The battery that Microsoft researchers are working on is in fact not a single battery. It is a battery system, made up of different kids of batteries, with different capacities and different output rates. The theory is that the OS will dictate which kind of battery is used. If a task requires more power, it will switch to using the high rate batteries. Menial tasks can be relegated to lower outputs that also have longer lives. In effect, it is almost like ARM’s big.LITTLE CPU architecture in wide use in mobile chips these days. These are composed of two sets of high-performance but energy-hungry cores and energy-efficient but low-performance cores.
Microsoft also sees a possible application of machine learning here. The operating system can observe user habits and determine how to best schedule and allocate battery consumption in the future based on these.
I can’t comment on the effectiveness, but it’s always interesting to see how one can find new ways to advance: in this case, analyze the intensity and nature of a workload, and see if it makes sense (for efficiency, in this case) to offer different capability for different purposes. A “micro-segmentation” of sorts, but in a technology context.