Lithium Secondary Battery with Negative Electrode Free of Active Material
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Solution Overview
Problem
Lithium secondary batteries face limitations in energy density and cycle characteristics, with lithium metal batteries prone to dendrite formation and capacity loss due to the use of negative electrode active materials, and mechanical pressure methods increasing battery weight and volume while reducing energy density.
Innovation Solution
A lithium secondary battery design featuring a positive electrode with Li(Ni, Co, Mn)O2 or Li(Ni, Co, Al)O2 crystals and a negative electrode without active materials, where lithium metal is deposited and eluted electrolytically, suppressing dendrite growth and enhancing energy density and cycle stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium metal is deposited on the negative electrode surface, then energy density is improved, but dendrites form causing short-circuiting and capacity loss
Solution Approach 1:
A solid electrolyte interface (SEI) layer is formed on the negative electrode surface to act as an intermediary between the lithium metal and the electrolyte. This SEI layer prevents direct contact and dendrite formation while allowing lithium ion transport, thus maintaining high energy density without sacrificing reliability.
Solution Approach 2:
The patent controls the deposition parameters of lithium metal on the negative electrode, including deposition rate, thickness, and uniformity. By optimizing these parameters, the lithium metal is deposited in a controlled manner that prevents dendrite formation while maximizing energy density.
2Reliability
If physical pressure is applied to suppress discrete growth during lithium metal precipitation, then cycle characteristics are improved, but weight and volume increase reducing energy density
Solution Approach 1:
The patent replaces the mechanical pressure system with an electrochemical control system. Instead of applying continuous physical pressure, the invention uses controlled potential deposition and SEI layer formation to suppress discrete growth, eliminating the need for heavy mechanical components and maintaining high energy density.
Solution Approach 2:
The solid electrolyte interface layer self-regulates the lithium metal precipitation process. The SEI layer forms spontaneously during initial charging cycles and automatically controls subsequent lithium deposition, suppressing discrete growth without requiring external mechanical intervention.
3Reliability
If negative electrode active material is used, then cycle characteristics are improved, but energy density decreases
Solution Approach 1:
The patent extracts the negative electrode active material from the battery system, using only a current collector for the negative electrode. Lithium metal is deposited directly on the current collector surface, eliminating the need for separate active material and maximizing energy density while maintaining cycle characteristics through controlled deposition.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The battery achieves high energy density and improved cycle characteristics by uniform lithium deposition and reduced dendrite growth, allowing for safe and efficient operation under high voltage conditions without the need for highly flammable lithium metal.
Implementation Method 1
a secondary battery that charges and discharges by transferring metal ions between a positive electrode and a negative electrode
Implementation Method 2
retains lithium by depositing lithium metal on the surface of the negative electrode
Data Source
AI summary
The present invention provides a lithium secondary battery that has high energy density and excellent cycle characteristics, and a method for using this battery. The present invention relates to a lithium secondary battery comprising: a positive electrode current collector; a positive electrode formed on at least one surface of the positive electrode current collector and having a positive electrode active material; a negative electrode free of a negative electrode active material; and a separator or solid electrolyte disposed between the positive electrode and the negative electrode, wherein the positive electrode contains a Li(Ni, Co, Mn)O2 crystal and/or a Li(Ni, Co, Al)O2 crystal whose full width at half maximum for the diffraction peak of the (003) plane as measured by X-ray diffraction that is greater than 0.00° and 0.10° or less in an amount of 20% by mass or more and 100% by mass or less relative to the total mass of the positive electrode active material.