The optimization of CMC concentration as graphite binder on the anode of LiFePO4 battery

Characteristics of CMC from Corncob and its Application as Electrode Binder in Lithium Ion Battery

Corncobs are a waste product from corn farming that are abundant in Indonesia. Corncobs have a high cellulose content, more than 40%, which made it useful for synthesizing CMC. CMC is a cellulose derivative that is widely used in many industries such as food, pharmaceutical, detergent, textile, cosmetic product and binder. In this paper, we use CMC that are synthesized from corncobs as binder in the electrodes of lithium ion battery. The steps of synthesizing CMC from corncobs started with the isolation of the cellulose, then followed by the processes of alkalization, carboxymethylation and finally the purification. FTIR spectrum shows that CMC are successfully synthesized. The presence of strong absorption band at 1613 cm-1 is related to the stretching vibration of the carboxyl group (COO-). The absorption in the 1300–1450 cm-1 region is due to symmetrical deformations of CH2 groups. While the broad absorption around 3427 cm-1 is due to the stretching of the hydroxyl groups (-OH). Test on three samples of different sizes, (mesh-100, mesh-60 and mesh-40) gives CMC purity values of 98.69%, 98.56% and 97.77%, respectively. In the application of CMC as anode binder, the best composition is 4% CMC, where it gives the highest conductivity of 0.587 S/cm. Voltammogram measurement with a scan rate of 50 mV/s in the voltage range of -1 to 1 Volt gives the capacitance value of 2237 μF.

Aqueous Processing of Na0.44MnO2 Cathode Material for the Development of Greener Na-Ion Batteries

The implementation of aqueous electrode processing of cathode materials is a key for the development of greener Na-ion batteries. Herein, the development and optimization of the aqueous electrode processing for the ecofriendly Na_0.44MnO₂ (NMO) cathode material, employing carboxymethyl cellulose (CMC) as binder, are reported for the first time. The characterization of such an electrode reveals that the performances are strongly affected by the employed electrolyte solution, especially, the sodium salt and the use of electrolyte's additives. In particular, the best results are obtained using the 1 M solution of NaPF₆ in EC/DEC (ethylene carbonate/diethyl carbonate) 3:7 (v/v) + 2 wt % FEC (fluoroethylene carbonate). With this electrolyte, the outstanding capacity of 99.7 mA h g^-1 is delivered by the CMC-NMO cathode after 800 cycles at a 1C charge/discharge rate. On the basis of this excellent long-term performance, a full sodium cell, composed of a CMC-based NMO cathode and hard carbon from biowaste (corn cob), has been assembled and tested. The cell delivers excellent performances in terms of specific capacity, capacity retention, and long-term cycling stability. After 75 cycles at a C/5 rate, the capacity of the NMO in the full-cell approaches 109 mA h g^-1 with a Coulombic efficiency of 99.9%.