Mobile technology has changed the way people work and live, but these devices could be so much more capable than they are today. However, battery technology has not kept pace with other innovations. Designing batteries with high capacity, fast charging, a long life span, and a low chance of catching fire is no simple feat. Researchers from the Japan Advanced Institute of Science and Technology (JAIST) might have found a way to help with the longevity issue, however. A new material could lead to lithium-ion batteries that maintain their full capacity even after years of use.
This isn’t just an abstract laboratory concern — JAIST aims to solve a problem we’ve all encountered. You get a new smartphone, and the battery life is good enough. The days of leaving the charger at home are long gone when even a 5,000mAh cell barely lasts you a day, which means more recharging. After a year or two of that, the battery no longer holds a full charge. That’s down to the binding agent that keeps graphite attached to the anode. Without the binder, graphite would just flake off.
Today, we use polyvinylidene fluoride (PVDF) in the anode, but the new study explores an alternative material that could vastly outperform PVDF. It’s a real mouthful: a copolymer called bis-imino-acenaphthenequinone-paraphenylene, or BP for short. In laboratory testing, BP provided much better anode stability and therefore a longer life span.
A traditional PVDF battery begins degrading after 500 charge cycles, usually retaining around 65 percent of its original capacity. So, if your smartphone or electric vehicle was just good enough when it was new, you’re going to be aching for a replacement at this point. The BP prototype, however, manages to retain 95 percent of its capacity after more than 1,700 cycles.
There are a few reasons the team believes BP is more effective as a binding agent. The material appears to have strong “pi interaction” with graphite, which allows the formation of non-covalent bonds that hold the amalgam together. BP is also more conductive than PVDF, and the lower resistance means less degradation. Likewise, BP doesn’t interact with the electrolyte, keeping it stable for longer. Using an electron microscope, the team showed that used BP cells showed only minor cracking on the anode, whereas the PVDF control showed larger cracks after one-third as many cycles.
Batteries are only going to become more important as electric vehicles replace internal combustion and the devices around our homes become smart. Whether or not BP copolymers make those batteries more reliable will depend on material cost, but there’s definitely value in batteries that don’t end up in a landfill after a few years.