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.