Large-scale synthesis of highly structural-connecting carbon nanospheres as an anodes material for lithium-ion batteries with high-rate capacity

Highly structural-connecting carbon nanospheres (CNSs) are prepared using thermal pyrolysis of acetylene at 580 °C with a yield of 1 kg h−1. The as-prepared CNSs present a particle-size distribution in a range of 60–90 nm, and display a highly-connected structure (the specific oil-adsorption value is 180 mL/100g according to the ASTM D2415-19 method) with a specific surface area of 30 m2 g−1. The as-prepared CNSs were treated with an acid purification (1M HNO3 80 °C for 2 h) or thermal treatments at higher temperatures (800 or 1000 °C for 2 h) under argon atmosphere. The CNSs-based samples demonstrate admirably electrochemical performance as the anode materials for lithium-ion batteries (LIBs). Additionally, HNO3-treated CNSs display better performances in LIBs comparing with pristine, thermal-treated CNSs, graphite, and carbon black-super-P and acetylene black. For the HNO3-CNSs sample, the first charge-discharge cycle of the specific charge capacity is 506 mAh g−1, and which maintains at 420 mAh g−1 of specific discharge capacity, the initial coulombic efficiency is 85.0%. Moreover, the rate capacity is conducted at various current densities from 0.05 to 2 A g−1, the capacitance retention rate can maintain above 98 % after 100 cycles. Remarkably, the HNO3-treated CNSs exists excellent rate capacity of 280 mAh g−1 at 2 A g−1, which is superior to those of previously reported CNSs. Herein, we provide a facile route to massively prepare a high-performance anode material for LIBs.