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

The use of water-soluble, abundant biopolymers as binders for lithium-ion positive electrodes is being explored because it represents a great step forward towards environmentally benign battery processing. However, so far most studies, employing, for instance, carboxymethyl cellulose (CMC) as binder, have focused on rather low electrode areal loadings with limited relevance concerning to industrial needs. Herein, we report for the first time the use of natural guar gum (GG) as binding agent for cobalt-free, high-voltage LiNi 0.5 Mn 1.5 O 4 (LNMO), allowing the realization of electrodes with substantially increased areal loadings, low binder content, and greatly enhanced cycling stability. Co-crosslinking GG via citric acid with CMC allows for an enhanced rate capability, while essentially maintaining the beneficial impact of using GG as binder rather than CMC only. Lithium-ion full-cells based on water-processed LNMO and graphite electrodes provide remarkably high cycling stability with 80% capacity retention after 1,000 cycles at 1C.