Advancements in Long Duration - Liquid Metal battery technology

D. Bradwell, A. Briggs, D. Alderton
Ambri Inc.,
United States

Keywords: long duration energy storage, liquid-metal battery, molten-metal battery


Originally inspired by the aluminum smelting process, we have developed a modular and self-contained ‘lunch-box sized’ cell technology based on liquid metal and molten salt components, coined the ‘Liquid Metal Battery’. The chemistry comprises a liquid calcium (Ca) alloy anode, a cathode of solid antimony (Sb) metal particles, and a molten salt electrolyte containing calcium chloride (CaCl2), herein referred to as the ‘Ca||Sb’ cell chemistry. This chemistry builds upon fundamental work performed by Professor Sadoway’s research group at the Massachusetts Institute of Technology (MIT). At the same time, this chemistry represents a significant departure from past work on liquid metal batteries, specifically due to the introduction of a cathode composed of solid Sb particles. In 2017, Ambri switched from an unspecified three-liquid layer ‘liquid metal battery’ (LMB), to this new Ca||Sb cell chemistry. The cells are self-contained and sealed (i.e., no pumps, tubing) and are connected in series in order to reach the voltages required for grid-connected systems. This change gives Ambri’s technology safety, performance, and cost advantages over future projections for lithium-ion batteries, which have become the most widely deployed battery technology for grid-scale storage systems. There are many system benefits Ambri's LMB technologies brings to the market, including: >U.S. invented and manufactured technology >20+ year life with only 5% degradation independent of energy throughput >Up to 25 lower cost than Li-Ion Systems (before the recent increases seen in the market) -Active materials are 1/3rd the cost of Li-Ion's cells -Lower oversizing due to fade curve advantages -No gas or fire detection required (sealed cells, non-flammable) -No HVAC system needed >Safe -Non-flammable system and materials (anode, cathode and electrolyte) -No gas generated within cells under any circumstances -No thermal runaway possibility -Liquid metals immediately solidify if exposed to ambient temperatures -No voltage at ambient temperatures (inert block of solid metal) >Produced with commonly available recyclable materials -Ambri materials not used in EV batteries -Reduces supply chain risks -Easy to recycle with positive value at end of life >Not sensitive to ambient temperature -No HVAC system required which reduces CAPEX & OPEX -Increases efficiency at very high or low temperature locations >No moving parts within system -Zero scheduled maintenance -No noise >High energy density -Stackable containerized DC-building block -29 kWh/sq-ft or 308 kWh/sq-m -Standard PCS operating voltages