-2 with 20 mg cm^-2 LFP loading were demonstrated.
• The strategy was successfully applied to LiNi_0.8Co_0.1Mn_0.1O₂ cathodes, showing its universality.

Conclusions:

• An efficient ion percolating network, achieved through vertical alignment of LLTO NWs, is more critical than previously thought for ASSLB performance.
• This magnetic manipulation strategy significantly enhances ionic conductivity and electrochemical performance of ASSLBs.
• The findings offer new avenues for designing high-energy and high-power all-solid-state lithium batteries.