All‐Nanomat Lithium‐Ion Batteries: A New Cell Architecture Platform for Ultrahigh Energy Density and Mechanical Flexibility

Abstract

The ongoing surge in demand for high‐energy/flexible rechargeable batteries relentlessly drives technological innovations in cell architecture as well as electrochemically active materials. Here, a new class of all‐nanomat lithium‐ion batteries (LIBs) based on 1D building element‐interweaved heteronanomat skeletons is demonstrated. Among various electrode materials, silicon (Si, for anode) and overlithiated layered oxide (OLO, for cathode) materials are chosen as model systems to explore feasibility of this new cell architecture and achieve unprecedented cell capacity. Nanomat electrodes, which are completely different from conventional slurry‐cast electrodes, are fabricated through concurrent electrospinning (for polymeric nanofibers) and electrospraying (for electrode materials/carbon nanotubes (CNTs)). Si (or rambutan‐shaped OLO/CNT composite) powders are compactly embedded in the spatially interweaved polymeric nanofiber/CNT heteromat skeletons that play a crucial role in constructing 3D‐bicontinuous ion/electron transport pathways and allow for removal of metallic foil current collectors. The nanomat Si anodes and nanomat OLO cathodes are assembled with nanomat Al2O3 separators, leading to the fabrication of all‐nanomat LIB full cells. Driven by the aforementioned structural/chemical uniqueness, the all‐nanomat full cell shows exceptional improvement in electrochemical performance (notably, cell‐based gravimetric energy density = 479 W h kgCell−1) and also mechanical deformability, which lie far beyond those achievable with conventional LIB technologies.

Recent Advances in Nanowire‐Based, Flexible, Freestanding Electrodes for Energy Storage

“…e) ARagone plot of atypical all-solid-state flexible supercapacitor. [45] Other cathode materials, such as LiFePO 4 ,c an also be incorporated into the electrospun CNF network to achieve enhanced electrochemical properties. Reproducedw ith permissions from ref.…”

“…Concurrent electrospinning and electrospray techniquesw ere also used to fabricate other heterostructured flexible Si/C electrodes. [45] Other cathode materials, such as LiFePO 4 ,c an also be incorporated into the electrospun CNF network to achieve enhanced electrochemical properties. [46]…”

“…Therefore, if used as a LIB anode, this flexible freestanding 3D Si/C fiber paper displayed an ultrahigh reversible capacity of about 1600 mAh g −1 with a capacity loss of less than 0.079 % per cycle for 600 cycles. Concurrent electrospinning and electrospray techniques were also used to fabricate other heterostructured flexible Si/C electrodes . Other cathode materials, such as LiFePO 4 , can also be incorporated into the electrospun CNF network to achieve enhanced electrochemical properties …”

Carbon‐Nanotube‐Cored Cobalt Porphyrin as a 1D Nanohybrid Strategy for High‐Performance Lithium‐Ion Battery Anodes

“…Intrigued by the 1D structure of the CC‐nanohybrids, all‐fibrous nanomat anode sheets were fabricated through concurrent electrospraying (for CC‐nanohybrids and single‐walled carbon nanotubes [SWCNTs]) and electrospinning (for polyacrylonitrile [PAN]) processes. The advantageous effects of the nanomat architecture on electrode performance were reported in our previous studies on metal oxide‐based cathodes and silicon (Si)‐based anodes . The schematic representation depicting the preparation of the nanomat anode sheet is shown in Figure a, along with its photographs.…”

Ultrahigh‐Capacity and Fire‐Resistant LiFePO4‐Based Composite Cathodes for Advanced Lithium‐Ion Batteries

“…First, because of the poor compatibilities between the organic‐based polymer binders and inorganic particles (active materials and conductive carbon additives), conventional electrode films often suffer from the particle aggregation and thus unsatisfactory electronic conductivity . Second, the lack of interconnected pore channels within the electrode composites usually leads to poor electrolyte accessibility and sluggish ion transportation of the conventional electrodes, especially for the electrodes with high mass loadings . Moreover, the technical nature of the slurry‐coating method and the poor physical connections of polymer binders often give rise to limited active material mass loadings (usually less than 20 mg cm −2 ) and areal capacities (around 4 mAh cm −2 ) of the conventional electrodes .…”