Hard Carbon Material with Expanded Layer Spacing for Ion Storage
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Solution Overview
Problem
Conventional negative electrode materials in ion batteries, such as graphite and its derivatives, suffer from low theoretical gram capacity and low discharge efficiency due to small layer spacing, which limits their ability to form a stable intercalation structure.
Innovation Solution
A hard carbon material with hydrogen content less than 2 wt.% and layer spacing greater than 0.36 nm is produced using a low-temperature sintering process and controlled through temperature adjustment and doping additives, ensuring an ordered length range of 0-20 nm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional graphite materials are used as negative electrode materials, then the battery structure is stable, but the theoretical gram capacity is low and discharge efficiency is low due to small layer spacing
Solution Approach 1:
The patent changes the layer spacing parameter from the conventional graphite value of 0.335 nm to greater than 0.36 nm through controlled carbonization and expansion treatments. This parameter change allows larger alkali metal ions to intercalate effectively, increasing the theoretical gram capacity while maintaining structural stability through the hard carbon material framework.
Solution Approach 2:
The patent uses composite materials by combining hard carbon material with specific binders and conductive agents to create a negative electrode that maintains structural stability while providing expanded layer spacing. The composite structure allows the hard carbon to provide mechanical stability while the expanded interlayer spacing provides high ion storage capacity.
2Quantity of substance
If layer spacing is increased to improve ion storage capacity, then alkali metal ions storage capacity increases, but manufacturing complexity increases due to process control requirements
Solution Approach 1:
The patent establishes specific parameter ranges for layer spacing (greater than 0.36 nm) and ordered length (0-20 nm) that can be achieved through controlled carbonization temperatures and expansion treatments. By defining these parameter ranges, the patent simplifies the manufacturing process while ensuring high alkali metal ion storage capacity.
3Quantity of substance
If high temperature processing is used to reduce hydrogen content, then material purity improves, but energy consumption increases and layer spacing narrows
Solution Approach 1:
The patent optimizes the carbonization temperature parameter to achieve the desired hydrogen content reduction without requiring excessive high temperatures. By carefully controlling the carbonization process parameters, the patent reduces hydrogen content to less than 2 wt% while minimizing energy consumption and preventing excessive layer spacing narrowing.
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 hard carbon material exhibits higher alkali metal ions storage capacity and improved coulombic efficiency, suitable for use in lithium-ion, sodium-ion, and potassium-ion batteries, with environmental benefits from lower energy consumption.
Implementation Method 1
the layer spacing is too small and they cannot form a stable intercalation structure
Implementation Method 2
The production method provided by the invention adopts a low-temperature sintering process to fabricate the hard carbon material for storing alkali metal ions
Implementation Method 3
the method comprises but is not limited to the steps of pre-carbonization, crushing, doping and carbonization
Data Source
AI summary
A hard carbon material for storing alkali metal ion and its producing method are disclosed. Specifically, the hard carbon material has a hydrogen content less than 2 wt. %, an ordered length between 0 and 20 nm, a layer spacing more than 0.36 nm and intensity ratio of the D band to G band in Raman spectrum is between 1.0 and 1.3. The producing method is operated below 1800° C., so it is an energy saving process.