Bio‐Inspired Nanospiky Metal Particles Enable Thin, Flexible, and Thermo‐Responsive Polymer Nanocomposites for Thermal Regulation

Abstract

Safety issues remain a major obstacle toward large‐scale applications of high‐energy lithium‐ion batteries. Embedding thermo‐responsive polymer switching materials (TRPS) into batteries is a potential strategy to prevent thermal runaway, which is a major cause of battery failures. Here, thin, flexible, highly responsive polymer nanocomposites enabled by bio‐inspired nanospiky metal (Ni) particles are reported. These unique Ni particles are synthesized by a simple aqueous reaction at gram‐scale with controlled surface morphology and composition to optimize electrical properties of the nanocomposites. The Ni particles provide TRPS films with a high room‐temperature conductivity of up to 300 S cm−1. Such TRPS composite films also have a high rate (<1 s) of resistance switching within a narrow temperature range, good reversibility upon on/off switching, and a tunable switching temperature (Ts; 75 to 170 °C) that can be achieved by tailing their compositions. The small size (≈500 nm) of Ni particles enables ready fabrication of thin and flexible TPRS films with thickness approaching 5 µm or less. These features suggest the great potential of using this new type of responsive polymer composite for more effective battery thermal regulation without sacrificing cell performance.

Smart Polymer Nanocomposites: Recent Advances and Perspectives

“…For the synthesis of stimuli-response nanocomposites, active nanofillers are mostly used because these materials can react to different stimuli. As a result, the obtained nanocomposite could respond to electric currents, light, temperature, magnetic field, pH changes, etc [30][31][32]. An example that demonstrates the effect that active nanofillers can generate when incorporated into polymer matrices is the work carried out by Chen et al, who reported the synthesis of a shapememory nanocomposite with a rapid light response and self-healing performance.…”

Advances in Prevention of Thermal Runaway in Lithium‐Ion Batteries

“…[118] Another strategy to increase conductivity is to use nickel nanoparticles in the polymer composite, which are much more conductive than carbon, leading to a 300 Scm À1 conductivity of the composite film at room temperature. [119] A practical feature of these PVdF/Ni films is that the temperature range of the PTC response can be tuned by altering the polymer/Ni ratio.…”

Thermo‐responsive polymers for thermal regulation in electrochemical energy devices

“… 76 Also, employing conductive fillers with high aspect ratios such as CNTs, 77 or polyaniline‐coated multiwalled CNTs (MWCNTs) 78 improved the formation of a robust conductive network that enhances the R.T. conductivity. One of the most prominent improvements of R.T. conductivity was achieved by the nano‐spiky Ni/PE system 79 . The synergistic effect of its nano‐size and the spiky shape significantly improves the R.T. conductivity of the TRPS polymer composite as a result of more conductive pathways and a smaller average distance between conducive fillers which enables the tunneling transfer of electrons (Figure 8(B)).…”

“…(C) Conductivity of Ni/PVDF films as a function of Ni volume fraction with different Ni conductive fillers (HM‐Ni, C‐Ni, and reduced HM‐Ni). (reproduced with permission 79 …”