Advanced Balancing of Next-Generation Lithium-Ion Batteries: Prelithiation of a-Silicon Nanowires Using Excess Lithium Positive Electrodes
Authors: Chesson William , Kuenzel Matthias , Sankaran Abinaya , Geaney Hugh , Ryan Kevin , Passerini Stefano 
Published: July 2022

Sustainability and high energy are key requirements for the next-generation lithium-ion batteries (LIBs) to match the rapidly growing electric vehicle (EV) market. On the positive electrode, lithium-rich layered oxides (LRLOs) are ideal candidates for next-generation LIBs since they are possibly free of the critical element cobalt and relatively rich in manganese. Additionally, LRLOs promise outstanding specific capacity (>250 mAh g-1), which is superior to any other cathode material reported so far.
On the negative electrode side, silicon-based materials are highly interesting.1 With their very high specific capacity and slightly higher de-/lithiation potential they can overcome intrinsic challenges of graphite limiting the energy density and high-rate capability of current Li-ion cells.2 Additionally, silicon is also more abundant and – in contrast to graphite and cobalt – not listed as a critical raw material by the EU and US.3,4

Certainly, both materials still face challenges, e.g., voltage and capacity fading due to structural transformation in LRLOs, or particle cracking and excessive SEI formation in Si-based anodes, which can be possibly overcome through modifications of the materials and, especially, design of the electrolyte.5,6

Herein, we present the achievement of excellent electrochemical performance of Li-ion cells with Co-free LRLO cathodes (Li1.2Ni0.2Mn0.6O2, LRNM) offering a capacity retention of >75% after 200 cycles when paired with an a-Si-NW anode, and even 81% after 1,000 cycles in LRNM||graphite cells. In both cases a cathode pre-lithiation additive, introduced during electrode slurry processing, was successfully used as a cycle life enhancer.7

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