Electrospinning Machine | Cellulose nanofiber/boron nitride/MXene ternary composite films with excellent thermal conductivity for high output triboelectric nanogenerators under high temperature

Based on the principles of triboelectrification and electrostatic induction, triboelectric nanogenerators (TENGs) have been widely used in energy management and self-powered sensing due to their low cost, light weight, and high sensitivity. As self-powered electronic devices, TENGs show great potential in energy harvesting and sensing, but they suffer from poor thermal stability and insufficient thermal conductivity under high-temperature conditions, leading to reduced output performance and shortened device lifespan. 

Recently, Professor Ma Mingguo's team at Beijing Forestry University published their latest research "Cellulose nanofiber/boron nitride/MXene ternary composite films with excellent thermal conductivity for high output triboelectric nanogenerators under high temperature" in the journal Chemical Engineering Journal. The researchers constructed a biomimetic layered cellulose nanofiber (TOCNF)/boron nitride (BNNS)/MXene ternary composite film (TCBM) via vacuum-assisted self-assembly technology. Utilizing the high thermal conductivity of BNNS and the conductivity and structural guidance of MXene, the composite synergistically improved the thermal management capability and triboelectric output stability, providing insights for the development of self-powered systems in high-temperature environments.

Using a multi-scale synergistic enhancement strategy, this study employed TOCNF as a flexible substrate to prepare biomimetic layered TCBM composite films via vacuum-assisted self-assembly technology (Figure 1). The abundant carboxyl (-COOH) and hydroxyl (-OH) groups on the TOCNF surface formed strong hydrogen bonds with the B-N polar bonds of BNNS. Additionally, through the bridging effect of TOCNF, a hydrogen bond network formed between BNNS and MXene, enhancing the interfacial continuity of the composite. The edge defects of BNNS generated local dipole moments, interacting with the polar groups of TOCNF via dipole-dipole interactions. The ordered arrangement effectively reduced interfacial thermal resistance and constructed continuous, efficient phonon transport channels.

Figure 1: Preparation and application of TCBM composite film

As shown in Figure 2, BNNS and MXene nanosheets significantly regulated the self-assembly behavior of TOCNF, forming a nacre-like layered structure in the TCBM film. This unique microstructure originated from the inherent three-dimensional network formation capability of TOCNF. It anchored BNNS and MXene nanosheets in the fiber network through hydrogen bonding interactions, achieving uniform dispersion of nanofillers (Figures 2a-c). 

Composite films with higher loadings of BNNS and MXene exhibited dense nanosheet layer arrangements and continuous permeability (Figures 2d,e). This biomimetic structure is expected to significantly enhance the in-plane thermal conductivity and charge transport efficiency of the composite film. The optimized composite structure achieved excellent mechanical properties while maintaining superior functional characteristics (Figures 2f-h). Compared to TOCNF composite films, the tensile strength of the composite film with 10wt% BNNS/MXene fillers increased from 150.25 MPa to 179.05 MPa, the elongation at break increased from 4.64% to 5.14%, and the Young's modulus and toughness increased from 4.47 GPa and 3.88 MJ m⁻³ to 4.93 GPa and 4.54 MJ m⁻³, respectively. The composite film also exhibited an excellent thermal conductivity of 16.72 W m⁻¹ K⁻¹.

Figure 2 (a-e) Cross-sectional SEM images of the films; (f) Tensile stress-strain curves of TCBM composite films with different BNNS and MXene contents; (g) Tensile strength and elongation at break; (h) Young's modulus and toughness; (i) TGA spectra of h-BN and BNNS; (j) TGA curves and (k) DTG curves of TCBM composite films; (l) In-plane and through-plane thermal conductivity of TCBM composite films.

Voc, Isc, and Qsc gradually increased with the loading of BNNS and MXene, rising from initial values of 28.6 V, 10.2 nC, and 2.1 μA (TOCNF-TENG) to 79.6 V, 30.7 nC, and 7.6 μA (TCBM5-TENG), respectively (Figure 3). As the contact area decreased from 2.0 cm × 2.0 cm to 0.5 cm × 0.5 cm, the open-circuit voltage (Voc) decreased from 79.6 V to 13.6 V, the electrostatic capacity (Qsc) decreased from 30.7 nC to 5.1 nC, and the short-circuit current (Isc) decreased from 7.6 μA to 0.87 μA. A larger triboelectric surface area collected more Qsc, resulting in higher triboelectric output.

Figure 3 (a) Schematic structure and (b) vertical contact-separation working mode of TCBM-TENG; (c) Voc, (d) Qsc, and (e) Isc of TCBM-TENG with different BNNS and MXene contents; (f-h) Voc, Qsc, and Isc of TCBM-TENG with different TCBM composite film areas; (i-k) Voc, Qsc, and Isc of TCBM-TENG under different impact frequencies.

The triboelectric nanogenerator achieved an open-circuit voltage of 79.6 V, a short-circuit current of 7.6 μA, an accumulated charge of 30.7 nC, and a maximum power density of 272.5 mW m⁻² (Figure 4). Even at a high temperature of 270°C, the TENG maintained excellent triboelectric output performance (voltage up to 55.8 V). The TENG operated continuously for 6000 cycles at 270°C while maintaining stable output performance, fully demonstrating its exceptional operational reliability. 

Additionally, the TENG can be used as a self-powered pressure sensor to monitor human motion in real-time. It exhibits high sensitivity (2.681 kPa⁻¹ in the 0-11 kPa range), fast response/recovery times (90/98 ms), and excellent stability, enabling real-time monitoring of human motion. By integrating a Bluetooth module, the sensor transmits electrical signals to mobile terminals, proving its feasibility in wearable electronic devices and health monitoring systems.

Figure 4 (a) Voc, Qsc, and Isc of TCBM composite film in contact with different polar materials; (b) Stability test; (c) Voc, Isc, and power density of TCBM-TENG under different external resistances; (d) TCBM-TENG charging different capacitors; TCBM-TENG charging and discharging a 10μF capacitor at 2Hz to power (e) a watch and (f) a calculator; (g) Charging images of the watch and calculator; (h) Voc and Qsc of TCBM-TENG at different temperatures; (j) Comparison of triboelectric performance between TCBM-TENG and other materials.

Paper link: https://doi.org/10.1016/j.cej.2025.167292