Chemistry: Electrolyte & Separator

Electrolyte Types And Research Areas In the electrolyte industry, technological advancements look toward overcoming key battery challenges: liquid electrolyte reactivity, temperature performance and lifetime of Li-ion; enabling emerging anodes Si, Li metal, “anode freeˮ). Borrowing from non-liquid technologies: All solid-state batteries are a significant industry thrust and are covered elsewhere, but semi-solid gels (polymer + liquid electrolyte) and liquified gases are being commercialized.

Liquified gas: South8ʼs LiGas, named Timesʼ best invention of 2025, non-toxic gases have a reduced fire risk and high rate capability (low viscosity + high conductivity).

Semi-solid and gel electrolytes: A step toward solid polymer electrolytes, a polymer matrix is saturated with liquid (solvent + salt). They are less flammable and often have higher temperature stability. Like solid electrolytes, ionic conductivity is lower compared to traditional liquids and advancements often seek to increase conductivity In Li metal cells, they exhibit less dendrite formation. Source 24M, Anthro Energy, QuantumScape, and others use gel polymers.

Expanding molecular library: Following the existing model for liquid electrolyte, advancements focus on discovery of new molecules to add to the blend.

Advancing salt chemistry: LiPF6 is the most commonly used electrolyte salt, but modifying concentration or chemistry to enhance performance.

AI Discovery: Companies such as Chemix or Sepion use AI and machine learning to discover new battery materials.

Nitrile chemistry: Recently several companies have announced nitrile solvents and additives. Asahi Kasei announced acetonitrile as a solvent to widen the optimal temperature range for electrolytes. Tesla publishes nitrile sulfites in a 2019 patent with Prof. Jeff Dahn while Sila publishes a 2023 patent. Ascend Performance materials manufactures Trinohex Ultra (shown on the left), a tritrile additive after winning a challenge with Samsung in 2021.

High salt concentrations: SES advertises “salt in solventˮ electrolytes (shown left) with high salt concentrations, promising higher Coloumbic efficiency and enabling lithium metal cells with a liquid electrolyte. PNNL popularized localized high concentration electrolytes LHCEs which use a second solvent (diluent) where the salt is poorly soluble to achieve a similar effect. This concept is moving to industry, such as Giner Inc's advertised development work.

Dual salt electrolytes: While LiPF6 is cost effective, adding secondary salts in the electrolyte improves performance while mitigating the the cost or solubility challenges with more appealing options. Several publications and patents1,2 mention the concept and several industrial electrolyte suppliers offer dual salt options. Ionic liquids ILs show promise for their stability and non-flammability, but cost and viscosity limit their utility. Recently, IL have been used as additives or cosolvents to balances to advantages against these challenges. Source

Extracted from the PDF; charts and images may read imperfectly.