Lithium ion batteries have become a standard part of many electronic devices. You have come to expect that phones, computers, and even hybrid cars will run on a rechargeable battery that will last for years. This article will briefly explore how this important technology powers your world.
1. The Power of Reversible Reactions
All batteries work in a similar way, whether disposable or rechargeable. A chemical reaction moves positively charged ions from an anode, through an electrolyte medium, to a cathode. This frees up electrons that travel through an external circuit, powering your device. In disposable batteries, this reaction only travels one way. Eventually the positive ions all move from the anode to the cathode, no more electrons are freed, and the battery reaches the end of its useful life.
Due to the design of a lithium ion battery which takes advantage of a reversible chemical reaction, the lithium ions can reverse direction, traveling from cathode back to anode, allowing the process to replay itself. This means that your battery can be used again and again, so long as the ions keep flowing.
2. Graphite: An Elegant Anode
The cathode of a lithium ion battery is often made of a lithium compound such as lithium cobalt oxide. The anode is another, more interesting, story. Graphite is a common material for this part of a lithium ion battery. It is an amazing substance, made of sheets of carbon atoms only one atom thick called graphene. In the charging process, lithium ions pass from the cathode through an electrolyte medium. They are then stored between layers of graphene, each surrounded by six carbon atoms, until they are released again in the discharge phase, powering your device.
3. It’s not the Years; it’s the Cycles
Even though lithium ion battery technology has greatly increased the life of your batteries, these devices cannot last forever. However, the longevity of lithium ion batteries is not normally measured in time but in cycles. With each discharging and recharging cycle, the graphite anode and the cathode become less effective at capturing lithium ions. As the battery becomes less efficient, you may notice it taking a longer time to reach a full charge or a shorter time holding a charge. Most lithium batteries are expected to last at least 1000 cycles, which, depending on usage, translates to years of battery life.
Research continues on lithium ion battery technology. Scientists and engineers are experimenting with different anodes, cathodes and electrolyte media in an effort to extend battery life and produce more power. With continuing innovations, these batteries will be an integral part of modern electronics for years to come.