Suppressing concentration polarization in lithium battery composite polymer electrolytes via piezo-assisted electromechanical coupling effect

The inherent limitation of Li+ transport and resulting severe concentration polarization in solid-state electrolytes have hindered the practical application of lithium metal batteries. Addressing this challenge, here we create a piezoelectric polymeric composite electrolyte based on poly(vinylidene fluoride) blended with 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3, which exploits volume fluctuations of lithium metal negative electrodes during cycling to activate a piezo-assisted electromechanical coupling effect. The resulting gradient piezo-field within the prepared electrolyte selectively accelerates Li+ while impedes anions movement, thereby effectively suppressing concentration polarization fundamentally. Consequently, the prepared electrolytes exhibit relatively low concentration polarization, enabling a high critical current density of 3.7 mA cm–2, stable Li plating/stripping even at high current density of 2 mA cm−2, and prolonged cycling stability of Li | |Ni0.8Co0.1Mn0.1O2 full cell over 2600 times at the specific current of 900 mA g−1 within a potential window of 2.8 to 4.5 V. This work proposes a mechanical-electrochemical conversion strategy by constructing a piezoelectric electrolyte that actively utilizes the unavoidable volume fluctuation of lithium metal to minimize Li+ concentration gradient, offering a promising pathway towards high-performance lithium metal batteries. Concentration polarization limits cycling stability of cells at high currents. Here, authors propose a mechanical-electrochemical conversion strategy by constructing a piezo electrolyte that actively utilizes the unavoidable volume fluctuation of lithium metal to minimize concentration polarization.