Exploring the Limits of the Rapid-Charging Performance of Graphite as the Anode in Lithium-Ion Batteries

Graphite is, in principle, applicable as a high-power anode in lithium-ion batteries (LIBs) given its high intralayer lithium diffusivity at room temperature. However, such cells are known to exhibit poor capacity retention and/or undergo irreversible side reactions including lithium plating when charged at current rates above ~2C (~740 mA g-1). To explore the inherent materials properties that limit graphite anodes in rapid-charge applications, a series of full-cells consisting of graphite as the anode and a standard Li[Ni0.8Mn0.1Co0.1]O2 (NMC811) cathode was investigated. Instead of a conventional cathode-limited cell design, an anode-limited approach was used in this work to ensure that the overall cell capacity is only determined by the graphite electrode of interest. The optimized N:P capacity ratio was determined as N/P = 0.67, enabling stable cycling across a wide range of charging rates (4-20C) without inhibition by the NMC811 cathode. The results show that unmodified, highly crystalline graphite can be an excellent anode for rapid-charge applications at up to 8C, even with a standard electrolyte and NMC811 cathode and in cells with 1.0 mAh cm-2 loadings. As a rule, capacity and specific energy are inversely proportional to crystallite size at high rates; performance can likely be improved by electrolyte/cathode tuning.

A sustainable strategy for spent Li-ion battery regeneration: microwave-hydrothermal relithiation complemented with anode-revived graphene to construct a LiFePO4/MWrGO cathode material

Spent LiFePO4 (LFP) cathodes were revived through a microwave-hydrothermal relithiation process, complemented with microwave-reduced graphene oxide (MWrGO) derived from spent graphite anodes, to form a composite LFP/MWrGO cathode material.

An In-Depth Analysis of the Transformation of Tin Foil Anodes during Electrochemical Cycling in Lithium-Ion Batteries

Tin foils have an impressive lithium-storage capacity more than triple that of graphite anodes, and their adoption could facilitate a drastic improvement in battery energy density. However, implementation of a dense foil electrode architecture represents a significant departure from the standard blade-cast geometry with a distinct electrochemical environment, and this has led to confusion with regards to the first cycle efficiency of the system. In this work, we investigate the unique behavior of a tin active material in a foil architecture to understand its performance as an anode. We find shallow cycling of the foil results in an irreversible formation (< 40 %) due to diffusional trapping, but intermediate and complete utilization allows for a remarkably reversible formation reaction (> 90 %). This striking nonlinearity stems from an in-situ transformation from bulk metal to porous electrode that occurs during formation cycles and defines electrode-level lithium-transport on subsequent cycles. An alternative cycling procedure for assessing the stability of foils is proposed to account for this chemomechanical effect.

Design and Manufacturing of Low Relative Humidity Chamber for Laser Processing of Lithium Metal

In order to overcome the energy density limitations of lithium-ion batteries consisting of graphite anodes, studies on lithium metal batteries (LMBs) have been actively conducted. However, most LMBs related studies focus on suppressing the growth of unpredictable dendrites. Research for production processes has been rarely conducted. In the paper, laser processing is introduced to improve the drawback of conventional processing for Li metal. Moreover, a low humidity maintenance chamber is manufactured to prevent oxidation of Li metal during laser processing because Li metal easily reacts with moisture. The chamber has a closed space that does not allow outside air to enter, and a glass that allows the laser beam to pass through is installed at the upper part. In addition, silica gel is installed to maintain low relative humidity. The dew point inside the chamber drops to -17.4 ℃ in 1 hour. This result implies that the chamber can prevent Li metal oxidation. Next, we analyze the effect of transparent plate glass on laser beam with Gaussian distribution. Finally, it is confirmed through experiments that lithium metal is not contaminated by moisture during laser processing using a manufactured chamber.