高功率储能电池端面电极均匀集流策略研究

Research on uniform current collection strategy of end face electrode of high power energy storage battery

高功率储能电池具有爬坡速率高、响应时间短的特点,在电力调频领域有良好的应用前景,端面电极的均匀集流对其电池内部均匀性和安全性至关重要。通过引入非线性等效电导率,建立了高功率储能电池的三维电流密度分布模型,并以电池单元水平方向上放电深度的离散程度(UI)值作为电池电流密度均匀度和集流效果的评价指标。在利用6.4V和28.8V电池实测放电曲线对比验证所建模型有效性的基础上,研究了端面电池单元集流端子数量、位置、横截面积、间距、集流体厚度和放电倍率对电池电流密度分布的影响。结果显示,对于面积为0.3m×0.4m的高功率储能电池,采用表面集流方式的UI值比边缘集流方式降低了约78.9%,采用表面双集流端子可进一步将UI值降低一半;双集流端子间距为0.2m时UI值达到最低;增加集流端子横截面积和集流体厚度也可降低UI值,但会增加电池自身重量。综合上述因素,设计了储能电池均匀集流的优化策略,可将传统边缘集流方式的电流密度均匀度提高10.6倍,且在高倍率下依然表现出极高的均匀度,非常适合于高功率储能电池的开发设计。

The high power energy storage battery has the characteristics of high climbing rate and short response time, showing good application prospect in the field of power frequency modulation. The uniform current collecting of the end face electrode is critical for the internal uniform and safety of the battery. By introducing the nonlinear equivalent conductivity, the three-dimensional current density distribution model was established, and the uniform index (UI) related with depth of discharge in the horizontal direction of the battery cell was used to evaluate the battery current density uniformity and current collecting effect. The reliability of the constructed model was validated by the comparison between the experimental discharge data of 6.4 and 28.8 V batteries with the simulated ones. Based on this, the influence of the number, position, cross-sectional area, spacing, current collector thickness and discharge rate of the current collection terminal on the current density distribution of the battery was studied. The results show that for the high power energy storage batteries with area of 0.3 m×0.4 m, the UI value of surface current collection method is about 78.9% lower than that of the edge current collecting method, and the value is further decreased by half when the surface double current collecting terminal is used. The UI value reaches the minimum when the distance between double current collecting terminals is 0.2 m. Adding the cross-sectional area of current collecting terminal and the thickness of current collector can decrease the UI value, but the mass of the battery increases. Considering above factors, the optimized strategy was designed for the uniform current collection of the energy storage battery, which can increase the current density uniformity by about 10.6 times compared with the conventional edge current collection method, and shows extremely high uniformity even at high rate. It's very suitable for the development and design of high power energy storage batteries.