Carrageenan as a Sacrificial Binder for 5 V LiNi_0.5Mn_1.5O₄ Cathodes in Lithium‐Ion Batteries

Abstract

Abstract5 V‐class LiNi0.5Mn1.5O4 (LNMO) with its spinel symmetry is a promising cathode material for lithium‐ion batteries. However, the high‐voltage operation of LNMO renders it vulnerable to interfacial degradation involving electrolyte decomposition, which hinders long‐term and high‐rate cycling. Herein, we overcome this longstanding challenge presented by LNMO by incorporating a sacrificial binder, namely, λ‐carrageenan (CRN), a sulfated polysaccharide. This binder not only uniformly covers the LNMO surface via hydrogen bonding and ion‐dipole interaction but also offers an ionically conductive cathode‐electrolyte interphase layer containing LiSOxF, a product of the electrochemical decomposition of the sulfate group. Taking advantage of these two auspicious properties, the CRN‐based electrode exhibited cycling and rate performance far superior to that of its counterparts based on the conventional poly(vinylidene difluoride) and sodium alginate binders. This study introduces a new concept, namely “sacrificial” binder, for battery electrodes known to deliver superior electrochemical performance but be adversely affected by interfacial instability.This article is protected by copyright. All rights reserved

Design of functional binders for high-specific-energy lithium-ion batteries: from molecular structure to electrode properties

“…128 The electrolyte readily reacts with the cathode surface to produce the astermed CEI. 129,130 In addition, various reactive intermediates from the electrolyte, such as HF, free radicals, etc., can destroy the pristine CEI and trigger more side reactions. Additionally, the intrinsically unstable crystal structure at the cathode surface in the high delithiated state undergoes dissolution of TM ions and release of O 2 , inducing chemical crossover with the anode surface.…”

“…128 The electrolyte readily reacts with the cathode surface to produce the as-termed CEI. 129,130 In addition, various reactive intermediates from the electrolyte, such as HF, free radicals, etc. , can destroy the pristine CEI and trigger more side reactions.…”

Polymeric Binder Design for Sustainable Lithium-Ion Battery Chemistry

“…The results demonstrated improved cycling and speed performance compared to conventional electrodes. The hydrophilicity of CRN enables it to cover the surface of active material particles uniformly, and the oxidative decomposition of the sulfate groups leads to the formation of a CEI/binder complex layer containing LiSO x F. This complex layer facilitates Li-ion conduction [36]. Reprinted with permission from [37], 2012, Elsevier B.V.…”

“…Even in the case of PVdF binders known for their high chemical stability, an exothermic reaction between the C-F bond and lithiated carbon can form LiF [28,29]. Additionally, LiOH generated by residual impurities, such as water, can react with PVdF to produce LiF [36]. While byproducts resulting from the chemical instability of binders can be utilized as components of the SEI layer on the electrode surface, excessive accumulation can reduce the Coulombic efficiency (CE) and contribute to poor cycling stability through electrode collapse [38].…”

Non-Electroconductive Polymer Coating on Graphite Mitigating Electrochemical Degradation of PTFE for a Dry-Processed Lithium-Ion Battery Anode

“…Recent research has primarily focused on two candidates: poly­(vinylidene fluoride) (PVDF) and polytetrafluoroethylene (PTFE). − PVDF holds a significant advantage due to its extensive repository of well-documented data sets regarding its usage. It has consistently demonstrated its superiority as a binder material for LIB electrodes since the advent of LIBs in the market. − Therefore, in terms of risk management considerations in the development of this new technology, PVDF can be considered as a preferred choice compared with other dry-processable binders. However, the dry process involving PVDF demands an elevated temperature, typically exceeding 160 °C, for PVDF to melt, which inevitably leads to high energy consumption and renders its feasibility open to question. − On the other hand, a dry process based on PTFE, which can be easily fibrillated by mechanical forces, probably due to its excellent plasticity over 30 °C (Figure S1), is attracting attention as the most promising path toward commercialization.…”