FeNb11O29 and related niobate anodes for fast-charging lithium-ion batteries: a review

Abstract

The main request to be fulfilled for the wide distribution of electric vehicles is the availability of fast-charging lithium-ion batteries (LIBs). However, fast charging accelerates the degradation of a battery, particularly at ambient temperature, and the main responsible one is the anode compartment. The research is indeed devoted to developing new anode materials for LIBs with outstanding performances at high rates. FeNb11O29 (FNO), a double shear phase, also known as a Wadsley–Roth phase, with an intrinsic pseudocapacitance, was recently proposed as anode in LIBs, thanks to its high theoretical capacity (400 mAh g−1), high operating voltage (~ 1.6 V vs Li+/Li) and an amazing structural stability. In this review, after the discussion of strengths and weaknesses of FNO, the structural features of both its polymorphic forms, with a particular focus on the niobium and iron neighbourhoods, will be described. Then, the working mechanism and the structure-electrochemistry relationships will be treated, with an in-depth analysis of the pseudo-capacitive behaviour, i.e., the key to understand its electrochemical performances. The strategies to mitigate its main drawbacks, i.e., the poor electronic conductivity and the limited lithium diffusion, will be also dealt with. In the final paragraph, the electrochemical performances of some other analogues niobates will be briefly described.