Directional Freezing Assisted 3D Printing to Solve a Flexible Battery Dilemma: Ultrahigh Energy/Power Density and Uncompromised Mechanical Compliance

Abstract

Flexible lithium‐ion batteries (LIBs) have been in the spotlight with the booming development of flexible/wearable electronics. However, the dilemma of simultaneously balancing excellent energy density with mechanical compliance in flexible electrodes impedes their practical applications. Here, for the first time, a directional freezing assisted 3D printing strategy is proposed to construct flexible, compressible, and ultrahigh energy/power density LIBs. Cellulose nanofibers (CNFs) and carbon nanotubes (CNTs) are entangled with each other to form an interwoven network and uniformly wrap the active materials, ensuring fast electron transfer and stress release through the entire printed electrode. Furthermore, vertical channels induced by directional freezing can act as high‐speed ion diffusion paths, which effectively solve the sluggish ion transport limitation of flexible 3D printed electrodes as the mass loading increases. As expected, the 3D printed LIB delivers a record‐high energy density (15.2 mWh cm–2) and power density (75.9 mW cm–2), outperforming all previously reported flexible LIBs. Meanwhile, the printed flexible full LIBs maintains favorable electrochemical stability in both bending and compression states. This work suggests a feasible avenue for the design of LIBs that resolves the long‐standing issue of high electrochemical performance and mechanical deformation in wearable and smart electronics.

3D Cold‐Trap Environment Printing for Long‐Cycle Aqueous Zn‐Ion Batteries

“…Herein, we develop an innovative 3D periodic MXene/Zn-P aerogel anode with high shape fidelity and excellent directional alignment via a novel 3D cold-trap environment printing (3DCEP) technology. Different from conventional 3D printing direct ink writing (DIW) and 3D cold plate printing (3DCPP) technologies, [17][18][19] the 3DCEP technology is implemented in a wholly cold environment, and the instantaneous freezing of inks eliminates the influence of temperature gradient on the flow of inks. In addition, the MXene nanosheets are ordered alignment spontaneously owing to the laminar flow effect of inks with low Reynolds number in the microchannel.…”

Architected Low‐Tortuosity Electrodes with Tunable Porosity from Nonequilibrium Soft‐Matter Processing

“…The electrodes were wet with an excess of 1 m LiPF 6 in EC:DMC 50/50 v/v and a polypropylene separator (Celgard) was used between electrodes. Full cells and LTO:Li half-cells were tested between 1-2.5 V, while LFP:Li half-cells were tested between 2.5 -3.8/4.0 V. [32,46,47] Within these voltage windows the carbon portion of the HIPI-composite contributed limited to no capacity, as demonstrated by a HIPI-architected pure carbon electrode cycled as a half-cell (Carbon:Li) shown in Figure S22 (Supporting Information). Currents below 1 mA were tested on an MTI BST8-WA battery tester, and currents above 1 mA were tested on either a Gamry Interface 1010 potentiostat/galvanostat or an MTI BST8-A6V0 battery tester.…”

Additive manufacturing for advanced rechargeable lithium batteries: A mini review

“…As schematically illustrated in Figure 2A, the types of thin film are the most commonly available architectures for both electrode and electrolyte modules, which can be manufactured into custom-designed dimension and shapes by multiple diverse 3D printing techniques (Maurel et al, 2021;Li et al, 2022). These planar modules can be easily applied for 2D sandwichedstructural batteries and microbatteries.…”