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The spinel LiMn2O4is considered a promising cathode option material because it provides three-dimensional pathways for Li-ion diffusion. However, LiMn2O4exhibits insufficient rate capabilities and rapid structural deterioration during prolonged cycling, particularly under conditions of high current or elevated temperatures. Herein, we introduce a Mg2+/Al3+co-doping strategy to evade these problems. As a result, the co-doping of Mg2+and Al3+facilitates the development of a polyhedral morphology, enhancing both structural stability and rapid Li-ion diffusion. Furthermore, the incorporation of Mg2+and Al3+, which have a stable electronic configuration, enhances structural stability through their relatively stronger MgO and AlO bonds compared to the MnO bond. Therefore, the LiMg0.02Al0.08Mn1.90O4delivers the first discharge capacity of 107.6 mAh‧g−1at 1 C. Importantly, the LiMg0.02Al0.08Mn1.90O4cathode achieves long cycling lifespans exceeding 1000 cycles at high current rates of 20 C. A capacity retention of 70.0 % is retained at 20 C after 1000 cycles, as well as a high-temperature capacity retention of 47.4 % after 500 cycles at 5 C and 55 °C. Moreover, the Mg2+/Al3+co-doping facilitates the kinetic process of Li+migration, leading to a relatively high Li+diffusion coefficient and a low apparent activation energy.

Ba0.85Ca0.15Ti0.9Zr0.1O3 (BCTZ) ceramics, one of the lead-free pizoelectric materials, were focused due to the environmental concern against lead. A modified BCTZ powder sol-gel fabrication process was experimentally introduced with the addition of glycerol, in order to provide an effective approach to optimize the piezoelectric response of BCTZ ceramics. The results showed that the piezoelectric properties enhanced in terms of the piezoelectric coefficient of d33, 510 pC/N and the electromechanical coupling coefficient of kp, 0.501. The enhancement in electrical properties, such as dielectric, ferroelectric and piezoelectric, could be related to the homogenous microstructure and larger grain size of BCTZ ceramic powders after the introduction of glycerol during the modified sol-gel strategy.

Piezoelectricity—the direct interconversion between mechanical and electrical energies—is usually remarkably enhanced at the morphotropic phase boundary of ferroelectric materials1–4, which marks a transition region in the phase diagram of piezoelectric materials and bridges two competing phases with distinct symmetries1,5. Such enhancement has enabled the recent development of various lead and lead-free piezoelectric perovskites with outstanding piezoelectric properties for use in actuators, transducers, sensors and energy-harvesting applications5–8. However, the morphotropic phase boundary has never been observed in organic materials, and the absence of effective approaches to improving the intrinsic piezoelectric responses of polymers9,10considerably hampers their application to flexible, wearable and biocompatible devices. Here we report stereochemically induced behaviour in ferroelectric poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) copolymers, which is similar to that observed at morphotropic phase boundaries in perovskites. We reveal that compositionally tailored tacticity (the stereochemical arrangement of chiral centres related to the TrFE monomers11,12) can lead to intramolecular order-to-disorder evolution in the crystalline phase and thus to an intermediate transition region that is reminiscent of the morphotropic phase boundary, where competing ferroelectric and relaxor properties appear simultaneously. Our first-principles calculations confirm the crucial role of chain tacticity in driving the formation of this transition region via structural competition between the trans-planar and 3/1-helical phases. We show that the P(VDF-TrFE) copolymer with the morphotropic composition exhibits a longitudinal piezoelectric coefficient of −63.5 picocoulombs per newton, outperforming state-of-the-art piezoelectric polymers10. Given the flexibility in the molecular design and synthesis of organic ferroelectric materials, this work opens up the way for the development of scalable, high-performance piezoelectric polymers.