Cathode Materials For Rechargeable Lithium-ion Batteries Research Articles

Lithium-Ion Battery Cathode-Electrolyte Interface

The global energy crisis, consumption of fossil fuels, and the associated environmental issues have stimulated extensive interest in searching for sustainable energy storage and conversion systems. Rechargeable lithium-ion batteries (LIBs) are widely used in mobile devices, hybrid, and electric vehicles. Electrode-electrolyte interface has a strong impact on battery capacity decrease and long-term cycling stability. In order to improve fundamental understanding of the involved phenomena to accelerate the rational design of cathode materials and stable interface, Li(Ni,Co,Mn)O2 (NCM) is a cathode material for rechargeable LIB and also a promising electrocatalyst for oxygen evolution reaction (OER). Their battery performance and catalytic activity are highly correlated to their structures. Multiple processes occurring at the cathode/electrolyte interface led to overall performance degradation. One failure mechanism is the dissolution of transition metals from the cathode. Our efforts employ thin film as a model cathode to monitor the Mn dissolution. Using LiMn2O4 and NCM as cathode materials, we will focus on electrochemical characterization, cation mixing, oxygen evolution, and thin film deposition with controlled crystal structures and composition. We will further introduce our work employing the scanning electrochemical microscope to study LIBs degradation and cathode-electrolyte interface in situ and in real-time.

Synthesis and application of Calix[6]quinone as a high-capacity organic cathode for plastic crystal electrolyte-based lithium-ion batteries

Conventional lithium-ion batteries (LIBs) utilizing inorganic cathode materials do not meet the increasing demand for high-capacity and green energy storage technologies, which have drawn increasing attention to the use of carbonyl compounds as high-capacity electrode materials. Herein, we describe the synthesis and application of an organic three-dimensional cyclic oligomer, calix[6]quinone (C6Q), as a high-capacity cathode material for rechargeable LIBs. Ex-situ UV–vis spectroscopy was used to compare the cycling-induced dissolution of calix[4]quinone with that of C6Q. Operando infrared spectroscopy was applied to uncover the discharge-charge mechanism of C6Q. An all-solid-state battery containing C6Q and a plastic crystal electrolyte (5 ​mol% solution of lithium bis(trifluoromethane)sulfonimide in succinonitrile) exhibits a specific initial capacity of 425 mAh g−1 and maintains at a stable value of 405 mAh g−1 after 500 cycles at 0.1 ​C. Thus, this study demonstrates the prospects of organic materials in high-power rechargeable devices.

Nitrogen-self-doped graphene as a high capacity anode material for lithium-ion batteries

Promising electrochemical energy conversion and storage devices constitute the main obstacles to the use of electrode materials of high energy and power density and long-cycling life to applications in lithium-ion batteries (LIBs). In this paper, we demonstrate a resin-based methodology for large-scale self-assembly of nitrogen-doped graphene (N-graphene), which has high capacity as an anode material for LIBs. The N-graphene is readily obtained using nitrogen- and metal ion-containing precursors. The N-graphene is characterized by Raman, AFM, TEM, SEM, and XPS measurements. It exhibits a very large reversible capacity of 1177 mA h g−1 at a current of 0.05 A g−1 as well as good cycling performance. The resulting N-graphene shows high capacity of 682 mA h g−1 over 95 cycles, representing a promising cathode material for rechargeable LIBs with high energy density. A good rate capability is also observed for N-graphene which exhibits large capacities of 540 and 443 mA h g−1 at large currents of 1 A g−1 and 2 A g−1, respectively. It is demonstrated that N-graphene can be a promising candidate for anode materials in high capacity LIBs.