Metalophilic Gel Polymer Electrolyte for in Situ Tailoring Cathode/Electrolyte Interface of High-Nickel Oxide Cathodes in Quasi-Solid-State Li-Ion Batteries

Abstract

High-Ni layered oxides are potential cathodes for high energy Li-ion batteries due to their large specific capacity advantage. However, the fast capacity fade by undesirable structural degradation in liquid electrolyte during long-term cycling is a stumbling block for the commercial application of high-Ni oxides. In this work, a functional gel polymer electrolyte, grafted with sodium alginate, is introduced to increase the stability of high-Ni oxide cathodes at the levels of both the particle and electrode. An in situ generated ion-conducting layer appears on the interface through the chemical interaction between transition-metal cations of the cathode and the metalophilic reticulum group in sodium alginate. Such a tailoring layer can not only enhance the interfacial compatibility on the cathode/electrolyte interface, reducing the interfacial resistance, but also inhibit the HF corrosion, suppressing the dissolution of transition-metal cations and harmful gradient distribution of components through the oxide cathode at the electrode level. Meanwhile, detrimental microcracks in oxide microspheres and between primary crystallites are impressively inhibited at the particle level. The high-Ni oxide cathode with the metalophilic gel polymer electrolyte shows excellent cycle stability with large initial capacity of 204.9 mA h g −1 at a 1.0C rate and high discharge capacity retention within 300 cycles at high temperature.

Thermal safety studies of high energy density lithium‐ion batteries under different states of charge

“…There is another layer with a thickness of approximately 10 μm in the middle of the electrode, which is the aluminum current collector. It can be observed from the detailed image of the active material that NCM particles maintain a regular spherical morphology, which indicates that NCM material can keep stable under different SOC conditions, in consistent with the studies about high nickel cathode materials . It is clearly seen that the spherical 10‐μm particles are secondary particles agglomerated by cubic primary particles having a diameter of approximately 100 nm.…”

Composite Cathodes with Succinonitrile‐Based Ionic Conductors for Long‐Cycle‐Life Solid‐State Lithium Metal Batteries

“…Recently, polymer‐based electrolytes have attracted much attention due to their good processibility and suitability for commercial applications [23–29] . The solid‐solid interfaces on the cathode side in the batteries with a polymer electrolyte also need to be optimized to enhance the electrochemical performance of batteries [30–34] . For instance, a composite cathode made of LiFePO 4 and super P was matched with a PEO‐based composite electrolyte membrane in a solid‐state battery and it is necessary to add a PVDF : SCN : LiClO 4 binder in the cathode to extend the cycle life of the battery at 60 °C [35] …”

Enabling a Durable Electrochemical Interface via an Artificial Amorphous Cathode Electrolyte Interphase for Hybrid Solid/Liquid Lithium‐Metal Batteries

“…However, the incompatibility caused by the inherent frail chemistry and electrochemistry on the cathode/electrolyte interface has usually been overlooked in recent hybrid solid/liquid battery systems . Actually, when coupling with LiNi x Mn y Co 1− x − y O 2 (NCM) cathodes, there are inevitable side reactions that deteriorate interfacial stability, owing to the addition of commercial liquid electrolyte . Besides, the aggregation of space charge still exists across the cathode/polymer or cathode/ceramic interface, which is liable to hinder ionic transportation .…”