Electrochemical Control of Lithium-Ion Batteries [Applications of Control]

While advanced batteries have enabled great improvements in society's mobility and energy efficiency, the high cost of batteries hampers further market penetration. Battery technology improvements are most often sought in electrochemical laboratories. But control engineers have an important role to play in advancing this technology. As a first step, the battery community must begin to merge the knowledge base of control theorists and practitioners with that of electrochemists and materials scientists. Robust integration of a battery into a high-power system is an experimentally burdensome process, with significant capital resources devoted to cycling batteries under a variety of power profiles and temperatures for several years to ensure reliability. A physics-based approach to battery integration offers the opportunity for streamlining control validation by setting physical limits that are accurate for all possible temperatures and operating scenarios. By introducing electrochemical state algorithms to existing Li-ion technology, usable power increases in the range of 20-50% seem possible for the entire family of Li-ion chemistries. Performance improvements may also be possible for Ni-MH chemistries with extensions to the method. In the end, improved accuracy and less conservative control limits mean more usable power and energy can be achieved for any given battery system. The outcome is that a smaller battery can provide the same capability, reducing both cost and weight.