Lithium metals are considered the ultimate anode material to create high-energy-density batteries, but lithium-metal batteries (LMBs) have proven unstable when it comes to the charge/discharge cycling performance users demand. One way to improve stability is to use highly concentrated electrolyte solutions that can work efficiently with the thin lithium-metal anode and high-voltage cathode. But current high-concentration electrolytes usually suffer from high viscosity and poor wetting of the cathode (especially for a high-loading cathode), making them difficult to use during the battery manufacturing process. These electrolytes are also expensive to produce.

Ideal for Rechargeable Battery Systems, Sensors, and Supercapacitors

Researchers at Pacific Northwest National Laboratory have developed low-cost, high-performance Localized High Concentration Electrolytes (LHCE) with low viscosity, improved conductivity, and good wettability. LHCE not only improve LMBs but are also compatible with Li-ion batteries (LIB). These LHCE include the following components:

• A high, effective concentration of an active salt, or combination of salts, that participates in the charge/discharge cycling of the battery. Example salts can include those of lithium, sodium, and magnesium.
• A solvent in which the active salt is soluble. The solvent can comprise a range of chemicals, from carbonates to ether and even water.
• A diluent in which the active salt is insoluble or poorly soluble, but in which the solvent is miscible. The diluent helps reduce the viscosity and increase conductivity by lowering the overall concentration of the salt in the solution.

The unique combination of these components provides a localized concentration of active electrolyte salts to deliver the kind of performance that is normally only associated with traditional high-concentration solutions, while at the same time, avoids the low conductivity and wetting problems also associated with traditional high-concentration solutions. PNNL’s LHCE compositions can increase anode efficiency, improve cycling stability, and reduce the cost of current and next-generation lithium batteries. 

APPLICABILITY

Besides stabilizing LMBs and LIBs, PNNL’s LHCE can be used in other types of rechargeable battery systems, sensors, and supercapacitors. Versions exist for low-flammability, low-volatility, high-voltage cathodes, Si-based anodes, and anode-free batteries.