Mechanical energy harvesting: From piezoelectric effect to ferroelectric/ferroelastic switching

Mechanical energy harvesters show great potential as clean and sustainable energy sources to replace or supplement currently used chemical batteries. Conventional piezoelectric energy harvesting is constrained by low power density, which cannot generate sufficient electrical power for some electronics, particularly in space-sensitive applications. This review systematically examines the existing literature on piezoelectric energy harvesting, with an emphasis on the improvement of energy density by using different energy harvesting strategies. Then, attempts to use the non-linear electromechanical properties of ferroelectric/ferroelastic switching for energy harvesting are reviewed. Critical aspects of mechanical energy harvesting are covered: principles of energy conversion, operational modes, structure design, material properties, energy output, and applications. Comparing the piezoelectric effect to ferroelectric/ferroelastic switching, orders of magnitude increase in power density can be achieved by controlling polarization and residual stress. This review indicates that ferroelectric/ferroelastic switching could be a promising alternative to piezoelectrics for mechanical energy harvesting and identifies opportunities and future directions for practical applications. © 2024 The Authors.