Effect of Lithium Substitution Ratio of Polymeric Binders on Interfacial Conduction within All-Solid-State Battery Anodes

Abstract

Problematic issues with electrically inert binders have been less serious in the conventional lithium-ion batteries by virtue of permeable liquid electrolytes (LEs) for ionic connection and/or carbonaceous additives for electronic connection in the electrodes. Contrary to electron-conductive binders used to maximize an active loading level, the development of ion-conductive binders has been lacking owing to the LE-filled electrode configuration. Herein, we represent a tactical strategy for improving the interfacial Li+ conduction in all-solid-state electrolyte-free graphite (EFG) electrodes where the solid electrolytes are entirely excluded, using lithium-substitution-modulated (LSM) binders. Finely tuning a lithium substitution ratio, a conductive LSM–carboxymethyl cellulose (CMC) binder is prepared from a controlled direct Na+/Li+ exchange reaction without a hazardous acid involvement. The EFG electrode employing LSM with a maximum degree of substitution of lithium (DSLi) of ∼68% in our study shows a considerably higher rate capability of 1.05 mA h cm–2 at 1 C and a capacity retention of ∼61.9% after 200 cycles at 0.5 C than those using sodium-CMC (Na-CMC) (0.78 mA h cm–2, ∼49.5%) and LSM with ∼35% lithium substitution (0.93 mA h cm–2, ∼55.4%). More importantly, the correlation between the phase transition near the bottom region of the EFG electrode and the state of charge (SOC) is systematically investigated, clarifying that the improvement of the interfacial conduction is proportional to the DSLi of the CMC binders. Theoretical calculations combined with experimental results further verify that creating the continuous interface through abundant pathways for mobile ions using the Li+-conductive binder is the enhancement mechanism of the interfacial conduction in the EFG electrode, mitigating serious charge transfer resistance.

Novel heat storage ionomer binder for thermal management of Li-ion batteries

“…17,34 The coordination-type conductive HSIB reduces the surface adsorption free energy at the interface, which is conducive to the transfer of Li + from the cathode to the interface 16 and is beneficial to the relaxation of the Li + concentration gradient. 35 Consequently, enhanced electrode kinetics bestow higher capacity upon the cell with HSIB.…”

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

“…28 The lithium-ionized functional groups reduced the ionic diffusion barrier and increased ionic conductivity. 162,163 At 0.2 C, N-P-LiPN/Si exhibited a discharge capacity of 2143 mA h g −1 after 100 cycles (Fig. 6e).…”

Enhanced lithium-ion conductivity and interficial stability of Li-IL@Fe-BDC composite polymer electrolytes for solid-state lithium metal batteries

“…2c) revealed CPE3 has the lowest energy barrier for ion mobilization with a value of 0.24 eV compared with other various CPEs, denoting a diminished energy barrier for ion mobilization. 40 Meanwhile, to assess the individual impact of Fe-BDC and Li-ILs on the PEO matrix, the composite polymer electrolytes comprising PEO/ LiTFSI/Fe-BDC and PEO/LiTFSI/Li-IL have been prepared. The content of Fe-BDC and Li-ILs in these CPEs is maintained at the same level as CPE3.…”