Nacre‐Inspired Composite Electrolytes for Load‐Bearing Solid‐State Lithium‐Metal Batteries

Abstract

Solid-state lithium metal batteries with solid electrolytes are promising for next-generation energy-storage devices. However, it remains challenging to develop solid electrolytes that are both mechanically robust and strong against external mechanical load, due to the brittleness of ceramic electrolytes and the softness of polymer electrolytes. Herein, we propose a nacre-inspired design of ceramic/polymer solid composite electrolytes with the "brick-and-mortar" microstructure. The nacre-like ceramic/polymer electrolyte (NCPE) simultaneously possesses a much higher fracture strain (1.1%) than pure ceramic electrolytes (0.13%) and a much larger ultimate flexural strength (7.8 GPa) than pure polymer electrolytes (20 MPa). The electrochemical performance of NCPE is also much better than pure ceramic or polymer electrolytes, especially under mechanical load. A 5 × 5 cm 2 pouch cell with LAGP/poly(ether−acrylate) (PEA) NCPE exhibits stable cycling with a capacity retention of 95.6% over 100 cycles at room temperature, even undergoes a large This article is protected by copyright. All rights reserved. point load of 10 N. In contrast, cells based on pure ceramic and pure polymer electrolyte show poor cycle life. The NCPE provides a new design for solid composite electrolyte and opens up new possibilities for future solid-state lithium metal batteries and structural energy storage. The rapid-growing demands for portable electronics and electric vehicles have bolstered needs for next-generation lithium batteries with high energy density [1-4]. However, lithium batteries become more thermally vulnerable as energy density increases. Thermal runaway and explosion are prone to be triggered by failures such as mechanical damage and lithium dendrite growth inside batteries [5, 6]. Nonflammable solid-state ceramic electrolytes (SSEs) provide alternatives to conventional flammable liquid electrolytes [7-9]. Various ceramic electrolytes with attractive ionic conductivities have been developed in the past two decades, including NASICON-type Li 1.5 Al 0.5 Ge 1.5 (PO 4) 3 (LAGP) [10] , Li 1.3 Al 0.3 Ti 1.7 (PO 4) 3 (LATP) [11, 12] , garnet Li 7 La 3 Zr 2 O 12 (LLZO) [13, 14] , and sulfides, such as This article is protected by copyright. All rights reserved. NCPEs, polymer electrolytes and ceramic electrolytes were cut with a thickness of 500 μm and a size of 1.5 cm. A loading rate of 0.5 mm min-1 and a support span of 1.5 cm were used in all tests. The results were averaged from those in five similar specimens. The flexural stress is and The flexural strain is , where F, L, w, h, and D are the applied point force, span length, sample width, thickness, and flexural deflection, respectively. Vickers indentation was carried out on SANS-UTM 6000 using a Vickers indenter. Finite Element Mechanical Simulation: 2D nonlinear finite element simulations were conducted using the software ABAQUS v6.14. In these simulations, the stress/strain distributions and crack propagation in a regular brick-mortar structure and a ceramic film are calculate...

Recent Developments of Nanomaterials and Nanostructures for High‐Rate Lithium Ion Batteries

“…Electrodes made of such nanomaterials present improved resistance to structural destruction. [39] weaknesses Large contact area between electrode and electrolyte tends to induce undesirable side reactions, such as additional consumption of lithium ions in electrolyte.…”

Ceramic Electrolytes Get “Tough” on Lithium Metal Batteries

“…1 They also possess high lithium-ion conductivity, stability under high temperatures, and flame resistance, making them ideal candidates for improving lithium metal battery safety. 1 However, ceramic-based electrolytes suffer from low fracture toughness, 2 and their brittle nature is an important challenge because lithium dendrite growth may cause fracture of the ceramic electrolyte. Prior attempts to improve the fracture toughness were unsuccessful because they led to unacceptable ionic conductivities.…”

“…Prior attempts to improve the fracture toughness were unsuccessful because they led to unacceptable ionic conductivities. 2,3 More broadly, the long-standing trade-off in ionic conductivity and mechanical properties has long been a challenge for both ceramic-based electrolytes and solid polymer electrolytes.…”

“…For perspective, there are only a few reports focusing on the fracture toughness of ceramic electrolytes, and these reports typically show a trade-off between fracture toughness and ionic conductivity. 2,3 For example, the effect of different relative densities of Li 6.19 Al 0.27 La 3 Zr 2 O 12 (LLZO) ceramic electrolytes prepared by hot pressing on the fracture toughness and ionic conductivity was investigated. 3 The fabrication process was simple as it only required processing LLZO at different densification times.…”

“…3 Similarly, Li 1.5 Al 0.5 Ge 1.5 (PO 4 ) 3 (LAGP)/polyethylene oxide (PEO) nacre-like electrolytes exhibited improved fracture toughness, but a deterioration in ionic conductivity was observed upon addition of PEO. 2 Separately, whereas past work on ceramics has demonstrated improved mechanical properties using 1D and 2D additives, [6][7][8] none have investigated them as ceramic electrolytes.…”