Lithium/ˈlɪθiəm/ Definition 1 of 2Pro Tip 1/3Battery Technology Lithium is key in rechargeable batteries for gadgets; it's common in daily tech language. My phone uses a lithium battery. Pro Tip 2/3Element Symbol In scientific contexts, lithium is often referred to by its symbol 'Li' on the periodic table. He added Li to the experiment. Pro Tip 3/3Lightest Metal Highlighting lithium as the lightest metal can suggest something revolutionary or high-tech. This lightweight alloy contains lithium.