Abstract

We propose a innovative concept to boost the electrochemical performance of cathode composite electrodes using surface-modified carbons with hydrophilic moieties to increase their dispersion in a Lithium Nickel Manganese Cobalt Oxide (NMC) cathode and in-situ generate Li-rich carbon surfaces. Using a rapid aqueous process, the hydrophilic carbon is effectively dispersed in NMC particles followed by the conversion of its acid surface groups (e.g. –COOH), which interact with the NMC particles due to their basicity, into grafted Li salt (–COO−Li+). The solid-state batteries prepared using the cathode composites with surface-modified carbon exhibit better electrochemical performance. Such modified carbons led to a better electronic conduction path as well as facilitating Li+ ions transfer at the carbon/NMC interface due to the presence of lithiated carboxylate groups on their surface.

Highlights

  • We propose a innovative concept to boost the electrochemical performance of cathode composite electrodes using surface-modified carbons with hydrophilic moieties to increase their dispersion in a Lithium Nickel Manganese Cobalt Oxide (NMC) cathode and in-situ generate Li-rich carbon surfaces

  • The modification procedure of different carbons is described in the “Methods” section, which is adapted from recent research works of our ­group[36,37]

  • The pH of the solution rapidly increases due to the LiOH and ­Li2CO3 present on the surface of NMC particles, which induce the immediate conversion of acid surface groups to grafted Li salt on carbon (Fig. 1), leading to the “Li-rich carbon” deposited on the surface of NMC particles

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Summary

Introduction

We propose a innovative concept to boost the electrochemical performance of cathode composite electrodes using surface-modified carbons with hydrophilic moieties to increase their dispersion in a Lithium Nickel Manganese Cobalt Oxide (NMC) cathode and in-situ generate Li-rich carbon surfaces. The solid-state batteries prepared using the cathode composites with surface-modified carbon exhibit better electrochemical performance. The Ni-rich NMC material contains high surface concentrations of LiOH and ­Li2CO3 originating from the residual Li precursors and reactions with humid a­ ir[5] As these species are detrimental for the stability of the polymer electrolyte in a battery, it is necessary to remove them; this may be achieved by additional w­ ashing[6]. The active material is firstly treated with a gelatin solution and the adsorbed gelatin controls the deposition of carbon black that led to its uniform distribution in the final composite Another strategy to enhance the contact between the active material of an electrode and the carbon additive is to load the active material in a carbon template such as CMK-3 and CMK-8 mesoporous ­carbons[31], vertical aligned carbon nanotubes (CNT)[32] or again CNT particles host containing spherical m­ acropores[33]. The high intensive shear mixing device Nobilta was often employed to produce intimate contact between the active material and the carbon through a dry mixing ­process[35]

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