Thursday, April 18, 2024

New method promises safe, more efficient solid-state batteries

The development of thin, dense, defect-free solid electrolyte films is key for achieving practical and commercially viable solid-state batteries.

Oak Ridge National Laboratory (ORNL) found that a small tweak created big performance improvements in a type of solid-state battery, a technology considered vital to broader electric vehicle adoption.

Solid-state batteries use a solid electrolyte instead of a potentially flammable liquid. When the battery charges or operates, ions move between electrodes through the electrolyte between them.

Now researchers developed a new method that produces a more uniform solid electrolyte than the traditionally processed material with more voids. The material can be integrated into a battery system for improved stability and rate performance.

The electrolyte film is made from antiperovskite (Li2OHCl), a promising class of solid electrolytes because of their inherent low-temperature processability and high ionic conductivities, in addition to their high electrochemical stability window. The solid electrolyte material can yield films/pellets with very high densities (∼100%) and higher conductivities compared with conventional uniaxially pressed pellets.

The approach involved heating the press after spreading the electrolyte on it, then letting the electrolyte cool under pressure. The resulting material was also almost 1,000 times more conductive, showing close to 50% improvement in the critical current density. Also, the team achieved an improved lithiophilicity due to the surface nitrogen enrichment of the processed pellets.

“It’s the same material – you’re just changing how you make it while improving the battery performance on a number of fronts,” ORNL lead researcher Marm Dixit said.

The results highlight the feasibility of the new processing pathway for engineering antiperovskite solid electrolytes at the grain scale as a highly desirable approach for practical all-solid-state batteries.

Journal reference:

  1. Marm Dixit, Nitin Muralidharan, Anuj Bisht, Charl J. Jafta, Christopher T. Nelson, Ruhul Amin, Rachid Essehli, Mahalingam Balasubramanian, and Ilias Belharouak. Tailoring of the Anti-Perovskite Solid Electrolytes at the Grain-Scale. ACS Energy Letter, 2023; DOI: 10.1021/acsenergylett.3c00265