通过羧甲基纤维素和硅氧烷的协同作用提升锂离子电池干法正极的循环稳定性

Improving the cycling stability of lithium-ion batteries with a dry-processed cathode via the synergistic effect of carboxymethyl cellulose and siloxane

近年来,无溶剂干法电极制备工艺由于其低成本和低污染等优点在锂电池领域获得了广泛关注.然而,现有干法制备工艺中采用的聚四氟乙烯(PTFE)粘结剂存在粘附力和循环稳定性不足等缺点,限制了其实际工业化应用.我们通过引入羧甲基纤维素(CMC)和硅氧烷作为粘结剂复合材料,发展了一种与现有工业化生产兼容的锂离子电池干法电极制备工艺.CMC和硅氧烷的协同作用增强了电极活性材料的粘附性能,实现了干法电极膜片机械强度和电化学性能的大幅提升.基于这种干法电极工艺制备的铝掺杂锰酸锂(LMA/CS)半电池在1 C下循环200圈后展示出79.8%的保持率.进一步地,制备的高负载(20.6 mg cm^(-2))锰酸锂-钛酸锂全电池(LMA/CS||LTO)实现了1000圈的超长稳定循环,容量保持率高达89.2%,超过现有基于PTFE粘结剂干法工艺和传统湿法工艺的电池性能.

The solvent-free dry process for fabricating battery electrodes has received widespread attention owing to its low cost and environmental friendliness.However,the conventional polytetrafluoroethylene(PTFE)used as a binder in the preparation of dry-processed electrodes results in in-sufficient adhesion,limiting their practical industrial appli-cations.Herein,we reported an industrially viable dry process for producing lithium-ion batteries using the combination of carboxymethyl cellulose(CMC)and siloxane as the binder composite.The synergistic effect of CMC and siloxane en-hanced the adhesive performance of the electrode,thereby improving the mechanical strength and electrochemical per-formance of the developed dry-processed electrode.Half cells based on aluminum-doped lithium manganese oxide(LMA)dry-processed electrodes with CMC and siloxane(LMA/CS)exhibited a capacity retention of 79.8%after 200 cycles at 1 C.Furthermore,LMA/CS||lithium titanate oxide full cells with a high mass loading of 20.6 mg cm^(-2) demonstrated an excellent capacity retention of 89.2%after 1000 cycles,which is con-siderably higher than that of cells based on slurry-processed electrodes prepared with a polyvinylidene fluoride binder and conventional dry-processed electrodes prepared using a PTFE binder.