Efficient cell design and fabrication of concentration‐gradient composite electrodes for high‐power and high‐energy‐density all‐solid‐state batteries

Abstract

All‐solid‐state batteries are promising energy storage devices in which high‐energy‐density and superior safety can be obtained by efficient cell design and the use of nonflammable solid electrolytes, respectively. This paper presents a systematic study of experimental factors that affect the electrochemical performance of all‐solid‐state batteries. The morphological changes in composite electrodes fabricated using different mixing speeds are carefully observed, and the corresponding electrochemical performances are evaluated in symmetric cell and half‐cell configurations. We also investigate the effect of the composite electrode thickness at different charge/discharge rates for the realization of all‐solid‐state batteries with high‐energy‐density. The results of this investigation confirm a consistent relationship between the cell capacity and the ionic resistance within the composite electrodes. Finally, a concentration‐gradient composite electrode design is presented for enhanced power density in thick composite electrodes; it provides a promising route to improving the cell performance simply by composite electrode design.

Improved Rate Capability in Composite Solid-State Battery Electrodes Using 3-D Architectures

“…These gradients in SOC are the major source of reduced accessible capacity during high-rate charging of composite SSB electrodes and have been shown to have a strong dependence on electrode composition, capacity/thickness, and cycling rate. 17,18,[21][22][23][24][25][26][27][28][29][30][31]35,36 The choice of graphite as a model system facilitates the direct visualization of local SOC among the active particle phase, which is attributed to the unique colors associated with the Li x C phases during lithiation of graphite, including dark gray (i.e., pristine or unlithiated), dark blue (LiC 18 ), red (LiC 12 ), and gold (LiC 6 ). 5,17,50,51 Operando visualization experiments were performed on polished cross-sectional surfaces of unpatterned and 3-D patterned electrodes during lithiation (charging) at C/8 and 1C rates using a CCCV protocol (Figure 4A).…”

“…Despite these benefits, examples of 3-D patterning of bulk SSB electrodes are scarce because of the fabrication/processing challenges of ceramic SEs and have been mostly limited to microbatteries. 4,13−15,19,32,41−48 A few recent studies have shown the feasibility of controlling the 3-D structure of composite electrodes for SSBs 22,[36][37][38]40 using concentration-gradient electrodes, 36 ionogel infiltration, 38 solution infiltration of the SE, 40 and SE coatings on the material. 49 However, there remains a need to develop new manufacturing approaches that are capable of generating highly ordered 3-D electrode architectures for SSBs using scalable and low-cost processing methods.…”

“…Using this platform, we have previously demonstrated the coexistence of two different categories of SOC gradients in composite SSB electrodes: (i) a through-plane gradient that results from the electrostatic potential (IR) drop along the interconnected SE pathways throughout the electrode thickness; and (ii) in-plane gradients that arise from solid-state Li diffusion from the active material/SE interface to the interior of the active material (Gr here). These gradients in SOC are the major source of reduced accessible capacity during high-rate charging of composite SSB electrodes and have been shown to have a strong dependence on electrode composition, capacity/thickness, and cycling rate. ,,− ,, The choice of graphite as a model system facilitates the direct visualization of local SOC among the active particle phase, which is attributed to the unique colors associated with the Li x C phases during lithiation of graphite, including dark gray (i.e., pristine or unlithiated), dark blue (LiC 18 ), red (LiC 12 ), and gold (LiC 6 ). ,,, …”

“…Important design variables include the electrode parameters (e.g., electrode composition, thickness, capacity loading, etc. ), material properties, and electrode geometry/architecture. ,,− The AM, conductive additive, and SE phases must be integrated with an optimized electrode composition so that continuous and efficient Li-ion and electron flux balances can be established/maintained throughout the electrode volume. ,,− ,− In addition to these material properties, it is also important to control the electrode microstructure to maximize the effective diffusion coefficients for ions and electrons. In particular, new strategies to reduce the electrode tortuosity in composite SSB electrodes are needed to improve the homogeneity of SOC through the electrode. ,− …”

High Performance Field-Effect Transistors Based on Partially Suspended 2D Materials via Block Copolymer Lithography

“…The 2D materials were actively used in the next generation electronics/optoelectronics devices [ 44 ] due to its promising potential. In some applications, however, there has been innate limitations because such devices performance was significantly deteriorated by interaction between substrate and 2D materials.…”