Mechanical Stirring Synthesis of 1D Electrode Materials and Designing of Pyramid/Inverted Pyramid Interlocking for Highly Flexible and Foldable Li-Ion Batteries with High Mass Loading

Abstract

Flexible and foldable Li-ion batteries (LIBs) are presently attracting immense research interest for their potential use in wearable electronics but are still limited to electrodes with very small mass loading, low bending/folding endurance, and poor electrochemical stability during repeated bending and folding movements. Moreover, one-dimensional (1D) structured electrode materials have shown excellent electrochemical performance but are still restricted by the high cost and complicated fabrication process. Here, we present a very simple yet novel approach for fabricating extra-long Li4Ti5O12 (LTO) and LiCoO2 (LCO) nanofiber precursors by directly stirring the reagents in an atmospheric vessel. In addition, we present multilayer pyramid/inverted pyramid interlocking inside the LTO and LCO nanofiber films as well as between films and current collectors, which can create strengthened interfacial bonding like a zipper and tangentially disperse the strains generated during folding through the pyramidal planes and edges, leading to the realization of thick-film electrodes with outstanding electrochemical stability during folding movements. The foldable LIBs that are assembled with LTO and LCO nanofiber electrodes at a practical level of mass loading (14.9–19.4 mg cm–2) can maintain 102% of the initial capacity after 15 000 times of fully folding (180°) motions.

LiNi0.6Co0.2Mn0.2O2 Cathodes Coated with Dual-Conductive Polymers for High-Rate and Long-Life Solid-State Lithium Batteries

“…With the development of battery technology, extensive attention has been paid to the improvement of safety and energy density. − Nowadays, it is difficult to further increase the energy density of commercial lithium-ion battery (LIB) systems, especially concerning the safety issues. − Replacing the flammable organic electrolytes with the stable solid electrolytes (SEs) is viewed as one of the most effective ways to improve the energy density and safety − because the SEs offer the capability of using the high-specific capacity lithium metal anodes and the high-voltage cathodes. , Furthermore, concerning the achievement of high energy density, cathodes with high mass loading and excellent kinetics are necessary. In previous reports, − a large number of electronically and ionically conductive additives were added in the cathodes, which took 20–30 wt % of the total mass of the cathode in order to form a continuous conductive network. This caused reduced occupation of active materials, hindering the improvement of energy density …”