Conductor‐Free Anode of Transition Metal Dichalcogenide Nanosheets Self‐Assembled with Graft Polymer Li‐Ion Channels

Abstract

The development of anodes for lithium‐ion batteries (LIBs) based on liquid‐phase‐exfoliated 2D transition metal dichalcogenide (TMD) nanosheets has been studied extensively because their intrinsic capacity is higher than graphite. Since most semiconducting TMDs possess low electrical conductivity and lithium‐ion diffusivity, expensive processes are necessary such as the addition of conductive fillers, chemically converted metallic phase transformation, and topological nano‐fabrication. Here, a novel conductor‐free TMD nanosheet anode with graft‐polymer ionic channels that ensures high stability and rate capability of the LIB is presented. The fluorinated polymer binder grafted with ionomers allows not only the efficient exfoliation of TMD nanosheets in the liquid phase to guarantee stable sheet‐to‐sheet separation but also provides self‐assembled ionic channels through which lithium ions in the electrolyte readily arrive close to the surface of the nanosheets. Efficient electrochemical reduction of lithium ions occurs on the surface of the binary anode of MoS2 nanosheets, self‐assembled with graft polymer ionic channels, resulting in a high‐performance LIB with stability (90% retention rate after 1,000 cycles), rate capability (50% at 5 A g−1), and high cell capacity (933.1 mAh g−1 at 0.1 A g−1). These TMD anodes that do not require additional processes, and offer a novel strategy for developing high performance large‐scale TMD‐based LIBs.

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

“…Sulfonated poly(styrene) (SPS) ionomers were grafted onto poly(vinylidene fluoride- co -trifluoroethylene) (PVDF-TrFE) for MoS 2 electrodes. 95 The SPS formed ionic channels by self-assembly to facilitate ionic transport. At a current density of 0.5 A g −1 , MoS 2 with PVDF-TrFE- g -SPS binders delivered a discharge capacity of 862.0 mA h g −1 and retained 91.0% capacity after 1000 cycles compared with a 450.1 mA h g −1 discharge capacity and ≈69% capacity retention of PVDF-TrFE binders.…”

Electrochemical coupling in subnanometer pores/channels for rechargeable batteries

“…Alternatively, Park and colleagues reported an exfoliated 2D TMD (MoS 2 ) nanosheets with interlayer channels of ≈1 nm for LIBs, which delivered a high specific capacity of 933.1 mA h g −1 at 0.1 A g −1 and excellent cycling stability with 90% retention after 1000 cycles. 633 The SNPCs between the layers with good tolerance to volume expansion and negatively charged channels for fast ion transportation were attributed to the enhancement of the electrochemical performance. It has also been reported that Ni 2 P anchored in nitrogen doped carbon (Ni 2 P@N–C) with rich SNPCs could deliver enhanced rate capability (197 mA h g −1 at 2 A g −1 ) and excellent cycling stability (0.06% capacity decay per cycle), as a result of the high electrical conductivity of the matrix and confinement effect of the SNPCs (Fig.…”

Interfacial engineering for metal oxide/nitride nano-heterojunctions towards high-rate lithium-ion storage

“…Therefore, this triggers a continuous search enthusiasm for seeking alternative anode materials to graphite. So far, various types of materials have sprung up like mushrooms, such as carbon materials, 1,2 non-metallic elements (Si, P), 3,4 transition metal dichalcogenides (TMDCs), 5,6 transition metal oxides (TMOs), 7,8 and transition metal nitrides (TMNs). 9,10 Particularly, TMOs have attracted considerable attention due to their high theoretical specific capacity via multielectron reactions and easy preparation with controllable morphology.…”