Double-carbon protected silicon anode for high performance lithium-ion batteries

Undoubtedly, silicon/carbon composites are one of the most promising anode classes for lithium-ion battery. However, they still suffer from poor cycle performance despite the introduction of carbon phase, which is usually expected to inhibit the volume expansion of Si phase and meanwhile enrich the electrode conductivity, improving the cycle stability. Here, a double-carbon protected silicon anode was designed and successfully synthesized through the liquid coating and in-situ polymerization method. In this structure, the primary seamless carbon layer make Si NPs maintain a close contact to conducting carbon, so that inserted Li+ could fully react with Si, improving the utilization of active materials. The secondary carbon skeleton could help to maintain the mechanical integrity of the structure and meanwhile enrich the charge transfer channels. The structural advantages enhance the mechanical integrity and electrochemical kinetics during cycling, that lead to superior electrochemical Li+ storage performance. The resulting double-carbon protected silicon anode demonstrates a high specific capacity, long-term stability (1919 mAh g(-1) at 0.5 mA g(-1), 90% retention after 400 cycles (vs. the capacity of second cycle)) and outstanding rate capability (1170 mAh g(-1) at 2 A g(-1)). (C) 2019 Elsevier B.V. All rights reserved.