A Smart Polymeric Sol‐Binder for Building Healthy Active‐Material Microenvironment in High‐Energy‐Density Electrodes

Abstract

but more importantly, on the electrode microstructures on the composite level. As a result, optimizing the electrode microstructures to achieve fast and stable ion/ electron transport for every individual AM particle is another urgent but challenging mission. [1,2] This challenge fundamentally comes from a poor understanding of the electrode microstructures and their formation process, which are sensitive to many factors, such as binder properties, slurry compositions, and electrode processing conditions. As an attempt to better understand the electrode microstructures, as illustrated in Figure 1a, we have recently got the inspiration of the concept of cell microenvironment well-known in biology, and proposed the concept of active material microenvironment (ME@AM). [2][3][4] Specifically, ME@AM is defined as the local non-active-material environment connecting the tested AM particle with its neighboring AM particles (see Figure 1b). The ME@AM skeleton consists of two primary parts: the local electron transport structure built by mainly the conductive agent (CA) and the ion transport channels determined by the pores around the AM particle, which are left for liquid electrolyte, [4][5][6] or directly built by solid electrolytes. Since the available capacity of AMs is fundamentally determined by the redox reaction of all the AM particles, it is reasonable to link the quality of ME@AM skeleton to the overall electrochemical performance, such as C-rate performance, specific capacity, energy density, cycle stability, mechanical properties, and so on. [3] The ME@AM focuses on both ionic and electronic conduction structures surrounding an individual AM particle. For high-quality electrodes, all the AM particles should be uniformly surrounded by "healthy" ME@AM skeleton with uniformly distributed CA and stable AM/CA interface. When the porous structures of ME@AM skeleton is filled by an electrolyte, the ionic conduction function of ME@AM is finally built. Thus, the features of the porous structure of the CA network, including porosity, pore tortuosity, and pore size, are all critical for the ME@AM capability of ionic conduction. It should be noted that the quality of ME@AM is a collective result contributed by many factors, such as electrode composition, [7][8][9] characteristics of Similar to the cell microenvironment in biology, the active material microenvironment (ME@AM) in battery electrodes determines the charge flux into/out the individual AM particles, and the overall device performance thereby. However, it is very challenging to understand and regulate the ME@AM structures due to the lack of advanced binders and their links to electrode microstructures. Here, to address this challenge, a high-performance sol-binder based on propylene carbonate (PC) and poly(vinylidene fluoride) is designed and the ME@AM structural evolution during its electrode fabrication is investigated. First, a pen-ink-like uniform slurry is successfully prepared in minutes with the PC solvent. Second, the sol-to-gel transition of the sol-bin...

Alginate-Xylan Biopolymer as a Multifunctional Binder for 5 V High-Voltage LNMO Electrodes

“…Interestingly, the SX28-LNMO electrode's specific capacity progressively increases with the number of cycles, which may be primarily attributable to the development of a protective layer on the surface. 46 As the number of cycles increases, the above-mentioned cracked surface protective layer conforms to the opened channel for Li + diffusion, leading to a gradual increase in capacity. Additionally, the SX28-LNMO electrode, without the process of pressure rolling, remains stable under high loading at 6.2 mg cm −2 (Figure S6c).…”

“…Since the microenvironment of active mass plays a significant factor in electrochemical performance, − the cross-section microstructures were observed. As shown in Figure , the active material particles of SX28-LNMO electrode are uniformly wrapped by Super P and firmly adhered to the current collector, which can create a favorable microenvironment .…”

“…The side reactions of PVDF-LNMO electrode are more serious. Interestingly, the SX28-LNMO electrode’s specific capacity progressively increases with the number of cycles, which may be primarily attributable to the development of a protective layer on the surface . As the number of cycles increases, the above-mentioned cracked surface protective layer conforms to the opened channel for Li + diffusion, leading to a gradual increase in capacity.…”

A Supertough, Nonflammable, Biomimetic Gel with Neuron‐Like Nanoskeleton for Puncture‐Tolerant Safe Lithium Metal Batteries

“…However, PVDF‐DES exhibits a discontinuous shear thickening behavior; when the frequency exceeds 25 rad s −1 , the viscosity sharply increases from 0.29 to 1.12 Pa s due to the increased surface friction among the PVDF nanoparticles. [ 34 ] This finding suggests that PVDF nanoparticles are dispersed in DES while PEO is well dissolved in DES to form a uniform polymer solution.…”

Architecting the Microenvironment Skeleton of Active Materials in High‐Capacity Electrodes by Self‐Assembled Nano‐Building Blocks

“…3D printing [16] and dry processing [17] are the representative strategies which are of great interest. The electrode slurry for 3D printing often has a high solid content (≈60 wt%) [4,18] and a high viscosity (≈10 2 Pa s under the shear rate of 1 s −1 ) [19] to achieve appropriate rheological properties. These properties alleviate the volume shrinkage and phase transition during the electrode drying.…”