Polymer solid-state electrolytes (PSSEs) are promising for solving the safety problem of Lithium (Li) metal batteries (LMBs). However, PSSEs with low modulus in nature are prone to be penetrated by lithium dendrites, resulting in short circuit of LMBs. Here, we design and prepare piezoelectric BaTiO₃ doped polyacrylonitrile (PAN@BTO) quasi-solid-state electrolytes (PQSSEs) by electrostatic spinning method to suppress dendritic growth. The piezoelectric polymer electrolytes are squeezed by nucleation and growth processes of Li dendrites, which can generate a piezoelectric electric field to regulate the deposition of Li⁺ ions and eliminate lithium bud. Consequently, piezoelectric PAN@BTO PQSSEs enables highly stable Li plating/stripping cycling for over 2000 h at 0.15 mA/cm² at room temperature (RT, 25 ℃). Also, LiFePO₄|PAN@BTO|Li full cells demonstrate excellent cycle performance (136.9 mA·h/g and 78% retention after 600 cycles at 0.5 C) at RT. Moreover, LiFePO₄|PAN@BTO|Li battery show extremely high safety and can still work normally under high-speed impact (2 Hz, ~30 kPa). We construct an in-situ cell monitoring system and disclose that the mechanism of suppressed lithium dendrite is originated from the generation of opposite piezoelectric potential and the feedback speed of intermittent piezoelectric potential signals is extremely fast.

Silicon-based anodes with high theoretical capacity have intriguing potential applications for high energy density lithium-ion batteries (LIBs), while suffer from immense volumetric change and brittle solid-state electrolyte interface that causes collapse of electrodes. Here, a stress-dissipated conductive polymer binder (polyaniline with citric acid, PC) is developed to enhance the mechanical electrochemical performance between Si nanoparticles (SiNPs) and binders. Benefiting from the stable triangle network node of citric acid and a considerable distributed of hydroxyl groups, the PC binder can effectively dissipate the stress from SiNPs, thus providing an excellent cyclic stability of Si anodes. Both experimental results and theoretical calculation demonstrate the enhanced adhesion between binders and SiNPs could bond the particles tightly to form a robust electrode. The as-fabricated Si anode exhibits outstanding structural stability upon long-term cycles that exhibit a highly reversible capability of 1021 mA·h·g⁻¹ over 500 cycles at a current density of 0.5 C (1 C = 4200 mA·g⁻¹). Evidently, this stress-dissipated binder design will provide a promising route to achieve long-life Si-based LIBs.

Lithium-ion capacitors (LICs) are becoming important electrochemical energy storage systems due to their great potential to bridge the gap between supercapacitors and lithium-ion batteries. However, capacity lopsidedness and low output voltage greatly hinder the realization of high-energy-density LICs. Herein, a strategy of balancing capacity towards fastest dynamics is proposed to enable high-voltage LICs. Through electrochemical prelithiation of Nb₂C to be 1.1 V with 165 mAh g⁻¹, Nb₂C // LiFePO₄ LICs show a broadened potential window from 3.0 to 4.2 V and an according high energy density of 420 Wh kg⁻¹. Moreover, the underlying mechanism between prelithiation and high voltage is disclosed by electrochemical dynamic analysis. Prelithiation declines the Nb₂C anode potential that facilitates electron transmission in the interlayer of two-dimensional Nb₂C MXene. This effect induces small drive force for Li⁺ ions deposition and hence weakens the repulsive force from adsorbed ions on the electrode surface. Benefiting from even more Li⁺ ions deposition, a higher voltage is eventually delivered. In addition, prelithiation significantly increases Coulomb efficiency of the 1st cycle from 74% to 90%, which is crucial to commercial application of LICs.