Electrochemically Induced Borate Allotropes for Expedite Charge Transfer in Lithium‐Ion Batteries and Hydroxyl Ion Capture Activity in Flexible Pseudocapacitor

Abstract Despite lithium‐ion battery (LIB) and supercapacitor materials have gone through numerous enhancements, achieving high energy density as well as power density together is still a dream for the industries. In this scenario, herein we report, boric acid coated α−MnO 2 anode with 1288 mAh g −1 at 0.1 C at the initial cycle and of an average discharge capacity of 570 mAh g −1 at 0.1 C over 20 cycles, high‐rate capability and 100 % Coulombic efficiency after 60 cycles for LIB. The Li + diffusion coefficient estimated from GITT and EIS measurements reveals that the H 3 BO 3 coated α−MnO 2 electrode has superior Li‐ion kinetics ( ∼10 −10 cm 2 s −1 ) than bare α−MnO 2 . Coin cells with boric acid coated α−MnO 2 electrode are able to power up red and blue LEDs continuously for about 24–32 hours. The ex‐situ investigations reveal an interesting self‐assembled active electrode‐electrolyte interfacial bridging Li 4 B 2 O 5 layer formation. This significant active layer allows free migration of lithium ions across interface that leads to good cyclability. In flexible supercapacitor, the boric acid coated α−MnO 2 yields excellent cyclability over 500 cycles with specific capacitance of 35 F g −1 at 1 A g −1 and further 200 cycles at 30° acute angle with 21 F g −1 at 1 A g −1 . The research overthrows the significance of boric acid in conversion reactions for active interfacial bridging layer in LIB and hydroxyl ion capturing agent in flexible supercapacitor.