In order to solve the problem of poor conductivity of traditional LiFePO_(4)cathode binders,we developed sodium alginate-Congo red copolymers(SA-CR)as water-soluble electrically conductive and mechanically robust composite binder.Unlike most other electrically conductive polymer binders,the procedure is straightforward and low-cost to prepare SA-CR binder.Various SA-CR copolymers were prepared with different degree of compounding of CR to investigate the effect of CR on the electrochemical and physical properties of the prepared electrodes.The copolymer whose composition was filled with a mixture of SA and CR at a 3:1 mass ratio showed the best cell performance,due to the well-balanced electrical conductivity and mechanical properties.It exhibited a specific capacity of 118.8 m Ah/g at the 100th cycle with 92.1%capacity retention,significantly better than the 108.5 m Ah/g of conventional acetylene black electrodes.CR as a conduction-promoting agent in water-soluble composite binder favors the formation of continuous and homogenous conducting bridges throughout the electrode and increases the compaction density of electrode by reducing the conducting agent content of acetylene black and thus the improvement of electrode performance is realized.
针对磷酸铁锂电池(LiFePO_(4))平坦的开路电压OCV(open circuit voltage)与荷电状态SOC(state of charge)滞回特性在充、放电切换工况下传统等效电路模型估计OCV存在精度较低的问题,提出电池迟滞建模。为了突出LiFePO_(4)电池考虑滞回特性的必要性,对3种电池模型的复杂性、准确性和适用性进行综合评价和对比分析。结果表明,一阶RC模型不考虑滞回的影响,仅适用纯充电或纯放电的工况;一阶RC滞回模型在一阶RC模型的基础上增加1个滞回量,虽考虑了滞回特性的影响,但滞回量受参数辨识影响较大,OCV估计存在波动;Preisach模型对存在充、放电切换工况的估算精度较好,但训练数据时间成本较高。NEDC(new European driving cycle)充、放电工况下对不同模型结合算法估计SOC,估计误差均在5%以内,其中Preisach误差在3%以内。
