Enhancing the Performance of a Silicon Anode by Using a New Conjugated Polymer Binder Prepared by Direct Arylation

Quinone-based conjugated polymer cathodes synthesized via direct arylation for high performance Li-organic batteries

Direct arylation cross-coupling reaction was employed to prepare quinone-based conjugated polymer cathodes, which realize a high reversible capacity of 200 mA h g^-1 at 0.05 A g^-1, an excellent rate capability of 111 mA h g^-1 at 30 A g^-1 (150C), and a stable cycling performance for more than 3000 cycles.

Polyethylene Oxide as a Multifunctional Binder for High-Performance Ternary Layered Cathodes

Nickel cobalt manganese ternary cathode materials are some of the most promising cathode materials in lithium-ion batteries, due to their high specific capacity, low cost, etc. However, they do have a few disadvantages, such as an unstable cycle performance and a poor rate performance. In this work, polyethylene oxide (PEO) with high ionic conductance and flexibility was utilized as a multifunctional binder to improve the electrochemical performance of LiNi_0.6Co_0.2Mn_0.2O₂ cathode materials. Scanning electron microscopy showed that the addition of PEO can greatly improve the adhesion of the electrode components and simultaneously enhance the integrity of the electrode. Thus, the PEO-based electrode (20 wt% PEO in PEO/PVDF) shows a high electronic conductivity of 19.8 S/cm, which is around 15,000 times that of the pristine PVDF-based electrode. Moreover, the PEO-based electrode exhibits better cycling stability and rate performance, i.e., the capacity increases from 131.1 mAh/g to 147.3 mAh/g at 2 C with 20 wt% PEO addition. Electrochemical impedance measurements further indicate that the addition of the PEO binder can reduce the electrode resistance and protect the LiNi_0.6Co_0.2Mn_0.2O₂ cathode materials from the liquid electrolyte attack. This work offers a simple yet effective method to improve the cycling performance of the ternary cathode materials by adding an appropriate amount of PEO as a binder in the electrode fabrication process.

A conductive self healing polymeric binder using hydrogen bonding for Si anodes in lithium ion batteries

A ureido-pyrimidinone (UPy)-functionalized poly(acrylic acid) grafted with poly(ethylene glycol)(PEG), designated PAU-g-PEG, was developed as a high performance polymer binder for Si anodes in lithium-ion batteries. By introducing both a ureido-pyrimidinone (UPy) unit, which is capable of self-healing through dynamic hydrogen bonding within molecules as well as with Si, and an ion-conducting PEG onto the side chain of the poly(acrylic acid), this water-based self-healable and conductive polymer binder can effectively accommodate the volume changes of Si, while maintaining electronic integrity, in an electrode during repeated charge/discharge cycles. The Si@PAU-g-PEG electrode retained a high capacity of 1,450.2 mAh g-1 and a Coulombic efficiency of 99.4% even after 350 cycles under a C-rate of 0.5 C. Under a high C-rate of 3 C, an outstanding capacity of 2,500 mAh g-1 was also achieved, thus demonstrating its potential for improving the electrochemical performance of Si anodes.

Chitosan-grafted-poly(aniline-co-anthranilic acid) as a water soluble binder to form 3D structures for Si anodes

We graft an electrically conductive poly(aniline-co-anthranilic acid) (PAAA) polymer capable of interacting with Si particles onto chitosan, a natural hydrophilic polymer, to form a chitosan-grafted-PAAA (CS-g-PAAA) copolymer, and use it as a new water soluble polymeric binder for Si anodes to relieve the physical stress resulting from Si volume change during charge/discharge cycles. The carboxylic acid functional groups within the PAAA structure, as well as the chitosan functional groups, bind to silicon particles to form a stable 3D network, resulting in high adhesion. Because the binder is conductive, the electrode using the CS-g-PAAA-8 : 1 with an optimal composition ratio of CS to PAAA of 8 : 1 shows a high initial capacity of 2785.6 mA h g⁻¹, and maintains a high capacity of 1301.0 mA h g⁻¹ after 300 cycles. We also extract chitosan directly from crab shells, and fabricate a Si@ECS-g-PAAA electrode by grafting PAAA onto the extracted-chitosan (ECS). This electrode records an initial capacity of 3057.3 mA h g⁻¹, and maintains a high capacity of 1408.8 mA h g⁻¹ with 51.4% retention after 300 cycles. Overall, we develop a polymeric binder with outstanding cell properties, ease of fabrication, and high water solubility for Si anodes by grafting a conductive PAAA onto chitosan.

We develop a polymeric binder with outstanding cell properties, and high water solubility for Si anodes by grafting a conductive PAAA onto chitosan.