Unusual Na+ Ion Intercalation/Deintercalation in Metal-Rich Cu1.8S for Na-Ion Batteries
Unusual Na+ Ion Intercalation/Deintercalation in Metal-Rich Cu1.8S for Na-Ion Batteries
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DOI：
10.1021/acsnano.8b00118
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发表时间：
2018-03-01
期刊：
影响因子：
17.1
通讯作者：
Lou, Xiong Wen (David)
中科院分区：
文献类型：
--
作者：
Park, Hyunjung;Kwon, Jiseok;Lou, Xiong Wen (David)
钠离子电池的一个关键问题是通过了解钠的储存机理来开发具有稳定的电化学可逆性的活性材料。本文报道了一种新型负极材料--闪锌矿Cu1.8S的储钠机理和性能。结果表明，由于11族元素中存在+1的独特氧化态，硫化铜(CuxS)可能具有富金属式(x>；=1.6)。这些相使晶胞由所有强的铜-S键组成，而不包括直接的S-S键，这些键容易受到外部应力/应变的影响，从而导致键断裂和分解。由于Cu1.8S的结构刚性，即使在相对于Na/Na+的0.1-2.2V的低电势窗口内，Cu1.8S也表现出插层/脱层反应机理，而不发生不可逆相变，大多数金属硫化物都经历了转化反应机理。平均每单位电池可吸收1.4个Na+离子(类似于250mAHg(-1))，在0.5-2.2V的调谐电压范围内，在2℃的1000次循环中表现出类似于100%的保持率，整个固溶体反应几乎不存在相分离。
A key issue with Na-ion batteries is the development of active materials with stable electrochemical reversibility through the understanding of their sodium storage mechanisms. We report a sodium storage mechanism and properties of a new anode material, digenite Cu1.8S, based on its crystallographic study. It is revealed that copper sulfides (CuxS) can have metal-rich formulas (x >= 1.6), due to the unique oxidation state of +1 found in group 11 elements. These phases enable the unit cell to consist of all strong Cu-S bonds and no direct S-S bonds, which are vulnerable to external stress/strain that could result in bond cleavage as well as decomposition. Because of its structural rigidness, the Cu1.8S shows an intercalation/deintercalation reaction mechanism even in a low potential window of 0.1-2.2 V versus Na/Na+ without irreversible phase transformation, which most of the metal sulfides experience through a conversion reaction mechanism. It uptakes, on average, 1.4 Na+ ions per unit cell (similar to 250 mAh g(-1)) and exhibits similar to 100% retention over 1000 cycles at 2C in a tuned voltage range of 0.5-2.2 V through an overall solid solution reaction with negligible phase separation.