A novel Li-ion supercapattery by K-ion vacant ternary perovskite fluoride anode with pseudocapacitive conversion/insertion dual mechanisms

An innovative K+vacant ternary perovskite fluoride(K_(0.89)Ni_(0.02)Co_(0.03)Mn_(0.95)F_(3.0),KNCMF-3#)anode was designed for advanced Li-ion supercapattery(i.e.,Li-ion capacitors/batteries,LIC/Bs).Owing to the conversion/insertion dual mechanisms and fast pseudocapacitive con-trol dynamics,the KNCMF-3#electrode exhibits superior electrochemical performance,especially the excellent cycle performance(467%(229 mAh·g^(-1))/1000 cycles/2 A·g^(-1)).Moreover,the hybrid KNCMF-3#/reduced gra-phene oxide(rGO)electrode can further increase the electrochemical performance(217-97 mAh·g^(-1)/0.1-3.2 A·g^(-1),150%(197 mAh·g^(-1))/1000 cycles/2 A·g^(-1)).Also,a novel capacitor/battery cathode,activated carbon(AC)+LiFePO_(4)+graphene(AC+LFP+G),exhibits impres-sive performance(128-82 mAh·g^(-1)/0.1-3.2 A·g^(-1),84%/1000 cycles/2 A·g^(-1)).By the synergistic optimization of anode and cathode,the Li-ion supercapattery KNCMF-3#@rGO//AC+LFP+G demonstrates remarkable per-formance,for example,111.9-23.8 Wh·kg^(-1)/0.4-8.0 kW·kg^(-1)/82%/2000 cycles/5 A·g^(-1)/0-4 V,which is superior to KNCMF-3#//AC LICs,KNCMF-3#@rGO//AC LICs,KNCMF-3#//AC+LFP+G LIC/Bs.In all,the novel Li-ion supercapattery idea adds a promising per-spective to develop advanced energy storage devices.