Highly Anisotropic Carbonized Wood as Electronic Materials for Electromagnetic Interference Shielding and Thermal Management

Lightweight carbonized wood has a hierarchically 3D porous framework and orthotropic channels along the growth direction, which demonstrate great potential for multifunctional electronic materials. Herein, carbonized wood with outstanding electromagnetic interference (EMI) shielding effectiveness (SE), high thermal conductivity, and excellent Joule heating property is fabricated. It also exhibits a highly anisotropic EMI shielding performance in the cross- and tangential-sections. In the tangential-section, the shielding performance of carbonized wood is tuned by monitoring the angle between the wood grain and the electric field vibration direction of the electromagnetic waves, and the SE value ranges from 29 to 77 dB when the angle changes from 90 degrees to 0 degrees. Benefiting from the high SE obtained from structural optimization and the low density, carbonized balsa wood displays a high SSE (the ratio of SE to density) and SSE/t (the ratio of SSE to thickness) of 1069 dB cm(3) g(-1) and 3263 dB cm(2) g(-1), respectively. The thermal conductivity of carbonized wood is also angle-dependent, which ranges from 0.865 to 1.897 W m(-1) K-1. With the improvement in thermal conductivity, carbonized wood can be used as a heat sink material. Meanwhile, excellent Joule heating properties are achieved due to the effective conductive pathway in carbonized wood.