A new soft-hard carbon composite derived from petroleum coke and glucose for high-performance sodium storage

Hard carbon is an ideal material for negative electrodes in sodium ion batteries, but it still has drawbacks such as high cost and poor conductivity. In contrast, soft carbon behaves the low acquisition cost and graphitization at high temperatures, which is beneficial for improving the performance of sodium ion batteries (SIBs). Herein, we have developed a new soft-hard carbon composite (PCGLU) using petroleum coke (PC) and glucose as (GLU) raw materials prepared through ball milling reaction and subsequent calcination technology. This PCGLU behaves the advantages of hard carbon and soft carbon, larger interlayer spacing, and porous structure, which could increase the active sites of Na+, which could increase the active sites of Na+, shorten the Na+ diffusion distance, and promote the penetration of electrolytes. As an anode for sodium-ion batteries, the PCGLU carbonization at 800 degrees C (PCGLU-800) with suitable graphite layer spacing (0.358 nm) can provide a specific capacity of 255.2 mAh g-1 at a rate of 25 mAh g-1 after 100 cycles. Even at a high current density of 500 mA g-1 , the PCGLU-800 can still deliver a capacity of 170.7 mAh g-1 after 1000 cycles. This study could provide a simple possible method for preparing high-performance soft-hard carbon electrode materials for SIBs, and the design strategy can be generalized to other biomass-based soft-hard carbon materials.