Absorbent glass mat battery for residential storage


From pv magazine Global

California-based storage specialist Gridtential Energy has secured around $12 million in funding from a group of investors led by U.S.-based venture capital firm 1955 Capital and has increased, to €28 million (AU$43 million), the capital it raised to date to boost the development of its “Silicon Joule” absorbent glass mat (AGM) battery technology.

“With Silicon Joule, we can use today’s battery manufacturing and recycling facilities to reduce vehicle emissions and put renewable energy storage into homes in high volumes right now,” said the company’s CEO, John Barton.

Gridtential’s flagship product is the lead-acid battery Silicon Joule 24V U1 — Deep-cycle Gen2 Battery, which it defines as the world’s first factory-ready, single-block, 24V, deep-cycle lead battery, and an alternative to lithium-ion batteries.

The 12-cell device measures 198x137x189mm and weighs 9.96kg. It has a nominal voltage of 24 V and a cycle use of 28.8 V, or 2.4 V per cell. The battery also features a maximum discharge current of 45 A and has an expected cycle life of 750 cycles.

Its gravimetric energy density is 40 Wh per kg and its volumetric energy density, 77 Wh per kg. The cycling temperature range is between -30 and 50 degrees Celsius.

The product is claimed to be ideal for personal mobility vehicles such as golf carts, scooters, and e-bikes, as well as for telecom backup and renewable energy storage in homes and offices.

AGM batteries are usually built with a special glass mat separator that absorbs the electrolyte solution between the battery plates. The Silicon Joule 24V U1 battery is manufactured with silicon wafers that are claimed to replace lead grids, to reduce battery weight.

“In conventional battery designs, electrons flow ​across​ the battery plate and high current is concentrated at the top contact,” the U.S. start-up explains on its website. “In Gridtential’s bipolar design, current flows ​through​ ​each silicon wafer evenly, making it a highly efficient conductor with a current path length equal to its thickness.”

The silicon wafers are said to reduce lead use by 40% and the battery weight by 30%. “Plus, they maintain the thermal stability and 99% recyclability of the conventional technology, creating a clear safety and sustainability advantage over lithium-ion,” the company said.


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