Dimethyl carbonate (DMC) is an important industrial solvent but is additionally a common component of liquid lithium-ion battery electrolytes. Pure DMC has a melting point of 277 K, so encountering solidification under outdoor climatic conditions is very likely in many locations around the globe. Even eutectic, ethylene carbonate:dimethyl carbonate commercial LiPF6 salt electrolyte formulations can start to solidify at temperatures around 260 K with obvious consequences for their performance. No structures for crystalline DMC are currently available which could be a hindrance for in situ battery studies at reduced temperatures. A time-of-flight neutron powder diffraction study of the phase behavior and crystal structures of deuterated DMC was undertaken to help fill this knowledge gap. Three different orthorhombic crystalline phases were found with a previously unreported low-temperature phase transition around 50–55 K. The progression of Pbca → Pbcm → Ibam space groups follow a sequence of group–subgroup relationships with the final Ibam structure being disordered around the central carbon atom.

碳酸二甲酯 (DMC) 是一种重要的工业溶剂，也是液态锂离子电池电解质的常见成分。纯 DMC 的熔点为 277 K，因此在全球许多地方很可能在室外气候条件下遇到凝固。即使是低共熔碳酸乙烯酯：碳酸二甲酯商用 LiPF 6盐电解质配方也可以在 260 K 左右的温度下开始凝固，对其性能产生明显影响。目前尚无结晶 DMC 的结构，这可能会阻碍原位研究降低温度下的电池研究。对氘代 DMC 的相行为和晶体结构进行了飞行时间中子粉末衍射研究，以帮助填补这一知识空白。发现了三种不同的斜方晶相，在 50-55 K 左右存在先前未报道的低温相变。Pbca → Pbcm → Ibam空间群的进展遵循一系列群-子群关系，最终的Ibam结构在中心周围无序。碳原子。