Facile Dual-Protection Layer and Advanced Electrolyte Enhancing Performances of Cobalt-free/Nickel-rich Cathodes in Lithium-Ion Batteries

High-entropy doping promising ultrahigh-Ni Co-free single-crystalline cathode toward commercializable high-energy lithium-ion batteries

The development of advanced layered Ni-rich cathodes is essential for high-energy lithium-ion batteries (LIBs). However, the prevalent Ni-rich cathodes are still plagued by inherent issues of chemomechanical and thermal instabilities and limited cycle life. For this, here, we introduce an efficient approach combining single-crystalline (SC) design with in situ high-entropy (HE) doping to engineer an ultrahigh-Ni cobalt-free layered cathode of LiNi0.88Mn0.03Mg0.02Fe0.02Ti0.02Mo0.02Nb0.01O2 (denoted as HE-SC-N88). Thanks to the SC- and HE-doping merits, HE-SC-N88 is featured with a grain-boundary-free and stabilized structure with minimal lattice strain, preventing mechanical degradation, reducing surface parasitic reactions, and mitigating oxygen loss. Accordingly, our HE-SC-N88 cathode demonstrates exceptional electrochemical properties particularly with prolonged cycling stability under strenuous conditions in both half and full cells, and the delayed O loss-induced phase transitions upon heating. More meaningfully, our design of HE doping in redefining the ultrahigh-Ni Co-free SC cathodes will make a tremendous progress toward industrial application of next-generation LIBs.

Durable lithium-ion insertion/extraction and migration behavior of LiF-encapsulated cobalt-free lithium-rich manganese-based layered oxide cathode

Lithium-rich manganese-based cathode has made a subject of intense scrutiny for scientists and application researchers due to their exceptional thermal stability, high specific capacity, high operating voltage, and cost-effectiveness. However, the inclusion of cobalt, as a crucial component in lithium-rich manganese-based cathode materials, has become a cause for concern due to its limited availability and non-renewable nature, which eventually limits the growth of the battery industry and increase costs. Considering the poor stability of cobalt-free cathode, this work proposes a coating strategy of LiF through a simple high-temperature melting method. Directly coating LiF on Li1.2Ni0.2Mn0.6O2 surface is found to be an effective way to protect the cathode material, decrease metal solubility, and inhibit irreversible phase transition processes, thus leading to an improved electrochemical performance. As a result, the battery employing LiF coated Li1.2Ni0.2Mn0.6O2 cathode can be stabilized over 280 cycles and maintain a capacity of 110 mAh g-1 at 1C. What's more, the mechanisms of ion insertion/extraction behavior and ion migration process are also studied systematically. This study will open the avenue to develop a high-energy battery system with cobalt-free cathode.

Polyimides as Promising Materials for Lithium-Ion Batteries: A Review

Lithium-ion batteries (LIBs) have helped revolutionize the modern world and are now advancing the alternative energy field. Several technical challenges are associated with LIBs, such as increasing their energy density, improving their safety, and prolonging their lifespan. Pressed by these issues, researchers are striving to find effective solutions and new materials for next-generation LIBs. Polymers play a more and more important role in satisfying the ever-increasing requirements for LIBs. Polyimides (PIs), a special functional polymer, possess unparalleled advantages, such as excellent mechanical strength, extremely high thermal stability, and excellent chemical inertness; they are a promising material for LIBs. Herein, we discuss the current applications of PIs in LIBs, including coatings, separators, binders, solid-state polymer electrolytes, and active storage materials, to improve high-voltage performance, safety, cyclability, flexibility, and sustainability. Existing technical challenges are described, and strategies for solving current issues are proposed. Finally, potential directions for implementing PIs in LIBs are outlined.