Entropy‐Driven Local Polarization Engineering for Superior Energy Storage Performance

Multilayer ceramic capacitors (MLCCs) with high recoverable energy storage density ( W rec ) and high efficiency ( η ) are essential electronic components in advanced electronic devices and pulsed power systems. However, achieving both high W rec and η remains a long‐standing challenge. Here, guided by phase‐field simulations, we propose a strategy of entropy‐driven local polarization fluctuations to realize excellent energy storage performance by judiciously introducing foreign ions with different ferroelectric activities. We validate this by fabricating high‐quality MLCCs and achieve a high W rec of 23.5 J cm −3 and an ultra‐high η of 95.1% simultaneously. Atomic‐scale structural analysis reveals local polarization fluctuations where ultra‐weak polarity regions coexist with short‐range polarity regions. This unique configuration has good flexibility and enables easy polarization switching and fast recovery, thereby achieving high polarization and near‐zero hysteresis. This approach offers a new paradigm for designing high‐performance capacitors.