Structure design and performance of cathode for battery-type capacitor
When the cathode material of battery-type capacitors is coated and dried,the surface tension will lead to the instability of the electrode interface,the large resistivity of the pole piece and the uneven distribution of porosity.High-voltage lithium cobalt oxide(LiCoO2)is used as the cathode material,the thickness gradient design of the LiCoO2 cathode plate is carried out by using multi-layer coating technology.By controlling the total thickness of the double-layer coated electrode plates to 30 μm,the thickness gradient distribution between the double-layer electrode plates is adjusted,the differential distribution of porosity between the upper and lower layers of the electrode plates is realized,the rapid transmission channel of Li+is constructed to reduce ion diffusion resistance and slow capacity attenuation.A pouch battery-type capacitor is assembled with a hard carbon(HC)anode with anisotropy and high space,its electrochemical performance is tested.The Coulombic efficiency in the initial cycle of the two-layer electrodes LH-18(the thickness of the first layer is 18 μm)reaches 80.85%,which is 6.27 percentage points higher than the single-layer electrode(LH-30).When cycled in 2.5-4.2 V,the discharge capacity at 20.00 C is 81.82%of that at 1.00 C.After 3 509 cycles of 100%depth of discharge(DOD)at 1.00 C,the capacity retention rate is still 80%,the cycle number is 2.27 times than that of the single-layer electrode(LH-30).
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