Chao Luo,Xiufen Wu,Tian Zhang,Shang-Sen Chi,Zhengying Liu,Jun Wang,Chaoyang Wang,Yonghong Deng
The large-scale application of Si-based anodes is impeded by their fast capacity decay, which is mainly attributed to the huge volume expansion upon cycling. The employment of functional binders is one efficient method to mitigate this issue. In this work, a four-armed polyacrylic acid (4A-PAA) homopolymer is explored as a remarkably effective binder for Si-based anodes. The 4A-PAA binder is prepared via an atom transfer radical polymerization, followed by ester hydrolysis. Compared to the conventional linear polyacrylic acid (PAA) binder, the 4A-PAA not only shows enhanced toughness due to its decreased molecular regularity and intramolecular hydrogen bond but also exhibits increased binding strength because of its multidimensional binding structure. As a result, the SiO x /graphite electrode using the 4A-PAA retains a capacity retention of 89.1% and a capacity of 558.1 mAh g −1 after 200 cycles at 0.16 A g −1 , which are superior to the PAA electrode, corresponding to 80.4% and 469.3 mAh g −1 , respectively. The improved performance is attributed to the employment of the 4A-PAA, which mitigates the volume change of the SiO x /graphite anode. This work not only offers a promising binder for Si-based anodes but also presents a universal solution for other anodes with high volume expansion during cycling.
Flexible solid-state batteries (FSSBs) are indispensable energy storage devices to fulfil the energy and safety requirements for future flexible applications. The bottlenecks of FSSBs are how to realize high energy density with competent ionic conductivity for room-temperature (RT) flexible applications. Here, the first fabrication of RT FSSB with high energy density is reported, which is realized by in situ integration of a 20-µm-thick hybrid polymer/ceramic/ionic liquid solid-state electrolyte (SSE) between the high energy combination of anode/cathode electrodes. The in situ electrode/electrolyte interfacial integration strategy provides an ultrathin SSE layer, ultralow resistance and superior flexibility, and the SSE guarantees both high ionic conductivity and good compatibility with high-energy cathode LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811). The fabricated Li 4 Ti 5 O 12 /NCM811 FSSB delivers super-low resistance approaching conventional liquid cells and excellent cycling stability up to 600 cycles at RT. The extension of anode to SiO x @graphite leads to a high theoretical energy density of 489.6 Wh kg −1 at material’s level, times higher than current options. In addition, the RT FSSB shows great flexibility, indicating a high performance application in future flexible electronics.
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