This story about Proterra and its new battery cell technology was first published on CleanTechnica.

Proterra and LG Chem are blowing the lid off a new battery cell that the pair have co-developed. The announcement comes as Proterra brings its new battery manufacturing Proterra LG Chem Battery Cell Electric Bus Factory Californiafacility online, which is capable of cranking out over 500 MWh of high-voltage packs per year for its heavy-duty electric vehicles.

The new battery cell was built specifically to meet the rigorous performance requirements of Proterra’s heavy-duty vehicles, which, like their diesel and natural gas-fired counterparts, are typically utilized upwards of 12 hours per day of constant use. To ensure availability throughout the entire day, the batteries were optimized for maximum energy throughput capability. That allows the packs to accept a charge at a very higher rate than conventional lithium-ion battery technologies.

The new battery cells set a new high bar for the industry in energy density — which is the amount of energy stored in a given volume of space. The new battery comes in at 160 Wh/kg (energy stored per kilo) and 260 Wh/L (energy stored per liter). To ensure safe operations and to protect the battery from disruption, the battery is housed in lightweight ballistic-grade materials. That translates into more room for passengers in Proterra’s buses and less room wasted on cabinets to house batteries. On the flipside, Proterra can pack the same bus with even more range without having to take away passenger space for extra batteries.

Proterra packages the new cells into battery packs for its Catalyst E2 bus in its Burlingame, California, battery factory. The E2 is the longest-range electric transit bus on the market and recently proved as much with a record-breaking 1101.2 miles on a single charge. The feat was confirmed by the Navistar Proving Grounds where the bus ran at a constant speed of 15 miles per hour for what amounts to an insane 73+ hours. The feat is clearly not a practical demonstration, but it serves to highlight the work Proterra and LG Chem have put into the new battery format.

“Between Proterra’s demonstrated leadership in the heavy-duty electric vehicle industry, and the company’s battery expertise, Proterra has been a strong partner for LG Chem to co-develop a battery cell with for this important market,” said Youngsun Kim, LG Chem vice president, marketing. “It is our commitment to be at the leading edge of designing and manufacturing advanced batteries to meet the increasing global demand coming from the electric transportation sector.”

The partnership and co-development of the new battery cell is a major step for Proterra as it ramps up operations across the board in support of new contracts being signed, like its largest LowNo customer, LADOT, which recently put in an order for 25 buses.

While energy density and battery chemistry discussions are sure to make even the most avid customer’s eyes glaze over, one thing they can all agree on is putting safety first. “Safety is paramount to our battery design philosophy,” said Dustin Grace, director of battery engineering at Proterra. “We have implemented redundant layers of passive and active safety features into the architecture of the battery in concert with the vehicle itself. Deploying energy storage systems of this scale has led us down a technology path to new and advanced safety features.”

Proterra continues to push forward just as electric vehicles all the way from e-bikes to massive heavy-duty transit buses are seeing adoption like never before, indicating a shift from early adopters to the early majority. “It is a pivotal time in the heavy-duty vehicle market as transit, delivery and refuse services wake up to the combined benefits of electric propulsion,” said Ryan Popple, Proterra CEO. “We are thrilled to be working with LG Chem to deliver best-in-class batteries to meet these unique market demands, and enable mass adoption of zero-emission battery-electric fleets.”

Check out our interview with Proterra CEO and former Tesla exec Ryan Popple for more details on the California electric bus giant.