Disordered Rock Salts

Disordered Rock Salts (DRX)

Research Overview

Disordered Rock Salts (DRX) are cobalt-free, crystalline rocksalt materials that typically contain excess Li for enhanced ion transport. All cations are randomly distributed on the octahedral sites in the structure, and a fraction of oxygen anions can be substituted by fluorine using either a solid state or mechanochemical synthesis method. These cathodes can deliver very high capacities and energy densities (up to 300 mAh/g and 1000 Wh/kg have been reported), making them attractive alternatives to today’s Lithium-Nickel-Manganese-Cobalt-Oxide (NMC)-type cathodes.

Researchers at Berkeley Lab are investigating a handful of these materials to understand the role of oxygen redox on capacity and cathode stability, the impact of fluorine substitution of oxygen to improve stability, synthesis routes to create materials of a uniform particle size, and the impacts that other components of a cathode may have on stability.

a) A schematic diagram of disordered rocksalt-type compounds. b, c) Capacity and energy retention of Gen1-DRX Li1.2Mn0.7Ti0.1O1.9F0.1 under various cycling conditions.
a) A schematic diagram of disordered rocksalt-type compounds. b, c) Capacity and energy retention of Gen1-DRX Li1.2Mn0.7Ti0.1O1.9F0.1 under various cycling conditions.


Research Tasks

In 2022, teams are organized around four topic areas:

Task 1: High voltage processes

Explore carbon morphology and high voltage stability. A high amount of amorphous carbon is used in our electrode making (unoptimized process). 

At high voltage, this is likely to assist in the catalytic decomposition of the electrolyte components and possible structural rearrangement of the active material surface.  We will attempt to use more graphitized carbons and/or novel carbon coatings of the cathode particles. 

Task 2: Alternative electrolytes and salts

Current electrolytes are not optimized for interaction with the DRX cathode surface and high voltage stability. Ethylene carbonate (EC) and hexafluorophosphate anion (PF6-) are likely culprits of the instability of the system when charged to high voltages. 

Use of EC-free (or low EC) electrolytes and lithium bis(fluorosulfonyl) imide (LiFSI) salt will be evaluated.  

Task 3: Thermal properties of DRX cathodes

Perform differential scanning calorimetry (DSC) experiments (among other thermal tests) and in-situ characterization of cathodes at different states of charge to evaluate the thermal response at elevated temperatures. 

Task 4: Optimization of DRX materials and scale up synthesis

Our current Gen1-DRX has not gone through material optimization process with respect to particle size and morphology.

This effort aims to optimize the synthesis conditions to produce particles with improved Li transport and stability against damaging processes at high voltages (such as oxygen loss, Mn dissolution and electrolyte degradation etc.), as well as improved packing density in the composite electrode. Scale up synthesis effort aims to deliver a large quantity of materials to the researchers in the entire DRX program.

The Battery Group Researchers

Research Scientist
Senior Scientist
Research Scientist

Additional Berkeley Lab Collaborators

Gerbrand Ceder Profile ImageGerbrand Ceder
DRX Research Area Lead
Faculty Senior Scientist, UC Berkeley
Senior Staff Scientist, Material Sciences Division




Kristin Persson profile imageKristin Persson
Faculty Senior Scientist, UC Berkeley
Director, Molecular Foundry
Senior Staff Scientist, Material Sciences Division

Wei Tong Profile picWei Tong
Staff Scientist, Energy Storage & Distributed Resources Division