Developing High-Energy, Stable All-Solid-State Lithium Batteries Using Aluminum-Based Anodes and High-Nickel Cathodes

Abstract

Aluminum (Al) exhibits excellent electrical conductivity, mechanical ductility, and good chemical compatibility with high-ionic-conductivity electrolytes. This makes it more suitable as an anode material for all-solid-state lithium batteries (ASSLBs) compared to the overly reactive metallic lithium anode and the mechanically weak silicon anode. This study finds that the pre-lithiated Al anode demonstrates outstanding interfacial stability with the Li6PS5Cl (LPSCl) electrolyte, maintaining stable cycling for over 1200 h under conditions of deep charge–discharge. This paper combines the pre-lithiated Al anode with a high-nickel cathode, LiNi0.8Co0.1Mn0.1O2, paired with the highly ionic conductive LPSCl electrolyte, to design an ASSLB with high energy density and stability. Using anode pre-lithiation techniques, along with dual-reinforcement technology between the electrolyte and the cathode active material, the ASSLB achieves stable cycling for 1000 cycles at a 0.2C rate, with a capacity retention rate of up to 82.2%. At a critical negative-to-positive ratio of 1.1, the battery’s specific energy reaches up to 375 Wh kg−1, and it maintains over 85.9% of its capacity after 100 charge–discharge cycles. This work provides a new approach and an excellent solution for developing low-cost, high-stability all-solid-state batteries.

1. Introduction

Sulfide-based all-solid-state lithium batteries (ASSLBs) with high energy density and safety are expected to satisfy the demands of long-range electric vehicles and electric flight [1]. As one of the key components of the battery, negative electrode plays a critical role in battery performance [2, 3]. Lithium (Li) metal anode, which exhibits low electrode potential (−3.04 V vs. standard hydrogen electrode) and high theoretical capacity (3860 mAh g−1), has been extensively investigated for ASSLBs [4]. Nonetheless, the issues related to interfacial instabilities between Li and sulfide electrolytes, as well as the short circuits caused by Li dendrites penetrating the electrolyte, have proved to be exceedingly challenging to address [5–7].

Other alternative anode materials such as Li alloys not only retain a significant capacity advantage, but also possess improved interfacial stability due to the reduced thermodynamic driving force for electrolyte reduction. Moreover, Li alloys can promote uniform plating and stripping of Li+ and thus prevent the safety hazards caused by the growth of Li dendrites [6]. Metal indium (In) is a commonly used reversible counter electrode tool in the study of cathodes for sulfide-based ASSLBs. Nevertheless, its high operating potential (0.62 V vs. Li/Li+) and small electrochemical capacity hinder it from being utilized as an actual battery anode [8, 9]. High-capacity silicon (Si) materials also encounter extremely challenging difficulties in all-solid-state batteries. The chemical instability at the interface with the electrolyte and the stress failure due to significant volume deformation are both concerning issues [10, 11]. In addition, the poor conductivity of Si also raises concerns of slow kinetics during charge and discharge period.

Aluminum (Al), as the most abundant metallic element in the earth’s crust, has a good conductivity and competitive capacity of 990 mAh g−1. Compared with Si anode, Al exhibits smaller volume changes during cycling (96% vs. 320%), which is favorable for maintaining good anode–electrolyte interface stability. Moreover, the moderate working potential of Li-Al alloy (~0.3 V vs. Li/Li+) can also facilitate the realization of high energy density in batteries. Since Al can be economically and efficiently fabricated as a freestanding foil, the application of Al does not involve any inactive conductive agents and binders, nor require an additional current collector.