BIKES BATTERIES AND BLAZES SPARK CONCERN IN NYC

A weekend fire that injured over three dozen people and forced firefighters to use ropes to pluck people from a 20th-story window - is drawing attention to a rising concern in New York City: battery fires that can arise in the electric bikes and scooters that have proliferated here.

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City officials are considering new laws after the fire department counted nearly 200 blazes and six fire deaths this year tied to problems with lithium-ion batteries in such "micromobility" devices.

WHAT ARE THESE BATTERIES? ARE THEY THE SAME TECH USED IN PHONES AND CARS?

Lithium-ion batteries are a Nobel Prize-winning innovation that entered the market in the early 1990s. Hailed as rechargeable, lightweight, powerful, durable and safe, the batteries have been envisioned as a key to greening the world's energy supply by storing energy, including from the sun, wind and other renewable sources.

The technology has woven its way into many people's everyday lives, powering phones, laptop computers, vehicles and more.

WHY CAN THEY CATCH FIRE?

The batteries' electrolyte a solution that lets electrical current flow - is flammable, explains Massachusetts Institute of Technology materials chemistry professor Dr. Donald Sadoway. The substance was chosen for its ability to handle the voltage involved, but fires can happen if the batteries are overcharged, overheated, defective or damaged, for instance.

Over the years, problems have periodically triggered fires involving laptops, cellphones, hoverboards, electric vehicles, airplanes and battery power storage installations. A U.N. aviation agency said in 2016 that lithium-ion batteries shouldn't be shipped on passenger planes.