Biomass-derived hard carbon (HC) is the most promising anode material for commercial sodium-ion batteries (SIBs). However, the commercialization of HC still faces technical issues related to its insufficient reversible capacity and low initial coulombic efficiency. Although some techniques have been developed to circumvent these issues, they suffer from drawbacks such as complex preparation processes, environmental unfriendliness, and high processing costs. Herein, an ecofriendly bioengineering strategy based on the microstructure and composition regulation of bamboo as an HC source has been reported. The designed biomass-derived HC anode has a high reversible capacity (428.21 mA h g⁻¹) and outstanding initial Coulomb efficiency (90.72%) at 30 mA g⁻¹ superior to that of previously reported plant-based HC electrodes. Self-growing Coriolus versicolor (CV), a bothersome fungus, was ingeniously used to regulate the lignin content of the bamboo precursor generating abundant closed pores and increasing porosity, and the removed lignin can be converted into CV carbon fibers in a green manner. Moreover, CV carbon fibers with their hyperbranched structure provide a natural interpenetrative path for fast ion diffusion and electron transport as well as rich sodium-ion storage sites, thereby boosting their electrochemical performance. Note that the ash content in bamboo could be decreased via this natural bioengineering process without using common acid/base treatments. This study provides a cost-effective and green approach to synchronously modulate the microstructure and composition of biomass toward high-performance biomass-derived SIB anodes.

Transition metal oxides (TMOs) can provide high theoretical capacitance due to the change of multiple valence states of transition metals. However, their intrinsic drawbacks, including poor electrical conductivity, lower energy density, and huge volume expansion, will result in the pulverization of electrode materials and restricted electrochemical kinetics, thus leading to poor rate capability and rapid capacity fading. Composite electrodes based on transition metal oxides and carbon-based materials are considered to be promising candidates for overcoming these limitations. Herein, we reported a preparation method of hybrid ZIFs derived Zn-doped Co₃O₄/carbon (Zn-Co₃O₄/C-230) particles semi-embedded in wood-derived carbon skeleton for integrated electrodes. A large specific surface area, excellent conductivity, and electrochemical stability provide a larger electrochemical activity and potential window for the electrode. Prepared Zn-Co₃O₄@CW-230 electrode (0.6 mm thick) displays ultrahigh area specific capacitances of 7.83 and 6.46 F cm⁻² at the current densities of 5 and 30 mA cm⁻², respectively. Moreover, a symmetric supercapacitor assembled by two identical Zn-Co₃O₄@CW-230 electrodes delivers a superior area-specific capacitance of 2.61 F cm⁻² at the current densities of 5 mA cm⁻² and great energy densities of 0.36 mWh cm⁻² (6.0 mWh cm⁻³) at 2.5 mW cm⁻², while maintaining 97.3% of initial capacitance over 10,000 cycles. It notably outperforms those of most carbon-based metal oxides, endowing the Zn-Co₃O₄@CW-230 with extensive prospects for practical application.