Nanoclay Reinforced Polymer Composite Dielectrics for Ultra‐Balanced Electrostatic Energy Storage

The vast energy storage potential of polymer composite dielectrics in high pulse power sources stands in stark contrast to the unbalanced improvements in discharge energy density (Ud), charge–discharge efficiency (η), and dielectric strength (Eb) as reported currently. Herein, a multistage coupled interface engineering design is proposed: a novel gradient alternating dielectric buffer layer (G‐A‐DBL) is constructed, which consists of inorganic low‐k nanoclay aluminosilicate layer and high‐k ferroelectric layer assembled in a highly oriented alternation as a basic unit and gradient distribution in polymer matrix. This design achieves electric field confinement from the nanoscale to the macroscopic level and achieves an ultra‐balanced enhancement effect, resulting in a Ud of 28.5 J cm−3, an η of 80%, and an Eb of 676 kV mm−1. The universal charge retention ability of charge traps from aluminosilicate heterogeneous skeletons is demonstrated by combining density functional theory calculations and scanning probe measurements. The G‐A‐DBL design integrates traditional charge trapping, heterostructure formation, and gradient modulation, effectively suppressing the entire process of carrier excitation, transport, and before capture. This work advances the basic understanding of charge confinement within inorganic interface charge traps, demonstrating the most well‐balanced enhancement effect and potential for broad application across dielectric polymer nanocomposites.