Experimental Investigation and Thermodynamic Modeling of LNMO High Voltage Spinel Cathode for the LIBs

锂离子电池用 LNMO 高压尖晶石阴极的实验研究和热力学建模

基本信息

批准号：
326070248
负责人：
Dr. Dajian Li
金额：
--
依托单位：
Institut für Angewandte Materialien (IAM)
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2017
资助国家：
德国
起止时间：
2016-12-31 至 2019-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/326070248?language=en
关键词：
Experimental Investigation Thermodynamic Modeling LNMO

项目摘要

High voltage Li-Ni-Mn-O (LNMO, stoichiometric composition LiNi0.5Mn1.5O4, 4.7 V vs. Li) spinels are very promising cathode materials for Li-ion batteries (LIBs) due to the high energy densities. Consistent thermochemical and electrochemical data are urgently required for the design of power and thermal management systems of LIBs based on these new materials. Although numerous cell property investigations have been published, thermochemical (enthalpy of formation, heat capacity) and electrochemical data (entropy of reaction during charge-discharge processes) are rare. Therefore, the aim of this project is to investigate the thermochemistry and electrochemistry of LNMO spinels and to use the results to develop self-consistent analytical descriptions of the Gibbs free energy of the respective phases for the first time.The experimental studies in this proposal include the synthesis of spinel samples with selected cation ratios using the sol-gel method. Heat treatments in defined atmospheres will be used to obtain samples with different oxygen vacancy concentrations. Sample characterization will be performed using powder-XRD, ICP-OES and SEM. Redox titration techniques will be employed to determine the average oxidation state of Mn cations, allowing the calculation of oxygen vacancy concentrations. Moreover, enthalpies of formation will be measured using drop solution calorimetry, and heat capacity measurements will be conducted using different DSC devices. Battery test cells (Coin cells, Swagelok cells) will be assembled with the spinel cathode against pure Li, and will be used for potentiometric investigation to obtain the entropy changes during lithiation-delithiation process. Both LMO and LNMO spinels compositions will be investigated.A model taking the crystal structure and Wyckoff site occupancies into account (oxygen vacancy concentrations, cation mixing), will be established based on the experimental data using the Calphad approach. Lithiation-delithiation process will be simulated by modeling the relation between Gibbs energy and correct sublattice site occupations for the first time. Predictions of battery behaviors including open circuit voltages, heat generation properties, and oxygen partial pressures with temperature dependencies under varying conditions, will be performed.As the output of the current project, conditions for synthesizing LNMO spinel with improved battery performance will be proposed according to thermodynamic calculations. Meanwhile, the obtained thermodynamic models will be key contributors to the ICME development of LIBs with novel spinel cathode materials. Furthermore, the thermochemical information is essential for the battery safety and preventing hazardous phenomena such as thermal runaway and flame generation.

高压LI-NI-MN-O（LNMO，化学计量组成lini0.5mn1.5O4，4.7 V vs. Li）尖晶石是由于高能量密度而引起的非常有前途的锂离子电池的阴极材料（LIBS）。基于这些新材料的功率和热量管理系统，迫切需要一致的热化学和电化学数据。尽管已经发表了许多细胞性能研究，但是很少有热化学（形成，热容量焓，热容量焓，热容量）和电化学数据（电荷释放过程中反应的熵）很少见。因此，该项目的目的是研究LNMO尖晶石的热化学和电化学，并使用结果首次对相应阶段的Gibbs自由能进行自洽分析描述。该提案中的实验研究包括使用spinel样品与所选的cation conthessions一起，其中包括使用spinel样品的合成，使用溶液比率。定义大气中的热处理将用于获取具有不同氧空位浓度的样品。样品表征将使用粉末-XRD，ICP-OE和SEM进行。将采用氧化还原滴定技术来确定Mn阳离子的平均氧化状态，从而计算氧气空位浓度。此外，将使用滴溶液量热法测量形成的焓，并将使用不同的DSC设备进行热容量测量。电池测试单元（硬币细胞，Swagelok细胞）将与尖晶石阴极组装纯LI，并将用于电位测量测量，以在静置降低过程中获得熵变化。将研究LMO和LNMO尖晶石组合物。将考虑到晶体结构和Wyckoff位点占用（氧空位浓度，阳离子混合）的模型，使用Calphad方法来建立。通过对Gibbs Energy和正确的Sublattice站点职业之间的关系进行建模，将模拟静电置义过程。电池行为的预测将在不同条件下进行温度依赖性，包括开路电压，热产生特性以及氧部分压力。由于当前项目的输出，将根据热力学计算提出，将提出与电池相关的LNMO尖晶石的输出。同时，获得的热力学模型将是使用新型尖晶石阴极材料的ICME开发的关键因素。此外，热化学信息对于电池安全性和防止危险现象（例如热失控和火焰产生）至关重要。