Large Capacitive Energy Storage in Linear-Like MLCCs with Tailored Atomic-Scale Polymorphic Polarization Fluctuations

The development of portable electronic devices and new energy fields has placed higher demands on the energy storage properties of lead-free multilayer ceramic capacitors (MLCCs). Here, we propose a strategy for inducing atomic-scale polymorphic polarization fluctuations via entropy engineering. This strategy promotes atomic-scale lattice disorder through increasing entropy, induces the formation of atomic-scale polymorphic polarization fluctuations with coexisting rhombohedral and tetragonal phase, significantly weakens polar anisotropy and domain switching barriers, and thus realizes a linear-like polarization behavior with low hysteresis. A giant recoverable energy density (W_rec) of 21.3 J·cm^-3 under a high electric field of 1045 kV·cm^-1 is obtained in the high-entropy MLCC, accompanied by a high energy efficiency (η) of 94.5%. Benefiting from such structural advantage, the MLCC prototype devices also possess excellent broad-temperature, frequency, and cyclic stability. This work presents a reliable technical approach for the design of superior-performing MLCCs by revealing the entropy-structure-performance correlation.