Complementary Strategies Toward the Aqueous Processing of High‐Voltage LiNi_0.5Mn_1.5O₄ Lithium‐Ion Cathodes

Abstract

Increasing the environmental benignity of lithium-ion batteries is one of the greatest challenges for their large-scale deployment. Toward this end, we present herein a strategy to enable the aqueous processing of high-voltage LiNi Mn O (LNMO) cathodes, which are considered highly, if not the most, promising for the realization of cobalt-free next-generation lithium-ion cathodes. Combining the addition of phosphoric acid with the cross-linking of sodium carboxymethyl cellulose by means of citric acid, aqueously processed electrodes with excellent performance are produced. The combined approach offers synergistic benefits, resulting in stable cycling performance and excellent coulombic efficiency (98.96 %) in lithium-metal cells. Remarkably, this approach can be easily incorporated into standard electrode preparation processes with no additional processing step.

Co‐Crosslinked Water‐Soluble Biopolymers as a Binder for High‐Voltage LiNi0.5Mn1.5O4|Graphite Lithium‐Ion Full Cells

“…CMC‐based LNMO electrodes showed a satisfactory electrochemical performance in lithium cells upon the introduction of CA and PA as processing additives (together CP–CMC) as well as a coating on the carbon‐coated aluminum current collectors for improved electrical contact and adhesion . As a result, electrodes that contain 5 wt % CA‐crosslinked CMC binder and subjected to a PA treatment during slurry preparation (CP–CMC‐5 %) exhibit a very stable cycling performance and retain a specific discharge capacity of 107 mA h g −1 after 400 cycles, which corresponds to a capacity retention of approximately 89 % (Figure a).…”

“…Interestingly, a low binder content of only 3 wt %, in the case of CP–CMC‐3 % and PA–CMC‐3 %, has a beneficial effect on the initial capacity, which does not show the typical increase at the beginning. This finding further supports our previous assignment that such an increase is caused by the slow electrolyte wetting of the crosslinked binder that covers the active material particles . With only 3 wt % binder, this effect is essentially absent.…”

“…SBR, for instance, is not sufficiently stable at such elevated potentials, which means that new (bio)polymers need to be identified to realize mechanically stable, high‐mass‐loading, high‐voltage electrodes for LIBs . Recently, it has been shown that the detrimental side effects of aqueous cathode processing, which especially include lithium leaching, aluminum current collector corrosion, and improvable adhesion of (high loading) electrode coating layers to the current collector, can be mitigated by implementing suitable processing additives, such as phosphoric acid (PA) and citric acid (CA), and by modifying the current collector . These strategies have effectively prevented corrosion of the aluminum current collector and have led to stabilized current collector–active material–electrolyte interfaces by forming a protective metal phosphate layer on the active material surface as well as the current collector that allows an improved binder network that is tethered covalently to the carbon‐coated aluminum current collector.…”

“…In this study, the employment of natural GG as a water‐soluble binder for LNMO cathodes in combination with suitable electrode processing additives and CA as a naturally available crosslinker was investigated. Such optimized electrode preparation allows for a substantial decrease in binder content compared to previous studies on CMC only (i.e., from 5 wt % to only 3 wt %) and extremely stable cycling for more than 500 cycles without significant capacity loss and, at the same time, enables greatly elevated mass loadings. The subsequent incorporation of minor amounts of CMC further enhances the rate capability.…”

Tailoring the Charge/Discharge Potentials and Electrochemical Performance of SnO2 Lithium‐Ion Anodes by Transition Metal Co‐Doping

“…All the cells have been prepared in an argon‐filled glovebox (MBraun UNIlab with a H 2 O and O 2 content of less than 0.01 ppm). For the full‐cell characterization, LNMO electrodes were prepared as reported in Kuenzel et al . and a three‐electrode setup was used to deconvolute the voltage profiles of the anode and cathode using auxiliary channels with lithium metal foil as reference electrode.…”