The JF/SiNP composites were assembled into 2032 coin cells versus lithium metal and underwent electrochemical analysis to evaluate their suitability as anodic material for use in lithium-ion batteries. Cyclic voltammetry (CV) was first conducted in order to assess the electrochemical activity of the SiNPs after laser writing along with characterizing the voltage window of the half-cells and is depicted in Figure . The CV was conducted within the voltage range of 0.05 to 1 V vs. Li/Li + using a scan rate of 0.02 mV/s, ensuring lithiation in accordance with the known charge and discharge range of silicon-lithium alloying. The resulting delithiation peaks observed at 0.49 V and 0.29 V, as well as the lithiation peaks at 0.21 V and 0.07 V, are sharp and definitive, matching the theoretical values and indicating that the electrochemical activity of the silicon was preserved after the lasing process . In order to assess the transformation of the JF biomass into conductive carbon, electrical impedance spectroscopy (EIS) was conducted on a JF/SiNP cell over a frequency range of 0.01 MHz to 1 Hz after delithiation over different cycling stages, as displayed in the Nyquist plot in Figure . The equivalent circuit utilized for the impedance analysis is illustrated in the inset, with further details on each circuit component provided in supplementary figure . The diameter of the depressed semicircle represents the charge transfer resistance (Rct). The impedance values confirm the sharp increase in conductivity after the lasing process, which are comparable to reported values of silicon/ graphene-based composites in LIBs and well above impedance values displayed by pristine SiNPs . As anticipated, the EIS analysis shows that the initial impedance of the battery was lower prior to cycling, with subsequent cycles resulting in the development of the solid electrolyte interphase (SEI) layer, leading to a small gradual increase in impedance. However, the overall impedance of the battery stabilized after a few cycles and remained relatively constant thereafter . Figure cycling is that of silicon. The gravimetric capacity of the cell was calculated by measuring the dry mass fraction (~30%) of silicon added after each spin-coated layer before the lasing process. The initial gravimetric capacity was 1402 mAh/g, with the early decrease in capacity observed in the first cycles being attributed primarily to the formation of the SEI passivation layer . The initial coulombic efficiency was measured to be 81%. Upon stabilization of the SEI, the battery exhibited excellent reversible capacity retention, as demonstrated by the voltage profiles of the cell depicted at different cycles in Figure . During the initial cycles, the battery displayed high retention of reversible capacity, with 82% retention between the 10 th cycle and 100 th from a starting reversible gravimetric capacity of ~1250 mAh/g. Notably, the capacity retention continued to improve with additional cycles, reaching an impressive retention rate of 98% between the 400th and 500th cycle, indicating significant improvement in long-term battery durability and performance. Overall, the battery demonstrated remarkable stability and capacity, exceeding the theoretical value of graphite anodes for all cycles, and retaining over 50% of reversible capacity with 690 mAh/g after 1000 cycles. The slow decay and high retention correlates to the high calculated coulombic efficiency, with an average of over 99%. Figure depicts the rate performance of a typical JF/SiNP cell. At a lower current density of 50 mA/g, the battery exhibits an excellent reversible gravimetric capacity of ~2000 mAh/g. The decline in capacity over increasing current densities was gradual, resulting in less than a 50% percent decrease in reversible capacity between cycling at 50 mA/g and faster cycling at 800 mA/g. Even when cycled rapidly at a current density of 1600 mA/g, the cell still exhibits and excellent gravimetric capacity of 850 mAh/g. The high retention rate and gravimetric capacities following changes in current densities, with respect to the complete absence of conductive additives, highlights the immense potential of these results.