Gas Evolution and Capacity Fading in LiFe x Mn 1-x PO 4 /Graphite Cells Studied by Neutron Imaging and Neutron Induced Prompt Gamma Activation Analysis
Gas Evolution and Capacity Fading in LiFe x Mn 1-x PO 4 /Graphite Cells Studied by Neutron Imaging and Neutron Induced Prompt Gamma Activation Analysis
复制标题
DOI：
10.1149/2.0011802jes
复制
发表时间：
2017
影响因子：
3.9
通讯作者：
Benjamin Starke;Stefan Seidlmayer;M. Schulz;Alexander Dinter;Z. Révay;R. Gilles;Karl-Heinz Pettinger
中科院分区：
文献类型：
--
作者：
Benjamin Starke;Stefan Seidlmayer;M. Schulz;Alexander Dinter;Z. Révay;R. Gilles;Karl-Heinz Pettinger
通过中子成像（NI）分析了LFP/石墨和LFMP/石墨电池在形成过程中的气体演化。结果表明，在LFMP/石墨电池中，与LFP/石墨电池相比，产生的气体大约多30%，并且Mn的存在与更强的气体释放有关。对于LFP/石墨电池，可以检测到气体演化速率的两个不同线性相，而LFMP/石墨电池则显示出额外的相。在这两个充满的电池中，已经确定了气体演化和电极电位之间的明显关系。为了关联长期Mn溶解和容量保持，进行了额外的中子诱导快速γ活化分析（PGAA）测量。长期循环表明LFMP/石墨电池的容量保持率更高。PGAA结果表明，随着循环次数的增加，Mn的溶解速率迅速降低，且LFMP的Mn溶解速率远低于氧化物型正极材料。长期循环表明，与LFP/石墨电池相比，LFMP/石墨电池在形成步骤中更高的不可逆容量损失和更多的气体释放的负面影响在几次循环后由于更高的容量保留而得到补偿。
The gas evolution in LFP/graphite and LFMP/graphite cells during the formation has been analyzed via neutron imaging (NI). The results show that in LFMP/graphite cells approximately 30% more gas is generated in comparison to LFP/graphite and stronger gas evolution is associated with the presence of Mn. For the LFP/graphite cell two different linear phases in gas evolution rate can be detected while LFMP/graphite cells reveal an additional phase. In both full-cells a distinct relation between gas evolution and electrode potentials has been determined. Additional neutron induced Prompt Gamma Activation Analysis (PGAA) measurements were carried out in order to correlate long-term Mn dissolution and capacity retention. Long-term cycling showed higher capacity retention for the LFMP/graphite cells. The results of PGAA prove that Mn dissolution decreases rapidly with increased cycle number and the Mn dissolution rate of LFMP is far below values observed for oxide-type cathode materials. Long-term cycling showed that the negative effects of higher irreversible capacity loss in the formation step and more gas evolution of LFMP/graphite cells in comparison to LFP/graphite cells is compensated after several cycles due to higher capacity retention.