Na2FeP2O7 as a Promising Iron-Based Pyrophosphate Cathode for Sodium Rechargeable Batteries: A Combined Experimental and Theoretical Study
Na2FeP2O7 as a Promising Iron-Based Pyrophosphate Cathode for Sodium Rechargeable Batteries: A Combined Experimental and Theoretical Study
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DOI：
10.1002/adfm.201201589
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发表时间：
2013-03-06
影响因子：
19
通讯作者：
Choi, Jang Wook
中科院分区：
文献类型：
--
作者：
Kim, Heejin;Shakoor, R. A.;Choi, Jang Wook
考虑到最近报道的焦磷酸盐系列在锂离子电池中具有良好的电化学性能，以及钠离子电池(SIB)在新兴的大规模应用中日益重要的作用，本文研究了首次报道的SIB用焦磷酸盐家族的Na2FeP2O7的晶体结构、电化学性能和热稳定性。Na2FeP2O7保持了良好的通道结构(P1空间群下的三斜骨架)，表现出约90mAhG1的可逆容量和良好的循环性能。准平衡测量和第一性原理计算都一致表明，Na2FeP2O7在2.04.5V(vs Na/Na+)的整个电压范围内经历了两种反应：2.5V附近的单相反应和3.03.25V电压范围内的一系列两相反应。Na2FeP2O7即使在部分脱盐状态(NaFeP2O7)也表现出高达500℃的优异热稳定性，这表明它的安全特性对于大规模电池应用非常关键。
Considering the promising electrochemical performance of the recently reported pyrophosphate family in lithium ion batteries as well as the increasing importance of sodium ion batteries (SIBs) for emerging large-scale applications, here, the crystal structure, electrochemical properties, and thermal stability of Na2FeP2O7, the first example ever reported in the pyrophosphate family for SIBs, are investigated. Na2FeP2O7 maintains well-defined channel structures (triclinic framework under the P1 space group) and exhibits a reversible capacity of approximate to 90 mAh g1 with good cycling performance. Both quasi-equilibrium measurements and first-principles calculations consistently indicate that Na2FeP2O7 undergoes two kinds of reactions over the entire voltage range of 2.04.5 V (vs Na/Na+): a single-phase reaction around 2.5 V and a series of two-phase reactions in the voltage range of 3.03.25 V. Na2FeP2O7 shows excellent thermal stability up to 500 degrees C, even in the partially desodiated state (NaFeP2O7), which suggests its safe character, a property that is very critical for large-scale battery applications.