Ultrahigh loading dry-process for solvent-free lithium-ion battery electrode fabrication

Abstract

The current lithium-ion battery (LIB) electrode fabrication process relies heavily on the wet coating process, which uses the environmentally harmful and toxic N-methyl-2-pyrrolidone (NMP) solvent. In addition to being unsustainable, the use of this expensive organic solvent substantially increases the cost of battery production, as it needs to be dried and recycled throughout the manufacturing process. Herein, we report an industrially viable and sustainable dry press-coating process that uses the combination of multiwalled carbon nanotubes (MWNTs) and polyvinylidene fluoride (PVDF) as a dry powder composite and etched Al foil as a current collector. Notably, the mechanical strength and performance of the fabricated LiNi0.7Co0.1Mn0.2O2 (NCM712) dry press-coated electrodes (DPCEs) far exceed those of conventional slurry-coated electrodes (SCEs) and give rise to high loading (100 mg cm−2, 17.6 mAh cm−2) with impressive specific energy and volumetric energy density of 360 Wh kg−1 and 701 Wh L−1, respectively.

Insights into the Chemistry of the Cathodic Electrolyte Interphase for PTFE-Based Dry-Processed Cathodes

“…It is interesting to note that some very recent studies have indicated that the property of the CEI layers formed on DPEs and conventional electrodes is different, and DPEs indeed exhibit better electrochemical performance than conventional electrodes do. 16,18,60 In view of the aforementioned analyses, the impact of the electrolytes on the high-loading PTFE-based DPEs can be ascribed to the following two aspects. (1) Electrolytes with different properties play a significant role in the electrochemical performance, especially ionic conductivity.…”

“…Thereby, the HRXPS analyses of the transition metal species confirm that the LiClO 4 -based electrolyte leads to a thinner CEI layer than the LiPF 6 -based electrolyte does. It is interesting to note that some very recent studies have indicated that the property of the CEI layers formed on DPEs and conventional electrodes is different, and DPEs indeed exhibit better electrochemical performance than conventional electrodes do. ,, …”

Self-powered recycling of spent lithium iron phosphate batteries via triboelectric nanogenerator

“…Lithium ion batteries (LIBs), which have the advantages of high capacity and power density, are considered to be a key component that determines the driving performance of overall vehicle. 1–4 Among the commercialized LIBs, lithium iron phosphate (LiFePO 4 , LFP) batteries are widely used and represent more than 32% of the overall LIB market share owing to their superior safety, earth-abundant iron sources, and relatively low production costs. Although LFP is regarded as an ecofriendly material, its improper disposal will create serious environmental crises.…”

Ozone-Treated Carbon Nanotube as a Conductive Agent for Dry-Processed Lithium-Ion Battery Cathode

“…This modification reduces their tendency to aggregate 32,33 while increasing their affinity for active materials, leading to improved electrochemical reaction kinetics of the given dryprocessed LIB electrode even with low amounts of conductive agents. 34 The use of liquid-phase strong acidic oxidizers, such as mixed acid, 29,30 can effectively introduce functional groups to the CNT surfaces; however, they can also severely damage the sp 2 system of nanotubes, resulting in decreased electrical conductivity, which calls for optimization based on trials and errors and extra drying processes.…”

“…However, their tendency to aggregate limits dispersion and active material contact when mixed without solvent, especially at high electrode loading levels. − Surface functionalization of CNTs with various strong liquid-phase oxidants − can introduce oxygen-based functional groups, such as carboxylic acid, hydroxyl, and carbonyl groups, to the surface of CNTs. This modification reduces their tendency to aggregate , while increasing their affinity for active materials, leading to improved electrochemical reaction kinetics of the given dry-processed LIB electrode even with low amounts of conductive agents . The use of liquid-phase strong acidic oxidizers, such as mixed acid, , can effectively introduce functional groups to the CNT surfaces; however, they can also severely damage the sp 2 system of nanotubes, resulting in decreased electrical conductivity, which calls for optimization based on trials and errors and extra drying processes.…”