Beijing Institute of Technology , Beijing 100081, China.
Research Institute of Chemical Defense , Beijing 100191, China.
ACS Appl Mater Interfaces. 2017 Jul 19;9(28):23766-23774. doi: 10.1021/acsami.7b05687. Epub 2017 Jul 6.
Sodium-ion batteries (SIBs) are expected to be a promising commercial alternative to lithium-ion batteries for grid electricity storage due to their potential low cost in the near future. Up to the present, the anode material still remains a great challenge for the application of SIBs, especially at room temperature. Graphite has an obvious limitation to store larger radius sodium ions (Na) in comparison with lithium ions (Li), while the hard carbon with large interlayer distance can demonstrate a relatively high storage capability and durable cycle life. However, the disadvantages of low initial Coulombic efficiency (ICE) mainly caused by large surface area and high cost synthetic approach hinder its practical applications. Herein, a new coupled carbonization strategy is presented to prepare a cost-effective hard carbon material by pyrolyzing and carbonizing the mixture of abundant sucrose and phenolic resin. Benefiting from the specialized pyrolysis reaction process and optimized conditions as studied in detail, the hard carbon has an extremely low surface area of 1.54 m g and high initial Coulombic efficiency of 87%, which have been rarely reported before and enhance the utilization efficiency of Na consumption within the cathode in the future. More importantly, the hard carbon, with a high interlayer distance 3.95 Å, can deliver a higher capacity of 319 mAh g and maintain a finer capacity retention of 90% over 150 cycles. Besides, a full cell with the configuration of as-prepared hard carbon anode versus an air-stable O3-Na[CuFeMn]O cathode is further presented, and it has a high ICE of 80% and energy density of 256 Wh kg (vs hard carbon) with reliable cycle performance. The results demonstrate that our synthetic strategy is feasible and extendable, while the tunable carbon-based materials should have wider applications in addition to the attractive properties in Na-ion batteries.
钠离子电池（SIBs）由于其在不久的将来可能具有低成本的优势，有望成为电网储能用锂离子电池的一种有前途的商业替代品。截至目前，与锂离子（Li）相比，用于 SIBs 的阳极材料仍然是一个巨大的挑战，尤其是在室温下。石墨在储存较大半径钠离子（Na）方面存在明显的局限性，而层间距离较大的硬碳可以表现出较高的存储能力和耐用的循环寿命。然而，低初始库仑效率（ICE）的缺点主要是由大表面积和高成本的合成方法引起的，这阻碍了其实际应用。在此，提出了一种新的耦合碳化策略，通过热解和碳化丰富的蔗糖和酚醛树脂混合物来制备具有成本效益的硬碳材料。受益于详细研究的特殊热解反应过程和优化条件，硬碳的比表面积极低，仅为 1.54 m g，初始库仑效率高达 87%，这在以前很少报道过，提高了未来阴极中 Na 消耗的利用率。更重要的是，硬碳具有较高的层间距 3.95 Å，可以提供更高的容量 319 mAh g，并在 150 次循环后保持 90%的更好容量保持率。此外，还进一步提出了一种由制备的硬碳阳极和空气稳定的 O3-Na[CuFeMn]O 阴极组成的全电池，其具有 80%的高 ICE 和 256 Wh kg（相对于硬碳）的能量密度，具有可靠的循环性能。结果表明，我们的合成策略是可行和可扩展的，而可调谐的碳基材料除了在钠离子电池中具有吸引力的特性外，还应该有更广泛的应用。
